A grinding bar structure for grinding internal threads with large length-diameter ratio

Abstract

The application provides a grinding rod structure for large-length-diameter-ratio internal thread grinding, and relates to the technical field of machining equipment.The grinding rod structure comprises a grinding rod body, a base, a direction-changing piece, a grinding assembly, a flexible shaft and a nut.The grinding assembly gap is sleeved on the throttling section of the direction-changing piece, a fluid chamber is formed between the grinding assembly and the direction-changing piece, the outer periphery of the throttling section is provided with an annular first dynamic pressure oil groove, and the end face of the grinding assembly is provided with an annular second dynamic pressure oil groove.When the grinding assembly does not rotate, the grinding assembly can be lifted to be separated from the contact with the direction-changing piece due to the certain pressure of the fluid at the moment;when machining, the grinding assembly rotates at high speed, the fluid in the fluid chamber has obvious dynamic pressure effect based on the first dynamic pressure oil groove and the second dynamic pressure oil groove, the fluid pressure is much larger than the external pressure, and the bearing rigidity is significantly improved, without wear and with long service life;at the same time, the structure form almost does not generate overturning moment, and can significantly improve the machining precision.

Description

Technical Field

[0001] This invention relates to the field of machining equipment technology, and in particular to a grinding rod structure for grinding internal threads with a large length-to-diameter ratio. Background Technology

[0002] When grinding small-hole, large-lead internal threads, due to the existence of the thread helix angle, in order to avoid interference between the grinding rod and the workpiece, the bent rod grinding method is generally adopted. By mounting the grinding tool on the bent rod, the special shape and operability of the bent rod allow the grinding tool to penetrate deep into the thread for grinding.

[0003] The typical structure used is a bent rod with a flexible shaft and miniature bearings. Specifically, the flexible shaft connects the grinding wheel shaft and the main shaft at a certain angle. The flexible shaft is used to transmit power, and the grinding wheel shaft is used to drive the grinding wheel to rotate. The grinding wheel shaft is supported by miniature rolling bearings.

[0004] Due to spatial constraints, the bearings and flexible shaft of the grinding wheel spindle must be very small in size, while simultaneously operating under high speed and high load conditions. This results in insufficient bearing rigidity, making the bearings prone to wear and failure under high speed and high load conditions, leading to a short lifespan. Furthermore, because the miniature bearings have very low rigidity, vibrations during grinding, fluctuations in grinding depth, and feed rate significantly impact the final machining result, causing low machining accuracy of internal threads. Therefore, this type of grinding rod structure severely restricts the machining accuracy and efficiency of internal thread grinding. Summary of the Invention

[0005] To address the shortcomings of existing bearing technology, such as insufficient rigidity leading to easy wear and failure under high-speed, high-load conditions and short lifespan, and the significant impact of vibration, grinding depth, and feed rate fluctuations during grinding on the final machining results due to the very low rigidity of miniature bearings, resulting in low machining accuracy of internal threads, this invention provides a grinding rod structure for grinding internal threads with large length-to-diameter ratios. The technical solution is as follows:

[0006] A grinding rod structure for grinding internal threads with a large length-to-diameter ratio is provided, the grinding rod structure comprising:

[0007] A grinding rod body, the grinding rod body including a spindle;

[0008] A base is mounted on the grinding rod body, and the base has a liquid inlet channel inside;

[0009] A variable direction piece is connected to the base at a preset angle, a middle part of the variable direction piece comprises a throttling section, a throttling passage is arranged in the variable direction piece and communicates with the liquid inlet passage, a throttling hole of the throttling passage is arranged in the throttling section, and an annular first dynamic pressure oil groove is arranged on the outer periphery of the throttling section.

[0010] A grinding assembly is gap-fitted on the throttling section and forms a fluid chamber between the variable direction piece, a fluid medium for supporting the grinding assembly is accommodated in the fluid chamber, an annular second dynamic pressure oil groove is arranged on the end face of the grinding assembly.

[0011] A flexible shaft is rotatably arranged through the base and the variable direction piece and axially extends along the base and the variable direction piece in sequence, and the flexible shaft is connected to the main shaft.

[0012] A nut is arranged between the front end face of the grinding assembly and the flexible shaft, and the flexible shaft drives the grinding assembly to rotate through the nut.

[0013] Optionally, the first dynamic pressure oil groove corresponds to the throttling hole of the throttling passage.

