External eccentric wheel assembly and polishing device

Abstract

According to the external eccentric wheel assembly and the polishing device, an independent motor assembly is integrated in an eccentric wheel, so that rotating force of a driven shaft is completely separated from eccentric rotating force driven by a driving shaft, the driven shaft is prevented from being stuck, and continuity and stability of the polishing process are ensured. Meanwhile, in combination with feedback of a pressure sensor of the grinding device, an external power supply control system can sense changes of grinding working conditions in real time, the torque and the rotating speed of a driven shaft are dynamically adjusted, high-quality and self-adaptive grinding of workpieces with complex curved surfaces and different materials is achieved, and the machining consistency and the yield are remarkably improved. A plurality of layers of lip-shaped oil seals and gas path channels are arranged at the end parts of the driving shaft and the driven shaft, and a stable gas curtain barrier is formed by utilizing gas pressure, so that cooling liquid and grinding impurities are effectively blocked, the fitting degree of the oil seals is enhanced through the gas pressure, and the sealing reliability and durability are remarkably improved; and the service life of the assembly in a wet or high-dust environment is prolonged.

Description

Technical Field

[0001] This invention relates to the field of grinding equipment technology, and more specifically, to an external eccentric wheel assembly and a grinding device. Background Technology

[0002] In the industrial manufacturing sector, especially in the surface finishing of workpieces made of metal, wood, and composite materials, grinding and polishing are crucial processes. To improve processing efficiency and surface quality, various automatic or semi-automatic grinding devices have been widely used.

[0003] A common solution is an eccentric wheel motor grinding device. However, existing eccentric wheel motor grinding devices still have the following technical problems: First, the driven shaft's power transmission relies on centrifugal force, resulting in poor adaptability to various operating conditions and a tendency to stall. In existing structures, the driven shaft's rotation is not driven by an independent power source but depends entirely on the centrifugal force generated by the eccentric wheel's revolution to overcome the friction between the grinding disc and the workpiece. When grinding resistance increases (e.g., encountering hard spots or uneven machining allowances), the centrifugal force may be insufficient to maintain the driven shaft's rotation, causing the grinding disc to momentarily "jam" or stop. This not only causes surface scratches and uneven grinding on the workpiece but also leads to increased equipment vibration, noise, and even overload damage to transmission components, severely impacting production efficiency and processing quality. Although the industry has attempted to alleviate this problem by increasing motor power or optimizing the eccentric mass, it has failed to fundamentally achieve independent, precise, and adaptive control of the driven shaft's power.

[0004] Secondly, the sealing structure fails, making it unable to effectively prevent the intrusion of coolant or grinding impurities. The unique characteristic of the eccentric wheel structure is that the driven shaft does not rotate around a fixed axis; its axis trajectory is a circle. This significant eccentric movement makes traditional shaft-end sealing methods (such as labyrinth seals or single-lip seals relying solely on small gaps) ineffective. In wet grinding environments with coolant or generating large amounts of grinding dust, liquids and impurities easily intrude into the device along the dynamically changing gap between the driven shaft and the housing. This not only contaminates and corrodes internal motor components and bearings, leading to rapid wear and electrical short-circuit failure, but also accelerates the damage to mechanical parts due to the erosion of lubricating grease, severely shortening the service life and reliability of the entire grinding device. Although "air curtain sealing" technology has mature applications in high-speed spindles and other fields, its design premise is a fixed rotating shaft. When directly applied to an eccentric wheel structure with a complex motion trajectory, the sealing airflow is disrupted, failing to form a stable and effective sealing barrier.

[0005] Therefore, it is necessary to further improve the structure of the grinding device and provide an eccentric wheel motor structure that can achieve adaptive control of the driven shaft torque and achieve long-term reliable sealing for the characteristics of eccentric motion. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned shortcomings by providing an external eccentric wheel assembly and a grinding device, in order to solve the technical problems in the prior art such as poor adaptability of the driven shaft to working conditions, easy stalling, and the inability of the sealing structure to effectively prevent the intrusion of coolant or grinding impurities.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides an external eccentric wheel assembly, comprising: The housing has a bearing mounting section at its second end opening; A drive shaft is rotatably supported in the bearing mounting portion by a first bearing. The drive shaft is used to connect to an external drive motor to receive a first rotational power. The drive shaft is provided with an eccentric mounting portion that is offset from its own axis of rotation. The driven shaft is rotatably supported in the eccentric mounting portion by a second bearing, such that the rotation of the driving shaft can drive the driven shaft to rotate eccentrically about the axis of the driving shaft. A motor assembly, housed within the eccentric mounting portion and electrically connected to an external power control system, to controllably drive the driven shaft to rotate independently about its own axis. When the drive shaft is connected to the external drive motor and receives the first rotational power, and the motor assembly is simultaneously controlled to drive the driven shaft to rotate independently, the driven shaft outputs a composite rotational power, which is a combination of the eccentric rotation driven by the drive shaft and the independent rotation driven by the motor assembly.

