Cycloidal gear, method for modifying cycloidal gear, and cycloidal pin gear planetary drive device

Abstract

The present disclosure relates to the technical field of mechanical drive. Specifically provided are a cycloidal gear, a method for modifying a cycloidal gear, and a cycloidal pin gear planetary drive device. The tooth profile of the cycloidal gear comprises non-meshing tooth tip sections, meshing working tooth sections and non-meshing tooth root sections, wherein the tooth surface of each working tooth section is a theoretical rotated-angle tooth surface or a combined modified tooth surface approximating the theoretical rotated-angle tooth surface, the tooth tip sections and the tooth root sections each comprise a non-working tooth section and a transition section, and each non-working tooth section is connected to a working tooth section by means of a transition section. The transition sections are formed on the cycloidal gear and are each located between a working tooth section and a non-working tooth section. Therefore, when there are different drive gaps between the sections of the cycloidal gear, roller pins can smoothly transition between the sections of the cycloidal gear. Modifying each working tooth section of the cycloidal gear to make same have a theoretical rotated-angle tooth surface or a combined modified tooth surface approximating the theoretical rotated-angle tooth surface does not require the combined modification of the entire tooth profile, thereby improving machining accuracy and efficiency and reducing manufacturing costs.

Description

A cycloidal wheel, a method for modifying the shape of the cycloidal wheel, and a cycloidal pinwheel planetary transmission device.

[0001] Cross-reference to related applications

[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202411808832.6, filed on December 10, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of mechanical transmission technology, and in particular to a cycloidal wheel, a method for modifying the shape of the cycloidal wheel, and a cycloidal pinwheel planetary transmission device. Background Technology

[0004] In related technologies, cycloidal gears in transmission devices such as speed reducers need to be modified to obtain the meshing working tooth segment and the non-meshing non-working tooth segment. Modification typically involves uniform modification of the entire tooth to achieve a reasonable meshing clearance, compensate for actual manufacturing and installation errors, and ensure a sufficient number of teeth meshing simultaneously, so that the working tooth segment approximates the conjugate tooth profile as closely as possible. Modification methods include equidistant modification, torque-shifting modification, angle modification, and combined modification. Combined modification typically combines equidistant modification with torque-shifting modification. However, uniform modification of the entire tooth makes it difficult to determine the boundary between the working and non-working tooth segments, failing to meet the technical requirements for high-precision cycloidal gears and hindering improvements in speed reducer performance and cost reduction. Summary of the Invention

[0005] In view of this, the present disclosure aims to provide a cycloidal wheel, a method for modifying the cycloidal wheel, and a cycloidal pinwheel planetary transmission device, which can improve transmission accuracy and reduce manufacturing costs.

[0006] A first aspect of this disclosure provides a cycloidal wheel, the tooth profile of which includes a non-meshing tooth tip section, a meshing working tooth section, and a non-meshing tooth root section. The tooth surface of the working tooth section is a combination of a rotational theoretical tooth surface or a modified tooth surface that approximates the rotational theoretical tooth surface. Both the tooth tip section and the tooth root section include a non-working tooth section and a transition section, and the non-working tooth section is connected to the working tooth section through the transition section.

[0007] In some embodiments, the non-working tooth segment includes a non-working tooth tip segment located in the tooth tip segment and a non-working tooth root segment located in the tooth root segment;

[0008] The tooth surface of the non-working section at the tooth tip is a first arc surface, and the center of the first arc surface is the center of the cycloidal wheel;

[0009] The tooth surface of the non-working section of the tooth root is a positively equidistant tooth surface of the standard theoretical tooth surface, or a second arc surface that approximates the positively equidistant tooth surface.

[0010] In some embodiments, the non-working tooth segment includes a non-working tooth tip segment located in the tooth tip segment and a non-working tooth root segment located in the tooth root segment;

[0011] The tooth surface of the non-working section at the tooth tip is a positively equidistant tooth surface of the standard theoretical tooth surface, or a third arc surface that approximates the positively equidistant tooth surface;

[0012] The tooth surface of the non-working section of the tooth root is a positively equidistant tooth surface of the standard theoretical tooth surface, or a second arc surface that approximates the positively equidistant tooth surface.

[0013] In some embodiments, the tooth surface of the transition section is an arc surface or a plane.

