Preload adjustment mechanism for double-nut ball screw and double-nut ball screw

Abstract

This invention provides a preload adjustment mechanism for a double-nut ball screw with a simple and reliable preload adjustment method, and a double-nut ball screw itself. The double-nut ball screw includes a screw shaft, a main nut and a secondary nut sleeved on the screw shaft, and a plurality of balls disposed between the main nut, the secondary nut, and the screw shaft. The preload adjustment mechanism for the double-nut ball screw includes: a preload portion disposed around the screw shaft between the main nut and the secondary nut, having a first end face and a second end face; and a feed mechanism that is rotatable, and by operating the feed mechanism, the preload portion is displaced such that at least one of the first end face and the second end face pushes against at least one of the main nut and the secondary nut, thereby increasing the distance between the main nut and the secondary nut.

Description

Technical Field

[0001] This invention relates to a double-nut ball screw, and more specifically, to a preload adjustment mechanism for a double-nut ball screw. Background Technology

[0002] Currently, for precision ball screw drives, in addition to requiring a certain unidirectional feed accuracy, axial clearance must also be strictly controlled; otherwise, backlash error will occur when rotating in the reverse direction. To eliminate backlash error caused by axial clearance, double-nut ball screws with preload adjustment are typically used.

[0003] One common method for adjusting preload is to adjust the size of the steel balls (ball bearings). Specifically, first, the steel ball size is pre-selected based on experience to adjust the gap between the two nuts (hereinafter referred to as main and auxiliary nuts), and then they are assembled. The preload of a double-nut ball screw is indirectly determined by the frictional torque. After assembly, the frictional torque is measured. If the measurement result is within the specifications, the adjustment is considered successful. Otherwise, steel balls of a different size need to be replaced and the previous steps repeated. In the production process of ball screws, adjusting the preload is a highly experience-intensive and cumbersome process.

[0004] Furthermore, wear on dual-nut ball screws leads to a decrease in preload, requiring replacement even before fatigue failure, which is costly. The conventional approach after wear is to add a shim between the two nuts. However, this is also complex and makes precise preload adjustment difficult.

[0005] Therefore, it is desirable to obtain a preload adjustment mechanism for a double-nut ball screw that is simple and reliable in terms of preload adjustment and can accurately adjust the preload.

[0006] In response to this, Patent Document 1 discloses a double-nut preloaded ball screw, which uses a wedge-shaped preload block between the two nuts and adjusts the radial movement of the preload block by using bolts or clamping strips, thereby adjusting the displacement between the two nuts to achieve the effect of adjusting the preload force.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: CN 106402308 A

[0010] However, the following problems still exist in Patent Document 1: (1) The contact surface between the wedge-shaped preload block and the nut is small. In actual use, stress concentration occurs on the part of the preload block that contacts the nut, which will lead to damage to the preload block; (2) When the clamping strip presses the preload block inward, the clamping force acting on each preload block is uncontrollable, making it difficult to ensure that the radial movement of each preload block is consistent, which will cause the two nuts to be misaligned and not run smoothly; (3) There is a gap between the two nuts, and the inner cavity of the two nuts is exposed to the outside through the gap, resulting in poor dust protection; (4) The structure between the two nuts protrudes from the outer diameter surface of the nut, which will interfere with the nut seat during installation, which is not conducive to installation and use. Summary of the Invention

[0011] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a preload adjustment mechanism for a double-nut ball screw with a simple and reliable adjustment method, as well as a double-nut ball screw, which can improve service life, adjustment accuracy, dust resistance and installation.

[0012] Specifically, to solve at least one of the above-mentioned problems, a first aspect of the present invention provides a preload adjustment mechanism for a double-nut ball screw, used to adjust the preload of the double-nut ball screw. The double-nut ball screw includes a screw shaft, a main nut and a secondary nut sleeved on the screw shaft, and a plurality of balls disposed between the main nut, the secondary nut and the screw shaft. The preload adjustment mechanism is characterized by comprising: a preload portion disposed between the main nut and the secondary nut in a manner surrounding the screw shaft, having a first end face and a second end face; and a feed mechanism that is rotatably operable, and by operating the feed mechanism, the preload portion is displaced such that at least one of the first end face and the second end face pushes against at least one of the main nut and the secondary nut, thereby increasing the distance between the main nut and the secondary nut.

