Large-load roller screw
By abolishing the ball holder and establishing the ball channel and return channel mechanism, and using the structure of a large load roller screw, the problem of insufficient axial impact resistance of the existing ball screw is solved, and higher impact resistance and longer service life are achieved.
Patent Information
- Application Number
- CN202411377829.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-10-13
- Filing Date
- 2024-09-30
- Publication Date
- 2025-04-15
AI Technical Summary
The existing ball screws have poor axial impact resistance, resulting in greater vibration and noise during high-speed movement and insufficient impact resistance.
By abolishing the ball holder, the steel ball channel and return channel mechanism of the bearing sleeve itself are established, and the structure of a large load roller screw is adopted, including a T-screw, trapezoidal spiral projection and depression, roller string and pre-pressure structure. The roller string is composed of a roller, roller and bottom roller, and the roller string is circulated through the return hole and return pipeline.
It significantly improves the axial impact resistance of traditional ball screws, has a compact structure, and significantly extends the use and maintenance time.
Smart Images
Figure CN119825883A_ABST
Abstract
Description
[Technical field]
[0001] The invention belongs to the field of mechanical and electronic technology, and is specifically a lead screw with rollers replacing balls, which can greatly increase the load and service life. [Background Technology]
[0002] As early as 1898, people first tried to put steel balls between the nut and the screw to replace sliding friction with rolling friction to improve the poor positioning and easy damage. In 1940, it began to be used in automobile steering devices to replace traditional Axle screws. Ball screws have become one of the most widely used components in the industry.
[0003] The traditional ball screw is composed of a screw, a nut, a steel ball, a preload sheet, a reverser, and a dust collector. It has the characteristics of high precision, reversibility, and high efficiency. The most commonly used ball screw is an ideal product for converting rotary motion into linear motion, or converting linear motion into rotary motion. It is the most commonly used transmission element in tool machinery and precision machinery. Its main function is to convert rotary motion into linear motion, or to convert torque into axial repeated force. Due to its small friction resistance, ball screws are widely used in various industrial equipment and precision instruments. There are two common circulation methods: external circulation and internal circulation. The circulation methods of balls include circulation duct type, circulator type, and end cover type. The preloading methods include double nut method, position preloading method, and constant pressure preloading; that is, the ball screw pair can be preloaded, and the preloading can make the axial clearance reach a negative value, thereby obtaining a higher rigidity (the ball screw is pressurized by applying pressure to the balls. When it is actually used in mechanical devices, the repulsion of the balls can enhance the rigidity of the nut part). . The appropriate type can be selected according to the purpose. The screw rods include precision ball screws that are processed by high-precision grinding and cold-rolled ball screw bearings that are formed by high-precision cold rolling. In addition, in order to cope with the situation where users need delivery urgently, there are finished products with processed shaft ends, semi-finished products and cold-rolled ball screw bearings that can be freely processed on the shaft ends. As peripheral parts of this bearing, the necessary screw support unit, nut support, lock nut, etc. have also been standardized and can be selected by users.
[0004] Pros and Cons Overview:
[0005] advantage:
[0006] * Small friction loss and high transmission efficiency. Since there are many balls rolling between the screw shaft and the screw nut of the ball screw pair, a higher motion efficiency can be obtained. Compared with the previous sliding screw pair, the driving torque is less than 1 / 3, that is, the power required to achieve the same motion result is 1 / 3 of that of the sliding screw pair. It is very helpful in saving electricity.
[0007] *High-precision ball screw pairs are generally produced continuously using the world's highest level of mechanical equipment. In particular, in the factory environment of grinding, assembly and inspection processes, temperature and humidity are strictly controlled. Due to the perfect quality management system, the accuracy can be fully guaranteed.
[0008] * High speed feed and micro feed possible
[0009] Since the ball screw pair utilizes ball motion, the starting torque is extremely small and there will be no creeping phenomenon like sliding motion, which can ensure accurate micro-feeding.
[0010] shortcoming:
[0011] *Linear bearings also have their limitations. The most important one is that the bearing impact resistance and load-bearing capacity are poor. Secondly, linear bearings vibrate and make a lot of noise when moving at high speed.