[0014] The cycloidal wheel provided in this embodiment has transition sections at the connection between the working tooth segment and the tooth tip segment, and transition sections at the connection between the working tooth segment and the tooth root segment. The cycloidal wheel has transition sections located between the working tooth segment and the non-working tooth segment. This allows the needle rollers to smoothly transition between the different segments of the cycloidal wheel when there are different transmission clearances. By modifying the working tooth segment of the cycloidal wheel to a theoretical tooth surface of rotation angle or a combined modified tooth surface approximating the theoretical tooth surface of rotation angle, it is not necessary to perform combined modification of the entire tooth profile, which can improve machining accuracy and efficiency, and reduce manufacturing costs.

[0015] A second aspect of this disclosure provides a method for modifying the shape of a cycloidal wheel, applied to the cycloidal wheel described above. The combined modification of the tooth surface is performed using a combined modification method, which includes a combination of an equidistant modification method and a displacement modification method.

[0016] In some embodiments, the combined shaping method includes a combination of positive isometric shaping and positive displacement shaping, wherein the shaping value of the positive isometric shaping is greater than the shaping value of the positive displacement shaping; or,

[0017] The combined shaping method includes a combination of negative equidistant shaping and negative displacement shaping, wherein the shaping value of the negative equidistant shaping is less than the shaping value of the negative displacement shaping.

[0018] This disclosure also provides a method for modifying a cycloidal wheel, applied to the cycloidal wheel described above, wherein the non-working tooth section is modified using wire cutting or coordinate grinding processes.

[0019] This disclosure also provides a method for modifying the shape of a cycloidal wheel, applied to the cycloidal wheel described above, wherein the working tooth segment is modified using coordinate grinding, profile grinding, slow wire cutting, or generating precision grinding processes.

[0020] In some embodiments, the shaping method further includes:

[0021] The working tooth segment is precision machined and shaped, and the tooth root segment is also precision machined and shaped.

[0022] The cycloidal wheel modification method provided in this disclosure can increase the number of teeth simultaneously meshing on the cycloidal wheel, and each segment of the tooth profile has a suitable transmission clearance. This improves the transmission accuracy and efficiency of the cycloidal wheel, reduces manufacturing costs, avoids high-pressure angle torque transmission in the non-working sections of the pin teeth, and makes the transmission smoother and reduces noise.

[0023] A third aspect of this disclosure provides a cycloidal pinwheel planetary transmission device, including the aforementioned cycloidal wheel or a cycloidal wheel obtained by the aforementioned cycloidal wheel shaping method.

[0024] This disclosure also provides a cycloidal pinwheel planetary transmission device, including:

[0025] The cycloidal wheel described above;

[0026] The housing has needle-tooth grooves;

[0027] The needle roller is disposed within the needle tooth groove;

[0028] The cross-section of the needle groove is larger than a semicircle, and the needle roller is at least partially exposed in the needle groove so as to be able to contact the cycloidal wheel.

[0029] In some embodiments, the needle groove is formed by wire cutting, coordinate grinding or broaching.

[0030] This disclosure also provides a cycloidal pinwheel planetary transmission device, including:

[0031] The cycloidal wheel described above;

[0032] The housing has needle-tooth grooves;

[0033] The needle roller is disposed within the needle tooth groove;

[0034] The cross-section of the needle groove is smaller than a semicircle.

[0035] In some embodiments, the needle groove is formed by a forming grinding process.

[0036] In some embodiments, the needle groove includes a non-meshing groove top section, a meshing working groove section, and a non-meshing groove bottom section;

[0037] The working groove section has a corner-shaped curved arc with a radius equal to the radius of the needle roller. The groove top section and the groove bottom section both have curved arcs with a radius greater than that of the needle roller. The groove top section and the groove bottom section are connected to the working groove section. Attached Figure Description

[0038] Figure 1 is a schematic diagram of the housing of a cycloidal pinwheel reducer in the related technology (where the cross-section of the pin tooth groove is smaller than a semicircle);

[0039] Figure 2 is a schematic diagram of the structure of the cycloidal wheel in the related technology;

[0040] Figure 3 is a schematic diagram of the modification of the cycloidal wheel in this disclosure;

[0041] Figure 4 is a magnified structural diagram of point A in Figure 3;

[0042] Figure 5 is a magnified structural diagram of point B in Figure 3;

[0043] Figure 6 shows the geometric relationship between the pressure angle and the meshing phase angle of the cycloidal wheel, where the vertical axis represents the pressure angle and the horizontal axis represents the meshing phase angle.

