A type of star wheel

Abstract

This application provides a planetary wheel, belonging to the field of semiconductor manufacturing technology. The planetary wheel includes: a wheel body, at least one workpiece hole, and an inner liner; the workpiece hole penetrates the wheel body; the inner liner is disposed along the inner sidewall of the workpiece hole; wherein a limiting structure is provided between the contact surfaces of the inner sidewall of the workpiece hole and the outer sidewall of the inner liner, the limiting structure being used to restrict the axial and radial movement of the inner liner along the workpiece hole. During the polishing process, this planetary wheel can prevent the inner liner from being squeezed and causing axial warping or sinking, ensuring that the inner liner and the wheel body are coplanar in the thickness direction, maintaining surface flatness and consistency, thereby ensuring uniform force on the silicon wafer edge and improving the uniformity of edge geometric parameters.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a planetary wheel. Background Technology

[0002] In semiconductor manufacturing, double-sided polishing of silicon wafers is a crucial process for achieving high flatness and a damage-free surface. In this process, the silicon wafer is placed within specific holes on a planetary gear. Under the friction of the upper and lower polishing pads, the wafer undergoes planetary motion (revolution and rotation) with the planetary gear, thereby achieving material removal and surface planarization on both sides. Typically, the silicon wafer to be polished is a semi-finished product processed by etching or fine grinding, and its surface has a certain thickness of damaged layer or morphological deviations.

[0003] The planetary wheel plays a crucial role in maintaining the parallelism of the upper and lower polishing discs in this process. The final thickness and uniformity of the polished silicon wafer are indirectly ensured by controlling the difference between the wafer thickness and the planetary wheel thickness. To prevent mechanical damage to the wafer edges during polishing, the inner edge of the planetary wheel is usually fitted with a liner. This liner directly contacts the wafer edge, providing cushioning and protection. In existing technologies, the liner is generally made of polymer materials (such as polyurethane or polyoxymethylene) through injection molding, followed by polishing to achieve a thickness comparable to the planetary wheel body and ensure a flat and uniform surface.

[0004] Regarding the fixing structure between the planetary gear and the liner, a common solution is to create a dovetail groove structure on the inner ring sidewall of the planetary gear, and then injection mold or embed the liner into the dovetail groove. The dovetail groove structure can effectively restrict the movement of the liner in the plane direction of the planetary gear (i.e., radial and tangential), preventing the liner from coming off or moving around due to centrifugal force or friction during the polishing process.

[0005] However, in practical production applications, the existing structure still has shortcomings. Because the dovetail groove can only constrain the planar degrees of freedom (radial and tangential) of the liner, there is a lack of a reliable fixing or limiting mechanism between the liner and the planetary wheel body in the direction perpendicular to the planetary wheel disk surface (i.e., the thickness direction or axial direction). During double-sided polishing, the upper and lower polishing pads press the silicon wafer and planetary wheel together under certain pressure, accompanied by continuous relative sliding friction. Under these complex stress conditions, the liner is subjected to repeated compression and shearing from the polishing pads and the edge of the silicon wafer, easily causing slight misalignment or warping in the thickness direction, i.e., deformation or displacement in the vertical direction. Once the liner experiences vertical misalignment, its surface flatness (i.e., coplanarity with the planetary wheel disk surface) will be compromised, leading to uneven stress on the edge area of ​​the silicon wafer during polishing, ultimately affecting the uniformity of the geometric parameters of the silicon wafer edge, such as edge warping and abnormal edge removal. It is evident that the existing planetary gear and liner fixing structure can only restrict radial movement, but cannot effectively restrict axial movement, making it difficult to simultaneously meet the bidirectional positioning requirements of axial and radial directions. Therefore, how to provide a planetary gear that can simultaneously restrict the liner's axial and radial movement to maintain the flatness and consistency of the liner and planetary gear disk surface has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a planetary wheel to solve the problem that the fixing structure of the planetary wheel and the inner liner in the prior art can only restrict the radial movement of the silicon wafer and cannot effectively restrict the axial movement of the silicon wafer.

