Large-load roller screw

Abstract

The utility model discloses a large-load roller screw and belongs to the field of machinery. The structure comprises a screw rod, a nut and a roller string, the screw rod is a T-shaped screw rod, and the nuts are divided into a left independent nut and a right independent nut; during working, when the screw rotates, the compressed roller string group rotates along the spiral surface and pushes the nut to translate; the roller string passes through the return hole, passes through the return pipeline and then flows back between the conical surfaces to circulate; the technical key pin roller string structure comprises a rolling shaft, a pin roller and a bottom pin roller. According to the assembly relation, the pin rollers and the bottom pin roller are coaxially connected through the rolling shaft, and all the pin rollers can rotate freely; the column top and the column bottom of the roller string are exposed roller protruding portions, or the pinnacle-shaped roller top of the uppermost roller is exposed. The contact working faces of the side walls of the left nut internal thread and the right nut internal thread are different and correspond to the different left side faces and the different right side faces of the trapezoidal concave portions of the nut internal threads respectively, and the side faces are conical faces making contact with the pin roller strings. The large-load roller screw is provided. The method can be widely applied to the precision rotation field.

Description

[Technical Field]

[0001] This invention belongs to the field of mechanical and electronic technology. More precisely, it is a lead screw that uses rollers instead of balls, which can greatly increase the load and service life. [Background Technology]

[0002] Traditional ball screws consist of a screw, nut, steel balls, preload plates, a reversing device, and a dust cover. They are characterized by high precision, reversibility, and high efficiency. The most commonly used ball screws are ideal products for converting rotary motion into linear motion, or vice versa. They are the most frequently used transmission components in machine tools and precision machinery. Their main function is to convert rotary motion into linear motion, or torque into axial reciprocating force. Due to their very low frictional resistance, ball screws are widely used in various industrial equipment and precision instruments. Common circulation methods include external circulation and internal circulation. Ball circulation methods include circulation guide type, circulator type, and end cap type. Preload methods include double nut type, positional preload type, and constant pressure preload; that is, a preload can be applied to the ball screw assembly. Because the preload can make the axial clearance reach a negative value, a higher rigidity is obtained (by applying pressure to the balls inside the ball screw, in actual use in mechanical devices, the repulsive force of the balls can enhance the rigidity of the nut). The appropriate type can be selected according to the application. The ball screws are available in two types: precision ball screws with high-precision grinding and cold-rolled ball screw bearings with high-precision cold rolling. Additionally, to meet urgent delivery needs, finished products with pre-machined shaft ends are available, as well as semi-finished products and cold-rolled ball screw bearings that can be further machined at the shaft ends. Peripheral components necessary for the bearing, such as screw support units, nut supports, and lock nuts, are also standardized and available for user selection.

[0003] Advantages and disadvantages overview:

[0004] advantage:

[0005] Low friction loss and high transmission efficiency: Due to the numerous rolling balls between the screw shaft and the screw nut in a ball screw pair, high motion efficiency can be achieved. Compared with the traditional sliding screw pair, the driving torque is reduced to less than 1 / 3, meaning that the power required to achieve the same motion result is only 1 / 3 of that required using a sliding screw pair. This is very helpful in saving energy.

[0006] High-precision ball screw assemblies are generally produced in a continuous process using the world's most advanced machinery. In particular, the factory environment for each process, including grinding, assembly, and inspection, is strictly controlled for temperature and humidity. Thanks to a comprehensive quality management system, precision is fully guaranteed.

[0007] High-speed feed and micro-feed are possible

[0008] Because ball screw pairs utilize the motion of rolling balls, the starting torque is extremely small, and there is no crawling phenomenon like in sliding motion, which ensures precise micro-feeding.

[0009] shortcoming:

[0010] Linear bearings also have their limitations. The most important ones are poor resistance to bearing impact and load-bearing capacity. Secondly, linear bearings produce more vibration and noise when moving at high speeds.

[0011] The axial stiffness is not as high as that of a regular trapezoidal lead screw, and there is an inherent defect in the point contact of the steel balls.