[0012] *The axial rigidity is not as high as that of ordinary trapezoidal lead screws, and there is an inherent defect of point contact of the steel ball.
[0013] *Compared with the traditional T-type screw, the ball screw cannot be self-locking; but it also has the reversibility of transmission. [Summary of the invention]
[0014] Purpose of the present invention:
[0015] The invention overcomes the shortcomings of the prior art and improves the inherent defect of the existing ball screw that the axial impact resistance is relatively poor.
[0016] The invention has the advantages of compact structure and large axial load-bearing capacity.
[0017] The key technology of the present invention is to eliminate the steel ball retainer and establish the steel ball channel and return channel mechanism of the bearing sleeve itself.
[0018] Specific content of the invention:
[0019] The structure of the heavy-duty roller screw includes a screw, a nut, a roller string and a preload structure;
[0020] The screw is a T-shaped screw, and its thread cross-section is a trapezoidal spiral protrusion. The side of the trapezoid is the spiral surface, and the angle between the normal of the spiral surface and the axis is 0-60 degrees. The bottom surface of the spiral protrusion is the bottom surface between the threads of the screw, which is the lowest position for limiting the roller string; the nut is divided into two independent nuts on the left and right, and its working surface is a trapezoidal spiral depression. The side walls of the inner threads of the nut are contact working surfaces, which are respectively located on different sides of the trapezoidal depression. The bottom surface of the spiral depression also takes into account the uppermost position of limiting the roller string. The two return holes are strip-shaped holes that pass through the side walls of the nut and are used to guide the overall flow of the roller string group; the return pipe is a curved strip-shaped return pipe used to connect the two return holes, and the inner wall of the hole has a constraint cam, which is used to guide the roller string group to flow between the two return holes for circulation.
[0021] The preload structure is a selective component. The simple solution is to rigidly tighten the left and right nuts with zero clearance, which requires frequent adjustment in subsequent use. The complex solution is to use springs, shrapnel, etc. to apply a certain preload force to the left and right nuts (preloading the roller string group is commonly known as negative clearance), which has greater rigidity and does not require frequent adjustment in subsequent use.
[0022] The roller string structure is the core of the present invention, and the roller string structure includes: roller shaft, roller, bottom roller; assembly relationship: the roller shaft connects the roller and bottom roller coaxially, and all rollers can rotate freely; the top and bottom of the roller string are exposed roller protrusions, or the top of the top roller is exposed. The purpose of the tip shape is to reduce the turning radius to reduce friction consumption. The number of all rollers in the roller string is 2-30, and the more rollers there are, the less sliding friction there is.
[0023] The inner wall of the return pipe is a smooth inner wall, or is processed with a constraint cam arranged along the flow direction of the roller string; the constraint cam is just embedded in the axial gap left between the rollers of the roller string to constrain the roller string; prevent the roller string from tipping over during the flow process on the inner wall of the return pipe, causing the circulation to be stuck.
[0024] Working principle:
[0025] The roller string clamped between the side surface of the screw thread and the side wall of the inner thread of the nut is arranged in a conical surface arrangement state. According to mathematical principles: the roller string clamped between the two conical surfaces will have the cone axis and the roller string axis always intersecting, so that the roller string cannot flip over in the gap between the two conical surfaces; the bottom rollers of adjacent roller strings are against each other, and the rollers do not abut against each other. Since the diameter of the bottom roller can be slightly smaller than the roller, the side surface of the thread does not contact the bottom roller under the support of the roller; the huge working pressure on the side surface of the thread cannot be applied to the bottom roller, so the abutment of the bottom roller will not produce a large friction obstacle.
[0026] When the screw rotates, the tightly compressed roller string group rotates along the spiral surface and pushes the nut to move horizontally; the roller string passes through the return hole, passes through the return pipe, and flows back between the conical surfaces to circulate back and forth; the inner wall of the return pipe can be processed with a constraint cam, which is inserted into the gap between the two rollers to guide the roller string not to fall over in the return pipe, so that the circulation is smooth.
[0027] In addition, the elastic deformation of the preload structure has the traditional characteristics of negative clearance, and the stiffness is greatly increased.