[0007] To achieve the above and other related objectives, this application provides a planetarium, comprising: The roulette wheel itself; At least one workpiece hole, the workpiece hole penetrating the wheel body; A liner is provided along the inner sidewall of the workpiece hole; A limiting structure is provided between the contact surfaces of the inner sidewall of the workpiece hole and the outer sidewall of the liner, the limiting structure being used to restrict the liner from moving axially and radially along the workpiece hole.

[0008] In one embodiment, the inner wall of the workpiece hole is provided with a plurality of grooves, and the limiting structure is disposed between the grooves and the inner liner.

[0009] In one embodiment, the groove is an irregularly shaped groove.

[0010] In one embodiment, the limiting structure includes a protruding limiting portion; the liner is an injection-molded part; a keyway is provided in the groove of the irregular groove, and the protruding limiting portion is formed and embedded in the keyway during the injection molding of the liner.

[0011] In one embodiment, the keyway is formed at the center of the irregular groove along the radial direction of the workpiece hole.

[0012] In one embodiment, the depth of the keyway is between 1 mm and 5 mm.

[0013] In one embodiment, the maximum length or maximum width of the keyway is between 0.3 mm and 0.8 mm.

[0014] In one embodiment, the limiting structure includes an embedded limiting portion; the edge of the inner wall of the workpiece hole located between adjacent irregular grooves extends into the inner liner to form the embedded limiting portion.

[0015] In one embodiment, the minimum height of the embedded limiting part is no greater than half the thickness of the inner lining.

[0016] In one embodiment, the width of the embedded limiting part is no more than 10mm.

[0017] As described above, the planetarium provided in this application has the following beneficial effects: The planetary wheel provided in this application, by setting a limiting structure between the contact surface of the inner wall of the workpiece hole and the outer wall of the liner, can simultaneously form a bidirectional limiting constraint on the liner in both the axial and radial directions, overcoming the defects of existing structures that can only limit in one direction and are prone to axial movement and misalignment of the liner. During the polishing process, this planetary wheel can prevent the liner from being squeezed and causing axial warping or sinking, ensuring that the liner and the wheel body are coplanar in the thickness direction, maintaining a flat and consistent surface, thereby making the silicon wafer edge subjected to uniform force and improving the uniformity of edge geometric parameters. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a planetary wheel in the prior art.

[0019] Figure 2 This is a schematic diagram of the structure of a workpiece hole in the prior art.

[0020] Figure 3 for Figure 2 Enlarged view of part A in the image.

[0021] Figure 4 Simulation diagram of edge parameters of each silicon wafer to polish silicon wafers using planetary gears before and after liner deformation in existing technology.

[0022] Figure 5 This is a schematic diagram of the planetary wheel provided in Embodiment 1 of this application.

[0023] Figure 6 This is a schematic diagram of the first structure of the keyway.

[0024] Figure 7 This is a schematic diagram of the second structure of the keyway.

[0025] Figure 8 This is a schematic diagram of the third type of keyway structure.

[0026] Figure 9 This is a schematic diagram of the fourth type of keyway structure.

[0027] Figure 10 This is a schematic diagram of the fifth structure of the keyway.

[0028] Figure 11 This is a schematic diagram of the sixth structure of the keyway.

[0029] Figure 12 This is a schematic diagram of the planetary wheel provided in Embodiment 2 of this application.

[0030] Figure 13 This is a schematic diagram of the first structure for embedding the limiting part.

[0031] Figure 14 This is a schematic diagram of the second structure for embedding the limiting part.

[0032] Figure 15 This is a schematic diagram of the third structure for embedding the limiting part.

[0033] Figure 16 This is a schematic diagram of the planetary wheel provided in Embodiment 3 of this application.

[0034] Figure 17 Simulation diagrams of edge parameters of each silicon wafer are generated to illustrate the use of planetary gears before and after deformation of the liner in the prior art and the planetary gears in Embodiment 3 of this application for polishing silicon wafers.

[0035] Component designation explanation 100, wheel body; 200, workpiece hole; 210, inner wall of workpiece hole; 220, dovetail groove; 300, inner liner; 400, groove; 410, protruding limiting part; 411, keyway; 420, embedded limiting part. Detailed Implementation

[0036] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present application.

[0037] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.

