Internal thread rolling tool

Abstract

According to the internal thread rolling tool provided by the utility model, the supporting strength and supporting force on a planetary roller are improved, the rolling force or extrusion force of the planetary roller on an inner hole of a workpiece during rolling of an internal thread is increased, rolling or extrusion forming of the internal thread of the workpiece can be rapidly and efficiently completed, the quality of the machined internal thread is high, and the working efficiency is improved. The internal thread rolling tool is simple in structure and long in service life. The planetary transmission comprises a central lead screw rotationally arranged on a support, at least two planetary rollers located on the same pitch circle are evenly distributed on the periphery of the central lead screw, the planetary rollers are rotationally arranged on the support, and threads on the periphery of the central lead screw are meshed with threads on the peripheries of the planetary rollers to form a planetary structure. The planetary pin rollers do planetary motion around the central lead screw; threads on the peripheries of the planetary rollers protrude out of the outer surface of the support in the radial direction of the central lead screw.

Description

Technical Field

[0001] This patent relates to a processing tool for extruding or rolling internal threads on the inner holes of parts. Background Art

[0002] CN113059098A discloses an internal thread rolling plastic forming device and method, which includes a base and a chuck assembly, a driving motor and an internal thread rolling mechanism arranged on the base; the driving motor and the internal thread rolling mechanism are both fixed on the base, and the driving motor can provide rotational power for the internal thread rolling mechanism; the chuck assembly is slidably connected to the base, and the chuck assembly can approach or move away from the internal thread rolling mechanism; the internal thread rolling mechanism includes a large gear and multiple groups of rolling assemblies evenly distributed on the outer side of the large gear along the circumferential direction; each rolling assembly includes a small gear and a thread rolling wheel arranged coaxially, the small gear is connected to the base and meshes with the large gear; the small gear can drive the thread rolling wheel to rotate, the outer circumferential surface of the thread rolling wheel is a formed thread structure, and there is a phase difference between the thread structures of multiple thread rolling wheels. However, the part with threads on the outer circumference of the thread rolling wheel is suspended and has no support, so it can bear a small extrusion force, and it can only extrude and form the internal thread once, and the required extrusion force is very large. Therefore, it is often difficult to complete the processing of the internal thread, and it is very easy to be damaged. Summary of the Invention

[0003] The purpose of this patent is to provide an internal thread rolling tool, which improves the support strength and support force for the planetary rollers, increases the rolling force or extrusion force of the planetary rollers on the inner hole of the workpiece when rolling the internal thread, can quickly and efficiently complete the rolling or extrusion forming of the internal thread of the workpiece, the processed internal thread has high quality, and the internal thread rolling tool has a simple structure and a long service life.

[0004] To achieve the above technical purpose, the technical solution adopted in this patent is as follows:

[0005] An internal thread rolling tool includes a central lead screw rotatably arranged on a bracket, at least two planetary rollers evenly distributed on the outer circumference of the central lead screw on the same pitch circle, the planetary rollers are rotatably arranged on the bracket, the threads on the outer circumference of the central lead screw and the threads on the outer circumference of the planetary rollers mesh with each other to form a planetary structure, and the planetary rollers make planetary motion around the central lead screw; the threads on the outer circumference of the planetary rollers protrude from the outer surface of the bracket in the radial direction of the central lead screw.

[0006] In the above internal thread rolling tool, the planetary rollers on the same pitch circle are in one group, there are more than two groups of planetary rollers, and each group of planetary rollers is arranged in the axial direction of the central lead screw. From one end to the other end along the axial direction of the central lead screw, the diameters of the planetary rollers in each group of planetary rollers increase or decrease, or the pitch circle diameters of each group of planetary rollers increase or decrease.

[0007] For the above internal thread rolling tool, each set of planetary rollers contains 3 - 4 planetary rollers.

[0008] For the above internal thread rolling tool, two sets of planetary rollers adjacent in the axial direction of the central lead screw are staggered from each other in the circumferential direction of the central lead screw.

[0009] For the above internal thread rolling tool, the bracket includes a plurality of rings connected in sequence in the axial direction of the central lead screw. Both ends of the central lead screw are rotatably supported on the inner circumferences of the two rings at both ends through bearings; on the end face where one ring contacts another ring, an embedding groove is provided. Both ends of the planetary roller located in the embedding groove are respectively rotatably supported in two support holes, one support hole is located on the bottom surface of the groove, and one support hole is located on the end face of another ring.

[0010] For the above internal thread rolling tool, the multiple rings are connected by bolts or screws passing through each ring.

[0011] For the above internal thread rolling tool, the planetary rollers located in the embedding grooves on the same ring are taken as one set, and there are more than 2 sets of planetary rollers. The planetary rollers in the same set are located on the same pitch circle. The diameters of the planetary rollers in each set of planetary rollers located in the embedding grooves on different rings are different. Along the axial direction of the central lead screw from one end to the other end, the diameters of the planetary rollers in the embedding grooves on each ring increase or decrease, or the pitch circle diameters where each set of planetary rollers is located increase or decrease.