[0014] Optionally, the grinding assembly comprises an outer rotor and a grinding wheel gap-fitted on the outer rotor.

[0015] The outer rotor and the nut are used to fix the grinding wheel from both ends.

[0016] Optionally, the front end diameter of the nut is smaller than the rear end diameter, and the included angle between the side wall of the nut and the axial direction is greater than or equal to the preset angle.

[0017] Optionally, an annular groove is arranged on the inner wall of the nut.

[0018] Optionally, an eccentric hole is arranged in the base, a slant hole is arranged at the front end of the base at a preset angle with the eccentric hole, the eccentric hole and the slant hole communicate with each other and are used to accommodate the flexible shaft.

[0019] Optionally, a fixing groove is formed at the end of the slant hole.

[0020] The variable direction piece comprises an inner bushing, a bearing bush and a thrust disc.

[0021] The inner bushing is interference-fitted in the fixing groove, the bearing bush is interference-fitted on the inner bushing, and the inner bushing and the bearing bush form the throttling passage.

[0022] The thrust disc is gap-fitted on the front end of the inner bushing and presses the bearing bush, and the thrust disc and the bearing bush are used to limit the grinding assembly from both ends.

[0023] Optionally, an annular flow channel is arranged on the front end surface of the inner sleeve, and a through hole is arranged on the inner sleeve and communicates with the flow channel and the liquid inlet channel;

[0024] A drainage channel, which communicates with the flow channel and the throttle hole, is further arranged on the contact surface of the inner sleeve and the bearing bush, and the through hole, the flow channel, the drainage channel and the throttle hole form the throttle channel;

[0025] The number of the throttle holes is at least one pair.

[0026] Optionally, the liquid inlet hole corresponding to the liquid inlet channel is arranged on the side surface of the base.

[0027] Optionally, the size of the liquid inlet channel gradually decreases from the liquid inlet hole inward.

[0028] The technical scheme provided by the embodiment of the present application has at least the following beneficial effects:

[0029] The grinding rod structure for grinding large-length-diameter-ratio internal thread provided by the present application is characterized in that a grinding assembly gap is sleeved on a throttle section of a direction-changing piece, a fluid chamber is formed between the grinding assembly gap and the direction-changing piece, an annular first dynamic pressure oil groove is arranged on the outer periphery of the throttle section, and an annular second dynamic pressure oil groove is arranged on the end surface of the grinding assembly. When the grinding assembly does not rotate, the grinding assembly can be floated to separate from the contact with the direction-changing piece due to the certain pressure of the fluid, and the rigidity of the grinding assembly is determined by the fluid pressure provided from outside. During machining, the grinding assembly rotates at high speed, and based on the first dynamic pressure oil groove and the second dynamic pressure oil groove, the fluid in the fluid chamber has a significant dynamic pressure effect, and can generate fluid pressure much greater than the external pressure, thereby significantly improving the rigidity of the bearing, without wear and with long service life. Meanwhile, this structure form almost does not generate overturning moment, and can also significantly improve the machining precision. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0031] Figure 1 is a schematic diagram of a grinding rod structure for grinding large-length-diameter-ratio internal thread provided by the embodiment of the present application;

[0032] Figure 2 is a partial structure schematic diagram of a grinding rod structure for grinding large-length-diameter-ratio internal thread provided by the embodiment of the present application;

[0033] Figure 3is a structural schematic view of a middle direction changing piece and a grinding assembly of a grinding rod structure for large length-diameter ratio internal thread grinding provided by the embodiment of the present application.

[0034] Reference signs:

[0035] 1, base; 11, liquid inlet channel; 12, eccentric hole; 13, inclined hole; 14, fixing groove; 15, liquid inlet hole;

[0036] 2, direction changing piece; 21, throttling channel; 211, throttling hole; 212, flow passage; 213, through hole; 214, flow guiding channel; 22, first dynamic pressure oil groove; 23, inner bushing; 24, bearing bush; 25, thrust disc;

[0037] 3, grinding assembly; 31, second dynamic pressure oil groove; 32, outer rotor; 33, grinding wheel;

[0038] 4, fluid chamber;

[0039] 5, flexible shaft;

[0040] 6, nut; 61, set screw. DETAILED DESCRIPTION

[0041] The technical solutions in the present application will be described below in combination with the drawings.