[0013] In the second aspect of the present invention, based on the first aspect, the pre-tightening part is composed of a plurality of arc-shaped washers with a wedge-shaped cross-section that can be assembled into a ring. The plurality of arc-shaped washers are assembled between the main nut and the secondary nut to form a ring with a certain gap. The first end face contacts the main nut, and the second end face contacts the secondary nut. One of the squares of the first end face and the second end face becomes a slope that is inclined relative to the radial direction. The feeding mechanism is provided in the middle part of the arc-shaped washers for each of the arc-shaped washers. It is composed of a connecting key with a width greater than the arc-shaped washers and pressing the outer diameter surface of the arc-shaped washers, and two feeding bolts that pass through the connecting key and extend beyond the two sides of the arc-shaped washers and are screwed into the main nut and the secondary nut. Corresponding to the slope of the plurality of arc-shaped washers, a slope is also formed on the opposite end face of the main nut or the secondary nut.

[0014] In the third aspect of the present invention, based on the first or second aspect, arc-shaped through notches are provided at corresponding positions at both ends of each of the above-mentioned arc-shaped gaskets. The pre-tightening part also includes a cylinder arranged in a certain gap in the cylindrical space formed by the through notches at the ends of two adjacent arc-shaped gaskets.

[0015] In the fourth embodiment of the present invention, based on the second or third embodiment, multiple keyways extending through to the end face are provided at opposite ends on the outer diameter surfaces of the main nut and the secondary nut, respectively. The number of keyways in each of the main nut and the secondary nut corresponds to the number of arc-shaped washers. The connecting key is disposed on the corresponding keyways of the main nut and the secondary nut, and the radial depth of the multiple keyways is set such that the head of the feed bolt does not protrude from the outer diameter surfaces of the main nut and the secondary nut.

[0016] In the fifth aspect of the present invention, it is also possible that, based on the second or third aspect, a groove is provided on the inner diameter surface of the connecting key for a portion of the arc-shaped gasket to be embedded, and / or, a groove is provided on the outer diameter surface of the arc-shaped gasket for a portion of the connecting key to be embedded.

[0017] In the sixth embodiment of the present invention, based on the first embodiment, one of the main nut and the secondary nut has a threaded portion at the end opposite to the other, and a self-locking thread is formed on the threaded portion. The preload portion is an adjusting nut screwed into the threaded portion, and a self-locking thread is formed on the inner diameter surface of the adjusting nut. The feeding mechanism is composed of the adjusting nut and the threaded portion.

[0018] In the seventh embodiment of the present invention, based on the sixth embodiment, at least one first threaded hole is formed on the adjusting nut, extending from the outer diameter surface to the inner diameter surface, and a first set screw is screwed into the first threaded hole.

[0019] In the eighth aspect of the present invention, based on the sixth or seventh aspect, an annular protrusion is provided on the opposite end of the main nut and the secondary nut in a manner that is continuous on the outer diameter surface. The inner diameter of the annular protrusion is larger than the outer diameter of the threaded portion. At least one second threaded hole is formed on the annular protrusion, extending from the outer diameter surface to the inner diameter surface. A second set screw is screwed into the second threaded hole.

[0020] In the ninth aspect of the present invention, based on the sixth or seventh aspect, the outer diameter of the end of the threaded portion is smaller than that of the main nut and the secondary nut, so that the adjusting nut screwed into the threaded portion does not protrude from the outer diameter surface of the main nut and the secondary nut.

[0021] To solve at least one of the above-mentioned problems, the tenth aspect of the present invention provides a double-nut ball screw having a preload adjustment mechanism for the double-nut ball screw described in any of the above aspects.

