A processing method of a sectional variable phase planetary roller

Abstract

The application relates to a machining method of a segmented variable-phase planetary roller, which comprises the following steps: S1, preparing a tool and clamping the roller to be machined on a lathe; S2, setting the machined roller as n thread segments, the pitch of each thread segment being p, and turning corresponding thread relief grooves at the boundaries of adjacent thread segments; S3, rotating the roller at a rotating speed Vc, the time for one rotation of the roller being t, and axially feeding the tool in each thread segment at a feeding speed F, namely F*t=p and F*2t=2p; increasing or decreasing the feeding speed of the tool in the thread relief groove according to the positive / negative direction requirement of thread variable phase; feeding from the first thread segment, the first thread relief groove, the second thread segment and the second thread relief groove in sequence until the Nth thread segment is machined; and S4, dismounting the machined roller. The method can change the distribution mode of the roller thread.

Description

Technical Field

[0001] This invention relates to a method for machining planetary rollers with segmented phase change, belonging to the field of thread machining technology. Background Technology

[0002] like Figure 1 As shown, a planetary roller screw pair is a mechanical transmission device that can convert rotary motion into linear motion. It consists of a screw, nut, rolling elements, planetary carrier, and internal gear ring. The rolling elements of a planetary roller screw pair are planetary rollers. Compared with commonly used roller screw pairs, planetary roller screw pairs have the characteristics of multi-point, multi-pair, and multi-body transmission, which determines its advantages such as large thrust, high precision, high rigidity, long service life, good dynamic performance, and convenient installation and maintenance.

[0003] With the rapid development of automation, intelligence, and modern high-end manufacturing, planetary roller screw pairs have been widely used in high-end precision equipment fields such as robots, injection molding machines, and high-precision heavy-duty machine tools, which operate under medium to high loads. These high-end precision equipment face the need for frequent reversing operations. Under heavy loads, significant contact stress and deformation will occur at the thread engagement points between the screw and rollers, and between the rollers and the nut. Consequently, a certain axial transmission clearance will be generated on the opposite side of the contact point of the thread raceway, such as... Figure 3 , 4 As shown, when the planetary rollers rotate clockwise, the meshing point between the planetary rollers and the leadscrew is on side a of the thread profile below the planetary roller axis, and there is an axial transmission clearance between the planetary rollers and the leadscrew threads on side b. The meshing point between the planetary rollers and the nut is on side b' of the thread profile above the planetary roller axis, and there is an axial transmission clearance between the planetary rollers and the nut threads on side a'. Therefore, during startup, shutdown, and especially reversal, the axial transmission clearance of the planetary roller leadscrew pair will lead to undesirable phenomena such as creep and impact, thus reducing the accuracy, transmission stiffness, and service life of the leadscrew pair.

[0004] To eliminate or reduce this type of axial transmission backlash, a preload is required for the planetary roller screw pair. Currently, planetary roller screw pairs often use a nut as the preload application point, such as double-nut thread preload, double-nut differential tooth preload, or split-type nut preload. However, the double-nut method increases the nut length and the axial space occupied; the nut thread is generally multi-start, and double nuts increase the complexity of the nut structure, increasing design, processing, and assembly costs; the split-type nut disrupts the continuity of the nut's helical raceway, negatively impacting the planetary roller screw pair's load-bearing capacity, transmission efficiency, and service life. Furthermore, the thread contact methods of planetary roller screw transmission pairs are of two types: screw and roller, and roller and nut. Preload using only the nut can only eliminate or reduce the thread backlash between the nut and roller, not between the roller and screw.

[0005] Chinese invention patent No. 201210118236.6 discloses a planetary roller screw mechanism that can eliminate axial backlash. This mechanism divides the screw into a long-shaft screw and a hollow screw. During installation, the long-shaft screw is inserted into the hollow screw, and the threads of the two screw sections and rollers are clamped together by an axial backlash adjustment component. A shrinking disc is used at the end to radially press both sections together, thus solving the problem of eliminating axial backlash between the screw and rollers. However, this solution's separate screw and nut design negatively impacts the load-bearing capacity, transmission efficiency, and service life of the planetary roller screw pair. Furthermore, its complex structure adds significant extra workload to manufacturing and debugging.