[0042] In the embodiments of the present application, the words such as "example", "for example" and the like are used to represent as an example, illustration or description. Any embodiment or design scheme described as "example" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. In fact, the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present application, the meaning expressed by "and / or" can be both, or can be one of the two.

[0043] In order to make the technical problems, technical solutions and advantages of the present application clearer, the following will be described in detail in combination with the drawings and specific embodiments.

[0044] The embodiment of the present application provides a grinding rod structure for large length-diameter ratio internal thread grinding, Figure 1 is a schematic view of a grinding rod structure for large length-diameter ratio internal thread grinding provided by the embodiment of the present application, please see Figure 1 .

[0045] The grinding rod structure comprises a grinding rod main body (not shown in the figure), a base 1, a direction changing piece 2, a grinding assembly 3, a flexible shaft 5 and a nut 6. Through the grinding rod structure, the grinding assembly 3 is deeply inserted into the screw hole to grind the internal thread, and the matching thread rise angle is matched.

[0046] The above grinding rod main body comprises a main shaft, and the grinding rod main body is used for providing power and fluid medium.

[0047] The base 1 is mounted on the grinding rod body through the rear end, and the base 1 is provided with a liquid inlet channel 11. The front end of the base 1 can be formed in a long rod structure, so as to be partially inserted into a threaded hole. The liquid inlet channel 11 is used for supplying fluid to the throttling channel 21. Specifically, the fluid has a certain pressure, so as to ensure that a certain dynamic pressure is provided.

[0048] The deflector 2 is connected to the base 1 at a preset angle, and specifically, the preset angle can be set according to requirements. The middle part of the deflector 2 includes a throttling section, and the deflector 2 is provided with a throttling channel 21 which is in communication with the liquid inlet channel 11. The throttling hole 211 of the throttling channel 21 is arranged in the throttling section, that is, the throttling hole 211 is arranged from inside to outside, and is used for guiding the fluid medium to flow out of the deflector 2. When the external pressure oil passes through the throttling hole 211, the pressure drop is caused due to the reduction of the flow area, and a stable static pressure oil film is formed, so as to float the shaft and preliminarily support the load.

[0049] Moreover, Figure 2 is a partial structure schematic view of a grinding rod structure for grinding of an internal thread with a large length-diameter ratio provided by an embodiment of the present application; Figure 3 is a structure schematic view of a middle deflector and a grinding assembly of a grinding rod structure for grinding of an internal thread with a large length-diameter ratio provided by an embodiment of the present application, please refer to Figures 2 to 3 The outer periphery of the throttling section is provided with an annular first dynamic pressure oil groove 22. Specifically, when the grinding assembly 3 rotates, the fluid between the surface of the grinding assembly 3 and the deflector 2 is dragged along the tangential direction of the first dynamic pressure oil groove 22 due to viscosity. The type of the first dynamic pressure oil groove 22 is not limited to a stepped groove, a spiral groove, a herringbone groove or a tilting pad which relies on the wedge principle to generate dynamic pressure effect. Based on this structure, the fluid is extruded in the converging gap, and according to the Reynolds equation, the flow rate is accelerated, which causes the dynamic pressure of the fluid to sharply rise. Finally, a dynamic pressure oil film is formed in the radial gap between the deflector 2 and the grinding assembly 3, and the pressure is much higher than the external static pressure, which significantly improves the radial bearing capacity and can support the weight and radial load of the grinding assembly 3.

[0050] The grinding assembly 3 is gap-mounted on the throttling section, that is, the grinding assembly 3 is mounted without contact with the throttling section, so that a fluid chamber 4 is formed between the grinding assembly 3 and the direction-changing piece 2, the throttling section is used to guide the fluid medium to the fluid chamber 4 and adjust the flow rate and pressure of the fluid medium through the inner diameter, so that the fluid chamber 4 contains the fluid medium for supporting the grinding assembly 3. The fluid medium is not limited to liquid medium such as water, hydraulic oil or gas medium such as air and nitrogen. An annular second dynamic pressure oil groove 31 is arranged on the end face of the grinding assembly 3. The type of the first dynamic pressure oil groove 22 is not limited to the types such as stepped groove, spiral groove, herringbone groove or tilting pad which rely on wedge principle to generate dynamic pressure effect. The second dynamic pressure oil groove 31 on the end face of the grinding assembly 3 generates centrifugal force with rotation, throws out the fluid in the radial direction, and forms an axial dynamic pressure oil film in the gap between the direction-changing piece 2 and the end face of the grinding assembly 3. The shape of the oil groove (such as spiral groove) guides the fluid to generate circumferential flow, forms a pressure wedge in the converging gap, offsets the axial load (such as fluid axial thrust or rotor axial movement), and avoids direct contact between the direction-changing piece 2 and the end face of the grinding assembly 3.