[0028] Further: the lowest roller in the roller string is the bottom roller: its diameter is equal to, or slightly smaller than (generally the diameter difference is between 2 threads and 200 threads) the diameter of the upper roller. The purpose is to ensure that when the roller string is clamped between the spiral surfaces of the screw rod and the nut, the bottom rollers that touch each other are not clamped by the spiral surfaces, but the rollers with slightly larger diameters are clamped; in this way, even if the bottom rollers that can rotate freely touch each other, very little consumption will be generated; in addition, two bottom rollers can also be set, located at the top and bottom ends, especially when the roller string is flipped over by the return pipeline during the transportation of the roller string.
[0029] Further: the rollers of the roller string are in seamless contact with each other, or an axial gap is left, and the gap is obtained by the washer and the boss at the center of the roller.
[0030] The technical progress of the present invention is that the axial impact resistance of the traditional ball screw (under the same size) is improved by more than one order of magnitude, the structure is compact, and the use and maintenance time are significantly extended. [Drawings]
[0031] The present invention will be further described below with reference to the accompanying drawings with regard to preferred embodiments of the present invention:
[0032] [ Figure 1 ]Schematic diagram of the overall and characteristic cross-section of a high-load roller screw.
[0033] [ Figure 2 ] Schematic diagram of the partial explosion of a heavy-load roller screw.
[0034] [ Figure 3} Schematic diagram of roller train structure. Schematic diagram of the cross section of a heavy-load roller screw. [ Figure 4}Schematic diagram of roller string structure and mechanical action.
[0035] Description of the numbers in the figure:
[0036] 1 screw
[0037] 1-1 Trapezoidal spiral protrusion
[0038] 1-2 Raised bottom surface
[0039] 1-3 axis
[0040] 1-4 Normal line of thread helicoid
[0041] 1-5 thread helical surface
[0042] Angle Q between 1-6 axis and normal
[0043] 2 nuts
[0044] 2-1 Trapezoidal spiral depression
[0045] 2-2 Concave bottom
[0046] 2-3 Return hole 1
[0047] 2-4 Return Pipeline
[0048] 2-5 Constrained convex rail
[0049] 2-6 Return hole 2
[0050] 2-7 fixing holes
[0051] 2-8
[0052] 2-9
[0053] 3 roller string
[0054] 3-1 Column top
[0055] 3-2 Roller
[0056] 3-3 Bottom roller
[0057] 3-4 Rollers
[0058] 3-5 Column bottom
[0059] 3-6 Roller Clearance
[0060] 4Pre-load structure
[0061] 4-1 Connecting screw
[0062] 4-2 Lock nut
[0063] 4-3 Preloaded spring
[0064] 4-4
[0065] 5 axis
[0066] 6 Cross-section
[0067] 7 Enlarged image
[0068] 8 thread section
[0069] 9 Roller string disassembly diagram
[0070] 10 Close to the part
[0071] 11 Gap
[0072] [Implementation Case]
[0073] like Figure 1 , Figure 2 , Figure 3 Shown:
[0074] The structure of a heavy-load roller screw comprises: a screw (1), a preload structure (4), a roller string (3) and a nut (2); the screw (1) is a T-shaped screw: its thread structure is a trapezoidal spiral protrusion (1-1), the angle between the normal line (1-4) of the spiral 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, and limits the position of the roller string (3); the working surface of the nut (2) is a trapezoidal spiral depression (2-1), which is divided into two left and right An independent nut, the contact working surface is located on different sides of the recess, the bottom surface (2-2) of the recess also takes into account the position of limiting the roller string (3), the return hole 1 (2-3) and the return hole 2 (2-6) are strip holes passing through the side wall of the nut (2), which are used to guide the overall flow of the roller string (3), and the return pipe (2-4) is a strip hole with a constraining convex rail (2-5), which is used to guide the roller string (3) to flow between the return hole 1 (2-3) and the return hole 2 (2-6).
[0075] 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), the preload spring (4-3) sandwiched between the connecting screws provides a preload thrust, and the connecting screw (4-1) is locked by the locking nut (4-2).