[0006] In addition, adjusting the pitch diameter of the nut, rollers, and screw thread raceway can also apply preload to the ball screw pair, but this places higher demands on the machining accuracy of the most widely used multi-start thread ball screw and nut, and to some extent reduces the load-bearing capacity of the planetary ball screw pair and increases the difficulty of maintenance. Summary of the Invention

[0007] The purpose of this invention is to provide a method for processing planetary rollers with segmented phase change, so as to improve or solve the technical problems existing in the prior art as described above.

[0008] The technical solution provided by this invention is as follows: A method for machining planetary rollers with segmented phase change, comprising the following steps:

[0009] S1: Prepare the cutting tool and clamp the roller to be machined on the lathe;

[0010] S2: Assume the machined roller consists of n threaded segments, each with a pitch of p. At the boundaries between adjacent threaded segments, machine corresponding thread relief grooves.

[0011] S3: The roller rotates at a constant speed Vc, and the time for one revolution of the roller is t. Within each threaded section, the cutting tool is fed axially at a constant feed rate F, i.e., F*t=p, F*2t=2p. The feed rate of the cutting tool is increased or decreased in the thread relief groove according to the positive / negative requirements of the thread phase change. The cutting tool is fed sequentially from the first threaded section, the first thread relief groove, the second threaded section, and the second thread relief groove until the Nth threaded section is completed.

[0012] S4: Remove the processed rollers.

[0013] Furthermore, the cutting tool includes a threading tool and a relief cutting tool. The relief cutting tool is used to machine the thread relief groove, and the threading tool is used to machine the thread section.

[0014] Furthermore, in step S3, the method for increasing or decreasing the feed rate of the cutting tool within the thread relief groove according to the positive / negative requirements of the thread phase change is as follows:

[0015] When machining the first section of thread, the feed rate of the thread cutting tool is F;

[0016] After the first thread section is machined, the feed rate of the thread cutting tool is adjusted to F'. The thread cutting tool passes through the first thread relief groove at a speed of F'. Let the difference between the speeds of F' and F be ΔF, that is, ΔF = F' – F.

[0017] When the second thread section is reached, adjust the feed rate of the thread cutting tool to F and continue machining the second thread section;

[0018] After the second thread section is machined, the feed rate of the thread cutting tool is set to F". The thread cutting tool passes through the second thread relief groove at a speed of F", and F"=F-△F;

[0019] When the third thread section is reached, adjust the feed rate of the thread cutting tool to F and continue machining the third thread section;

[0020] Repeat the above processing procedure until the Nth threaded section is processed.

[0021] Furthermore, the width of the thread relief groove is 2p to 5p.

[0022] Furthermore, when the width of the thread relief groove is 2p, according to △F=F'-F, F*2t=2p, F'*2t=2p', the stroke of the thread cutting tool in the time it takes for the roller to rotate 2 revolutions is 2p'. At this time, 2p'-2p=s, where s is the phase offset of the thread phase change.

[0023] Furthermore, s is 1‰ to 10‰ of the pitch p.

[0024] Furthermore, the pitch and tooth profile of each thread section remain consistent.

[0025] Furthermore, the feed rate of the thread cutting tool is set according to the machining requirements and the program.

[0026] Compared with the prior art, the technical solution provided by this invention has the following beneficial effects: The roller processed by the method of this invention includes two or more threaded sections, wherein the threaded sections include original phase sections and variable phase sections, and the section between two adjacent threaded sections is a smooth section (i.e., thread relief groove). This can change the distribution mode of the roller thread, thereby simultaneously eliminating the double-sided axial transmission clearance between the roller and the screw, and between the roller and the nut threads, making the preload in the planetary roller screw pair symmetrical and uniform, so as to eliminate adverse phenomena such as reverse crawling and impact, and thus improve the axial transmission stiffness, reverse transmission accuracy and service life of the roller screw pair. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an existing planetary roller screw pair;

[0028] Figure 2 This is a schematic diagram of an existing planetary roller structure;

[0029] Figure 3 A schematic diagram of the axial transmission clearance structure generated on the opposite side of the contact point of the thread raceway in an existing roller screw pair;

[0030] Figure 4 for Figure 3 Enlarged structural diagram at point A in the middle;

[0031] Figure 5 This is a schematic diagram of the method for segmented phase change of roller threads according to the present invention;

[0032] Figure 6 This is a schematic diagram of the roller thread phase change principle of the present invention;

[0033] Figure 7 for Figure 6 A magnified structural diagram at point B;

[0034] Figure 8 This is a schematic diagram of the structure of the planetary rollers simultaneously pre-tightening the screw and nut after the phase change of the threaded section according to the present invention.