[0051] The flexible shaft 5 is rotatably arranged through the base 1 and the direction-changing piece 2 and axially extends along the base 1 and the direction-changing piece 2 in sequence, the flexible shaft 5 is connected with the main shaft and is used to transmit power.

[0052] The front end face of the grinding assembly 3 is connected with the flexible shaft 5 through the nut 6, based on the structure, the flexible shaft 5 drives the grinding assembly 3 to rotate through the nut 6, and the nut 6 plays a role of power transmission.

[0053] Through the direction-changing piece 2 in the above structure, an outer grinding assembly 3 dynamic and static pressure bearing is formed, specifically, the direction-changing piece 2 is equivalent to a bearing inner ring, the fluid medium in the fluid chamber 4 is equivalent to a rolling body, and the grinding assembly 3 is equivalent to a bearing outer ring.

[0054] The fluid with a certain pressure flows into through the liquid inlet channel 11 arranged on the base 1, flows through the direction-changing piece 2, and flows out through the throttling hole 211, and finally enters the fluid chamber 4. When the grinding assembly 3 does not rotate, the grinding assembly 3 can be floated to separate from the contact with the direction-changing piece 2 due to the fluid with a certain pressure at this time, but the rigidity is determined by the fluid pressure provided from outside; during machining, the grinding assembly 3 rotates at high speed, the first dynamic pressure oil groove 22 is arranged on the outer circle of the throttling section, the second dynamic pressure oil groove 31 is arranged on the end face of the grinding assembly 3, and the fluid in the fluid chamber 4 has obvious dynamic pressure effect and can generate fluid pressure far greater than the external pressure, thereby significantly improving the bearing rigidity; at the same time, the grinding assembly 3 is not cantilevered installed like the grinding wheel 33 in the traditional curved bar structure, and the bearing needs to bear the overturning moment; the outer grinding assembly 3 dynamic and static pressure bearing structure form almost does not generate the overturning moment, which is very favorable for improving the machining precision.

[0055] The grinding rod structure for grinding large-length-diameter-ratio internal thread is provided by the application, the grinding assembly 3 is sleeved on the throttling section of the direction-changing piece 2 with a gap, a fluid chamber 4 is formed between the grinding assembly 3 and the direction-changing piece 2, the outer periphery of the throttling section is provided with an annular first dynamic pressure oil groove 22, and the end surface of the grinding assembly 3 is provided with an annular second dynamic pressure oil groove 31. When the grinding assembly 3 does not rotate, the grinding assembly 3 can be floated to separate from the direction-changing piece 2 due to the fluid pressure, and the rigidity of the grinding assembly 3 is determined by the fluid pressure provided from outside. During machining, the grinding assembly 3 rotates at high speed, the fluid in the fluid chamber 4 has a significant dynamic pressure effect based on the first dynamic pressure oil groove 22 and the second dynamic pressure oil groove 31, the fluid pressure is much greater than the external pressure, and the bearing rigidity is significantly improved, the bearing has no wear and has a long service life. Meanwhile, the structure can hardly generate overturning moment, and the machining precision is significantly improved.

[0056] In an embodiment of the application, the first dynamic pressure oil groove 22 corresponds to the throttling hole 211 of the throttling passage 21, that is, the first dynamic pressure oil groove 22 is aligned or communicated with the throttling hole 211 in the spatial position, and the fluid medium flowing out of the throttling hole 211 can directly enter the first dynamic pressure oil groove 22, so that the dynamic pressure effect is superimposed and improved.

[0057] In an embodiment of the application, the grinding assembly 3 comprises an outer rotor 32 and a grinding wheel 33 sleeved on the outer rotor 32. The outer rotor 32 and the nut 6 are used for fixing the grinding wheel 33 from both ends. Specifically, the nut 6 is threadedly connected with the outer rotor 32, the nut 6 fixes the grinding wheel 33 from the front end, and the rear end of the outer rotor 32 is widened to form a boss for fixing the grinding wheel 33. The nut 6 and the outer rotor 32 form axial clamping force to prevent the grinding wheel 33 from moving along the axial direction during high-speed rotation. The positioning is reliable and the transmission is stable by mechanical clamping.

