CN-121988761-A - Electric spindle structure with directional heat conduction function and design method thereof

CN121988761ACN 121988761 ACN121988761 ACN 121988761ACN-121988761-A

Abstract

The invention discloses an electric spindle structure with directional heat conduction function and a design method thereof, wherein a plurality of heat pipes are embedded in the front and rear bearing areas of an electric spindle shell to reduce the heat resistance of axial heat transfer, the high heat conduction material component is arranged on the rotating shaft to strengthen the conduction of heat to the bearing, and the jet flow cooling local heat sink structure is arranged at the end part of the rotating shaft to directly and rapidly dissipate the heat. The method comprises the steps of identifying a key region with limited heat flow transmission in the electric spindle through entropy sensitivity analysis, optimally designing a heat conduction path of the region on the premise of not changing the original structural form of the electric spindle, strengthening local heat transfer capacity by means of heat pipes, high heat conduction materials, jet cooling and the like, efficiently guiding heat generated in the electric spindle to heat sink regions such as a shell cooling water jacket and the like along a preset path, improving temperature field distribution in the electric spindle, reducing temperature gradient and hot spot temperature of the electric spindle, reducing thermal deformation, and improving operation precision and stability of the electric spindle.

Inventors

NIU QINGBO
LI XIAOHU
WAN SHAOKE
Zhan Zichuo
LIU XINLIANG
HUI YICONG
XU CHENGXI

Assignees

西安交通大学

Dates

Publication Date: 20260508
Application Date: 20260120

Claims (10)

1. The design method of the electric spindle directional heat conduction structure is characterized by comprising the following steps of: Establishing an electric spindle thermal network model, quantitatively evaluating the influence degree of each heat transfer path on the integral irreversible loss by adopting an entropy production sensitivity analysis method, and sequencing according to the influence degree to obtain a part with higher entropy production sensitivity; The electric spindle is provided with a heat sink structure, a directional heat conduction structure is introduced to the position with higher entropy sensitivity, and the electric spindle is subjected to local structural optimization; And integrating a local heat sink structure at the end part of the rotating shaft to form a heat exchange passage.
2. The method for designing the directional heat conducting structure of the electric spindle according to claim 1, wherein the heat conducting structure is introduced into a position with higher entropy production sensitivity on the premise of maintaining the structural integrity of the original electric spindle, and the heat conducting structure is connected with the heat sink structure, wherein the heat conducting structure comprises the steps of introducing a heat pipe or a high heat conducting material component into a key position of a static part of the electric spindle to improve the heat conducting coefficient of the static part of the electric spindle, guiding local accumulated heat to a heat sink such as a cooling water jacket and the like, and arranging the high heat conducting material component into the key position of a rotating part of the electric spindle, and directionally transmitting the heat inside a rotor and a rotating shaft to a bearing and a shell.
3. The method for designing the directional heat conduction structure of the electric spindle according to claim 1, wherein the method for quantitatively evaluating the influence degree of each heat transfer path on the overall irreversible loss by adopting the entropy production sensitivity analysis method, and sequencing according to the influence degree, the method for obtaining the part with higher entropy production sensitivity comprises the following steps of defining the overall entropy production of the system as the sum of the entropy production of each branch based on the electric spindle thermal network model: Wherein: Is a node And Equivalent thermal conductivity therebetween; And The temperature of the corresponding node; on the basis, the heat conductivity of a certain heat transfer branch is biased, so that the sensitivity of the global entropy product to the branch can be obtained: and after the entropy sensitivity of each heat transfer branch is obtained, sequencing the absolute values of the entropy sensitivity to obtain the priority distribution of the heat flow bottleneck in the electric spindle.
4. An electric spindle with a directional heat conduction function is characterized by comprising a soaking plate (13), a shell heat pipe (12), a back bearing seat heat pipe (14) and a front bearing seat heat pipe (15), wherein the shell heat pipe (12) is arranged along the circumferential direction of a shell (11), the front bearing seat heat pipe (15) is arranged along the circumferential direction of a front bearing seat (2), the back bearing seat heat pipe (14) is arranged along the circumferential direction of a back bearing seat (16), heat conduction silicone grease is filled in holes of the shell heat pipe (12), the back bearing seat heat pipe (14) and the front bearing seat heat pipe (15), a cooling water channel communicated with the shell (11) and the front bearing seat (2) is arranged in the front bearing end cover (1), a cooling air flow channel is arranged in the front bearing end cover (1), fins are arranged outside the front bearing locking nut (3), fin gaps of the front bearing locking nut (3) are communicated with the air flow channel of the front bearing end cover (1), the front bearing heat conduction structure (4) and the back bearing heat conduction structure (8) are sleeved on a rotating shaft (21) in an interference fit mode, and the end faces of the front bearing heat conduction structure (4) and the back bearing heat conduction structure (8) are respectively contacted with inner rings of a corresponding front bearing group (20) and a back end face group (18).
5. The electric spindle with the directional heat conduction function according to claim 4, wherein the front bearing locking nut (3), the front bearing heat conduction structure (4) and the rear bearing heat conduction structure (8) are annular structures, the front bearing heat conduction structure (4) and the rear bearing heat conduction structure (8) are respectively arranged on a shaft section of the rotating shaft (21) in contact with the corresponding bearing inner ring through interference fit, and the material heat conductivity of the front bearing heat conduction structure (4) and the rear bearing heat conduction structure (8) is not lower than that of a bearing material.
6. The electric spindle with directional heat conduction function according to claim 4, wherein at least one shell heat pipe (12) is uniformly arranged along the circumferential direction of the shell (11), the shell heat pipe (12) penetrates through the shell (11), one end of the shell heat pipe (12) is connected with the vapor chamber (13), the other end of the shell heat pipe extends to the position close to the end face of the shell (11), the front bearing seat heat pipe (15) penetrates through the front bearing seat (2) and stretches into a mounting hole of the shell heat pipe (12), and a heat conduction material is filled between the shell heat pipe (12) and the front bearing seat heat pipe (15).
7. The electric spindle with the directional heat conduction function according to claim 4, wherein an axial hole is formed in the rear bearing seat (16), a rear bearing seat heat pipe (14) is installed in the axial hole, one end of the rear bearing seat heat pipe (14) extends into the rear bearing seat (16), and the other end of the rear bearing seat heat pipe is installed on the vapor chamber (13).
8. The electric spindle with directional heat conduction function as set forth in claim 4 wherein the shell heat pipe (12), the back bearing seat heat pipe (14) and the front bearing seat heat pipe (15) are sintered core copper pipes containing low boiling point working media, and gaps of the shell heat pipe (12), the back bearing seat heat pipe (14) and the front bearing seat heat pipe (15) are filled with heat conduction materials.
9. The electric spindle with the directional heat conduction function according to claim 4, wherein a cooling water jacket (10) is arranged on the outer side of the motor stator (6), the cooling water jacket (10) is in sealing connection with the inner wall of the shell (11), a cooling water channel is arranged between the cooling water jacket (10) and the shell (11), a cooling liquid inlet (23) is formed in the front bearing seat (2), one side opposite to the cooling liquid inlet (23) is communicated with the cooling water channel on the shell (11), a cooling liquid water outlet (24) is formed in the shell (11), a spiral water channel is formed in the shell (11) or the cooling water jacket (10) and is used as the cooling water channel, and the cooling water channel of the front bearing seat (2) is the spiral water channel.
10. A machine tool, characterized in that an electric spindle with directional heat conduction function as claimed in any one of claims 4-9 is used.