[0038] Please see Figures 1 to 17 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0039] In the semiconductor wafer fabrication field, double-sided polishing is a crucial process for the precision forming of silicon wafers. It primarily involves performing fine polishing on both sides of the etched or polished silicon wafer to ensure thickness uniformity and surface flatness. Double-sided polishing is performed using polishing equipment, which is equipped with a planetary wheel (such as...) between the upper and lower polishing discs. Figure 1 As shown, the planetary wheel's disk body 100 has a through workpiece hole 200. The silicon wafer is loaded into the workpiece hole 200 and rotates synchronously with the planetary wheel, achieving double-sided polishing through friction with the polishing pad. The planetary wheel uses its own thickness as a parallel reference for the upper and lower polishing disks. By controlling the thickness difference between the silicon wafer and the planetary wheel, the thickness and surface accuracy of the silicon wafer after polishing are precisely controlled.

[0040] To prevent the hard hole walls of the planetary gear from directly contacting the edge of the silicon wafer, which could cause defects such as edge chipping, scratches, and over-polishing of the edge, such as... Figure 2 As shown, in existing technology, an inner liner 300 is fitted onto the inner wall 210 of the workpiece hole of the planetary gear, thereby protecting the edge of the silicon wafer. The inner wall 210 of the workpiece hole is generally made of stainless steel; the inner liner 300 is generally manufactured using an injection molding and then integral polishing process to match the thickness of the planetary gear and ensure a smooth and uniform surface. By creating a dovetail groove 220 in the stainless steel inner wall of the workpiece hole 200, the radial displacement of the inner liner 300 is limited by the lateral constraint effect of the dovetail groove 220, thus achieving initial fixation of the inner liner 300.

[0041] like Figure 3 As shown, the existing dovetail groove 220 fixing structure has obvious defects, only achieving single radial limitation of the inner liner 300, and failing to effectively lock the axial displacement of the inner liner 300. During the polishing process, the inner liner 300 is continuously subjected to bidirectional compression and friction between the polishing pad and the silicon wafer, making it extremely prone to axial misalignment, loosening, and deformation, which damages the flatness of the inner liner 300 itself and affects the uniformity of the silicon wafer edge parameters (such as...). Figure 4 As shown in the figure, the silicon wafer polishing yield is reduced, which cannot meet the processing requirements of ultra-high precision double-sided polishing of high-end semiconductor wafers.

[0042] To address the above-mentioned deficiencies and background technology, this application provides a planetary wheel. The following embodiments will provide a detailed description.

[0043] Example 1 This embodiment provides a planetary wheel, such as Figure 1 and Figure 5 As shown, the device includes a wheel body 100, at least one workpiece hole 200, and an inner liner 300. The workpiece hole 200 penetrates the wheel body 100; the inner liner 300 is disposed along the inner sidewall 210 of the workpiece hole; a limiting structure is provided between the contact surfaces of the inner sidewall 210 of the workpiece hole and the outer sidewall of the inner liner 300, the limiting structure being used to restrict the axial and radial movement of the inner liner 300 along the workpiece hole 200.

[0044] The planetary wheel provided in this embodiment, by setting a limiting structure between the inner sidewall 210 of the workpiece hole and the outer sidewall of the inner liner 300 to simultaneously restrict the axial and radial movement of the inner liner 300, can reduce the axial warping or sinking of the inner liner 300 due to compression during the polishing process. This helps to keep the inner liner 300 and the wheel body 100 coplanar in the thickness direction, maintain surface flatness and consistency, thereby making the silicon wafer edge subjected to uniform force and improving the uniformity of edge geometric parameters (such as reducing edge warping and controlling the consistency of removal amount).

[0045] As one implementation method, such as Figure 5 As shown, the inner wall 210 of the workpiece hole is provided with a plurality of grooves 400, which are spaced apart circumferentially along the inner wall 210 of the workpiece hole, and the interval between two adjacent grooves 400 is equal. The limiting structure is provided between the grooves 400 and the inner liner 300, which can utilize the multi-point or continuous interlocking interface provided by the grooves 400 to enhance the bonding stability between the limiting structure and the wheel body 100. This helps to more evenly disperse the extrusion and shear forces from the inner liner 300 during the polishing process, thereby further reducing the possibility of local warping or axial misalignment of the inner liner 300 and improving the consistency of the inner liner 300 and the wheel body 100 in the thickness direction.