[0058] Based on the detachable structure of the outer rotor 32 and the grinding wheel 33, the grinding wheel 33 can be quickly disassembled, different particle sizes or shapes of the grinding wheel 33 can be replaced, and the machining efficiency is improved.

[0059] Through the above structure, an outer rotor 32 dynamic and static pressure bearing is formed. The fluid medium with a certain pressure can flow out from the gap between the outer rotor 32 and the direction-changing piece 2 at a certain flow rate. In an embodiment of the application, the nut 6 and the soft shaft 5 are connected through a clamping screw 61 to improve the fixing effect of the nut 6. The fluid medium with a certain pressure can also flow out from the gap between the nut 6 and the soft shaft 5 at a certain flow rate.

[0060] In an embodiment of the application, the nut 6 and the soft shaft 5 are connected through a clamping screw 61 to improve the fixing effect of the nut 6.

[0061] In an embodiment of the present application, the front end diameter of the nut 6 is smaller than the rear end diameter, and the side wall of the nut 6 has an angle with the axial direction greater than or equal to a preset angle. This structure ensures that the nut 6 does not interfere with the internal thread when the grinding structure is in use.

[0062] In an embodiment of the present application, an annular groove is provided on the inner wall of the nut 6, which can correspond to the deflector 2 to avoid interference with the deflector 2.

[0063] In an embodiment of the present application, an eccentric hole 12 is provided in the base 1, which can leave space for the liquid inlet channel 11. By optimizing the space layout, the diameter of the long rod-shaped structure at the front end of the base 1 is not enlarged, which is beneficial for deepening into the screw hole. The front end of the base 1 is provided with an inclined hole 13 at a preset angle with the eccentric hole 12, the eccentric hole 12 and the inclined hole 13 are connected, and the inclined hole 13 is used to accommodate the flexible shaft 5. The communication structure of the inclined hole 13 and the eccentric hole 12 can change the direction of the flexible shaft 5 in a limited space.

[0064] Further, in an embodiment of the present application, the end of the inclined hole 13 is formed with a fixing groove 14; the deflector 2 includes an inner bushing 23, a bearing bush 24 and a thrust disc 25; the inner bushing 23 is installed in the fixing groove 14 with interference, the bearing bush 24 is installed on the inner bushing 23 with interference, and the inner bushing 23 and the bearing bush 24 form a throttling channel 21; the thrust disc 25 is sleeved on the front end of the inner bushing 23 and presses the bearing bush 24, and the thrust disc 25 and the bearing bush 24 are used to limit the grinding assembly 3 from both ends.

[0065] The fluid with pressure enters the inner bushing 23 from the inclined hole 13, flows into the throttling channel 21 between the inner bushing 23 and the bearing bush 24, and enters the fluid chamber 4 after being affected by the throttling hole 211. When the outer rotor 32 is stationary, the fluid pressure will float it up, reducing the contact friction with the bearing bush 24 and the thrust disc 25; when the outer rotor 32 rotates at high speed, the first dynamic pressure oil groove 22 of the outer circle of the bearing bush 24 and the second dynamic pressure oil groove 31 of the end surface of the outer rotor 32 make the fluid in the fluid chamber 4 produce dynamic pressure effect, superimposed with static pressure to form strong fluid pressure, supporting the outer rotor 32 and driving the grinding wheel 33 to work, and the thrust disc 25 and the bearing bush 24 limit the grinding assembly 3 from both ends, ensuring stable operation.

[0066] The throttling channel 21 is combined with the dynamic pressure oil groove to realize dynamic and static pressure lubrication. Compared with a single lubrication mode, stable support can be provided in the full speed range, wear is reduced, and the service life is prolonged; the fixing groove 14, the inner bushing 23 and other components form a stable mounting structure, which cooperates with the limiting of the thrust disc 25 and the bearing bush 24 on the grinding assembly 3 to improve the stability and precision of the grinding assembly 3 during work; the oil film formed by fluid lubrication can buffer vibration and impact, reduce noise, improve the stability of equipment operation, reduce the dependence on external high-pressure oil supply system, and reduce energy consumption.