[0008] Furthermore, the motor assembly includes a stator disposed within the eccentric mounting portion, the stator being electrically connected to the external power control system via wires; The rotor is fixedly sleeved on the driven shaft and rotatably housed within the stator; The stator is controlled by the external power supply control system to drive the rotor and the driven shaft to rotate around their own axis.

[0009] Furthermore, the bottom of the eccentric mounting part is provided with a wire hole, which passes through the drive shaft, and the stator is electrically connected to the external power control system through a wire that passes through the wire hole and extends out of the drive shaft.

[0010] Furthermore, the wire is electrically connected to the external power control system via a power supply component; The power supply assembly includes two conductive rings, which are insulated from the outside of the second end of the drive shaft by an insulating component and are electrically connected to the conductors of the stator respectively. An insulating ring is sandwiched between the two conductive rings as two electrodes led out from the stator. Two carbon brushes are mounted on the second end of the housing via an insulating plate. The insulating plate has two carbon brush mounting brackets. The rear ends of the two carbon brushes are slidably mounted in the carbon brush mounting brackets against elastic members. The front ends of the two carbon brushes are in sliding contact with the two conductive rings. The two carbon brushes are used to electrically connect to the two electrodes of the external power control system.

[0011] Furthermore, an upper oil seal and a lower oil seal are provided at intervals along the axial direction of the drive shaft between the first end of the housing and the first end of the drive shaft via a first retaining ring; The outer rings of the upper oil seal and the lower oil seal abut against the inner side of the first end of the housing. The inner rings of the upper oil seal and the lower oil seal are lip structures with wedges facing the outer side of the first end of the housing. The lip structure elastically abuts against the outer side of the first end of the drive shaft. A first airtight cavity is formed between the upper oil seal and the lower oil seal; The housing sidewall is provided with an air passage that can be connected to an external air source. The first retaining ring has a notch that faces the air outlet of the air passage. The air outlet of the air passage is connected to the first airtight cavity. When the air passage is connected to the external air source and gas is introduced into the first airtight cavity, the gas pushes open the upper oil seal lip structure wedge and blows out from the gap between the upper oil seal and the drive shaft toward the first end of the housing; the gas presses the other side of the lower oil seal lip structure wedge, thereby pressing the lower oil seal toward the drive shaft; forming an air curtain seal at the drive shaft.

[0012] Furthermore, a protective cover is provided on the first end opening of the housing, and the protective cover has a through hole with a gap through which the first end of the drive shaft protrudes. The protective cover is used to seal the upper side of the upper oil seal.

[0013] Furthermore, a locking nut is provided on the first end opening of the eccentric mounting part for locking the second bearing.

[0014] Furthermore, a third oil seal is provided between the inner side of the locking nut and the driven shaft; The outer ring of the third oil seal abuts against the inner side of the locking nut, and the inner ring of the third oil seal is a lip structure with a wedge facing the outer side of the first end of the housing. The lip structure elastically abuts against the outer side of the driven shaft. A first gap is left between the outer side of the locking nut and the first end opening of the eccentric mounting part, and a second gap is left between the inner side of the locking nut and the driven shaft. The second gap is located on the side of the third oil seal facing the first end of the housing. The first end sidewall of the drive shaft is provided with a first through hole to connect the first airtight cavity with the first gap, and the sidewall of the locking nut is provided with a second through hole to connect the first gap with the second gap; When gas enters the first gap and the second gap from the first airtight cavity, the gas is blown out from the gap between the locking nut and the driven shaft to the first end of the housing; the gas in the second gap squeezes the other side of the wedge of the third oil seal lip structure, thereby pressing the third oil seal against the driven shaft; forming an air curtain seal at the driven shaft.

[0015] Furthermore, the second end of the drive shaft is provided with a keyway hole for power connection with an external drive motor to receive the first rotational power.

[0016] Additionally, a grinding device is provided, including an external power control system, an external drive motor electrically connected to the external power control system, and an external eccentric wheel assembly as described in any of the above claims. The external eccentric wheel assembly is poweredly connected to the external drive motor to receive a first rotational power, and the external eccentric wheel assembly is electrically connected to the external power control system to controllably drive the driven shaft to rotate independently about its own axis. It also includes a pressure sensor electrically connected to the external power control system. The pressure sensor collects the grinding pressure between the workpiece and the grinding device and transmits it to the external power control system for real-time adjustment of the torque and speed of the driven shaft.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention integrates an independent motor assembly within the eccentric wheel, completely separating the rotational power of the driven shaft from the eccentric rotational power driven by the drive shaft. The speed and torque of the driven shaft are no longer limited by the eccentric centrifugal force, but are directly and independently provided by the built-in motor according to external control commands. This fundamentally overcomes the defect of traditional structures where the driven shaft is prone to jamming when grinding resistance increases, ensuring the continuity and stability of the grinding process. Simultaneously, combined with pressure sensor feedback from the grinding device, the external power control system can sense changes in grinding conditions in real time and dynamically adjust the torque and speed of the driven shaft, achieving high-quality, adaptive grinding of complex curved surfaces and workpieces of different materials, significantly improving processing consistency and yield.