[0022] Invention Effects

[0023] According to the first scheme mentioned above, the preload adjustment mechanism of the double-nut ball screw has a simple and reliable preload adjustment method, and can accurately adjust the preload. Furthermore, since the preload portion surrounds the screw shaft and contacts at least one of the main and auxiliary nuts with its end face, the contact area with the nuts is large, avoiding stress concentration.

[0024] According to the second scheme mentioned above, each wedge-shaped arc-shaped washer (preload) can be adjusted individually by the feed bolt. The radial displacement of each wedge-shaped arc-shaped washer can be adjusted as needed, which can control the movement of the two nuts within the allowable range and achieve the effect of adjusting the preload.

[0025] According to the third scheme described above, the cylinder can be used to position two adjacent arc-shaped gaskets. Furthermore, because there is a certain gap between the cylinder and the arc-shaped gaskets, the radial movement of the arc-shaped gaskets will not be affected when adjusting the preload. In addition, the cylinder can also provide a dustproof effect.

[0026] According to the fourth scheme mentioned above, in the preload adjustment mechanism of the double nut ball screw, there is no structure protruding from the outer diameter surface of the main and auxiliary nuts, so it will not interfere with the nut seat or the like during actual use and installation.

[0027] According to the fifth scheme above, when the connecting key is pressed down by adjusting the feed bolt, thereby pushing the arc-shaped shim downward by the connecting key, the arc-shaped shim and / or the groove of the connecting key can be used to prevent the arc-shaped shim from being misaligned.

[0028] According to the sixth scheme mentioned above, the adjusting nut's end face is in complete contact with the end face of the main nut or auxiliary nut, ensuring uniform force application and eliminating the problem of excessive local stress, thus ensuring safety and reliability. Furthermore, the uniform contact stress between the adjusting nut's end face and the main nut or auxiliary nut's end face prevents misalignment of the main and auxiliary nuts during preload adjustment, achieving precise preload adjustment. Moreover, the structural components between the main and auxiliary nuts are precisely connected, with no gaps leading to the nut's inner cavity, providing excellent dust protection.

[0029] According to the seventh scheme above, after adjusting the preload to the specified value, the adjusting nut can be fixed by tightening the first set screw to prevent it from loosening.

[0030] According to the above-mentioned scheme 8, after adjusting the preload to the specified value, the main nut and the secondary nut can be prevented from rotating relative to each other by locking the second set screw.

[0031] According to the above-mentioned ninth scheme, in the preload adjustment mechanism of the double nut ball screw, there is no structure protruding from the outer diameter surface of the main and auxiliary nuts, so it will not interfere with the nut seat or the like during actual use and installation.

[0032] According to the 10th scheme, a double-nut ball screw with the advantages described in any of the above schemes can be obtained. Attached Figure Description

[0033] Figure 1 This is a schematic diagram showing the basic structure of the double-nut ball screw according to the first embodiment of the present invention.

[0034] Figure 2 This is a structural diagram illustrating the preload adjustment mechanism of the double-nut ball screw according to the first embodiment of the present invention.

[0035] Figure 3 yes Figure 1 An enlarged view of part A.

[0036] Figure 4 yes Figure 1 A magnified view of part A from the P direction.

[0037] Figure 5 yes Figure 2 An enlarged view of the decomposed state of part B.

[0038] Figure 6 yes Figure 2 An enlarged view of part C.

[0039] Figure 7 This is a diagram showing the basic structure of the double-nut ball screw according to the second embodiment of the present invention.

[0040] Figure 8 yes Figure 7 A sectional view of the W section.

[0041] Explanation of reference numerals in the attached figures:

[0042] 100: Double nut ball screw; 1: Screw shaft; 2: Main nut; 3: Secondary nut; 4: Feed bolt; 5: Connecting key; 6: Arc-shaped washer; 7: Cylindrical body; 8, 9: Keyway; 10: Threaded part; 11: Annular protrusion; 13: Adjusting nut; 14: First set screw; 16: Second set screw. Detailed Implementation

[0043] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0044] [First Implementation]

[0045] First, the double-nut ball screw of the first embodiment of the present invention will be described. Figure 1 This is a schematic diagram illustrating the basic structure of the double-nut ball screw according to the first embodiment of the present invention. Figure 1 As shown, the double-nut ball screw 100 mainly includes a screw shaft 1, a main nut 2 and a secondary nut 3 sleeved on the screw shaft 1, and a plurality of balls (not shown) disposed between the main nut 2 and the secondary nut 3 and the screw shaft 1.