[0012] For the above internal thread rolling tool, a force - applying shaft is connected to the ring at one end of the central lead screw in the axial direction, which is closer to the planetary roller with the largest diameter. The diameter of the force - applying shaft is smaller than the outer diameter of the ring.

[0013] The beneficial effects of this patent are as follows: When the planetary rollers extrude or roll the internal thread, the threads on the outer periphery of the planetary rollers extrude the inner hole wall of the workpiece. The planetary rollers are subjected to a relatively large extrusion force from the workpiece. This patent uses the central lead screw to support the threaded part of the planetary rollers, improving the support strength and support force for the planetary rollers. In this way, the planetary rollers can withstand a relatively high extrusion force without being damaged, the internal thread can be quickly formed, and the surface quality of the internal thread is high.

[0014] There are more than 2 sets of planetary rollers, and the diameters of the planetary rollers in each set increase or decrease. When machining the internal thread, the set of planetary rollers with the smallest diameter first performs preliminary extrusion or rolling on the inner hole of the workpiece to obtain a preliminarily formed internal thread, and then the planetary rollers with larger and larger diameters perform secondary extrusion or rolling on the preliminarily formed internal thread, so that the internal thread is gradually formed. This can reduce the extrusion force required for each set of planetary rollers and can quickly machine the required internal thread.

[0015] The bracket is composed of multiple rings, and the planetary rollers are located in the grooves communicating with the docking end faces of the two rings, which facilitates the assembly, processing and manufacturing of the tool, and it is very convenient to produce the tool.

[0016] The force application shaft is used to conveniently apply force to the bracket to rotate the bracket. The diameter of the force application shaft is smaller than the diameter of the ring to prevent interference between the force application shaft and the inner hole of the workpiece.

[0017] This patent is particularly applicable to the processing of internal threads with small hole diameters or short axial lengths. Description of the Drawings

[0018] Figure 1 、 2 is a perspective view of the internal thread rolling tool.

[0019] Figure 3 is the front view of the internal thread rolling tool.

[0020] Figure 4 is the side view of the internal thread rolling tool.

[0021] Figure 5 、 6 is a perspective view of the third ring.

[0022] Figure 7 is a schematic diagram of the internal thread rolling tool in use. Detailed Implementation Modes

[0023] The following further explains the detailed implementation modes of this patent according to the drawings:

[0024] As Figure 1 shown, the internal thread rolling tool mainly includes a bracket 1, a force application shaft 3, a central lead screw 4, and planetary rollers 7.

[0025] The bracket 1 includes multiple rings 11 connected in sequence along the axial direction of the central lead screw. The rings 11 are, from left to right, the leftmost ring, i.e., the first ring 111, the second ring 112, the third ring 113, the fourth ring 114, and the rightmost ring, i.e., the fifth ring 115. The multiple rings 11 are connected by bolts or screws 2 passing through each ring (if screws are used, threaded holes can be machined on the first ring, and the screws pass through the second ring 112, the third ring 113, the fourth ring 114, and the fifth ring 115 and are threadedly connected to the first ring). The left end of the first ring 111 is integrally formed with the force application shaft 3, and the diameter of the force application shaft 3 is smaller than the outer diameter of the ring 11.

[0026] Both ends of the central lead screw 4 are rotatably supported on the inner circumferences of the first ring 111 and the fifth ring 115 through bearings.

[0027] The structures of Ring Two 112, Ring Three 113, Ring Four 114, and Ring Five 115 are similar. On the left end faces of Ring Two 112, Ring Three 113, Ring Four 114, and Ring Five 115, three equally spaced slots 5 are provided, and on the bottom surfaces of the slots 5, first support holes 61 are provided.

[0028] On the right end faces of Ring One 111, Ring Two 112, Ring Three 113, and Ring Four 114, three equally spaced second support holes 62 are provided.

[0029] Both ends of a planetary roller 7 located in each slot are respectively rotatably supported (or through bearings, bearing bushes, etc.) in the first support hole 61 and the second support hole 62.

[0030] The three planetary rollers 7 located in the three slots on the same ring have the same diameter and form a group. From left to right, there are four groups of planetary rollers, namely Planetary Roller Group One 71, Planetary Roller Group Two 72, Planetary Roller Group Three 73, and Planetary Roller Group Four 74. The diameters of the planetary rollers in Planetary Roller Group One 71, Planetary Roller Group Two 72, Planetary Roller Group Three 73, and Planetary Roller Group Four 74 decrease successively. Of course, the pitch circle diameters of the three planetary rollers in Planetary Roller Group One 71, Planetary Roller Group Two 72, Planetary Roller Group Three 73, and Planetary Roller Group Four 74 also decrease successively.

[0031] The threads on the outer periphery of the central lead screw mesh with the threads on the outer periphery of each planetary roller to form a planetary structure, and the planetary rollers perform planetary motion around the central lead screw; the threads on the outer periphery of the planetary rollers protrude beyond the outer surface of the ring in the radial direction of the central lead screw.