[0035] Figure 9 for Figure 8 Enlarged structural diagram at point C;

[0036] Figure 10 for Figure 8 Enlarged structural diagram at point D;

[0037] Figure 11 This is a schematic diagram of the planetary carrier structure of the present invention;

[0038] Figure 12 This is a schematic diagram of the internal gear ring of the present invention;

[0039] Figure 13 This is a schematic diagram of the nut unit of the present invention;

[0040] Figure 14 This is a schematic diagram of the planetary roller screw assembly of the present invention;

[0041] Figure 15 This is a schematic diagram showing the feed rate of the thread cutting tool for the planetary rollers of the present invention;

[0042] In the diagram, 1 is the lead screw; 2 is the planetary roller; 201 is the first threaded section; 202 is the second threaded section; 203 is the third threaded section; 204 is the fourth threaded section; 205 is the gear tooth; 206 is the journal; 3 is the nut; 4 is the polished section; 401 is the first thread relief groove; 402 is the second thread relief groove; 403 is the third thread relief groove; 6 is the internal gear ring; and 7 is the planetary carrier. Detailed Implementation

[0043] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0044] As shown in the figure, Figure 5 As shown, a planetary roller includes two or more threaded sections, with a smooth section 4 between two adjacent threaded sections. The threaded sections include a primary phase section and a secondary phase section.

[0045] like Figure 6 and Figure 7 As shown, on the same axial tooth crest line of the planetary roller 2, the starting position of each tooth crest in the phase-changing section has a forward / backward offset s compared to the corresponding tooth crest position of the conventional planetary roller 2. s is a pitch of 1‰ to 10‰, and s is less than or equal to the axial transmission clearance between the roller thread and the lead screw thread. It should be noted that the conventional planetary roller 2 refers to a planetary roller 2 whose external thread is a continuous original-phase thread.

[0046] The more specific structure of the planetary roller 2 and its mounting structure on the planetary roller screw pair are as follows:

[0047] like Figure 14 As shown, the planetary roller screw pair includes a screw 1, planetary rollers 2, and a nut 3. The screw 1 is inserted into the nut 3, and the axis of the screw 1 coincides with the axis of the nut 3. Multiple planetary rollers 2 are evenly installed around the screw 1. Each planetary roller 2 has two or more threaded sections. A smooth section 4 is provided between two adjacent threaded sections. The threaded sections include a primary phase section and a secondary phase section. The planetary rollers 2 mesh simultaneously with the external threads of the screw 1 and the internal threads of the nut 3.

[0048] The threads of the planetary roller 2 are not as described. Figure 2 The traditional continuous thread shown is not as shown in the figure. Figure 5 The segmented phase-changing intermittent thread shown in the figure enables the planetary roller 2 and the external thread of the lead screw 1 and the internal thread of the nut 3 to engage simultaneously without gaps.

[0049] It should be noted first that the original phase section refers to the section where the thread on the roller maintains its original form and position distribution, satisfying the original phase angle correspondence. The original phase angle correspondence means that in the existing planetary roller 2 lead screw 1 structure, the thread structure on the planetary roller 2 and the gear teeth 205 at both ends need to satisfy the phase angle correspondence based on the form and position distribution in the circumferential direction, so that the planetary roller 2 can simultaneously satisfy the meshing of the thread on the planetary roller 2 with the external thread on the lead screw, the thread on the planetary roller 2 with the internal thread of the nut 3, and the gear teeth 205 with the internal gear ring 6 at any position.

[0050] The method for dividing the thread of planetary roller 2 is as follows: (e.g.) Figure 5 As shown, based on the length of the planetary roller 2, the assumed continuous thread is appropriately divided into segments, each segment being at least two segments; each segment has an equal length and contains an equal number of complete thread turns; a polished section 4 is provided between adjacent thread segments, the polished section 4 being a thread relief groove, the diameter of the polished section 4 being slightly smaller than the inner diameter of the thread, and the length of the polished section 4 being equal to several complete thread pitches. In this embodiment, the length of the polished section 4 is equal to 2 thread pitches; of course, the length of the polished section 4 can be longer or shorter; for example... Figure 5 The diagram shows the principle of the planetary roller 2 thread segmentation phase change method. When segmenting, the starting point of each thread segment corresponds to the same phase of the radial section on the assumed continuous thread.

