High-stability precision fine-tuning lead screw assembly

Abstract

A highly stable precision fine-tuning lead screw assembly includes a lead screw and a nut. The outer surface of the lead screw is provided with an external thread, the top end face is provided with a screw slot, and the bottom end face is a spherical surface. The inner wall of the nut is provided with an internal thread adapted to the external thread. The dimensional tolerances of the two ends and the middle part of the internal thread are different, so that an interference thread pair at the two ends and a clearance thread pair at the middle part are formed through thread fit with the external thread. The interference thread pair is an interference fit, and the interference amount is less than 50 μm, which does not affect the thread transmission. In the present invention, by locally applying appropriate interference to the nut, the assembly can achieve precise transmission and self-locking during precise transmission. In the non-adjustment state, local interference rigid connection between the lead screw and the nut is realized through the interference fit between the threads, improving the position stability of the adjustment device, and it can be used in various precision pose adjustment mechanisms with high requirements for position stability.

Description

Technical Field

[0001] The present invention relates to a highly stable precision fine-tuning screw rod assembly, which is mainly used in various precision pose adjustment mechanisms with high requirements for position stability. Background Art

[0002] In common fine-tuning screw rod assemblies, there is usually a certain fitting clearance between the screw rod and the nut. For smooth adjustment, some manufacturers will also fill lubricating grease in this fitting clearance. On the one hand, this kind of fine-tuning screw rod assembly is affected by the fitting clearance, resulting in poor adjustment accuracy and guiding property. On the other hand, it is easily affected by environmental micro-vibrations and temperature, resulting in a slow position drift between the screw rod and the nut, thereby affecting the position stability of the optical lens or precision instrument installed in the adjustment mechanism. For mechanisms with fewer adjustment times within a long period, the static position stability of the adjustment mechanism is particularly important. In order to improve the micro-position change between the screw rod and the nut caused by the existence of the thread fitting clearance, the traditional method is to add a stop screw or a flexible sheet on the nut to lock the relative positions of the screw rod and the nut. Due to the locking force introduced by this kind of locking, during the locking process, since there is a certain clearance between the screw rod and the nut, the screw rod will deviate from its original position, thus affecting the adjustment accuracy. In severe cases, the radial offset amount can reach dozens of micrometers. For the optical lens applied in an optical or laser device, the pointing and positioning accuracy of the light beam reaches the micrometer or even sub-micrometer level, and the position drift of dozens of micrometers in the traditional locking mechanism will directly affect the optical axis or imaging quality. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a highly stable precision fine-tuning screw rod assembly to improve the position stability of the adjustment mechanism with fewer adjustment requirements in the non-adjustment state.

[0004] The technical solution of the present invention is as follows:

[0005] A highly stable precision fine-tuning screw rod assembly includes a screw rod and a nut. Its characteristics are that the outer surface of the screw rod is provided with an external thread, the top end face is provided with a screw slot, and the bottom end face is a spherical surface;

[0006] The inner wall of the nut is provided with an internal thread adapted to the external thread. The dimensional tolerances of the two ends and the middle part of this internal thread are different, so that an interference thread pair at the two ends and a clearance thread pair at the middle part are formed through thread fitting with the external thread. The interference thread pair is an interference fit, and the interference amount is less than 50μm, which does not affect the thread transmission.

[0007] The screw rod is in the shape of a long cylinder; the nut is in the shape of a short cylindrical stepped cylinder with a step at the bottom and is sleeved outside the screw rod.

[0008] Preferably, the interference amount ranges from 0.1 to 30 μm.

[0009] Preferably, the screw groove is an internal hexagonal groove for inserting a screwdriver.

[0010] The adjustment process of the present invention:

[0011] The external thread of the lead screw is thread - mated with the internal thread of the same pitch of the nut as the transmission mechanism. During use, the outer cylindrical surface of the nut is in clearance or interference fit with the cylindrical hole of the same diameter pre - machined on the fixed plate. When adjusting the relative position of the lead screw and the nut, through the thread fit between the lead screw and the nut, a screwdriver that matches the screw groove on the end face of the lead screw is inserted into the screw groove to realize the position adjustment of the lead screw relative to the nut, and further realize the position adjustment of the moving part abutted by the spherical tip of the lead screw. When the adjustment is completed, through the interference fit between the lead screw and the nut, partial rigid connection of the lead screw relative to the nut is realized, and further the relative position stability of the components is realized.

[0012] Compared with the prior art, the technical effects of the present invention:

[0013] 1) By appropriately making some of the thread fits in the components have interference, more precise conduction can be achieved during the precise transmission of the components and they can be locked. In the non - adjustment state, partial rigid connection between the lead screw and the nut is realized through the interference fit between some of the threads, avoiding the fit clearance that always exists in the ordinary structure or the position drift introduced by adding lubricating grease, and further realizing the position stability of the adjustment device.