[0067] Further, in one embodiment provided by the present application, an annular flow groove 212 is arranged on the front end surface of the inner bush 23, and a through hole 213 is arranged on the inner bush 23 and connected with the flow groove 212 and the liquid inlet channel 11; a flow guide channel 214 is further arranged on the contact surface of the inner bush 23 and the bearing bush 24 and connected with the flow groove 212 and the throttling hole 211; the number of the throttling holes 211 is at least one pair.

[0068] The fluid with pressure enters the liquid inlet channel 11 through the external pipeline, and flows into the annular flow groove 212 on the front end surface of the inner bush 23 through the through hole 213. The fluid in the flow groove 212 is divided into the throttling holes 211 on the contact surface of the inner bush 23 and the bearing bush 24 through the flow guide channel 214. The annular flow groove 212 serves as a fluid distribution hub, and through the symmetrically distributed flow guide channel 214 and throttling hole 211, it ensures that the fluid uniformly flows into the throttling channel 21, avoids the wear or vibration caused by the unbalanced load, and prolongs the service life of the components. The flow groove 212, the through hole 213, the flow guide channel 214 and the like are integrated in the inner bush 23, without the need for additional pipelines or complex sealing, simplifying the assembly process and reducing the size of the equipment. The through hole 213, the flow groove 212, the flow guide channel 214 and the throttling hole 211 form the throttling channel 21 described above, which is integrated in the inner bush 23, without the need for additional pipelines or complex sealing, simplifying the assembly process and reducing the size of the equipment.

[0069] In one embodiment provided by the present application, the liquid inlet hole 15 corresponding to the liquid inlet channel 11 is arranged on the side surface of the base 1, facilitating the connection of the external pipeline and the spatial layout.

[0070] In one embodiment provided by the present application, the size of the liquid inlet channel 11 gradually decreases inward from the liquid inlet hole 15. The liquid inlet channel 11 adopts a tapered structure, which utilizes the Venturi effect in fluid mechanics: on the one hand, the fluid with a certain pressure flows into the liquid inlet channel 11 from the liquid inlet hole 15, and due to the gradually decreasing cross-sectional area of the channel, the flow rate of the fluid increases, and part of the static pressure energy is converted into kinetic energy; on the other hand, when the fluid enters the downstream throttling hole 211 and throttling channel 21, due to the high flow rate and large kinetic energy, a stable static pressure oil film can be quickly established after throttling, thereby improving the response speed of the lubrication system.

[0071] The tapering structure accelerates the fluid flow rate, shortens the time difference of "liquid supply - pressure building", and can form an oil film to support the grinding assembly 3 faster, especially at the moment of starting the device, thereby reducing dry friction wear. During the channel contraction process, the increase of fluid kinetic energy can inhibit the instability of the oil film caused by external liquid supply pressure fluctuations. The use of fluid kinetic energy to assist in pressure building can reduce the requirement for external liquid supply pump output pressure, adapt to lower power pump stations, and reduce energy consumption and equipment cost. The tapering channel makes the fluid flow more uniform, reduces the vortex or cavitation phenomenon caused by sudden changes in cross-sectional area, and improves the stability of fluid transmission. The tapering channel can accelerate the fluid in a limited length without the need for additional extension of the pipeline, and is suitable for devices with limited internal space of the base 1.

[0072] The grinding rod structure for large-length-diameter-ratio internal thread grinding provided by the application is characterized in that the grinding assembly 3 gap is sleeved on the throttling section of the direction-changing piece 2, a fluid chamber 4 is formed between the grinding assembly 3 and the direction-changing piece 2, the outer periphery of the throttling section is provided with an annular first dynamic pressure oil groove 22, and the end face of the grinding assembly 3 is provided with an annular second dynamic pressure oil groove 31. When the grinding assembly 3 does not rotate, the grinding assembly 3 can be lifted to separate from the direction-changing piece 2 due to the fluid pressure, and the rigidity is determined by the external fluid pressure. During machining, the grinding assembly 3 rotates at high speed, and based on the first dynamic pressure oil groove 22 and the second dynamic pressure oil groove 31, the fluid in the fluid chamber 4 has a significant dynamic pressure effect, can generate fluid pressure much greater than the external pressure, and can significantly improve the bearing rigidity, has no wear, and has a long service life. At the same time, this structure form almost does not generate overturning moment, and can significantly improve the machining precision.