[0032] For two adjacent groups of planetary rollers in the axial direction of the central lead screw, they are staggered with each other in the circumferential direction of the central lead screw.

[0033] When using this internal thread rolling tool to extrude the inner hole of the workpiece 8, Planetary Roller Group Four 74 first extends into the inner hole of the workpiece 8 from the left end to perform preliminary extrusion on its inner hole. The thread rolling tool gradually moves to the right, and the planetary roller with the largest diameter finally extrudes the inner hole (the preliminarily formed internal thread). Usually, the processing of internal threads adopts turning and grinding processing techniques. The surface finish of the turning process is low, and the machining quality of the parts is poor. Although the grinding process can obtain a higher surface finish, it is not suitable for the processing of internal threads with small hole diameters or short axial lengths. Moreover, the production efficiency of the above two processes is low. In the conventional internal thread extrusion forming process, the friction force is large, it is not easy to obtain a high surface finish, and the processing load is large, and the surface is prone to adhesion.

[0034] The internal thread rolling tool of this patent includes at least one central lead screw located in the center, and at least 3 planetary rollers rotating around the central lead screw are distributed along the circumference of the lead screw. The planetary rollers perform planetary motion around the central lead screw, and the planetary lead screw is fixed on the bracket. The threads of the central lead screw and the planetary rollers are mutually engaged to form a planetary roller structure. The said planetary roller structure includes at least 2 groups, and the diameters of the planetary rollers in the two groups are different. The diameters of the rollers in the group that first enters the inner hole of the part are the smallest, and increase sequentially backward.

[0035] Advantages of this patent: In rolling processing, the smaller the diameter of the rolling wheel (planetary roller), the smaller the rolling force, which is more conducive to forming. However, the rolling wheel with a small diameter has low strength and short service life. Therefore, this mechanism adopts a structure with a central lead screw arranged in the center, so that the planetary rollers are all supported on the central lead screw, thereby greatly improving the rolling force and support strength of the planetary rollers. When multiple levels are combined together, parts can be processed quickly, the product quality is good, and the tool life is long.

[0036] The protection scope of this patent includes but is not limited to the above embodiments. The protection scope of this patent is subject to the claims. Any replacement, deformation, and improvement that are easily conceivable by those skilled in the art for this technology fall within the protection scope of this patent.

Claims

1. Internal thread rolling tool, characterized by: It includes a central lead screw rotatably arranged on a bracket, at least two planetary rollers located on the same pitch circle are evenly distributed on the outer circumference of the central lead screw, the planetary rollers are rotatably arranged on the bracket, the threads on the outer circumference of the central lead screw and the threads on the outer circumference of the planetary rollers are meshed with each other to form a planetary structure, and the planetary rollers perform planetary motion around the central lead screw; the threads on the outer circumference of the planetary rollers protrude from the outer surface of the bracket in the radial direction of the central lead screw.

2. The internal thread rolling tool according to claim 1, characterized in that: The planetary rollers located on the same pitch circle are a group. There are more than two groups of planetary rollers. Each group of planetary rollers is arranged in the axial direction of the central lead screw. From one end to the other end along the axial direction of the central lead screw, the diameter of the planetary rollers in each group of planetary rollers increases or decreases, or the diameter of the pitch circle where each group of planetary rollers is located increases or decreases.

3. The internal thread rolling tool according to claim 2, characterized in that: There are 3-4 planetary rollers in each set of planetary rollers.

4. The internal thread rolling tool according to claim 2, characterized in that: Two sets of planetary rollers adjacent to each other in the axial direction of the central screw are staggered in the circumferential direction of the central screw.

5. The internal thread rolling tool according to claim 1, characterized in that: The bracket includes a plurality of circular rings connected in sequence in the axial direction of the central screw, and the two ends of the central screw are rotatably supported on the inner circumferences of the two circular rings located at the two ends through bearings; an embedding groove is opened on the end face where one circular ring contacts the other circular ring, and the two ends of the planetary roller located in the embedding groove are rotatably supported in two supporting holes respectively, one supporting hole is located on the bottom surface of the groove, and the other supporting hole is located on the end face of the other circular ring.

6. The internal thread rolling tool according to claim 5, characterized in that: The multiple rings are connected by bolts or screws passing through each ring.

7. The internal thread rolling tool according to claim 5, characterized in that: The planetary rollers located in the grooves on the same circular ring are a group. There are more than two groups of planetary rollers. The planetary rollers in the same group are located on the same pitch circle. The diameters of the planetary rollers in each group of planetary rollers located in the grooves on different circular rings are different. Along the axial direction of the central screw from one end to the other end, the diameters of the planetary rollers in the grooves on each circular ring increase or decrease, or the diameter of the pitch circle where each group of planetary rollers is located increases or decreases.

8. The internal thread rolling tool according to claim 7, characterized in that: A force-applying shaft is connected to a circular ring close to one end of the planetary roller with the largest diameter in the axial direction of the central lead screw, and the diameter of the force-applying shaft is smaller than the outer diameter of the circular ring.

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