[0044] Figure 7 is a schematic diagram of the housing of a cycloidal pinwheel reducer in one embodiment of the present disclosure (wherein the cross-section of the pin tooth groove is larger than a semicircle);

[0045] Figure 8 is a schematic diagram of the structure of the cycloidal wheel in one embodiment of the present disclosure;

[0046] Figure 9 is a partial structural schematic diagram of the cycloidal gear tooth profile shown;

[0047] Figure 10 is a schematic diagram of the cycloidal wheel in the second embodiment of this disclosure;

[0048] Figure 11 is a partial structural schematic diagram of the cycloidal gear tooth profile shown;

[0049] Figure 12 is a schematic diagram of the modification of a portion of the needle groove in the housing in an embodiment of the present disclosure (wherein, the cross-section of the needle groove is larger than a semicircle);

[0050] Figure 13 is a schematic diagram of the modification of a portion of the needle groove in the housing in an embodiment of the present disclosure (wherein the cross-section of the needle groove is smaller than a semicircle). Detailed Implementation

[0051] The embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of this disclosure.

[0052] It should be noted that the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this specification, references to terms such as "some embodiments," "exemplarily," etc., mean that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the embodiments of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine different embodiments or examples and features of different embodiments or examples described in this disclosure without contradiction. In this disclosure, "multiple" refers to two or more.

[0053] In related technologies, please refer to Figures 1 and 2. To improve the manufacturing precision of the reducer, the pin tooth groove 10a1 of the housing 101 and the tooth profile of the cycloidal wheel 20 are both formed by profile grinding precision grinding. The cross-section of the pin tooth groove 10a1 can only be less than or equal to a semicircle. When the reducer is running, the needle rollers cannot maintain their designed center position in the pin tooth groove 10a1, and more than half of the needle rollers roll ineffectively relative to the cycloidal wheel 20. The cycloidal wheel tooth profile must be uniformly formed by profile grinding using a combined shaping method, which limits the improvement of reducer precision and keeps the processing cost high. The cycloidal wheel is processed using a full-tooth combined shaping method. Full-tooth combined shaping is generally based on the theory of generating method, adjusting the processing parameters to process the tooth profile so that after the cycloidal wheel is applied to the reducer, the meshing clearance between the cycloidal wheel and the needle rollers gradually increases from the working area to the non-working area, that is, from the middle of the tooth surface to the tooth tip or tooth root, the meshing clearance gradually increases.

[0054] To improve the transmission accuracy of the cycloidal wheel and needle rollers, the profile of the cycloidal wheel is precision machined. However, it is difficult to achieve the accuracy requirements of a high-precision cycloidal reducer with a fully modified tooth surface, resulting in low production efficiency and high cost. Therefore, this disclosure provides a cycloidal wheel, as shown in Figures 3-5. The tooth profile of the cycloidal wheel includes a non-meshing tooth tip section 211, a meshing working tooth section 213, and a non-meshing tooth root section 212. The tooth surface of the working tooth section 213 is a combination of a rotation angle theoretical tooth surface or a modified tooth surface approximating the rotation angle theoretical tooth surface. Both the tooth tip section 211 and the tooth root section 212 include a non-working tooth section and a transition section 210. The non-working tooth section is connected to the working tooth section 213 through the transition section 210. Figure 3 shows the tooth profile of the equidistant tooth surfaces of the tooth tip section 211 and the tooth root section 212, the tooth profile of the rotation angle theoretical tooth surface of the working tooth section 213, and a comparison with the standard theoretical tooth profile 2100.

[0055] When the tooth profile 21 of the cycloidal wheel 20 meshes with the needle roller, it can be divided into a non-meshing tooth tip section 211, a meshing working tooth section 213, and a non-meshing tooth root section 212. The working tooth section 213 refers to the tooth surface that participates in conjugate meshing during the transmission of motion and torque. For example, the tooth profile area of ​​the working tooth section 213 is less than one-third of the total tooth profile area of ​​the cycloidal wheel 20.