[0046] A preload adjustment mechanism is provided for adjusting the preload of the double-nut ball screw 100. In this embodiment, the preload adjustment mechanism does not require replacing the steel balls during preload adjustment; the preload can be adjusted by directly adjusting the gap between the main nut and the auxiliary nut using the feed mechanism.

[0047] Next, refer to Figures 1-6 The preload adjustment mechanism of the first embodiment will be described in detail. Figure 2 This is a structural diagram illustrating the preload adjustment mechanism of the double-nut ball screw according to the first embodiment of the present invention. Figure 3 yes Figure 1 An enlarged view of part A. Figure 4 yes Figure 1 A magnified view of part A from the P direction. Figure 5 yes Figure 2 An enlarged view of the decomposed state of part B. Figure 6 yes Figure 2 An enlarged view of part C.

[0048] like Figure 1 and Figure 2 As shown, the preload adjustment mechanism includes: a plurality of arc-shaped washers 6 serving as preload portions, the cross-section of which is wedge-shaped, the plurality of arc-shaped washers 6 being assembled as a whole into a ring with multiple gaps, disposed between the main nut 2 and the secondary nut 3, having a first end face in contact with the main nut 2 and a second end face in contact with the secondary nut 3; and a connecting key 5 and two feed bolts 4 serving as a feed mechanism, which are provided for each arc-shaped washer 6 and located in the middle of the outer periphery of the plurality of arc-shaped washers 6.

[0049] Here, in Figure 1 and Figure 2The diagram shows a case where the first end face of the arc-shaped washer 6 that contacts the main nut 2 is a slope, and the second end face that contacts the auxiliary nut 3 is a vertical surface. Correspondingly, a slope is also formed on the end face of the main nut 2, which is the same as the slope of the arc-shaped washer 6. However, this is not a limitation. Alternatively, the first end face of the arc-shaped washer 6 that contacts the main nut 2 may be a vertical surface, and the second end face that contacts the auxiliary nut 3 may be a slope. Correspondingly, a slope is also formed on the end face of the auxiliary nut 3, which is the same as the slope of the arc-shaped washer 6.

[0050] In addition, such as Figure 3 , 4 As shown, keyways 9 and 8, extending through to the end faces, are respectively provided on the outer diameter surfaces of the main nut 2 and the auxiliary nut 3 at their opposite ends. A connecting key 5 is embedded in the keyway 9 of the main nut 2 and the keyway 8 of the auxiliary nut 3, pressing against the outer diameter surface of the arc-shaped washer 6. The width of the connecting key 5 is greater than that of the arc-shaped washer 6. Two feed bolts 4 penetrate the portions of the connecting key 5 that extend beyond the arc-shaped washer 6 on both sides and are screwed into the main nut 2 and the auxiliary nut 3.

[0051] Here, it is preferable to set the radial depth of the keyway portions 8 and 9 such that the head of the feed bolt 4 does not protrude beyond the outer diameter surfaces of the main nut 2 and the auxiliary nut 3. Consequently, other components of the preload adjustment mechanism will also not protrude beyond the outer diameter surfaces of the main and auxiliary nuts.

[0052] In addition, such as Figure 2 As shown, arc-shaped through-holes are provided at corresponding positions at both ends of each arc-shaped gasket 6. A cylinder 7 is placed in the cylindrical space formed by the through-holes at the ends of two adjacent arc-shaped gaskets 6 to position the two adjacent arc-shaped gaskets 6. Moreover, as Figure 6 As shown, when a cylinder 7 is placed in an arc-shaped through-hole, a small gap is left.