[0014] 2) Since the clearance of the internal thread pair is reduced, while the nut and the lead screw achieve more precise transmission of the thread, due to the partial interference of the thread pair, the relative position of the lead screw and the nut can be fixed and locked through the interference fit after the adjustment is completed. Furthermore, the position stability of the adjusted moving part relative to the fixed part is ensured. For mechanisms that only need to be adjusted during initial installation or mechanisms with fewer adjustment times, the present invention can greatly improve the position stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the assembly sectional view of the high - stability precision fine - tuning lead screw assembly of the present invention

[0016] Figure 2 is the partial sectional view of the lead screw of the high - stability precision fine - tuning lead screw assembly of the present invention

[0017] Figure 3 is the sectional view of the nut of the high - stability precision fine - tuning lead screw assembly of the present invention

[0018] Figure 4 is the high - stability precision fine - tuning lead screw assembly of the present invention Figure 1 is the partial enlarged view of a in Detailed implementation mode

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention should not be limited accordingly.

[0020] Please refer to Figures 1 to 4 As can be seen from the figure, a highly stable precision fine-tuning screw rod assembly includes a screw rod 1 and a nut 2. The screw rod 1 is a cylindrical rod, the surface of the cylinder is an external thread 13, there is a screw groove 12 on the upper end face, the lower end face is a spherical surface 11, and the external thread 13 cooperates with the internal threads 23 at both ends and the internal thread 24 in the middle section of the nut 2; the nut 2 is a cylindrical stepped cylinder, the inner wall of the cylinder is an internal thread hole with the same specification as the external thread 13 of the screw rod 1, and the internal threads 23 at both ends and the internal thread 24 in the middle section have the same specification but slightly different dimensional tolerances. The outer wall of the cylinder is an external cylindrical surface 21, and the lowermost end of the outer wall of the cylinder is a short step 22; the external thread 13 of the screw rod 1 and the internal threads 23 at both ends and the internal thread 24 in the middle section of the nut 2 form an interference thread pair 31 and a clearance thread pair 32 through thread fitting.

[0021] The interference thread pair 31 between the screw rod 1 and the nut 2 is an interference fit, and the interference amount A is greater than 0 and less than 50 μm, so as not to affect the thread transmission.

[0022] The screw groove 12 on the upper end face of the screw rod 1 is an internal hexagonal or other specific-shaped groove.

[0023] The external thread 13 of the screw rod 1 and the internal threads 23 at both ends and the internal thread 24 in the middle section of the nut 2 with the same pitch are thread-fitted to form a thread pair as a transmission mechanism, and the interference thread pair 31 formed at both ends has an interference amount of A μm. During use, the external cylindrical surface 21 of the nut 2 is in clearance or interference fit with the cylindrical hole with the same diameter pre-processed on the fixed plate. When adjusting the relative position of the screw rod 1 and the nut 2, through the thread fit between the screw rod 1 and the nut 2, an interference thread pair 31 and a clearance thread pair 32 are formed. A screwdriver matching the screw groove 12 is inserted into the screw groove 12 to realize the position adjustment of the screw rod 1 relative to the nut 2, and further realize the position adjustment of the moving part abutted by the spherical surface 11 of the screw rod 1. When the adjustment is completed, the interference fit of the interference thread pair 31 between the screw rod 1 and the nut 2 realizes the partial rigid connection of the screw rod 1 relative to the nut 2, and further realizes the relative position stability of the assembly.

[0024] Tests have shown that in the case where the present invention maintains the rotation function of the tool by means of the screw-nut fit, appropriate interference is applied locally to the nut, so that the assembly can achieve precise transmission and self-locking during precise transmission. In the non-adjustment state, the local interference rigid connection between the screw and the nut is achieved through the interference fit between the threads, avoiding the fit clearance that always exists in the traditional screw-nut fit or the position drift introduced by adding grease, thereby realizing the position stability of the overall adjustment mechanism. This fine-tuning screw assembly can improve the position stability of the adjustment device and can be used in various precision pose adjustment mechanisms with high requirements for position stability.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A highly stable precision fine-tuning lead screw assembly, comprising a lead screw (1) and a nut (2), characterized in that, The outer surface of the lead screw (1) is provided with an external thread (13), the top end face is provided with a screw slot (12), and the bottom end face is a spherical surface (11); The inner wall of the nut (2) is provided with an internal thread (23) adapted to the external thread (13). The dimensional tolerances of the two end portions and the middle portion of the internal thread (23) are different, so that an interference thread pair (31) at the two end portions and a clearance thread pair (32) at the middle portion are formed through thread fit with the external thread (13). The interference thread pair (31) is an interference fit, and the interference amount is less than 50 μm, which does not affect the thread transmission.

2. The highly stable precision fine-tuning lead screw assembly according to claim 1, wherein The lead screw (1) is in the shape of a long cylinder; the nut (2) is in the shape of a short cylindrical stepped cylinder with a step (22) at the bottom and is sleeved outside the lead screw (1).

3. The highly stable precision fine-tuning lead screw assembly according to claim 1 or 2, characterized in that, The range of the interference amount is 0.1-30 μm.

4. The highly stable precision fine-tuning lead screw assembly according to claim 1, wherein The screw slot (12) is an internal hexagonal groove for a screwdriver to be inserted.

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