[0018] By setting multiple layers of lip seals and air passages at the ends of the drive shaft and driven shaft, a stable air curtain barrier is formed by using gas pressure. This not only effectively blocks coolant and grinding impurities, but also enhances the fit of the oil seal through gas pressure, significantly improving the reliability and durability of the seal and extending the service life of the component in wet or high-dust environments.

[0019] The stator and rotor of the motor assembly driving the driven shaft are integrated into the eccentric mounting section of the drive shaft and the driven shaft, respectively, resulting in an extremely compact structure that requires no additional external space. Simultaneously, the conductive ring and carbon brush located at the second end of the drive shaft cleverly solve the problem of power and signal transmission between the rotating drive shaft and the stationary external power source. This highly integrated design allows the entire external eccentric wheel assembly to maintain a similar external size and interface to traditional single-power eccentric wheel assemblies while providing the powerful function of independent dual-power control. This facilitates upgrades to existing grinding equipment and allows for a more compact layout in new equipment.

[0020] This invention's grinding device integrates a pressure sensor and connects it in a closed loop to an external power control system that controls the driven shaft motor assembly, enabling online sensing and real-time control of the grinding process. The device can automatically adjust the output torque of the driven shaft based on the grinding pressure, avoiding overload or under-grinding, making it particularly suitable for precision grinding scenarios in automated production lines where consistency is crucial. This intelligent capability allows the device to not only replace traditional equipment but also open up new areas of precision machining applications. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of the external eccentric wheel assembly along the rotation axis of the drive shaft in an embodiment of the present invention; Figure 2 This is a schematic diagram showing the disassembled external eccentric wheel assembly in an embodiment of the present invention; Figure 3 This is a schematic diagram of the drive shaft structure in an embodiment of the present invention. Figure 1 ; Figure 4 This is a schematic diagram of the drive shaft structure in an embodiment of the present invention. Figure 2 ; Figure 5 This is a schematic diagram of the upper oil seal structure in an embodiment of the present invention; Figure 6 This is a schematic diagram of the insulating plate structure in an embodiment of the present invention.

[0022] The annotations in the attached figures are explained as follows: 10. Housing 11. Bearing mounting part 12. Air passage 12. Drive shaft 20. Eccentric mounting part 21. Wire hole 22. First through hole 23. Keyway hole 24. First bearing 30. Driven shaft 40. Second bearing 50. Motor assembly 60. Stator 61. Rotor 62. Power supply assembly 70. Conductive ring 71. Insulating part 72. Insulating ring 73. Carbon brush 74. Insulating plate 75. Carbon brush mounting bracket 751. Elastic part 76. First retaining ring 80. Upper oil seal 90. Lower oil seal 100. First airtight cavity 110. Protective cover 120. Locking nut 130. First gap 131. Second gap 132. Second through hole 133. Third oil seal 140. Detailed Implementation

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] refer to Figure 1 , Figure 2 and Figure 4 As shown, an embodiment of the present invention is an external eccentric wheel assembly, including a housing 10, a drive shaft 20, a first bearing 30, a driven shaft 40, a second bearing 50, and a motor assembly 60.

[0025] The housing 10 constitutes the main body of the assembly, typically cylindrical in shape, and is precision-machined from materials such as aluminum alloy or stainless steel to provide sufficient rigidity and lightweight. At the second end opening of the housing 10, an inwardly protruding annular step or bearing hole with precise dimensions and roundness is machined by turning or boring, forming the bearing mounting part 11. This bearing mounting part 11 is used for precise installation and positioning of the first bearing 30.

[0026] The drive shaft 20 is the main drive shaft that passes through the housing 10 and is rotatably supported in the bearing mounting part 11 by the first bearing 30. The first bearing 30 is preferably two paired ball bearings to withstand combined radial and axial loads and ensure the rotational accuracy of the drive shaft 20. The outer ring of the bearing is pressed into the bearing mounting part 11 with an interference fit and is axially fixed by a retaining ring or pressure cap on the end face. The middle journal of the drive shaft 20 is interference-fitted with the inner ring of the first bearing 30. Thus, the drive shaft 20 is rotatably supported in the housing 10 by the first bearing 30. The second end of the drive shaft 20 extends out of the housing 10, and its end is machined with a keyway, spline, or flange bolt. The output shaft of an external drive motor (such as a servo motor) is poweredly connected to the second end of the drive shaft 20 via a flat key or corresponding structure, thereby achieving a high-torque power connection and receiving the first rotational power.