[0046] In one implementation, the groove 400 is an irregularly shaped groove. This irregularly shaped groove forms a non-linear interlocking interface with the inner liner 300. Compared to a regular rectangular groove, it enhances the degree of mechanical interlocking, more effectively transferring the compressive and shear forces borne by the inner liner 300 to the wheel body 100. This reduces the tendency for the inner liner 300 to axially shift or edge warping during polishing, and helps maintain the thickness consistency between the inner liner 300 and the wheel body 100 over the long term. Optionally, the irregularly shaped groove can be a dovetail groove.

[0047] As one implementation method, such as Figure 5 As shown, the limiting structure includes a protruding limiting part 410; the inner liner 300 is an injection-molded part; as Figures 5 to 11As shown, a keyway 411 is provided in the groove of the irregular groove, and a protruding limiting part is formed in the keyway 411 during the injection molding of the liner 300. By injection molding the liner 300 and directly embedding the protruding limiting part 410 into the inner wall 210 of the workpiece hole, a mechanical interlocking structure can be integrally formed during the molding process, reducing subsequent assembly steps; at the same time, the fitting method between the inner wall 210 of the workpiece hole and the protruding limiting part helps to improve the anti-displacement capability of the liner 300 in the axial and radial directions, reduce the risk of misalignment or warping of the liner 300 due to extrusion during the polishing process, and thus help to maintain the thickness consistency between the liner 300 and the wheel body 100.

[0048] As one implementation method, such as Figure 5 As shown, the keyway 411 is formed at the center of the irregular groove along the radial direction of the workpiece hole 200 and extends towards the inner wall 210 of the workpiece hole, so that the protruding limiting part 410 formed by injection molding of the inner liner 300 can be symmetrically embedded in the inner wall 210 of the workpiece hole. The protruding limiting part 410 is symmetrically distributed in the central force-bearing area of ​​the wheel body 100, which helps to more evenly transmit the radial and axial loads from the inner liner 300 during the polishing process, reduces the local stress concentration that may be caused by the offset structure, and thus helps to improve the positional stability of the inner liner 300 during long-term use. Optionally, as Figure 5 As shown, along the tangential direction of AA, the shape of the keyway 411 can be a regular shape, such as a circle (e.g., ...). Figure 6 As shown), rectangle (as shown) Figure 7 As shown), triangle (as shown) Figure 8 As shown), rhombus (as shown) Figure 9 As shown), cross-shaped (as shown) Figure 10 (as shown), or it can be an irregular shape (such as...) Figure 11 As shown in the figure, the shape of the keyway 411 can be selected according to the actual processing, and this embodiment does not impose specific limitations.

[0049] As one implementation method, such as Figure 5 As shown, the depth of the keyway 411 is between 1 mm and 5 mm. Optionally, the depth of the keyway 411 can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc. Controlling the depth of the keyway 411 within the above range helps to provide sufficient fitting depth while avoiding difficulties in injection molding or a decrease in local strength of the wheel body 100 due to an excessively deep keyway 411. This depth range enables the protruding limiting part 410 formed by injection molding of the liner 300 to obtain a more reliable axial and radial positioning capability, which helps to reduce the possibility of misalignment or warping of the liner 300 during polishing, thereby achieving a relative balance between processing convenience and limiting stability.

[0050] In one implementation, the maximum length or maximum width of the keyway 411 is between 0.3mm and 0.8mm. Specifically, the maximum length or maximum width of the keyway 411 refers to the longest line segment or the widest line segment selected after connecting two opposite boundary points of the keyway 411 in a cross-sectional view of the keyway 411. The length of this line segment is the maximum length or maximum width of the keyway 411. For example, selecting... Figure 6 The diameter of the circular keyway is equal to its maximum length; select Figure 7 The length of the square keyway is the maximum length; select Figure 8 The maximum side length of the triangular keyway is the maximum length; select Figure 9 The longest diagonal of the central diamond keyway is the maximum length; select Figure 10 The longest straight-line distance between the two opposite sides of the cross-shaped keyway is the maximum length; select Figure 11 The maximum length is the farthest distance between the two opposite boundaries of the irregularly shaped keyway. Optionally, the maximum length or maximum width of the keyway 411 can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc. These ranges help to arrange multiple limiting structures within a limited space, while avoiding significant weakening of the local strength of the wheel body 100 due to an excessively large keyway 411; they also facilitate the formation of a clearly contoured and fully filled raised limiting part during the injection molding of the inner liner 300, thereby improving the fitting reliability and position retention capability of the limiting structure.