[0051] The scheme for changing the phase of the planetary roller 2 thread is as follows: From left to right, the thread section is divided into odd-numbered and even-numbered sections, keeping about half of the sections as original phase sections. The number of original phase sections and changing phase sections is the same. In this way, the force on the roller screw pair during forward transmission is equal to or close to the force on the roller screw during reverse transmission, resulting in better stability. In addition, in this embodiment, the odd-numbered thread section is the original phase section, which ensures that the first thread section of the planetary roller 2 is the original phase section. The remaining sections are used as changing phase sections, that is, the even-numbered thread section is used as the changing phase section. The phase angle of the starting point of the even-numbered thread section is appropriately increased or decreased, that is, the changing phase section thread is rotated forward or backward by rotating the thread. On the same axial tooth crest line of the roller, the starting position of each tooth crest of the changing phase section has a forward / backward offset s compared with the corresponding tooth crest position of the conventional planetary roller 2, such as... Figure 6and 7 As shown. Through the aforementioned phase-changing method, the distance between the threaded section of the phase-changing segment and the threaded section of the original phase segment can be appropriately increased or decreased, achieving the purpose of simultaneous pre-tightening of the planetary rollers 2 on the screw 1 and nut 3 during meshing, such as... Figures 8-9 As shown; on the other hand, it can also ensure that the threads in the phase-changing section can still be smoothly screwed in and out on the lead screw 1 and nut 3, so that the roller lead screw 1 pair can work normally.

[0052] like Figure 5 As shown, the planetary roller 2 has four threaded sections. The first threaded section 201 and the third threaded section 203 are the original phase sections, and the second threaded section 202 and the fourth threaded section 204 are the variable phase sections.

[0053] In addition, in this embodiment, the planetary roller 2 further includes gear teeth 205 and journals 206, with the two gear teeth 205 respectively disposed at both ends of the planetary roller 2, and the journals 206 being cylindrical. Figure 13 As shown, the nut 3 has a three-stage stepped inner hole, with the inner diameter of the two end holes being larger than that of the middle hole, and two stepped surfaces forming at the boundary between the two end holes and the middle hole. The middle hole has an internal thread that meshes with the external thread of the planetary roller 2. The surfaces of the two end holes are smooth, and each is fitted with an internal gear ring 6 and a planetary carrier 7. The gear teeth 205 mesh with the internal gear ring 6, and the journal 206 is mounted on the planetary carrier 7. In this invention, the planetary roller 2 and planetary carrier 7 with segmented phase changes in thread form a planetary roller unit. The planetary roller unit is installed in the nut 3 through the internal gear ring 6 and the elastic open retaining ring. The nut 3, internal gear ring 6, planetary carrier 7, and elastic open retaining ring form a nut unit. After the lead screw 1 is embedded in the planetary roller unit, it can automatically form a planetary roller lead screw pair (such as...). Figure 14 (As shown). More specifically, the two ends of the planetary roller 2 are smooth cylindrical journals 206 with a diameter smaller than the minor diameter of the external thread, as shown. Figure 5 As shown; the planetary carrier 7 is mounted on both ends of the nut 3, and the smooth cylindrical journal 206 is inserted into the array hole of the planetary carrier 7, as shown. Figure 11 As shown, the planetary rollers 2 are radially evenly distributed; the smooth cylindrical journal 206 and the intermediate threaded section are connected by gear teeth 205, as shown. Figure 5 As shown, they mesh with the internal gear rings 6 at both ends of the nut 3, as follows: Figure 12 , 14 As shown, the planetary motion of the planetary rollers 2 around the lead screw 1 can be realized by the constraints of the planet carrier 7 and the internal gear ring 6.

[0054] In this embodiment, the lead screw 1 has a multi-start external thread with a triangular tooth profile; the nut 3 has a multi-start internal thread with a triangular tooth profile; the planetary roller 2 has a single-start external thread with a circular arc tooth profile, and there are 11 planetary rollers 2.