[0073] The bearing structure adopts a dynamic and static pressure structure form, mainly relies on the dynamic pressure effect to ensure the bearing rigidity (without the need for a complex high-pressure fluid supply system), and the damping of the high-rigidity fluid film has a good inhibitory effect on the vibration in the transmission of the soft shaft 5, and can significantly improve the surface machining quality. The bearing adopts an outer rotor 32 structure, the grinding wheel 33 grinding reaction force is directly applied to the outer rotor 32, there is no overturning moment, the overall rigidity is good, and the machining precision is high. The bearing has no contact friction, has no wear, and has a long service life.

[0074] It should be understood that the term "and / or" herein only describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent three cases of A alone, A and B together, and B alone, wherein A and B can be singular or plural. In addition, the character " / " herein generally represents that the front and rear associated objects have an "or" relationship, but can also represent an "and / or" relationship, which can be understood according to the context.

[0075] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions means any combination of the items, including any combination of single item or multiple items. For example, at least one of a, b, or c can mean a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0076] It should be understood that the order of the above processes does not mean the order of execution in various embodiments of the present application. The order of execution of the processes should be determined by their functions and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0077] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A grinding rod structure for grinding internal threads with a large length-to-diameter ratio, characterized in that, The grinding rod structure includes: A grinding rod body, the grinding rod body including a spindle; A base is mounted on the grinding rod body, and the base has a liquid inlet channel inside; A reversing component is connected to the base at a preset angle. The middle part of the reversing component includes a throttling section. The reversing component is provided with a throttling channel that communicates with the liquid inlet channel. The throttling orifice of the throttling channel is provided in the throttling section. An annular first dynamic pressure oil groove is provided on the outer periphery of the throttling section. A grinding assembly, wherein the grinding assembly is fitted onto the throttling section and forms a fluid chamber with the reversing member, the fluid chamber contains a fluid medium for supporting the grinding assembly, and an annular second dynamic pressure oil groove is provided on the end face of the grinding assembly; A flexible shaft rotatably passes through the base and the reversing member, and extends axially along the base and the reversing member in sequence; the flexible shaft is connected to the main shaft. The front end face of the grinding assembly is connected to the flexible shaft via the nut, and the flexible shaft drives the grinding assembly to rotate via the nut.

2. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 1, characterized in that, The first dynamic pressure oil groove corresponds to the throttling orifice of the throttling channel.

3. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 1, characterized in that, The grinding assembly includes an outer rotor and a grinding wheel mounted on the outer rotor; The outer rotor and the nut are used to secure the grinding wheel from both ends.

4. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 1, characterized in that, The front diameter of the nut is smaller than the rear diameter, and the angle between the sidewall of the nut and the axial direction is greater than or equal to the preset angle.

5. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 1, characterized in that, The inner wall of the nut is provided with an annular groove.

6. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 1, characterized in that, The base has an eccentric hole, and the front end of the base has an oblique hole at a preset angle to the eccentric hole. The eccentric hole and the oblique hole are connected and are used to accommodate the flexible shaft.

7. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 6, characterized in that, A fixing groove is formed at the end of the oblique hole; The steering component includes an inner bushing, a bearing shell, and a thrust plate; The inner bushing is interference-fitted into the fixing groove, and the bearing bush is interference-fitted onto the inner bushing, forming the throttling channel between the inner bushing and the bearing bush; The thrust plate is fitted onto the front end of the inner bushing and presses against the bearing shell. The thrust plate and the bearing shell are used to limit the grinding assembly from both ends.

8. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 7, characterized in that, The inner liner has an annular flow groove on its front end face and a through hole on its upper surface that connects the flow groove and the liquid inlet channel. The contact surface between the inner bushing and the bearing bush is also provided with a flow channel connecting the flow groove and the throttling hole, and the through hole, the flow groove, the flow channel and the throttling hole form the throttling channel; The number of throttling orifices is at least one pair.

9. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 1, characterized in that, The liquid inlet hole corresponding to the liquid inlet channel is located on the side of the base.

10. The grinding rod structure for grinding internal threads with a large length-to-diameter ratio according to claim 1, characterized in that, The size of the liquid inlet channel gradually decreases from the liquid inlet hole inwards.

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