[0056] To obtain the tooth tip section 211, working tooth section 213, and tooth root section 212, the cycloidal gear needs to be modified. Cycloidal gear modification involves correcting the standard theoretical tooth profile. For example, when the cycloidal gear is used in a cycloidal pinwheel planetary reducer, the cycloidal gear meshes with the needle rollers to transmit torque and power. To avoid interference between the cycloidal gear tooth profile and the needle rollers during meshing, affecting transmission, modification is needed to achieve appropriate clearances between the cycloidal gear and the needle rollers in different tooth profile sections, thereby improving transmission accuracy. Before modification, based on the distribution pattern of the pressure angle and meshing phase angle at various points on the tooth profile 21 of the cycloidal gear 20, a geometric relationship diagram (or table) of the pressure angle and meshing phase angle at each point on the tooth profile 21 of the cycloidal gear 20 is created, as shown in Figure 6. Here, L3 corresponds to the meshing working tooth section 213, and L1 and L2 correspond to the non-meshing tooth tip section 211 and tooth root section 212. A maximum permissible pressure angle, such as 50°, is selected, and the tooth tip segment 211, working tooth segment 213, and tooth root segment 212 are divided based on this maximum permissible pressure angle. The meshing phase angles corresponding to the maximum permissible pressure angle are θb1 and θb2, which are the two endpoints of the working tooth segment 213. Specifically, parameters such as the center circle radius, number of teeth, and eccentricity of the needle roller can be input into a MATLAB program for calculation, yielding a geometric relationship diagram of the parametric equations between the pressure angle and the meshing phase angle. This diagram can determine the phase angles at the start and end points of the cycloidal gear meshing. Simultaneously, the number of meshing teeth is a crucial parameter in the design calculation of the cycloidal reducer, controlling the meshing pressure angle within the permissible range. Clarifying the boundaries of the tooth tip segment 211, working tooth segment 213, and tooth root segment 212 forms the basis of this disclosed segmented modification method. Modification methods include equidistant modification, displacement modification, angle modification, and combined modification. The combined modification method is a combination of equidistant modification and displacement modification. The equidistant shaping method refers to appropriately adjusting the radius of the cutting tool, such as a grinding wheel or polishing wheel, during the machining of the tooth profile 21 of the cycloidal wheel 20, thereby shaping the tooth profile 21. When the radius of the cutting tool's radius is greater than the set radius of the needle roller, it is a positive equidistant shaping; when the radius of the cutting tool's radius is less than the set radius of the needle roller, it is a negative equidistant shaping. The displacement shaping method refers to moving the cutting tool, such as a grinding wheel or polishing wheel, a certain distance radially from the set needle roller center circle position relative to the center of the machining table during the machining of the tooth profile 21 of the cycloidal wheel 20, thereby shaping the tooth profile 21 of the cycloidal wheel 20. When the cutting tool moves towards the worktable, it is a negative displacement shaping; when the cutting tool moves away from the worktable, it is a positive displacement shaping. The corner-shaped shaping method refers to the process of rotating the cycloidal wheel 20 around its own center by a certain angle relative to the position of the cutting tool or grinding wheel during the initial machining, or rotating the worktable around its own center by a certain angle, thereby shaping the tooth profile 21 of the cycloidal wheel 20.

[0057] The tooth surface of the working tooth segment 213 is either a tooth surface based on the rotation theory or a combined modified tooth surface that approximates the rotation theory tooth surface. The rotation theory tooth surface is obtained by modifying the tooth surface according to the rotation theory, while the combined modified tooth surface is obtained by modifying the tooth surface according to the combined modification method, approximating the rotation theory tooth surface. For example, the combined modification method includes a combination of positive equidistant modification and positive displacement modification, where the modification value of positive equidistant modification is greater than that of positive displacement modification; or, the combined modification method includes a combination of negative equidistant modification and negative displacement modification, where the modification value of negative equidistant modification is less than that of negative displacement modification. Using a combined modification of negative equidistant modification and negative displacement modification to correct the tooth profile curve can reduce the backlash caused by the meshing of the working tooth segment 213 tooth surface with the needle roller.

