Manufacturing method of rolled lead screw nut and lead screw nut

Abstract

The invention discloses a manufacturing method of a rolled lead screw nut and the lead screw nut. The manufacturing method comprises the steps that A, according to requirements, a metal flat plate base body meeting the size requirement is machined; b, buckle structures matched with each other are machined on the two sides of the flat plate base body in the width direction; c, a thread tooth-shaped structure is machined on the upper surface of the flat plate base body, the thread tooth-shaped structure is obliquely arranged relative to the width direction of the flat plate base body, and a flat plate nut base body is formed; d, the flat nut base body formed in the step C is rolled and formed into a cylindrical shape, the buckle structures on the two sides of the flat nut base body are buckled with each other to achieve self-locking, and the thread tooth-shaped structures are spliced to form a complete internal thread; and E, the splicing seam is welded and fixed through a laser spot welding or electric resistance welding technology. According to the manufacturing method, the problems of high cost and precision of traditional deep hole thread machining are solved, the production efficiency is improved, and the manufacturing process of the lead screw nut is optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of screw nuts, and particularly to a manufacturing method for a rolled and formed screw nut and a screw nut. Background Art

[0002] In the prior art, screw nuts are usually manufactured by turning, tapping, broaching, grinding and other methods. However, with the expansion of the application scenarios of screw nuts, there are many problems in the existing conventional processing of screw nuts. Specifically, it is manifested as follows: (1) For the precision screw nuts used in the field of robots, they are thin and long, and the length-diameter ratio far exceeds that of the screw nuts in conventional application scenarios. However, the precision requirements are higher. When processing this type of screw nut by traditional methods such as turning, tapping, and broaching, affected by the rigidity of the tool and chip removal, vibration and tool deflection are likely to occur, resulting in a decrease in thread precision and thus unable to meet the precision requirements.

[0003] In addition, although grinding can improve the precision, since the grinding wheel rod needs to be at the thread lead angle with the axis of the nut, the space is limited in deep hole processing, and it is impossible to effectively grind the full thread. Therefore, it is very difficult for the traditional screw nut processing method to process this type of slender precision screw nut that meets the precision requirements.

[0004] (2) The traditional screw nut is processed by removing materials. For the large-diameter screw nuts used in some scenarios, a large amount of metal materials need to be removed during the processing, resulting in serious material waste and low material utilization rate, leading to high production costs.

[0005] (3) The traditional screw nut processing method usually requires multiple processes (rough machining + finish machining), resulting in a long production cycle and high costs. For example, in grinding processing, due to the slow processing speed, large grinding wheel loss, and high equipment requirements, the unit cost increases. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to solve the technical defects that the screw nut processing method in the prior art has great processing difficulty and difficult to guarantee precision when processing slender screw nuts, low material utilization rate when processing large-diameter screw nuts, and long production cycle and high costs.

[0007] To solve the above technical problems, the technical solution provided by the present invention is as follows: A manufacturing method for a rolled and formed screw nut, comprising the following steps: Step A: Process a metal flat substrate that meets the dimensional requirements according to the needs; Step B: Process mutually adapted snap structures on both sides in the width direction of the flat substrate; Step C: According to requirements, process a thread profile structure on the upper surface of the flat substrate. The thread profile structure is inclined with respect to the width direction of the flat substrate to form a flat nut substrate; Step D: Roll the flat nut substrate formed in Step C into a cylindrical shape. The buckle structures on both sides of the flat substrate are buckled with each other to achieve self-locking, and the thread profile structures are spliced to form a complete internal thread; Step E: Fix the splicing seam by laser spot welding or resistance welding process; Among them, the processes of Step B and Step C are interchanged.

[0008] In a preferred embodiment, in Step B, the buckle structure includes a male buckle and a female buckle that are adapted to each other.

[0009] In a preferred embodiment, a male buckle and a female buckle are provided on each side in the width direction of the flat substrate.

[0010] In a preferred embodiment, several of the buckle structures are arranged and distributed along the axial direction of the screw nut; or, several of the buckle structures are arranged and extended in a spiral direction on the screw nut.

[0011] In a preferred embodiment, in Step C, the thread profile structure is processed and formed by any one of numerical control milling, roll forming or laser etching.

[0012] In a preferred embodiment, in Step C, the thread profile structure is any one of trapezoidal thread, T-shaped thread, triangular thread, arc thread, rectangular thread.

[0013] In a preferred embodiment, after Step E, a finishing process for the outer surface of the nut substrate is further included.