[0027] The drive shaft 20 is provided with an eccentric mounting portion 21 offset from its own axis of rotation. A circular hole or cavity offset from its own axis of rotation (i.e., the common axis of the first bearing 30) is machined in the middle of the shaft body of the drive shaft 20 or near its first end; this cavity constitutes the eccentric mounting portion 21. The central axis of the eccentric mounting portion 21 is parallel to but does not intersect with the axis of rotation of the drive shaft 20; the distance between them is the eccentricity. The magnitude of the eccentricity is designed according to the required grinding trajectory amplitude. The rotational motion of the drive shaft 20 is directly converted into the spatial circular motion of the eccentric mounting portion 21 through its geometric eccentricity.

[0028] The driven shaft 40 is rotatably supported within the eccentric mounting portion 21 via the second bearing 50, allowing the rotation of the drive shaft 20 to drive the driven shaft 40 to rotate eccentrically around the axis of the drive shaft 20. The driven shaft 40 is a power output shaft, one end of which is used to mount tools such as grinding discs, sandpaper pads, or polishing heads. The driven shaft 40 is rotatably supported in the inner hole of the eccentric mounting portion 21 via the second bearing 50 (usually a pair of ball bearings or needle bearings of the same or different sizes). The outer ring of the second bearing 50 is fixed to the inner wall of the eccentric mounting portion 21, and the inner ring is fixed to the corresponding shaft segment of the driven shaft 40. Due to the eccentric characteristic of the eccentric mounting portion 21, when the drive shaft 20 rotates, the driven shaft 40 and the inner ring of the second bearing 50 thereon are forced to follow the eccentric mounting portion 21 in a circular motion around the axis of the drive shaft 20; this is the eccentric rotation (revolution) of the driven shaft 40.

[0029] The motor assembly 60 is housed within the eccentric mounting portion 21 and is electrically connected to an external power control system to controllably drive the driven shaft 40 to rotate independently about its own axis.

[0030] The motor assembly 60 is housed and installed within the internal space formed by the eccentric mounting portion 21. The motor assembly 60 is electrically connected to an external power control system. This external power control system can control the motor assembly 60 independently of the external drive motor driving the drive shaft 20, but is completely electrically and power-separated, to drive the driven shaft 40 to rotate independently around its own axis. The motor assembly 60 can be a brushless DC motor, an AC servo motor, or the like.

[0031] Specifically, the working principle and output characteristics of this external eccentric wheel assembly are as follows: During the grinding operation, an external drive motor drives the drive shaft 20 to rotate at a constant or variable speed, causing the driven shaft 40 to rotate in a directional direction (revolution), forming the basic grinding trajectory. Simultaneously, the external power control system, according to process requirements, controls the motor assembly 60 to operate, driving the driven shaft 40 to rotate independently. Therefore, the grinding disc mounted at the end of the driven shaft 40 ultimately achieves a composite motion; while revolving around the axis of the drive shaft 20, it also rotates at high speed (self-rotation). The combination of these two motion vectors creates a composite motion trajectory that is far more complex than a single revolution or rotation, producing a more uniform grinding effect and being more conducive to the application of complex curved surfaces. More importantly, the power of the self-rotation (torque and speed) is completely independent and controllable, no longer relying on the periodically changing centrifugal force generated by the revolution. When the grinding resistance increases instantaneously, the external power control system can immediately increase the output torque of the motor assembly 60 to ensure that the rotation is not stopped. This fundamentally overcomes the defect of the driven shaft being prone to jamming when the grinding resistance increases in traditional structures, ensuring the continuity and stability of the grinding process.

[0032] In some embodiments, such as Figure 1 and Figure 2 As shown, the motor assembly 60 is a built-in brushed or brushless motor. Specifically, the motor assembly 60 includes a stator 61 disposed in the eccentric mounting portion 21, the stator 61 being electrically connected to an external power control system via wires; and a rotor 62 fixedly sleeved on the driven shaft 40 and rotatably housed within the stator 61.

[0033] The stator 61 includes a stator core and windings, which are fixedly installed in the inner cavity of the eccentric mounting part 21 by means of interference fit, adhesive, or screw fastening. The winding leads of the stator 61 are electrically connected to an external power control system, and are energized and controlled.

[0034] The rotor 62 includes a rotor permanent magnet, which is fixedly sleeved on the driven shaft 40 by means of interference fit or key connection. The rotor 62 is located entirely in the inner hole of the stator 61, with a uniform air gap between them. When the external power control system supplies a controlled current to the windings of the stator 61, a rotating magnetic field is generated, driving the rotor 62 together with the driven shaft 40 to rotate around the axis of the driven shaft 40, and enabling precise and rapid response of the driven shaft 40's rotational speed and output torque.