[0058] It should be noted that the tooth surface of the working tooth segment in the tooth profile is a combination of the theoretical tooth surface of the rotation angle or a modified tooth surface that approximates the theoretical tooth surface of the rotation angle. The non-working segment and the transition segment use different shaping methods than the working tooth segment. For example, referring to Figure 7, the cross-section of the needle groove 10a on the housing 10 of the cycloidal pinwheel planetary reducer is larger than a semicircle. The needle roller can maintain its rotation at the design center position in the needle groove 10a. The needle roller and the cycloidal wheel 20 do not contact each other in the non-working tooth segment of the tooth tip segment 211, so there is no need to perform full tooth surface combination shaping according to the conjugate tooth surface. That is to say, the tooth tip segment 211 can be shaped using concentric circular arcs, thereby improving processing efficiency and reducing manufacturing costs. Because there will be obvious contour changes at the junction of the tooth tip segment and the tooth root segment with the working tooth segment, a transition segment 210 is required to make the transition of the needle roller between the segments of the cycloidal wheel smoother. For example, the tooth surface of the transition segment 210 can be a circular arc surface or a plane. The cycloidal wheel 20 provided in this embodiment has a transition section 210 at the connection between the working tooth segment 213 and the tooth tip segment 211, and a transition section 210 at the connection between the working tooth segment 213 and the tooth root segment 212. Referring to Figure 3, the cycloidal wheel 20 has a transition section 210 located between the working tooth segment 213 and the non-working tooth segment. This allows the needle rollers to smoothly transition between different segments of the cycloidal wheel when there are different transmission clearances. By modifying the working tooth segment 213 of the cycloidal wheel 20 into a combined modified tooth surface that approximates the theoretical tooth surface of the rotation angle, it is not necessary to perform combined modification of the entire tooth profile, which can improve processing efficiency and reduce manufacturing costs.

[0059] In some embodiments, the non-working tooth segment includes a non-working tooth tip segment located at the tooth tip segment 211 and a non-working tooth root segment located at the tooth root segment 212.

[0060] The tooth surface of the non-working section at the tooth tip is the first arc surface, and the center of the first arc surface is the center of the cycloidal wheel 20;

[0061] The tooth surface of the non-working section of the tooth root is the equidistant tooth surface of the standard theoretical tooth surface, or the second arc surface that approximates the equidistant tooth surface.

[0062] In some embodiments, the cycloidal wheel 20 is modified, including machining the non-working section of the tooth tip.

[0063] For example, referring to Figures 8 and 9, the non-working section at the tooth tip is machined and shaped into a first arc surface, the center of which is the center of the cycloidal wheel 20. In this way, making the non-working section at the tooth tip an arc surface reduces the material and machining costs of the cycloidal wheel 20, eliminating the need for a finishing allowance for the non-working section; rough machining during material preparation is sufficient. This saves time and reduces manufacturing costs.

[0064] For example, referring to Figures 10 and 11, the non-working section at the tooth tip is machined and shaped to a positively equidistant tooth surface of the standard theoretical tooth surface. That is, the shape is shaped according to the positively equidistant correction curve. There is a uniform gap between the wheel and the teeth, which can prevent the needle rollers from meshing with the cycloidal wheel 20 at a high pressure angle, thereby reducing the transmission noise of the cycloidal pinwheel reducer.

[0065] For example, the non-working section at the tooth tip is machined and shaped into a third arc surface that approximates the equidistant tooth surface. In other words, the equidistant tooth surface is decomposed into multiple segments, and multiple arc segments are used to approximate the equidistant tooth surface. These multiple arc segments are connected to form a third arc surface, which can reduce the machining difficulty.

[0066] In some embodiments, machining and shaping the cycloidal wheel 20 further includes machining and shaping the non-working section of the tooth root.

[0067] For example, please refer to Figures 8-11, where the non-working section of the tooth root is machined and modified to a positively equidistant tooth surface of the standard theoretical tooth surface. That is, the modification is performed according to the positively equidistant correction curve, resulting in a uniform gap between the wheel and the tooth. This avoids the needle rollers meshing with the cycloidal wheel 20 at a high pressure angle, thereby reducing the transmission noise of the cycloidal pinwheel reducer.

[0068] For example, the non-working section of the tooth root is machined and shaped into a second arc surface that approximates the equidistant surface. In other words, the equidistant tooth surface is decomposed into multiple segments, and multiple arc segments are used to approximate the equidistant tooth surface. The multiple arc segments are connected to form the second arc surface, which can reduce the machining difficulty.

[0069] Specifically, the machining and shaping of the non-working sections of the tooth root and the non-working sections of the tooth tip can be adapted to the actual meshing transmission requirements.

[0070] This disclosure also provides a method for modifying a cycloidal wheel 20, applied to the aforementioned cycloidal wheel 20, the method comprising:

[0071] The cycloidal wheel is preliminarily machined and shaped to form the tooth tip and tooth root sections, and machining allowance is left for the working tooth sections;

[0072] After preliminary machining and shaping, the working tooth segment is then precision machined and shaped. The machining accuracy of the working segment is greater than that of the tooth tip and tooth root segments.