[0055] like Figure 12 As shown, the internal gear ring 6 is a circular ring structure, axially positioned by the bottom surface near the gear teeth 205 and the stepped surfaces at both ends of the nut 3, and its outer circular surface is positioned by interference fit with the two end holes of the nut 3. The inner bore surface of the internal gear ring 6 is divided into two parts along the axial direction; one half has internal teeth that mesh with the gear teeth 205 at both ends of the planetary roller 2; the other half is a smooth surface, the inner diameter of which is smaller than the diameter of the root of the internal teeth, and the side of the internal teeth can form the axial positioning surface of the planet carrier 7; the planet carrier 7 is installed on the smooth surface, the length of the smooth surface is greater than the length of the planet carrier 7, and an annular groove is provided in the middle of the remaining smooth part, which can be used to install an elastic open retaining ring to fix the planet carrier 7 axially in the internal gear ring 6.

[0056] like Figure 11 As shown, the planetary carrier 7 is a thin conical part with a large central hole. Its conical surface serves as the constraint surface of an elastic open retaining ring. Several small holes in a circular array are evenly distributed around the central hole, and these small holes serve as constraint holes for the planetary rollers 2. The large bottom surface of the planetary carrier 7 serves as the axial limiting surface for the planetary rollers 2, restricting the axial relative position between the planetary rollers 2 and the nut 3.

[0057] Taking a planetary roller 2 with two threaded sections as an example, the first threaded section 201 is the original phase section, and the second threaded section 202 is the variable phase section. The working principle of its planetary roller screw pair is as follows:

[0058] like Figure 8 , 9 As shown, the lead screw 1 is the drive shaft. When the lead screw 1 rotates to the right, in the first thread section 201, which is the original phase section, the zero-backlash meshing point between the planetary roller 2 and the lead screw 1 is on the a1 side of the thread profile below the axis of the planetary roller 2. There is an axial transmission clearance between the b1 side of the thread profile below the axis of the planetary roller 2 and the thread of the lead screw 1. The second thread section 202 is the variable phase section, that is, the phase angle of the starting point of the second thread section is appropriately increased or decreased. At this time, as... Figure 8 , 10 As shown, within the second threaded section 202, the backlash-free meshing point between the planetary roller 2 and the lead screw 1 is on the b2 side of the thread profile below the axis of the planetary roller 2. There is an axial transmission clearance between the a2 side of the thread profile below the axis of the planetary roller 2 and the thread of the lead screw 1. Adjusting the mating position of the adjusting nut 3 and the planetary roller 2, as... Figure 8 , 9 As shown, in the first threaded section 201, the gapless meshing point between the planetary roller 2 and the nut 3 is on the a1' side of the thread profile above the axis of the planetary roller 2, and the planetary roller 2 and the nut 3 have an axial transmission clearance on the b1' side; while in the second threaded section 202, as... Figure 8 , 10As shown, the zero-backlash engagement point between the planetary roller 2 and the nut 3 is on the b2' side of the thread profile above the axis of the planetary roller 2, and the planetary roller 2 and the nut 3 have an axial transmission clearance on the a2' side. Therefore, when the lead screw 1 rotates forward to the right, the force points of the planetary roller 2 are on the a1 side within the first thread section 201 and the b2' side within the second thread section 202. The zero-backlash engagement of the threads of the lead screw 1 and the planetary roller 2 on the a1 side curved surface within the first thread section 201 pushes the planetary roller 2 to move axially to the right, and the zero-backlash engagement of the threads of the planetary roller 2 on the b2' side curved surface within the second thread section 202 with the nut 3 pushes the nut 3 to move axially to the right. Conversely, when the lead screw 1 rotates to the left and retracts, the force points of the planetary roller 2 are on the b2 side within the second threaded section 202 and the a1' side within the first threaded section 201. The threads of the lead screw 1 and the planetary roller 2 mesh without clearance on the curved surface on the b2 side within the second threaded section 202, pushing the planetary roller 2 to move axially to the left. Similarly, the threads of the lead screw 1 and the nut 3 mesh without clearance on the curved surface on the a1' side within the first threaded section 201, pushing the nut 3 to move axially to the left. This not only eliminates the double-sided axial transmission backlash between the threads of the planetary roller 2 and the lead screw 1, and between the planetary roller 2 and the nut 3, during reversal, but also makes the preload in the planetary roller lead screw pair symmetrical and uniform.

[0059] Therefore, the planetary roller 2 with segmented variable phase structure can change the meshing point position between the planetary roller 2 and the lead screw 1 and nut 3, eliminate the double-sided axial transmission clearance between the threads of the planetary roller 2 and the lead screw 1, and between the planetary roller 2 and the nut 3, so that the preload in the planetary roller lead screw pair is symmetrical and uniform, thereby eliminating adverse phenomena such as reverse crawling and impact, and thus improving the axial transmission stiffness, reverse transmission accuracy and service life of the roller lead screw pair.