[0012] Compared to traditional T-type lead screws, ball screws cannot self-lock; however, they do have the ability to reverse transmission. [Summary of the Invention]

[0013] The purpose of this invention:

[0014] To overcome the shortcomings of existing technologies and improve the inherent defect of poor axial impact resistance of existing ball screws.

[0015] The features of this invention are: compact structure and large axial load capacity.

[0016] The key technology of this invention is to eliminate the ball retainer and establish a ball channel and return channel mechanism within the bearing sleeve itself.

[0017] Specific details of the invention:

[0018] The high-load roller screw consists of a screw, a nut, a roller string, and a preload structure. Its features include: a T-shaped screw with a trapezoidal helical protrusion on its thread cross-section; the side of the trapezoid is the helical surface; the angle between the normal to the helical surface and the axis is 0-60 degrees; the bottom surface of the helical protrusion is the bottom surface between the threads of the screw, which is the lowest position restricting the roller string; two independent nuts, left and right, with a trapezoidal helical recess on their working surface; the inner thread sidewall of the nut is the contact working surface, located on different sides of the trapezoidal recess; the bottom surface of the helical recess also serves to restrict the uppermost position of the roller string; two return holes are strip-shaped holes passing through the nut sidewalls to guide the overall flow of the roller string group; a curved strip-shaped return pipe connects the two return holes, with a constraint rail on its inner wall. This constraint rail guides the roller string group to flow between the two return holes for circulation.

[0019] The preload structure is an optional component. A simple solution is to rigidly tighten the left and right nuts with zero clearance, which requires frequent adjustment during subsequent use. A more complex solution is to apply a certain preload force to the left and right nuts using springs, leaf springs, etc. (preloading the roller group is commonly known as negative clearance), which provides greater rigidity and does not require frequent adjustment during subsequent use.

[0020] The roller string structure is the core of this invention. The roller string structure includes: rollers, rollers, and bottom rollers. The assembly relationship is as follows: the rollers and bottom rollers are coaxially connected by the rollers, allowing all rollers to rotate freely. The top and bottom of the rollers are exposed protruding parts of the rollers, or the pointed tops of the uppermost rollers. The pointed shape is intended to reduce the radius of rotation and thus reduce frictional wear. The total number of rollers in the roller string is between 2 and 30; the more rollers, the less sliding friction occurs.

[0021] The inner wall of the return pipe is smooth, or it is machined with constraint protrusions arranged along the flow direction of the roller string. These constraint protrusions fit precisely into the axial gaps between the rollers in the roller string to constrain the roller string and prevent it from tipping over during flow on the inner wall of the return pipe, thus preventing the circulation from getting stuck. The assembly relationship is achieved by using a single screw and a pair of nuts, ensuring that the cylindrical roller string cannot tip over into the gap between the two conical surfaces.

[0022] Working principle:

[0023] The roller string, clamped between the threaded side of the screw and the internal threaded sidewall of the nut, is arranged in a conical configuration. According to mathematical principles, the roller string clamped between two conical surfaces will always have its conical axis intersecting the roller string axis, preventing the roller string from flipping into the gap between the two conical surfaces. The bottom roller sections of adjacent roller strings abut together, while the rollers themselves do not abut against each other. Since the diameter of the bottom roller can be slightly smaller than the top roller, the threaded side does not contact the bottom roller under the support of the roller. The enormous working pressure on the threaded side is not applied to the bottom roller, so the abutment of the bottom rollers does not generate significant frictional resistance.

[0024] As the screw rotates, the tightly packed rollers rotate along the helical surface, pushing the nut to move horizontally. The rollers pass through the return hole, then through the return pipe, and flow back between the conical surfaces in a continuous cycle. The inner wall of the return pipe can be machined with a restraining convex rail, which inserts into the gap between two rollers to guide the rollers and prevent them from tipping over in the return pipe, ensuring smooth circulation. Furthermore, the preloaded structure exhibits the traditional characteristic of negative clearance in its elastic deformation, resulting in a significant increase in stiffness.