[0051] Example 2 This embodiment also provides a planetary wheel, such as Figure 1 and Figure 12 As shown, the device includes a wheel body 100, at least one workpiece hole 200, and an inner liner 300. The workpiece hole 200 penetrates the wheel body 100; the inner liner 300 is disposed along the inner sidewall 210 of the workpiece hole; a limiting structure is provided between the contact surfaces of the inner sidewall 210 of the workpiece hole and the outer sidewall of the inner liner 300, the limiting structure being used to restrict the liner 300 from moving axially and radially. This embodiment differs from Embodiment 1 in that: like Figure 12 As shown, the limiting structure includes an embedded limiting portion 420; the edge of the inner wall 210 of the workpiece hole located between adjacent irregular grooves extends into the inner liner 300 to form the embedded limiting portion 420. This embedded limiting portion 420 can form an embedded constraint on the inner liner 300 from the area between adjacent circumferential grooves, which helps to distribute the extrusion pressure from different directions during the polishing process and reduces the possibility of the inner liner 300 edge lifting or overall displacement.

[0052] Two adjacent irregularly shaped grooves are named the first irregularly shaped groove and the second irregularly shaped groove. The axis of symmetry between the first and second irregularly shaped grooves is located in the inner wall 210 of the workpiece hole between them, and the embedding limiting part 420 is also symmetrical about this axis of symmetry. Specifically, the embedding limiting part 420 includes at least a first gradient segment and a second gradient segment. The first gradient segment gradually extends from the edge of the first irregularly shaped groove towards the interior of the inner lining 300, and the second gradient segment gradually extends from the edge of the second irregularly shaped groove towards the interior of the inner lining 300. When the embedding limiting part 420 includes only the first gradient segment and the second gradient segment, both the first gradient segment and the second gradient segment are smooth curve segments to achieve direct connection (e.g., ...). Figure 13 (As shown). When the embedded limiting part 420 includes a first gradient segment, a second gradient segment, and an embedded segment connecting the first gradient segment and the second gradient segment, the first gradient segment and the second gradient segment can be inclined straight line segments, and the embedded segment is a vertical straight line segment (as shown). Figure 14 As shown); the first and second gradient segments can also be smooth curve segments, and the embedded segment is a vertical straight line segment (such as...). Figure 15 (As shown). However, it is not limited to the above structure; any structure that can achieve an embedded structure between the inner wall 210 of the workpiece hole and the inner liner 300 is acceptable, rather than like... Figure 3 There is no interlocking between the edge of the inner wall 210 of the workpiece hole and the edge of the inner liner 300; there is only a clear straight boundary.

[0053] As one implementation method, such as Figures 13 to 15 As shown, the minimum height of the embedded limiting part 420 is no greater than half the thickness of the inner lining 300 (the thickness direction of the inner lining 300 is perpendicular to the inner lining 300). Figures 13 to 15 The vertical direction is parallel, which helps to avoid excessive occupation of the thickness space of the liner 300 while providing effective axial constraint. This reduces the possibility of poor local injection filling or weakening of structural strength of the liner 300 due to excessive embedding. It is conducive to achieving a reasonable balance between the reliability of the limit and the integrity of the liner 300 itself.

[0054] As one embodiment, the width of the embedded limiting part 420 is no greater than 10mm (e.g., Figures 13 to 15 As shown, the embedded limiting part 420 is the portion embedded within the inner lining 300, and its width direction is perpendicular to... Figures 13 to 15 The horizontal direction is parallel, which helps to avoid significant obstruction to the injection flow of the inner liner 300 due to excessive width of the limiting part, while reducing the risk of local stress concentration; this width range can maintain the continuity of the inner liner 300 structure while providing sufficient lateral support area, which is beneficial to balancing the limiting effect and the injection molding quality.