[0014] In a preferred embodiment, in Step C, for screw nuts with different wall thickness / diameter ratios (T / D), different strategies are adopted to process the thread profile structure: When T / D << 1 / 12, directly process the thread profile structure on the flat substrate; When 1 / 12 ≤ T / D < 1 / 6, when processing the thread profile structure on the flat substrate, the thread profile structure is adjusted abnormally so that during the roll forming process in Step D, the thread profile structure after material deformation still meets the accuracy requirements; the abnormal adjustment method is: after making the blank of the thread profile structure on the flat substrate based on the helix angle at the pitch diameter of the thread, the thread profile is modified so that the helix angle of the thread is larger towards the crest of the thread and smaller towards the root of the thread.

[0015] In a preferred embodiment, in step C, when the wall thickness / diameter ratio (T / D) of the screw nut is ≥1 / 12, the cross-section of the flat nut base along the width direction is trapezoidal, and the width of the upper surface of the flat nut base is smaller than the width of the lower surface.

[0016] In a preferred embodiment, before the rolling in step D, a pre-tensile force is applied to the flat nut base to reduce the uneven internal stress; during the rolling in step D, a reverse tensile force is applied to make the flat nut base deform uniformly; during the rolling in step D, a multi-step progressive bending is adopted to make the flat nut base gradually approach the target shape.

[0017] In a preferred embodiment, in step D, an elastic recovery compensation step is further included, and the elastic recovery compensation step includes any one of the following: Over-bending compensation, calculating the springback angle, and appropriately increasing the rolling angle so as to reach the target size after springback; Or, after rolling, a slight reverse bending is performed to generate residual stress in the opposite direction inside the material to offset the springback effect.

[0018] The present invention also discloses a screw nut manufactured by the manufacturing method, and the internal thread of the screw nut is a single-start thread or a multi-start thread.

[0019] The manufacturing method of the roll-formed screw nut and the screw nut of the present invention change the traditional manufacturing method of the screw nut. Compared with the prior art, the following beneficial effects are achieved: (1) By first machining the thread profile structure on the flat base and then roll-forming the screw nut, the high cost and accuracy problems of traditional deep-hole thread machining are solved, the production efficiency is improved, and the manufacturing process of the screw nut is optimized.

[0020] (2) By arranging mutually adapted buckle structures on both sides in the width direction of the flat base, the self-locking and positioning effects are achieved after curling and forming, ensuring that the thread profile structures are butted in place to form a complete internal thread.

[0021] (3) The buckle structure plays a positioning and self-locking role before welding, ensuring the reliability of welding, and improving the structural strength of the screw nut and the reliability of long-term use.

[0022] (4) It is applicable to the processing of screw nuts with different thread profiles and different numbers of starts of threads, and has a wider application range. Description of the Drawings

[0023] Figure 1 It is a schematic top-view state structure diagram of the flat nut base shown in Embodiment 1; Figure 2 It is a schematic cross-sectional state structure diagram of the flat nut base shown in Embodiment 1 cut along the length direction; Figure 3 Schematic diagram of the sectional view of the flat nut base shown in Embodiment 1 along the width direction; Figure 4 Schematic diagram of the lead screw nut formed by rolling the flat nut base shown in Embodiment 1; Figure 5 Top view schematic diagram of the flat nut base shown in Embodiment 2; Figure 6 Schematic diagram of the lead screw nut formed by rolling the flat nut base shown in Embodiment 2. Detailed implementation manners

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0026] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, an integral connection, or a detachable connection; it can be the communication inside two elements; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0027] A manufacturing method of a rolled lead screw nut in this embodiment takes Figures 1-3 the flat nut base shown in Embodiment 1 as well as Figure 4 the lead screw nut formed by rolling the flat nut base shown in Embodiment 1 as an example for description.

[0028] In this embodiment, the manufacturing method of the rolled lead screw nut includes the following steps: Step A: According to requirements, process the metal flat base 10 that meets the dimensional requirements. It should be noted that the dimensions of the metal flat base are calculated based on the dimensions of the target lead screw nut when unfolded.

[0029] Step B: As shown in Figure 1As shown in the figure, a number of mutually adapted concave buttons 12 and convex buttons 11 are processed on both sides in the width direction of the flat substrate 10, and the concave buttons 12 and convex buttons 11 on both sides form a snap structure.

[0030] Preferably, a convex button 11 and a concave button 12 are provided on each side in the width direction of the flat substrate 10.

[0031] Step C: According to requirements, a thread profile structure 20 is processed on the upper surface of the flat substrate 10, and a number of thread profile structures 20 are evenly arranged along the length direction of the flat substrate 10. Among them, the thread profile structure 20 is inclined relative to the width direction of the flat substrate 10, so that after the flat nut substrate of this embodiment is rolled into a cylindrical shape, it can be spliced into a complete internal thread.