[0035] Furthermore, in some embodiments, such as Figure 1 , Figure 3 and Figure 4 As shown, in order to lead out the conductors of the stator 61, the bottom of the eccentric mounting part 21 is provided with a wire hole 22. The wire hole 22 passes through the drive shaft 20, and the stator 61 is electrically connected to the external power control system through the conductors that pass through the wire hole 22 and extend out of the drive shaft 20.

[0036] To transmit electrical energy and signals from the stationary external environment to the stator 61, which rotates with the drive shaft 20, one or more through holes 22 are machined at the bottom of the eccentric mounting portion 21. These through holes 22 penetrate the wall thickness of the drive shaft 20 radially or obliquely. Wires leading from the stator 61 pass through these through holes 22, enter a pre-designed wiring groove or cavity inside the drive shaft 20, and then extend towards the second end of the housing 10.

[0037] Furthermore, in some embodiments, such as Figure 1 , Figure 2 and Figure 6 As shown, in order to enable the wire leading out from the second end of the driven shaft 20 to connect with the stationary external power control system, the wire is electrically connected to the external power control system through the power supply component 70.

[0038] Since the drive shaft 20 rotates continuously, while the stator 61's wires are fixed relative to it, a rotary connector is needed to transmit electrical power from the stationary housing 10 to the rotating drive shaft 20. The power supply assembly 70 performs this function.

[0039] Specifically, the power supply assembly 70 includes conductive rings 71 and carbon brushes 74. Two conductive rings 71 (e.g., copper rings) are spaced apart and insulatedly fitted onto the outer circumference of the second end of the drive shaft 20 by an insulating member 72 (e.g., a polytetrafluoroethylene sleeve). An insulating ring 73 is also sandwiched between the two conductive rings 71 to achieve insulation between them. Two wires leading out from the stator 61 and passing through the wire hole 22 are electrically connected to the two conductive rings 71 respectively.

[0040] Two carbon brushes 74 (typically copper-graphite brushes) are mounted at the end or inside of the second end of the housing 10 via an insulating plate 75. The insulating plate 75 has two brush mounting brackets 751. Each carbon brush 74 is placed within a hole in one of the brush mounting brackets 751, and its rear end (the end furthest from the drive shaft 20) is continuously pressed forward by an elastic element 76 (such as a coil spring or leaf spring). Under the action of the elastic element 76, the front ends of the two carbon brushes 74 maintain constant sliding contact with the outer circumferential surfaces of the two rotating conductive rings 71. The tail ends of the carbon brushes 74 are connected to carbon brush cables, thereby transmitting electrical energy and signals from the external power control system to the rotating stator 61 windings through the sliding frictional contact between the carbon brushes 74 and the conductive rings 71. The constant pressure design of the springs ensures the stability of the contact resistance during carbon brush wear.

[0041] Furthermore, in some embodiments, such as Figure 1-5 As shown, for relative rotational sealing between the drive shaft 20 and the housing 10, an upper oil seal 90 and a lower oil seal 100 are provided at intervals along the axial direction of the drive shaft 20 between the first end of the housing 10 and the first end of the drive shaft 20 via a first retaining ring 80. The outer rings of the upper oil seal 90 and the lower oil seal 100 abut against the inner side of the first end of the housing 10, and the inner rings of the upper oil seal 90 and the lower oil seal 100 are lip structures with wedges facing the outer side of the first end of the housing 10, and the lip structure elastically abuts against the outer side of the first end of the drive shaft 20.

[0042] Specifically, on the inner side of the first end of the housing 10 (the end closest to the grinding working area), along the axial direction of the drive shaft 20, an upper oil seal 90 and a lower oil seal 100 are installed at a certain distance apart by a first retaining ring 80. The upper oil seal 90 is closer to the opening of the first end of the housing 10, and the lower oil seal 100 is further inward. Both the upper oil seal 90 and the lower oil seal 100 are lip-type sealing rings (such as TC-type skeleton oil seals), and their skeleton outer ring is interference-fitted and fixed to the inner hole of the first end of the housing 10. The sealing lip structure of its inner ring is a rubber or polyurethane elastomer with a wedge shape, and the wedge direction of the lip structure faces the outer side of the first end of the housing 10 (i.e., towards the external environment). In its natural state, this lip structure holds the outer side of the first end of the drive shaft 20 tightly under its own elasticity.

[0043] An annular sealed space, namely the first airtight cavity 110, is formed between the upper oil seal 90 and the lower oil seal 100.

[0044] An air passage 12 is machined inside the side wall of the housing 10. One end of the passage can be connected to an external air source (such as compressed air), and the other end opens on the inner side wall of the first end of the housing 10, with its outlet facing the notch of the first retaining ring 80. Due to the presence of the notch in the first retaining ring 80, the compressed air blown out from the air passage 12 can smoothly enter the first airtight cavity 110.