[0073] Whether machining allowance is needed for the tooth tip and root sections depends on specific requirements. It's possible to only perform preliminary machining to obtain the tooth tip and root sections; or, machining allowance can be left for further finishing and shaping of the tooth tip and / or root sections. Understandably, the finishing precision of the tooth tip and / or root sections can be the same as or different from the finishing precision of the working tooth sections.

[0074] For example, when the working tooth section is precision machined and shaped, the tooth root section is also precision machined and shaped at the same time. This can improve the meshing accuracy between the cycloidal wheel 20 and the needle roller.

[0075] For example, when performing finishing and shaping on the working tooth segment, simultaneously performing finishing and shaping on the tooth root segment includes: while performing finishing and shaping on the working tooth segment 213 to form a theoretical tooth surface or a combined modified tooth surface, finishing and shaping on the tooth root segment 212, including the transition segment 210, together to form a positively spaced tooth surface of the standard theoretical tooth surface on the non-working tooth segment. This is suitable for form grinding finishing, which can improve processing efficiency and reduce manufacturing costs.

[0076] In some embodiments, when the working tooth segment is finished and shaped, the tooth tip segment and tooth root segment are also finished and shaped together. This includes: while the working tooth segment 213 is finished and shaped to form a theoretical tooth surface or a combined modified tooth surface, it is simultaneously finished and shaped together with the tooth tip segment 211 and tooth root segment 212, which include the transition segment 210, so that the non-working tooth segments of the tooth tip segment 211 and tooth root segment 212 are all formed into equidistant tooth surfaces with standard theoretical tooth surfaces. This is suitable for form grinding finish machining and can significantly improve the transmission accuracy of the cycloidal gear.

[0077] This disclosure also provides a method for shaping a cycloidal wheel 20, applied to the aforementioned cycloidal wheel 20, wherein the non-working tooth sections are shaped using wire cutting or coordinate grinding. Wire cutting improves machining efficiency, surface finish of the non-working tooth sections, and machining accuracy. Coordinate grinding improves machining efficiency and reduces manufacturing costs.

[0078] This disclosure also provides a method for shaping a cycloidal wheel 20, applied to the aforementioned cycloidal wheel 20, wherein the working tooth section is shaped using a profile grinding process. Using a profile grinding process improves machining accuracy. This disclosure also provides a method for shaping a cycloidal wheel 20, applied to the aforementioned cycloidal wheel 20, using a slow wire EDM process. This simplifies the machining process, improves machining efficiency, and enhances machining accuracy. For example, using slow wire EDM to machine small cycloidal wheels simplifies the machining process, improves machining efficiency, and enhances machining accuracy.

[0079] This disclosure also provides a method for shaping a cycloidal wheel 20, applied to the aforementioned cycloidal wheel 20, wherein the working tooth section is shaped using a coordinate grinding process. Using a coordinate grinding process improves processing efficiency and reduces manufacturing costs. This disclosure also provides a method for shaping a cycloidal wheel, applied to the aforementioned cycloidal wheel, wherein the working tooth section is shaped using a generating precision grinding process. This method is used to process the cycloidal wheel of this disclosure in ordinary reducers, resulting in high processing efficiency and low manufacturing costs. The needle rollers of ordinary reducer cycloidal wheels often use a pin and sleeve structure; the tooth tip section 211 can use the aforementioned first arc surface, which does not require grinding (rapid feed on the grinding machine), offering a more significant advantage.

[0080] A third aspect of the present disclosure provides a cycloidal pinwheel planetary reducer, which includes a cycloidal wheel 20, wherein the cycloidal wheel 20 is any of the cycloidal wheels described above.

[0081] This disclosure also provides a cycloidal pinwheel planetary reducer, which includes a cycloidal wheel 20, which is a cycloidal wheel 20 obtained by any of the above-described shaping methods.

[0082] In some embodiments, the cycloidal pinwheel planetary reducer further includes a housing 10 and needle rollers. The housing 10 has a needle tooth groove 10a; the needle rollers are disposed within the needle tooth groove 10a; the cross-section of the needle tooth groove 10a is larger than a semicircle, and the needle rollers are at least partially exposed in the needle tooth groove 10a so as to be able to contact the cycloidal wheel 20.