[0055] Example 3 This embodiment also provides a planetary wheel, such as Figure 1 and Figure 16As shown, the device includes a wheel body 100, at least one workpiece hole 200, and an inner liner 300. The workpiece hole 200 penetrates the wheel body 100; the inner liner 300 is disposed along the inner sidewall 210 of the workpiece hole; a limiting structure is provided between the contact surfaces of the inner sidewall 210 of the workpiece hole and the outer sidewall of the inner liner 300, the limiting structure being used to restrict the liner 300 from moving axially and radially. This embodiment differs from Embodiment 1 or Embodiment 2 in that: The limiting structure includes a raised limiting part 410 and an embedded limiting part 420. A keyway 411 is provided within the groove of the irregularly shaped groove. During injection molding, the liner 300 forms a raised limiting part embedded within the keyway 411. The edge of the inner wall 210 of the workpiece hole located between adjacent irregularly shaped grooves extends into the liner 300 to form the embedded limiting part 420. By combining the raised limiting part 410 and the embedded limiting part 420, two different limiting structures can be alternately formed circumferentially within the same workpiece hole 200. This helps to distribute the load borne by the liner 300 from multiple directions, reducing the risk of axial movement or circumferential displacement of the liner 300 during polishing. Simultaneously, it reduces reliance on a single limiting form, improving the overall structural adaptability and stability.

[0056] By simulating the planetary gear in Example 3 and the planetary gear in the prior art, the edge parameters of the silicon wafer after polishing under the above conditions were compared, such as... Figure 17 As shown, the edge parameter consistency of the silicon wafer after polishing with the planetary wheel provided in this embodiment is improved by at least 5%.

[0057] As one implementation method, the limiting structure can be formed by: first machining a V-shaped groove before cutting the dovetail groove, so that the mating position of the planetary gear liner 300 is chamfered (i.e., the structure of the embedded limiting part 420 is formed later), and after machining the dovetail groove, drilling a hole of 0.3mm to 0.8mm in the center of the dovetail groove (i.e., the structure of the raised limiting part 410 is formed later). After injection molding, the liner 300 restricts the radial direction through the dovetail groove, and restricts the axial and radial directions through the raised limiting part 410 and the embedded limiting part 420.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A planetary wheel, characterized in that, include: The roulette wheel itself; At least one workpiece hole, the workpiece hole penetrating the wheel body; A liner is provided along the inner sidewall of the workpiece hole; A limiting structure is provided between the contact surfaces of the inner sidewall of the workpiece hole and the outer sidewall of the liner, the limiting structure being used to restrict the liner from moving axially and radially along the workpiece hole.

2. The planetary wheel according to claim 1, characterized in that, The inner wall of the workpiece hole is provided with multiple grooves, and the limiting structure is disposed between the grooves and the inner lining.

3. The planetary wheel according to claim 2, characterized in that, The groove is an irregularly shaped groove.

4. The planetary wheel according to claim 3, characterized in that, The limiting structure includes a protruding limiting part; the inner liner is an injection molded part; a keyway is provided in the groove of the irregular groove, and the protruding limiting part is formed and embedded in the keyway during the injection molding of the inner liner.

5. The planetary wheel according to claim 4, characterized in that, The keyway is formed at the center of the irregular groove along the radial direction of the workpiece hole.

6. The planetary wheel according to claim 5, characterized in that, The depth of the keyway is between 1mm and 5mm.

7. The planetary wheel according to claim 5 or 6, characterized in that, The maximum length or maximum width of the keyway is between 0.3mm and 0.8mm.

8. The planetary wheel according to claim 3, characterized in that, The limiting structure includes an embedded limiting portion; the edge of the inner wall of the workpiece hole located between adjacent irregular grooves extends into the inner liner to form the embedded limiting portion.

9. The planetary wheel according to claim 8, characterized in that, The minimum height of the embedded limiting part is no more than half the thickness of the inner lining.

10. The planetary wheel according to claim 8, characterized in that, The width of the embedded limiting part is no more than 10mm.

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