[0045] The sealing principle is as follows: When compressed air is introduced, the pressure inside the first airtight chamber 110 increases. The gas pressure acts on the back of the wedge of the upper oil seal 90 lip, slightly pushing the lip open, allowing gas to be blown out at high speed from the tiny gap between the upper oil seal 90 lip and the drive shaft 20, forming an outward air curtain outside the first end of the housing 10, actively blocking the intrusion of external coolant and dust. At the same time, the gas pressure acts on the other side of the wedge of the lower oil seal 100 lip structure (i.e., the side facing the outside of the first end of the housing 10), which is equivalent to pressing the lip of the lower oil seal 100 more tightly against the surface of the drive shaft 20 from behind, thereby enhancing the sealing effect of the oil seal and preventing gas leakage into the bearing cavity.

[0046] The gas flow rate and pressure blown out from the upper oil seal 90 need to be calculated and adjusted to ensure that an effective air curtain is formed without causing excessive wear or overheating of the lip structure. With the assistance of air pressure, the lower oil seal 100 becomes a highly reliable safety valve. This combination of a non-contact air curtain (main seal) and a contact oil seal (auxiliary seal, which is reinforced) provides double protection for the first sealing interface.

[0047] Furthermore, in some embodiments, such as Figure 1 and Figure 2As shown, in order to provide physical protection and prevent flying debris or tools from directly impacting and damaging the upper oil seal 90, a protective cover 120 is provided on the first end opening of the housing 10. The protective cover 120 has a through hole with a gap that extends through the first end of the drive shaft 20. The protective cover 120 is used to seal the upper side of the upper oil seal 90 and mainly plays a physical protection role to prevent large foreign objects from directly impacting the oil seal, while allowing the air curtain to be blown out.

[0048] Furthermore, in some embodiments, such as Figure 2 As shown, in order to lock the second bearing 50, a locking nut 130 is provided on the first end opening of the eccentric mounting part 21 to press the outer ring of the second bearing 50, thereby locking the second bearing 50 and achieving its axial fixation.

[0049] Furthermore, in some embodiments, such as Figure 1 As shown, in order to seal between the driven shaft 40 and the eccentric mounting part 21, a third oil seal 140 is press-fitted into the inner hole of the locking nut 130. The structure of the third oil seal 140 is similar to that of the upper oil seal 90 and the lower oil seal 100. Its lip structure wedge direction also faces the outer side of the first end of the housing 10 (i.e., towards the harsh environment), and relies on elasticity to hold the outer surface of the driven shaft 40.

[0050] A first gap 131 is left between the lower outer part of the locking nut 130 and the first end opening of the eccentric mounting part 21. At the same time, a second gap 132 is also left between the inner hole of the locking nut 130 and the driven shaft 40 on the side of the lip structure of the third oil seal 140 facing the first end of the housing 10.

[0051] At least one first through hole 23 is machined on the side wall of the first end of the drive shaft 20 (i.e., the outer wall of the eccentric mounting portion 21). Typically, multiple first through holes 23 are provided around the circumference of the side wall. This hole connects the aforementioned first airtight cavity 110 with the first gap 131 on the outer side of the locking nut 130. At least one second through hole 133 (which can be a radial hole or an oblique hole) is machined on the side wall (threaded portion or unthreaded cylindrical portion) of the locking nut 130. Typically, multiple second through holes 133 are provided around the circumference of the side wall. This hole connects the first gap 131 with the second gap 132 on the inner side of the locking nut 130.

[0052] The dynamic sealing principle is as follows: When compressed air is introduced into the first airtight chamber 110, a portion of the gas enters the first gap 131 outside the locking nut 130 through the first through hole 23 on the drive shaft 20 (this hole periodically aligns with the first airtight chamber 110 when the drive shaft rotates). After being throttled by the first gap 131, the gas enters the second gap 132 through the second through hole 133 on the locking nut 130. Finally, the gas is blown out from the second gap 132 toward the first end of the housing 10, that is, into the annular gap between the end face of the locking nut 130 and the driven shaft 40.

[0053] The key effect of this design is that the blown gas adheres closely to the surface of the driven shaft 40, which is eccentrically rotating. Since the driven shaft 40's rotation trajectory is a circle, its axis is constantly oscillating, making traditional single air curtains easily disrupted and ineffective. However, in this embodiment, the air outlet (second gap 132) moves eccentrically along with the driven shaft 40 (because the locking nut 130 is fixed to the eccentric mounting part 21, which is rotating). This allows the blown airflow to always closely surround the journal section of the driven shaft 40, forming a dynamic gas barrier that moves with the axis, effectively driving away liquids and impurities in the vicinity. Simultaneously, the gas pressure within the second gap 132 also acts on the other side of the wedge-shaped lip structure of the third oil seal 140 (i.e., the side facing the outer side of the first end of the housing 10), assisting in pressing it firmly against the driven shaft 40, achieving synergistic reinforcement of the gas seal and the contact oil seal. This system cleverly utilizes the eccentric motion itself to upgrade the traditional static-to-static or static-to-rotational air seal to a dynamic-to-dynamic following air seal, thus solving the difficulties of sealing eccentric structures.