[0083] After machining, the cross-section of the needle tooth groove 10a is larger than a semicircle. In other words, the cross-sectional contour of the needle tooth groove 10a is an arc. The needle roller can maintain its rotation at the design center position in the needle tooth groove 10a and can mesh with the cycloidal wheel 20 for transmission. This can prevent the needle roller from falling out of the needle tooth groove 10a during operation, eliminate the ineffective rolling of the needle roller in the tooth tip section 211 and tooth root section 212, reduce reducer noise, and improve transmission efficiency.

[0084] For example, the needle tooth groove is formed by wire EDM. Using wire EDM can improve processing efficiency, improve the surface finish of the needle tooth groove, and improve processing accuracy.

[0085] For example, the needle grooves are formed by coordinate grinding. Using coordinate grinding can improve processing efficiency and reduce manufacturing costs.

[0086] For example, the needle groove is formed by broaching. Using broaching to form the needle can improve processing efficiency and reduce manufacturing costs.

[0087] This disclosure also provides a cycloidal pinwheel planetary reducer, which further includes a housing 10 and needle rollers. The housing 10 has a needle tooth groove 10a; the needle rollers are disposed within the needle tooth groove 10a; the cross-section of the needle tooth groove 10a is smaller than a semicircle.

[0088] For example, the cycloidal pinwheel planetary reducer is an RV reducer.

[0089] For example, the needle groove 10a is formed by a forming grinding process. Using a forming grinding process can improve machining accuracy.

[0090] It is understandable that, since the cross-section of the needle groove 10a is smaller than a semicircle, in order to prevent more than half of the needles from rolling ineffectively relative to the cycloidal wheel 20, the tooth tip section 211 is machined and modified into a conjugate tooth surface with equidistant tooth surface, or a third arc surface that approximates the equidistant tooth surface, when the cycloidal wheel 20 is initially machined and modified.

[0091] For example, the tooth tip section 211 and tooth root section 212 of the cycloidal wheel adopt a positive equidistant tooth profile and are individually formed using coordinate grinding, wire cutting, or a special grinding machine, while the working tooth section 213 adopts a rotational theoretical tooth profile and is formed using a profile grinding process. This can improve the transmission accuracy of the reducer and further improve the machining efficiency of the cycloidal wheel, while reducing manufacturing costs.

[0092] In some embodiments, referring to Figures 12 and 13, for high-precision cycloidal pinwheel planetary reducers, in addition to segmented modification of the cycloidal wheel 20 tooth profile, segmented modification of the pin tooth groove 10a is also required to ensure that the center of the needle roller does not deviate from the center circle R1 of the needle roller during meshing, and that there is a suitable clearance between the needle roller and the pin tooth groove 10a. This can significantly improve the transmission accuracy and load-bearing capacity of the reducer. The pin tooth groove 10a includes a non-meshing groove top section 10a1, a meshing working groove section 10a3, and a non-meshing groove bottom section 10a2; the groove shape of the working groove section 10a3 is a corner-modified arc, the radius of which is equal to the radius of the needle roller; the groove shapes of the groove top section 10a1 and the groove bottom section 10a2 are arcs larger than the radius of the needle roller, and the groove top section 10a1 and the groove bottom section 10a2 are connected to the working groove section 10a3. No transition section is required. The shaping method of this embodiment can be used for both the cross-section of the needle groove 10a being larger than a semicircle (as shown in Figure 12) and smaller than a semicircle (as shown in Figure 13).

[0093] The radius of the corner shaping arc of the working groove section 10a3 is equal to the radius of the needle roller, so that the center of the needle roller is on the center circle R1 of the needle roller, and at the same time, the needle roller has a suitable clearance with the needle tooth groove 10a. The arc radii of the groove top section 10a1 and the groove bottom section 10a2 are both greater than the radius of the needle roller, so that the needle roller has a suitable clearance with the needle tooth groove 10a.

[0094] The above embodiments are all illustrated using a cycloidal pinwheel planetary reducer as an example. However, the cycloidal wheel and the cycloidal wheel modification method of the above technical solutions of the present disclosure embodiments are not limited to cycloidal pinwheel planetary reducers. They can also be applied to cycloidal pinwheel planetary speed increasers, cycloidal pinwheel planetary transmissions with speed increase and speed decrease combination switching functions, and other cycloidal pinwheel planetary transmission devices.