[0053] Here, in Figure 2 The illustration shows a configuration with two arc-shaped gaskets 6 and two cylinders 7, but the number is not limited to this and can be set according to actual needs. Moreover, it is preferable that each arc-shaped gasket 6 has the same size and shape, and can be combined into a ring shape, thereby ensuring that each arc-shaped gasket 6 applies the same force.

[0054] In addition, such as Figure 5 As shown, a groove is provided on the outer diameter surface of the arc-shaped gasket 6 for a portion of the connecting key 5 to be embedded, but it can also be replaced by a groove on the inner diameter surface of the connecting key 5 for a portion of the arc-shaped gasket 6 to be embedded.

[0055] Next, the usage and effects of the preload adjustment mechanism of the double-nut ball screw according to the first embodiment of the present invention will be explained.

[0056] In the preload adjustment mechanism of the double-nut ball screw in the first embodiment, two feed bolts 4 are provided on the connecting key 5 in the keyway portions 9 and 8 of the main nut 2 and the auxiliary nut 3. By adjusting the feed bolts 4, the connecting key 5 can be moved downward. The downward pressure of the connecting key 5 causes the wedge-shaped arc-shaped washer 6 to move downward. Since the contact surface between the arc-shaped washer 6 and the main nut 2 is inclined, as the feed bolts 4 are adjusted, the first end face and the second end face of the wedge-shaped arc-shaped washer 6 push against the two nuts, thereby increasing the distance between the two nuts and achieving the purpose of increasing the preload.

[0057] The preload adjustment mechanism for the double-nut ball screw according to this embodiment is simple, reliable, and allows for precise preload adjustment. Furthermore, because multiple arc-shaped washers 6 contact the main and auxiliary nuts with their approximately annular end faces, the contact area with the main and auxiliary nuts is large, avoiding stress concentration.

[0058] In addition, since each wedge-shaped arc-shaped washer 6 can be adjusted individually by the feed bolt 4, the radial displacement of each wedge-shaped arc-shaped washer 6 can be adjusted as needed, which can control the movement of the two nuts within the allowable range and achieve the effect of adjusting the preload.

[0059] Furthermore, since the cylinder 7 positions two adjacent arc-shaped gaskets 6, and there is a certain gap between the cylinder 7 and the through-hole of the arc-shaped gasket 6, the radial movement of the arc-shaped gasket 6 will not be affected when adjusting the preload. Moreover, the cylinder 7 also provides a dustproof effect.

[0060] In addition, the preload adjustment mechanism of the double-nut ball screw has no structure protruding from the outer diameter surface of the main and auxiliary nuts, so it will not interfere with the nut seat or other components during actual use and installation.

[0061] In addition, when the connecting key 5 is pressed down by adjusting the feed bolt 4, thereby pushing the arc-shaped washer 6 downward by the connecting key 5, the arc-shaped washer 6 can be prevented from misaligning by the groove of the connecting key 5 and / or the arc-shaped washer 6.

[0062] [Second Implementation]

[0063] Next, refer to Figure 7 and Figure 8 The second embodiment of the present invention describes a double-nut ball screw. Figure 7 This is a diagram showing the basic structure of the double-nut ball screw according to the second embodiment of the present invention. Figure 8 yes Figure 7 A sectional view of the W section.

[0064] In the second embodiment, similar to the first embodiment, the steel balls do not need to be replaced during the preload adjustment process. The preload can be adjusted by directly adjusting the gap (axial relative distance) between the main nut and the secondary nut using the feed mechanism. Here, structures identical to those in the first embodiment are labeled with the same reference numerals and descriptions are omitted.

[0065] In the second embodiment, the preload adjustment mechanism for the double-nut ball screw is as follows: Figure 7 , Figure 8 As shown, a threaded portion 10 is provided at the end of the secondary nut 3 opposite to the main nut 2. In this embodiment, the end with the threaded portion 10 is formed by necking relative to the outer diameter surface of the secondary nut 3. Furthermore, a self-locking thread is formed on the threaded portion 10, preferably a triangular thread. An adjusting nut 13 is screwed onto this threaded portion 10. Here, the adjusting nut 13 constitutes the preload portion of the present invention.