[0054] In some embodiments, such as Figure 1 and Figure 3 As shown, a keyway hole 24 is provided at the second end of the drive shaft 20 to facilitate power connection with an external drive motor. The keyway hole 24 is machined at the second end of the drive shaft 20. The keyway hole 24 is a standardized, highly reliable power interface. Its dimensions are designed according to national standards (such as GB / T 1095) based on the transmitted torque and the shaft diameter of the external drive motor. Compared to the keyless expansion sleeve connection described above, this connection method has the advantages of good alignment and no stress concentration.

[0055] In addition, this application also provides a grinding device, which includes at least one external power control system (such as a servo driver), an external drive motor driven or independently controlled by the control system, an external eccentric wheel assembly as described in any of the above, and a pressure sensor.

[0056] The drive shaft 20 of the external eccentric wheel assembly is connected to the output shaft of the external drive motor. Its motor assembly 60 (stator 61) is connected to the external power control system through the power supply assembly 70 (carbon brushes 74 and conductive rings 71).

[0057] Pressure sensors (such as piezoelectric or strain gauge sensors) are mounted on the frame or tool head of the grinding device to detect the contact pressure between the grinding disc and the workpiece in real time. The signal output of the pressure sensor is connected to the signal input of an external power control system.

[0058] The working process of this grinding device is as follows: an external drive motor drives the drive shaft 20 to rotate, determining the grinding trajectory and frequency. The external power control system supplies power to the motor assembly 60, controlling the rotation speed and torque of the driven shaft 40; simultaneously, it receives feedback signals from the pressure sensor in real time. When an increase in grinding pressure is detected (indicating increased resistance), the control system immediately increases the output torque of the motor assembly 60 to ensure that the driven shaft 40 and the grinding disc do not stop rotating. At the same time, it can also adjust the rotation speed according to the preset process curve and pressure changes to achieve constant force grinding or adaptive grinding, thereby significantly improving grinding quality, efficiency, and automation.

[0059] This grinding device integrates a pressure sensor and is connected in a closed loop to an external power control system that controls the driven shaft motor assembly 60, enabling online sensing and real-time control of the grinding process. The device can automatically adjust the output torque of the driven shaft according to the grinding pressure, avoiding overload or under-grinding, making it particularly suitable for precision grinding scenarios in automated production lines where consistency is crucial. This intelligent capability allows the device to not only replace traditional equipment but also open up new areas of precision machining applications.

[0060] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.

[0061] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter arrangement within the scope of the disclosure, drawings, and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. An external eccentric wheel assembly, characterized in that, It includes: The housing (10) has a bearing mounting part (11) at its second end opening. The drive shaft (20) is rotatably supported in the bearing mounting part (11) by a first bearing (30). The drive shaft (20) is used to be powered by an external drive motor to receive a first rotational power. The drive shaft (20) is provided with an eccentric mounting part (21) that is offset from its own rotation axis. The driven shaft (40) is rotatably supported in the eccentric mounting part (21) by a second bearing (50), so that the rotation of the driving shaft (20) can drive the driven shaft (40) to rotate eccentrically about the axis of the driving shaft (20); The motor assembly (60) is housed within the eccentric mounting portion (21) and electrically connected to an external power control system to controllably drive the driven shaft (40) to rotate independently about its own axis. When the drive shaft (20) is connected to the external drive motor and receives the first rotational power, and the motor assembly (60) is controlled to drive the driven shaft (40) to rotate independently, the driven shaft (40) outputs a composite rotational power, which is a combination of the eccentric rotation driven by the drive shaft (30) and the independent rotation driven by the motor assembly (60).

2. The external eccentric wheel assembly according to claim 1, characterized in that: The motor assembly (60) includes a stator (61) disposed within the eccentric mounting portion (21), the stator (61) being electrically connected to the external power control system via wires; The rotor (62) is fixedly sleeved on the driven shaft (40) and rotatably housed within the stator (61); The stator (61) is controlled by the external power supply control system to drive the rotor (62) and the driven shaft (40) to rotate around their own axis.

3. The external eccentric wheel assembly according to claim 2, characterized in that: The bottom of the eccentric mounting part (21) is provided with a wire hole (22), which passes through the drive shaft (20). The stator (61) is electrically connected to the external power control system through a wire that passes through the wire hole (22) and extends out of the drive shaft (20).