[0060] like Figure 15 As shown, the machining method for segmented phase-changing planetary rollers includes the following steps:

[0061] S1: Prepare the cutting tools, which include a thread cutting tool and a relief cutting tool. Use the relief cutting tool to machine the thread relief groove and the thread cutting tool to machine the thread section. Clamp the roller to be machined on a CNC lathe. Use a chuck to hold the roller. Use a double center to fix the center hole of the roller to ensure the positioning accuracy of the axis. And press the chuck lever against the jaws and rotate it in the opposite direction to drive the roller to rotate at a uniform speed. The rotation direction of the chuck is determined according to the selection of the cutting tool.

[0062] S2: Assume the machined roller consists of n threaded segments, each with a pitch of p. At the boundaries between adjacent threaded segments, machine corresponding thread relief grooves.

[0063] S3: The roller rotates at a constant speed Vc, and the time for one revolution of the roller is t. Within each threaded section, the cutting tool is fed axially at a constant feed rate F, i.e., F*t=p, F*2t=2p; within the thread relief groove, the feed rate of the cutting tool is increased or decreased according to the positive / negative requirements of the thread phase change; such as Figure 15 As shown, from left to right, the cutting tool is fed sequentially from the first thread section 201, the first thread relief groove 401, the second thread section 202, the second thread relief groove 402, the third thread section 203, the third thread relief groove 403, and the fourth thread section 204 until the fourth thread section 204 is completed.

[0064] In step S3, the method for increasing or decreasing the feed rate of the cutting tool within the thread relief groove according to the positive / negative requirements of the thread phase change is as follows:

[0065] When machining the first thread section 201, the feed rate of the thread cutting tool is F;

[0066] After the first thread section 201 is machined, the feed speed of the thread cutting tool is adjusted to F'. The thread cutting tool passes through the first thread relief groove 401 at a speed of F'. Let the difference between the speeds of F' and F be ΔF, that is, ΔF = F' – F.

[0067] When the second thread section 202 is reached, adjust the feed rate of the thread cutting tool to F and continue machining the second thread section;

[0068] After the second thread section 202 is machined, the feed speed of the thread cutting tool is set to F". The thread cutting tool passes through the second thread relief groove 402 at a speed of F". F" = F - ΔF.

[0069] When the third thread section 203 is reached, adjust the feed rate of the thread cutting tool to F and continue machining the third thread section 203;

[0070] After the third thread section 203 is machined, the feed rate of the thread cutting tool is set to F', and the thread cutting tool passes through the third thread relief groove 403 at a speed of F'.

[0071] When the fourth thread section 204 is reached, adjust the feed rate of the thread cutting tool to F and continue machining the fourth thread section 204.

[0072] If the roller consists of n threaded sections, repeat the above processing procedure until the nth threaded section is processed.

[0073] S4: Remove the processed rollers.

[0074] The width of the thread relief groove is 2p to 5p. In this embodiment, when the width of the thread relief groove is 2p, according to △F=F'-F, F*2t=2p, F'*2t=2p', the stroke of the thread cutting tool in the time it takes for the roller to rotate 2 revolutions is 2p'. At this time, 2p'-2p=s, where s is the phase offset of the thread phase change, and s is 1‰ to 10‰ of the pitch p.

[0075] The pitch and tooth profile of each thread section remain consistent.

[0076] The feed rate of the thread cutting tool is set according to the machining requirements and the program.

[0077] The more specific turning method for thread phase-changing turning is as follows: Based on the thread distribution on the roller and the division into n equal sections, corresponding thread relief grooves are machined at the boundaries of each section; the traditional continuous turning of threads on rollers is transformed into intermittent turning of n equal sections. The non-turning position of the intermittent turning is at the boundary of each section, i.e., within the corresponding thread relief groove; the width of the relief groove is 2p, so as to control the feed rate of the cutting tool as needed, and change the phase of the thread starting point of the phase-changing section in either the positive or negative direction; except for the thread starting point, the external shape parameters and cutting parameters of the threads in the original phase section and the phase-changing section are the same, i.e., the same thread cutting tool and the same cutting parameters are used for machining.