[0066] A self-locking thread, preferably a triangular thread, is formed on the inner diameter surface of the adjusting nut 13. The adjusting nut 13 and the threaded portion 10 constitute the feed mechanism of the present invention.

[0067] Furthermore, a plurality of first threaded holes extending from the outer diameter surface to the inner diameter surface are formed on the adjusting nut 13, and a first set screw 14 is screwed into the first threaded holes. At the end of the main nut 2 opposite to the secondary nut 3, an annular protrusion 11 is provided in such a manner that its outer circumferential surface is continuous with the outer circumferential surface of the main nut 2. The inner diameter of the annular protrusion 11 is larger than the outer diameter of the threaded portion 10. A plurality of second threaded holes extending from the outer diameter surface to the inner diameter surface are formed on the annular protrusion 11, and a second set screw 16 is screwed into the second threaded holes.

[0068] Preferably, the outer diameter of the end with the threaded portion 10 is smaller than that of the main nut 2 and the auxiliary nut 3, so that the adjusting nut 13 screwed into the threaded portion 10 will not protrude from the outer diameter surfaces of the main nut 2 and the auxiliary nut 3.

[0069] Here, in Figure 7 , Figure 8 The example shown has a threaded portion 10 formed at the end of the secondary nut 3 and an annular protrusion 11 formed at the end of the main nut 2, but the arrangement can also be reversed. Furthermore, Figure 7 The diagram shows two first set screws 14 and two second set screws 16, but the number of first set screws and second set screws can be set according to actual needs, with at least one being sufficient.

[0070] Next, the usage and effects of the preload adjustment mechanism of the double-nut ball screw according to the second embodiment of the present invention will be explained.

[0071] In this embodiment, the threaded portion 10 at the end of the secondary nut 3 has a self-locking thread. An adjusting nut 13, also with a self-locking thread, is screwed into the threaded portion 10 of the secondary nut 3. The main nut 2 and the assembled secondary nut 3 are then installed together into the lead screw shaft 1. The relative positions of the main nut 2 and the secondary nut 3 are adjusted so that the end face of the adjusting nut 13 contacts the end face of the main nut 2. Simultaneously, the main nut 2 and the secondary nut 3 are fixed, and the adjusting nut 13 is rotated so that its end face pushes against the main nut 2, increasing the distance between the main nut 2 and the secondary nut 3, thus adjusting the preload to the specified value. Then, the first set screw 14 and the second set screw 16 are tightened.

[0072] Furthermore, if the ball screw wears down and the preload decreases, loosen the first set screw 14 and the second set nut 16 while fixing the main nut 2 and the auxiliary nut 3. Rotate the adjusting nut 13 so that its end face presses against the main nut 2, increasing the distance between the main nut 2 and the auxiliary nut 3, thus increasing the preload. Then tighten the first set screw 14 and the second set nut 16. This allows for the adjustment of the preload.

[0073] The preload adjustment mechanism for the double-nut ball screw according to this embodiment is simple, reliable, and allows for precise preload adjustment. Furthermore, since the adjusting nut 13 is in complete contact with the main nut 2 via its annular end face, the contact area with the main nut 2 is large, avoiding stress concentration, ensuring uniform force application, and eliminating the problem of excessive local stress, thus ensuring safety and reliability.

[0074] Furthermore, the contact stress between the end face of the adjusting nut 13 and the end face of the main nut 2 is uniform, preventing the main and auxiliary nuts from misaligning during preload adjustment, thus achieving precise preload adjustment. Additionally, the structural components between the main and auxiliary nuts are precisely connected, with no gaps leading to the nut's inner cavity, providing excellent dust protection.

[0075] In addition, after adjusting the preload to the specified value, the adjusting nut 13 can be fixed by tightening the first set screw 14 to prevent it from loosening.

[0076] In addition, after adjusting the preload to the specified value, the main nut 2 and the secondary nut 3 can be prevented from rotating relative to each other by locking the second set screw 16.