[0095] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A cycloidal wheel, the tooth profile of which includes a non-meshing tooth tip section, a meshing working tooth section, and a non-meshing tooth root section, wherein the tooth surface of the working tooth section is a combination of a rotation angle theoretical tooth surface or a modified tooth surface that approximates the rotation angle theoretical tooth surface, and both the tooth tip section and the tooth root section include a non-working tooth section and a transition section, wherein the non-working tooth section is connected to the working tooth section through the transition section.

2. The cycloidal wheel according to claim 1, wherein, The non-working tooth segment includes the non-working tooth tip segment located in the tooth tip segment and the non-working tooth root segment located in the tooth root segment; The tooth surface of the non-working section at the tooth tip is a first arc surface, and the center of the first arc surface is the center of the cycloidal wheel; The tooth surface of the non-working section of the tooth root is a positively equidistant tooth surface of the standard theoretical tooth surface, or a second arc surface that approximates the positively equidistant tooth surface.

3. The cycloidal wheel according to claim 1, wherein, The non-working tooth segment includes the non-working tooth tip segment located in the tooth tip segment and the non-working tooth root segment located in the tooth root segment; The tooth surface of the non-working section at the tooth tip is a positively equidistant tooth surface of the standard theoretical tooth surface, or a third arc surface that approximates the positively equidistant tooth surface; The tooth surface of the non-working section of the tooth root is a positively equidistant tooth surface of the standard theoretical tooth surface, or a second arc surface that approximates the positively equidistant tooth surface.

4. The cycloidal wheel according to any one of claims 1 to 3, wherein, The tooth surface of the transition section is either a circular arc or a plane.

5. A method for modifying the shape of a cycloidal wheel, applied to the cycloidal wheel of claim 1, wherein the combined modification of the tooth surface is performed by a combined modification method, the combined modification method comprising a combination of an equidistant modification method and a displacement modification method.

6. The reshaping method according to claim 5, wherein, The combined shaping method includes a combination of positive isometric shaping and positive displacement shaping, wherein the shaping value of the positive isometric shaping is greater than the shaping value of the positive displacement shaping; or, The combined shaping method includes a combination of negative equidistant shaping and negative displacement shaping, wherein the shaping value of the negative equidistant shaping is less than the shaping value of the negative displacement shaping.

7. A method for shaping a cycloidal wheel, applied to the cycloidal wheel of claim 1, wherein the non-working tooth section is shaped by wire cutting or coordinate grinding.

8. A method for shaping a cycloidal wheel, applied to the cycloidal wheel of claim 1, wherein the working tooth segment is shaped using coordinate grinding, profile grinding, slow wire cutting, or generating precision grinding processes.

9. The reshaping method according to claim 8, wherein, The reshaping method also includes: The working tooth segment is precision machined and shaped, and the tooth root segment is also precision machined and shaped.

10. A cycloidal pinwheel planetary transmission device, the cycloidal pinwheel planetary transmission device comprising a cycloidal wheel according to any one of claims 1 to 4 or a cycloidal wheel obtained by the shaping method of the cycloidal wheel according to any one of claims 5 to 9.

11. A cycloidal pinwheel planetary transmission device, the cycloidal pinwheel planetary transmission device comprising: The cycloidal wheel as described in claim 2; The housing has needle-tooth grooves; The needle roller is disposed within the needle tooth groove; The cross-section of the needle groove is larger than a semicircle, and the needle roller is at least partially exposed in the needle groove so as to be able to contact the cycloidal wheel.

12. The cycloidal pinwheel planetary transmission device according to claim 11, wherein, The needle groove is formed by wire cutting, coordinate grinding or broaching.

13. A cycloidal pinwheel planetary transmission device, the cycloidal pinwheel planetary transmission device comprising: The cycloidal wheel as described in claim 3; The housing has needle-tooth grooves; The needle roller is disposed within the needle tooth groove; The cross-section of the needle groove is smaller than a semicircle.

14. The cycloidal pinwheel planetary transmission device according to claim 12, wherein, The needle groove is formed by a forming grinding process.

15. The cycloidal pinwheel planetary transmission device according to claim 11 or 13, wherein, The needle groove includes a non-meshing groove top section, a meshing working groove section, and a non-meshing groove bottom section; The working groove section has a corner-shaped curved arc with a radius equal to the radius of the needle roller. The groove top section and the groove bottom section both have curved arcs with a radius greater than that of the needle roller. The groove top section and the groove bottom section are connected to the working groove section.

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