[0032] Among them, the structural form of the thread profile structure 20 includes but is not limited to any one of trapezoidal threads, T-shaped threads, triangular threads, arc threads, and rectangular threads, and is not limited in this embodiment.

[0033] Among them, the processing method of the thread profile structure 20 is not limited, and any one of the existing numerical control milling, rolling forming, laser etching, etc. can be used for processing and forming.

[0034] Preferably, in this embodiment, in order to ensure the thread accuracy after curling forming, different strategies are adopted to process the thread profile structure for screw nuts with different wall thickness / diameter ratios (T / D). Specifically, when T / D < 1 / 12 (for example, T / D = 20), the thread profile structure is directly processed on the flat substrate, and the thread deformation caused by material deformation after bending can be ignored. When 1 / 12 ≤ T / D < 1 / 6, when processing the thread profile structure 20 on the flat substrate 10, the thread profile structure 20 is adjusted abnormally, so that in the subsequent rolling forming process, the thread profile structure 20 after material deformation still meets the accuracy requirements.

[0035] Specifically in this embodiment, the abnormal adjustment method of the thread profile structure 20 is as Figure 1 shown. After making the blank of the thread profile structure on the flat substrate based on the helix angle at the pitch diameter of the thread, the thread profile is modified so that the helix angle of the thread is larger towards the thread crest and smaller towards the thread root. Among them, the helix angle α at the thread root is the smallest, and the helix angle β at the thread crest is larger.

[0036] It should be noted that during the rolling forming process of the flat nut base, the stresses on its inner and outer sides are different. The position of the thread profile structure 20 close to the inner side will be compressed and deformed, and the position close to the outer side will be stretched and deformed. In particular, when the wall thickness to major diameter ratio (T / D) is relatively large, this different stress deformation inside and outside will have an adverse effect on the thread accuracy. In this embodiment, preferably, in order to reduce the influence of this different stress deformation inside and outside on the thread accuracy, as Figure 3 shown, when the wall thickness to major diameter ratio (T / D) ≥ 1 / 12, the cross-section of the flat nut base in the width direction is trapezoidal, that is, the width of the upper surface of the flat nut base is smaller than the width of the lower surface. In this way, by reasonably distributing the material deformation, it is ensured that the internal thread of the rolled and formed screw nut meets the accuracy requirements.

[0037] It should be noted that in this embodiment, the processes of the above step B and step C can be interchanged.

[0038] Step D: Roll the flat nut base formed in step C into a cylindrical shape. After rolling and forming, the screw nut is as Figure 4 shown. The concave buckle 12 and the convex buckle 11 are buckled with each other to achieve self-locking, so as to ensure that the thread profile structure joins to form a complete internal thread. It should be noted that in this embodiment, the specific shapes and specific numbers of the concave buckle 12 and the convex buckle 11 are not limited. The technical purpose is that after the concave buckle 12 and the convex buckle 11 are buckled with each other to achieve self-locking, the spliced internal thread will no longer be misaligned, so as to facilitate the subsequent processes for fixing.

[0039] In this embodiment, in order to improve the good docking of the thread profile structure after curling and forming, a tension control technology can also be adopted in this step D. Specifically in this embodiment, before rolling in step D, a pre-tensile force is applied to the flat nut base to reduce the uneven internal stress and reduce the influence of springback after curling. During the rolling process of step D, a reverse pulling force is applied through a back pressure roller or a traction system to make the flat nut base deform uniformly and prevent local wrinkles or excessive deformation. In addition, during the rolling process of step D, multi-step progressive bending is adopted to make the flat nut base gradually approach the target shape instead of bending it in place at one time.

[0040] In this embodiment, since the flat base 10 has a certain elasticity, in order to reduce the influence of springback after curling and forming, this embodiment also includes an elastic recovery compensation step in step D. For example, an overbending compensation method can be adopted, calculating the springback angle and appropriately increasing the rolling angle so as to reach the target size after springback; or after rolling, a slight reverse bending can be carried out to generate residual stresses in the opposite direction inside the material to offset the springback effect.

[0041] Of course, before curling and forming, the yield strength of the material can also be reduced through pre-treatment (such as annealing, aging treatment) to make it more easily plastically deformed, thereby reducing springback. Cold working hardening can also be utilized to increase the rigidity after rolling and reduce the amount of springback.

[0042] Step E: Through laser spot welding or resistance welding process, weld and fix at Figure 4 the splicing seam 30 shown. In this embodiment, no limitation is imposed on the specific welding form.

[0043] It should be noted that the curled and formed lead screw nut manufactured by the manufacturing method of this embodiment can be either a single-start thread or a multi-start thread.