[0025] Further: The bottom roller of the roller string is called the bottom roller: its diameter is equal to or slightly smaller than (generally the diameter difference is between 2 and 200 microns) the diameter of the upper rollers. The purpose is to ensure that when the roller string is clamped between the helical surfaces of the screw and nut, the bottom rollers that are in contact with each other are not clamped by the helical surface, but the rollers with a slightly larger diameter are clamped instead. In this way, even if the bottom rollers that can rotate freely touch each other, they will produce very little wear. In addition, there can also be two bottom rollers, located at the top and bottom ends, especially when the roller string is overturned during the return pipeline transport.

[0026] Furthermore: the rollers in the roller string are in seamless contact or have axial clearance, which is obtained by the washer and the boss at the center of the roller.

[0027] The technological advancements of this invention include: increasing the axial impact resistance of traditional ball screws (under the same size) by more than an order of magnitude, achieving a compact structure, and significantly extending the service and maintenance time. [Image Description]

[0028] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments:

[0029] [ Figure 1 Schematic diagram of the overall structure and characteristic cross-section of a high-load roller screw.

[0030] [ Figure 2 Schematic diagram of a localized explosion of a high-load roller screw.

[0031] [ Figure 3 Schematic diagram of roller string structure. Schematic diagram of cross-section of high-load roller screw.

[0032] [ Figure 4 Schematic diagram of the structure and mechanical action of the roller string.

[0033] Explanation of the labels in the diagram:

[0034] 1 screw

[0035] 1-1 Trapezoidal spiral protrusion

[0036] 1-2 raised bottom surface

[0037] 1-3 axis

[0038] 1-4 Thread helical surface normal

[0039] 1-5 Threaded Helical Surface

[0040] 1-6 Angle between axis and normal Q2 nut

[0041] 2-1 Trapezoidal Spiral Concave

[0042] 2-2 Concave bottom surface

[0043] 2-3 return hole 1

[0044] 2-4 return pipeline

[0045] 2-5 Constrained Convex Rail

[0046] 2-6 Return Hole 2

[0047] 2-7 Fixing Holes

[0048] 3 roller strings

[0049] 3-1 Column Top

[0050] 3-2 rollers

[0051] 3-3 bottom roller

[0052] 3-4 rollers

[0053] 3-5 column bottom

[0054] 3-6 roller clearance 4 preload structure

[0055] 4-1 Connecting screw

[0056] 4-2 Locking Nut

[0057] 4-3 Preloaded Spring

[0058] 7. Enlarged section of cross-section

[0059] 8 thread section

[0060] Disassembly of 9 roller sets

[0061] 10. Close-fitting parts

[0062] 11 gaps

[0063] 12. Preload direction [Detailed Implementation]

[0064] like Figure 1 , Figure 2 , Figure 3 As shown:

[0065] The high-load roller screw consists of: a screw (1), a preload structure (4), a roller string (3), and a nut (2); the screw (1) is a T-shaped screw. Figure 3 The thread section (8) shows that its thread structure is a trapezoidal helical protrusion (1-1). The angle between the normal (1-4) of the helical surface and the axis (1-3) is 0-60 degrees. The bottom surface (1-2) of the protrusion is the bottom surface between the threads of the screw, which restricts the position of the roller string (3). The working surface of the nut (2) is a trapezoidal helical recess (2-1), which is divided into two independent nuts on the left and right. The contact working surfaces are located on different sides of the recess. The bottom surface (2-2) of the recess also restricts the position of the roller string (3). The return hole 1 (2-3) and the return hole 2 (2-6) are strip holes that pass through the side wall of the nut (2) and are used to guide the overall flow of the roller string (3). The return pipe (2-4) is a strip hole with a constraint protrusion (2-5) and is used to guide the flow of the roller string (3) between the return hole 1 (2-3) and the return hole 2 (2-6). The mounting holes (2-7) are used for connecting to the sliding platform of the machine.

[0066] The preload structure (4) applies a certain preload force to the left and right nuts: the distance between the left and right nuts is changed by rotating the connecting screw (4-1), and the preload spring (4-3) sandwiched between the connecting screws provides the preload thrust, which is the direction of the preload force (12); the connecting screw (4-1) is locked by the locking nut (4-2).