[0078] Set up a thread turning program on a CNC lathe to achieve the following turning requirements:

[0079] Throughout the turning process, the roller rotates at a constant speed Vc, and the time for one revolution of the roller is t. Within each thread section, the thread cutting tool is fed axially at a constant feed rate F, i.e., F*t=p, F*2t=2p. In the relief groove, the feed rate of the cutting tool is increased or decreased according to the positive / negative requirements of the thread phase change. Due to the change in feed rate (△F=F'-F), the travel of the cutting tool in the time period (2t) of 2 revolutions of the roller is 2p', at which time 2p'-2p=s. Therefore, when the cutting tool contacts the next phase change section, the thread starting point changes and the phase changes naturally, ensuring that the starting position of each tooth crest in the phase change section has a forward or backward offset s compared to the corresponding tooth crest position of a conventional planetary roller.

[0080] When the cutting tool contacts the phase-change section, the feed rate of the cutting tool, F', returns to F, and the internal thread turning of this section can be performed. After the machining of this section is completed and the cutting tool enters the relief groove, the feed rate of the thread cutting tool needs to be changed to F" so that F" = F - ΔF. At this time, when the cutting tool contacts the next section, the thread start point naturally coincides with the original phase thread start point, that is, the phase is restored. At this time, the feed rate of the cutting tool, F", returns to F, and the internal thread turning of this section can be performed.

[0081] Repeat the above process to complete the machining of the entire threaded section phase-changing roller.

[0082] The implementation method of this invention is simple and does not require increasing the complexity of the structure and manufacturing of nut 3. By simply dividing the roller thread into segments and changing the phase, the reverse backlash between the roller and the screw 1, and between the roller and the nut 3 can be eliminated or reduced simultaneously, thereby increasing the overall preload of the planetary roller screw pair.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for machining planetary rollers with segmented phase variation, characterized in that, Includes the following steps: S1: Prepare the cutting tool and clamp the roller to be machined on the lathe; S2: Assume that the machined roller has n threaded sections, and the pitch of each threaded section is p. At the boundary between adjacent threaded sections, the corresponding thread relief groove is machined. S3: The roller rotates at a constant speed Vc, and the time for one revolution of the roller is t. Within each threaded section, the cutting tool is fed axially at a constant feed rate F, i.e., F t=p, F 2t=2p; Increase or decrease the feed rate of the cutting tool in the thread relief groove according to the positive / negative requirements of the thread phase change; feed the tool sequentially from the first thread section, the first thread relief groove, the second thread section, and the second thread relief groove until the Nth thread section is completed; S4: Remove the processed rollers; In step S3, the method for increasing or decreasing the feed rate of the cutting tool within the thread relief groove according to the positive / negative requirements of the thread phase change is as follows: When machining the first section of thread, the feed rate of the thread cutting tool is F; After the first thread section is machined, the feed rate of the thread cutting tool is adjusted to F'. The thread cutting tool passes through the first thread relief groove at a speed of F'. Let the difference between the speeds of F' and F be ΔF, that is, ΔF = F' – F. When the second thread section is reached, adjust the feed rate of the thread cutting tool to F and continue machining the second thread section; After the second thread section is machined, the feed rate of the thread cutting tool is set to F". The thread cutting tool passes through the second thread relief groove at a speed of F". F" = F - ΔF. When the third thread section is reached, adjust the feed rate of the thread cutting tool to F and continue machining the third thread section; Repeat the above processing procedure until the Nth threaded section is completed; The width of the thread relief groove is 2p to 5p; When the width of the thread relief groove is 2p, according to △F=F'-F, F 2t=2p, F' 2t = 2p', the stroke of the thread cutting tool during the time it takes for the roller to rotate 2 revolutions is 2p', at this time 2p' - 2p = s, s is the phase offset of the thread change phase.

2. The method for machining planetary rollers with segmented phase change according to claim 1, characterized in that, The cutting tool includes a threading tool and a relief cutting tool. The relief cutting tool is used to machine the thread relief groove, and the threading tool is used to machine the thread section.

3. The method for machining planetary rollers with segmented phase change according to claim 1, characterized in that, The value of s is 1‰ to 10‰ of the pitch p.

4. The method for machining planetary rollers with segmented phase change according to claim 1, characterized in that, The pitch and tooth profile of each thread section remain consistent.

5. The method for machining planetary rollers with segmented phase change according to claim 1, characterized in that, The feed rate of the thread cutting tool is set according to the machining requirements and the program.

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