[0076] Thread Section(8)
[0077] Axis (5)
[0078] The cross-sectional view (6) shows
[0079] It can be seen from the cross-sectional enlarged view (7) of the return pipe (2-4) that the restraining convex rail (2-5) can control the direction of the roller string (3) and prevent it from falling in the return pipe (2-4); the roller gap (3-6)
[0080] like Figure 4 Shown:
[0081] The core structure of the roller string (3) can be seen from the roller string disassembly diagram (9): under the support of the roller (3-4), the roller (3-2) and the bottom roller (3-3) can rotate freely through the shaft hole. The top (3-1) and the bottom (3-5) of the column can be the protruding part of the roller (3-4), or can be the pointed roller installed at both ends of the roller. The purpose of the pointed top is to make the center part contact the raised bottom surface and the recessed bottom surface, so as to reduce the friction consumption with a small turning radius.
[0082] The lower figure is a relative position diagram of the roller string (3) when it is working. The close contact part (10) between the adjacent bottom rollers (3-3) will have mutual friction. When the diameter of the bottom roller is smaller than that of the upper roller, the bottom roller will not contact the side surface of the screw thread and the side wall of the inner thread of the nut (working surface), so no friction consumption will be generated on the working surface. Similarly, the natural gap (11) will also prevent friction consumption between the adjacent rollers (3-2).
Claims
1. High-load roller screw, the structure includes screw, nut and roller string; the screw is a T-shaped screw, the nut is divided into two independent nuts on the left and right, the two return holes of the nut pass through the side wall of the nut, which are strip-shaped holes; an independent return pipe or a return pipe directly processed on the side wall of the nut connects the two return holes; the roller string is clamped between the side surface of the screw thread and the side wall of the inner thread of the nut and in the return pipe; the assembly relationship is the coordinated use of a single screw and a pair of nuts; the preload structure is a selective component, and the simple solution is to rigidly tighten the left and right nuts with zero clearance, which requires frequent adjustment of the tightening in subsequent use; the complex solution is to use springs, spring pieces, etc. to apply a certain preload force to the left and right nuts for tightening, which has greater rigidity and does not require frequent adjustment in subsequent use; the working principle is: when clamped between the side surface of the screw thread and the side surface of the inner thread of the nut The roller strings between the walls are arranged in a conical surface. Mathematics determines that the roller string sandwiched between the two conical surfaces will have the following characteristics: the cone axis and the roller string axis always intersect and intersect at one point, so that the cylindrical roller string cannot flip over in the gap between the two conical surfaces; the bottom roller parts of the adjacent roller strings clamped between the screw thread side and the nut inner thread side wall are against each other, and the rollers do not abut against each other. Since the diameter of the bottom roller can be slightly smaller than the roller, the thread side does not contact the bottom roller under the support of the roller; the huge working pressure on the thread side cannot be applied to the bottom roller, so the abutment of the bottom roller will not produce a large friction barrier; during operation, when the screw rotates, the tightly pressed roller string group rotates along the spiral surface and pushes the nut to move horizontally; the roller string passes through the return hole, flows back to the conical surface through the return pipe, and circulates back and forth; Its characteristics are: The roller train structure includes: Roller, roller, bottom roller; Assembly relationship: The roller and the bottom roller are coaxially connected on the roller shaft, and all rollers can rotate freely; the top and bottom of the roller string are the exposed protruding parts of the roller shaft, or the top of the roller with a pointed top shape of the uppermost roller is exposed; The contact working surfaces of the left and right side walls of the internal threads of the nut are different, corresponding to the left and right different side surfaces of the trapezoidal depression of the internal threads of the nut, and the side surfaces are the conical surfaces in contact with the roller string.
2. The roller train according to claim 1, characterized in that: The number of all 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 upper roller; in addition, two bottom rollers can be provided, located at the uppermost and lowermost ends; the rollers in the roller string with a diameter smaller than that of the upper roller are in seamless contact, or an axial gap is left, and the gap is obtained by means of washers and bosses at the center of the rollers.
3. The return pipeline according to claim 1, characterized in that: The inner wall of the return pipe is a smooth inner wall, or is processed with a constraint cam arranged along the flow direction of the roller string; the constraint cam is just embedded in the axial gap left between the rollers of the roller string.