[0044] It should be noted that in this embodiment, after step E, a finishing process for the outer surface of the nut base is further included to meet the accuracy requirements of the outer surface. It should be noted that the finishing process for the outer surface is an existing conventional technology and will not be elaborated in this embodiment.

[0045] In this embodiment, as Figure 4 shown, several of the snap structures are arranged and distributed along the axial direction of the lead screw nut.

[0046] The flat nut base shown in Embodiment 2 and the lead screw nut curled and formed from the flat nut base shown in Embodiment 2 are as Figure 5 、 Figure 6 shown. The difference from Embodiment 1 is that several of the snap structures are arranged and extended in a spiral direction on the lead screw nut. The advantage of such a setting is that the force is more dispersed, which can provide better shear resistance and improve the overall rigidity of the lead screw nut housing.

[0047] In summary, the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A manufacturing method of a rolled and formed lead screw nut, characterized in that, It includes the following steps: Step A: Process a metal flat substrate that meets the dimensional requirements according to the needs; Step B: Process mutually adapted snap structures on both sides in the width direction of the flat substrate; Step C: Process a thread profile structure on the upper surface of the flat substrate according to the needs, and the thread profile structure is inclined with respect to the width direction of the flat substrate to form a flat nut substrate; Step D: Roll the flat nut substrate formed in Step C into a cylindrical shape, and the snap structures on both sides of the flat substrate are mutually engaged to achieve self-locking, and the thread profile structures are spliced to form a complete internal thread; Step E: Fix the splicing seam by laser spot welding or resistance welding process; Among them, the processes of Step B and Step C are interchanged.

2. The manufacturing method according to claim 1, characterized in that, In Step B, the snap structure includes a male snap and a female snap that are mutually adapted.

3. The manufacturing method according to claim 2, characterized in that, Both sides in the width direction of the flat substrate are provided with male snaps and female snaps.

4. The manufacturing method according to claim 3, characterized in that, A plurality of the snap structures are arranged and distributed along the axial direction of the lead screw nut; or, a plurality of the snap structures are arranged and extended in a spiral direction on the lead screw nut.

5. The manufacturing method according to claim 1, characterized in that In Step C, the thread profile structure is processed and formed by any one of numerical control milling, roll forming or laser etching.

6. The manufacturing method according to claim 1, characterized in that, In Step C, the thread profile structure is any one of trapezoidal thread, T-shaped thread, triangular thread, arc thread, rectangular thread.

7. The manufacturing method according to claim 1, characterized in that, After Step E, it further includes a finishing process for the outer surface of the nut substrate.

8. The manufacturing method according to any one of claims 1-7, characterized in that, In Step C, for lead screw nuts with different wall thickness / diameter ratios (T / D), different strategies are adopted to process the thread profile structure: When T / D << 1 / 12, directly process the thread profile structure on the flat substrate; When 1 / 12 ≤ T / D < 1 / 6, when processing the thread profile structure on the flat substrate, the thread profile structure is subjected to alienation adjustment so that the thread profile structure after material deformation during the rolling forming process in Step D still meets the accuracy requirements; the alienation adjustment method is: after making the blank of the thread profile structure on the flat substrate based on the helix angle at the pitch diameter of the thread, the thread profile is modified so that the helix angle of the thread is larger towards the thread crest and smaller towards the thread root.

9. The manufacturing method according to any one of claims 1-7, characterized in that, In Step C, when the wall thickness / diameter ratio (T / D) of the lead screw nut ≥ 1 / 12, the cross-section of the flat nut substrate along the width direction is trapezoidal, and the width of the upper surface of the flat nut substrate is smaller than the width of the lower surface.

10. The manufacturing method according to claim 8 or 9, characterized in that, Before the rolling in Step D, a pre-tensile force is applied to the flat nut substrate to reduce the uneven internal stress; during the rolling in Step D, a reverse pulling force is applied to make the flat nut substrate deform uniformly; during the rolling in Step D, multi-step progressive bending is adopted to make the flat nut substrate gradually approach the target shape.

11. The manufacturing method according to claim 10, characterized in that, In Step D, it further includes an elastic recovery compensation step, and the elastic recovery compensation step includes any one of the following: Overbending compensation, calculating the springback angle, and appropriately increasing the rolling angle so that the target size is reached after springback; Or, after rolling, perform slight reverse bending to generate residual stress in the opposite direction inside the material to offset the springback effect.

12. A lead screw nut, characterized in that, Manufactured by the manufacturing method according to any one of claims 1-11, the internal thread of the lead screw nut is a single-start thread or a multi-start thread.

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