Description

Electric spindle structure with directional heat conduction function and design method thereof Technical Field The invention relates to the field of motorized spindle thermal regulation of numerical control machine tools, in particular to an motorized spindle structure with a directional heat conduction function and a design method thereof. Background Motorized spindles are the core features of high-speed numerically controlled machine tools, and typically the internal motors and bearings generate a significant amount of heat during high-speed operation. If the heat cannot be effectively dissipated in time, a hot spot area with too high local temperature is generated in the electric spindle, the overall temperature field is unevenly distributed, thermal stress and thermal deformation are induced, and the machining precision and the operation stability are obviously reduced. In the prior art, means such as a cooling water jacket, bearing oil cooling or air cooling are arranged in an electric spindle shell to cool the electric spindle, but because the internal structure of the electric spindle is complex, heat flow transmission is often hindered by the existence of multiple material interfaces and geometric abrupt change positions, and a heat flow bottleneck is formed. Research shows that the key reason for unbalanced temperature field inside the electric spindle is not the lack of heat dissipation means, but the low efficiency of the heat flow transmission path under the existing structural system. For example, localized geometric abrupt changes in structure, differences in thermal conductivity of different materials, and areas of high thermal resistance often occur at contact interfaces of components, limiting heat transfer out. In addition, the core components such as the rotor, the stator, the rotating shaft and the like of the electric spindle are limited by the requirements of electromagnetic performance, natural frequency, dynamic balance and the like, and the structural form or the materials of the electric spindle are difficult to be changed greatly in engineering design. Therefore, a technical solution for improving the efficiency of the internal heat conduction path without significantly changing the original structure and mechanical properties of the electric spindle is needed to dredge the internal accumulated heat, improve the temperature field distribution, and reduce the influence of thermal deformation on the performance of the electric spindle. The prior patent with publication No. CN102120266A provides a high-speed precise electric spindle cooling system, which adopts a loop type shell heat pipe and a shaft core heat pipe, wherein an evaporation end extends to a front end bearing and a stator position, a cooling fin is arranged at a condensation end, a cooling air conditioner and a temperature controller are combined, the high-speed conductivity and the constant temperature of the heat pipe are used for cooling, the temperature stability of the electric spindle is ensured, the processing precision error caused by the thermal expansion of the electric spindle is reduced, the service life of the bearing is prolonged, the lubrication effect is improved through uniform lubrication distribution, the method focuses on changing the cooling structure of the electric spindle so as to enhance the cooling characteristic of the whole electric spindle, the method firstly changes the electric spindle structure, has great influence on the mechanical property of the electric spindle, and secondly, the method introduces new energy sources and increases the energy consumption of the electric spindle. Disclosure of Invention The invention aims to efficiently transfer heat generated in the electric spindle to a heat sink part along a preset direction by optimizing an internal heat conduction path under the condition of not changing the integral structure form of the electric spindle, thereby remarkably reducing the temperature gradient and the hot spot temperature in the electric spindle, reducing the adverse effect of thermal deformation on the processing precision and improving the operation precision and the reliability of the electric spindle. In order to achieve the above object, in a first aspect, the present invention provides a method for designing an electric spindle directional heat conduction structure, including the following steps: Establishing an electric spindle thermal network model, quantitatively evaluating the influence degree of each heat transfer path on the integral irreversible loss by adopting an entropy production sensitivity analysis method, and sequencing according to the influence degree to obtain a part with higher entropy production sensitivity; The electric spindle is provided with a heat sink structure, a directional heat conduction structure is introduced to the position with higher entropy sensitivity, and the electric spindle is subjected to local structural optimization; And