[0077] In addition, the preload adjustment mechanism of the double-nut ball screw has no structure protruding from the outer diameter surface of the main and auxiliary nuts, so it will not interfere with the nut seat or other components during actual use and installation.

[0078] The preload adjustment mechanism for the double-nut ball screw according to the present invention simplifies the assembly process of the double nuts. During preload adjustment, the steel balls do not need to be replaced; only the feed mechanism needs to be adjusted to regulate the gap (axial relative distance) between the two nuts to adjust the preload. It requires minimal experience from assembly workers and is easy to operate. Furthermore, even if the preload decreases due to wear (before reaching fatigue spalling life), simply adjusting the feed mechanism to adjust the gap between the two nuts to increase the preload allows the ball screw to regain its preload.

[0079] The above is merely a detailed description of preferred embodiments of the present invention. Those skilled in the art can make various modifications and additions to the described specific embodiments or use similar methods to replace them. The scope of the present invention should be determined by the claims, and should also include all modifications within the meaning and scope equivalent to the content of the claims.

Claims

1. A preload adjustment mechanism for a double-nut ball screw, used to adjust the preload of the double-nut ball screw, the double-nut ball screw comprising a screw shaft, a main nut and a secondary nut sleeved on the screw shaft, and a plurality of balls disposed between the main nut and the secondary nut and the screw shaft, characterized in that the preload adjustment mechanism of the double-nut ball screw comprises: A preload portion, which is disposed between the main nut and the auxiliary nut in a manner surrounding the lead screw shaft, has a first end face and a second end face; and The feeding mechanism is rotatable, and by operating the feeding mechanism, the preload portion is displaced such that at least one of the first end face and the second end face pushes against at least one of the main nut and the secondary nut, thereby increasing the distance between the main nut and the secondary nut. The preload portion consists of multiple arc-shaped washers with a wedge-shaped cross-section that can be assembled into a ring. These arc-shaped washers are arranged between the main nut and the secondary nut to form multiple rings with certain gaps. The first end face contacts the main nut, and the second end face contacts the secondary nut. One of the square faces of the first and second end faces forms a slope that is inclined relative to the radial direction. Each of the aforementioned arc-shaped gaskets is identical in size and shape. The feeding mechanism is positioned at the middle of each arc-shaped washer for each of the arc-shaped washers. It consists of a connecting key with a width greater than that of the arc-shaped washer and pressing against the outer diameter surface of the arc-shaped washer, and two feed bolts that pass through the connecting key and extend beyond both sides of the arc-shaped washer and are screwed into the main nut and the auxiliary nut, respectively. Corresponding to the inclined surfaces of the plurality of arc-shaped washers, inclined surfaces are also formed on the opposite end faces of the main nut or the secondary nut.

2. The preload adjustment mechanism for the double-nut ball screw according to claim 1, characterized in that, Each of the aforementioned arc-shaped gaskets has an arc-shaped through-hole at a corresponding position at both ends. The pre-tightening part also includes a cylinder arranged with a certain gap in the cylindrical space formed by the through notch at the ends of two adjacent arc-shaped gaskets.

3. The preload adjustment mechanism for the double-nut ball screw according to claim 1 or 2, characterized in that, On the outer diameter surfaces of the main nut and the auxiliary nut, multiple keyways extending through to the end faces are provided at opposite ends. The number of keyways in each of the main nut and the auxiliary nut corresponds to the number of arc-shaped washers. The connecting key is disposed in the corresponding keyway portion of the main nut and the auxiliary nut. The radial depth of the plurality of keyways is set such that the head of the feed bolt does not protrude beyond the outer diameter surface of the main nut and the secondary nut.

4. The preload adjustment mechanism for the double-nut ball screw according to claim 1 or 2, characterized in that, The inner diameter surface of the connecting key is provided with a groove for embedding a portion of the arc-shaped gasket, and / or, the outer diameter surface of the arc-shaped gasket is provided with a groove for embedding a portion of the connecting key.

5. A double-nut ball screw, comprising the preload adjustment mechanism of any one of claims 1 to 4.

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