4. The external eccentric wheel assembly according to claim 3, characterized in that: The wire is electrically connected to the external power control system via the power supply assembly (70); The power supply assembly (70) includes two conductive rings (71). The two conductive rings (71) are insulated from the outside of the second end of the drive shaft (20) by an insulating member (72) and are electrically connected to the conductors of the stator (61). An insulating ring (73) is sandwiched between the two conductive rings (71) as two electrodes led out from the stator (61). Two carbon brushes (74) are disposed at the second end of the housing (10) via an insulating plate (75). The insulating plate (75) is provided with two carbon brush mounting brackets (751). The rear ends of the two carbon brushes (74) are slidably disposed in the carbon brush mounting brackets (751) against the elastic element (76). The front ends of the two carbon brushes (74) are in sliding contact with the two conductive rings (71). The two carbon brushes (74) are used to electrically connect to the two electrodes of the external power control system respectively.

5. The external eccentric wheel assembly according to claim 1, characterized in that: An upper oil seal (90) and a lower oil seal (100) are provided at intervals along the axial direction of the drive shaft (20) between the first end of the housing (10) and the first end of the drive shaft (20) via a first retaining ring (80). The outer rings of the upper oil seal (90) and the lower oil seal (100) abut against the inner side of the first end of the housing (10). The inner rings of the upper oil seal (90) and the lower oil seal (100) are lip structures with wedges facing the outer side of the first end of the housing (10). The lip structure elastically abuts against the outer side of the first end of the drive shaft (20). A first airtight cavity (110) is formed between the upper oil seal (90) and the lower oil seal (100). The housing (10) has an air passage (12) that can be connected to an external air source in the side wall. The first retaining ring (80) has a notch facing the air outlet of the air passage (12). The air outlet of the air passage (12) is connected to the first airtight cavity (110). When the air passage (12) is connected to the external air source and gas is introduced into the first airtight cavity (110), the gas pushes open the lip structure wedge of the upper oil seal (90) and blows out from the gap between the upper oil seal (90) and the drive shaft (20) to the first end of the housing (10); the gas squeezes the other side of the lip structure wedge of the lower oil seal (100), thereby pressing the lower oil seal (100) against the drive shaft (20); forming an air curtain seal at the drive shaft (20).

6. The external eccentric wheel assembly according to claim 5, characterized in that: The housing (10) has a protective cover (120) on the first end opening. The protective cover (120) has a through hole with a gap through which the first end of the drive shaft (20) is exposed. The protective cover (120) is used to seal the upper side of the upper oil seal (90).

7. The external eccentric wheel assembly according to claim 6, characterized in that: The eccentric mounting part (21) has a locking nut (130) on the first end opening for locking the second bearing (50).

8. The external eccentric wheel assembly according to claim 7, characterized in that: A third oil seal (140) is provided between the inner side of the locking nut (130) and the driven shaft (40). The outer ring of the third oil seal (140) abuts against the inner side of the locking nut (130), and the inner ring of the third oil seal (140) is a lip structure with a wedge facing the outer side of the first end of the housing (10), and the lip structure elastically abuts against the outer side of the driven shaft (40). A first gap (131) is left between the outer side of the locking nut (130) and the first end opening of the eccentric mounting part (21), and a second gap (132) is left between the inner side of the locking nut (130) and the driven shaft (40). The second gap (132) is located on the side of the third oil seal (140) facing the first end of the housing (10). The first end sidewall of the drive shaft (20) is provided with a first through hole (23) to connect the first airtight cavity (110) with the first gap (131), and the sidewall of the locking nut (130) is provided with a second through hole (133) to connect the first gap (131) with the second gap (132). When gas enters the first gap (131) and the second gap (132) from the first airtight cavity (110), the gas is blown out from the gap between the locking nut (130) and the driven shaft (40) to the first end of the housing (10); the gas in the second gap (132) squeezes the other side of the wedge of the lip structure of the third oil seal (140), thereby pressing the third oil seal (140) against the driven shaft (40); forming an air curtain seal at the driven shaft (40).

9. The external eccentric wheel assembly according to claim 1, characterized in that: The second end of the drive shaft (20) is provided with a keyway hole (24) for connecting with an external drive motor to receive the first rotational power.

10. A polishing device, comprising an external power control system and an external drive motor electrically connected to the external power control system, characterized in that: It also includes an external eccentric wheel assembly as described in any one of claims 1 to 9, the external eccentric wheel assembly being poweredly connected to the external drive motor to receive a first rotational power, and the external eccentric wheel assembly being electrically connected to the external power control system to controllably drive the driven shaft (40) to rotate independently about its own axis. It also includes a pressure sensor electrically connected to the external power control system. The pressure sensor collects the grinding pressure between the workpiece and the grinding device and transmits it to the external power control system for real-time adjustment of the torque and speed of the driven shaft (40).

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