[0067] from Figure 3 It can be seen from the local magnification (7) of the cross-section of the return pipe (2-4) that the constraint convex rail (2-5) can be embedded in the roller gap (3-6), guiding and holding the posture of the roller string (3) without overturning in the return pipe (2-4).

[0068] like Figure 4 As shown:

[0069] From the disassembly of the roller string (9), we can see the core structure of the roller string (3): under the support of the roller shaft (3-4), the roller (3-2) and the bottom roller (3-3) can rotate freely through the shaft hole. The top (3-1) and bottom (3-5) of the roller can be the protruding part of the roller shaft (3-4) or the pointed roller installed at both ends of the roller shaft. The purpose of the pointed top is to make the center part contact the raised bottom surface and the concave bottom surface, so as to reduce friction consumption with a small turning radius.

[0070] The lower figure shows the relative positions of the roller string (3) during operation. The close-fitting parts (10) between adjacent bottom rollers (3-3) will rub against each other. When the diameter of the bottom roller is smaller than that of the upper roller, the bottom roller will not contact the side of the screw thread and the side wall of the nut internal thread (working surface), so there will be no frictional wear on the working surface. Similarly, the natural gap (11) will also prevent frictional wear between adjacent rollers (3-2). (3-6) is the roller clearance.

Claims

1. High-load roller screw, consisting of a screw, nut, and roller string; the screw is a T-shaped screw, and the nut consists of two independent nuts, left and right. Two return holes in the nut pass through the nut's sidewall and are strip-shaped openings; an independent return channel or a return channel directly machined into the nut's sidewall connects the two return holes; the roller string is clamped between the screw thread sidewall and the nut's internal thread sidewall, and within the return channel; the assembly relationship is a single screw and a pair of nuts; the preload mechanism is optional. A simple solution is to rigidly tighten the left and right nuts with zero clearance, requiring frequent adjustments during use; a more complex solution uses springs and spring sheets to apply a certain preload force to the left and right nuts, providing greater rigidity and eliminating the need for frequent adjustments during use; the working principle is: when clamped between the screw thread sidewall and the nut's internal thread sidewall... The roller strings are arranged in a conical pattern. Mathematics dictates that the roller strings sandwiched between two conical surfaces will always have the axis of the conical surface intersecting the axis of the roller string at a single point, preventing the cylindrical roller strings from flipping into the gap between the two conical surfaces. The bottom rollers of adjacent roller strings, held between the threaded side of the screw and the internal threaded sidewall of the nut, abut together, while the rollers themselves do not abut against each other. Since the diameter of the bottom roller can be slightly smaller than that of the main roller, the threaded side does not contact the bottom roller under the support of the roller. The enormous working pressure on the threaded side is not applied to the bottom roller, so the abutment of the bottom roller does not generate significant frictional resistance. During operation, as the screw rotates, the tightly pressed roller strings rotate along the helical surface and push the nut to move horizontally. The roller strings pass through the return hole, flow back through the return pipe, and circulate between the conical surfaces repeatedly. Its characteristics are: The roller string construction includes: Rollers, rollers, bottom rollers; Assembly relationship: The rollers and bottom rollers are coaxially connected by the rollers, and all rollers can rotate freely; the top and bottom of the roller string are the exposed roller protrusions, or the exposed pointed top of the uppermost roller. The contact working surfaces of the inner thread sidewalls of the two nuts on the left and right are different, corresponding to the left and right sides of the trapezoidal recess of the inner thread of the nut, which are the conical surfaces that contact the roller string.

2. The high-load roller screw according to claim 1, characterized in that: The total number of rollers in the roller string is between 2 and 30; the diameter of the rollers in the roller string can be equal to that of the bottom roller, or the diameter of the bottom roller can be smaller than that of the top roller; in addition, there are two bottom rollers, located at the top and bottom ends; there is no gap between the rollers, or there is an axial clearance, which is obtained by the washers and the boss at the center of the roller.

3. The high-load roller screw according to claim 1, characterized in that: The inner wall of the return pipe is a smooth inner wall, or it is machined with constraint convex rails arranged along the flow direction of the roller string; these constraint convex rails fit precisely into the axial gaps left between the rollers in the roller string.

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