A free bearing

Abstract

A free bearing belongs to the field of machinery. Its structure includes: a bearing sleeve, an end cover and a steel ball; the bearing sleeve; its working principle is: when the cylindrical optical axis performs a composite motion of rotation and translation relative to the bearing sleeve, the load-bearing cylinder and the return cylinder area of ​​the inner cylindrical surface of the bearing sleeve will circulate and guide the steel ball to move, and the return cycle will be repeated continuously; the full surface and partial surface load-bearing cylinder of the bearing sleeve structure include two types: the intersection area between the partial surface load-bearing cylinder and the return cylinder is gradually changed and smoothly connects the two surfaces; the gap between the return cylinder and the optical axis cylinder forms a return channel for the steel ball; the other is that a return hole is provided on the end surface of the bearing sleeve, and the guide comb-shaped structure of the guide surface of the end cover is similar to the streamline shape of the bow, guiding the steel ball to enter and exit the return channel; the free bearing can support any movement of the optical axis and can be widely used in the field of precision rotation and translation composite requirements.

Description

[Technical field]

[0001] The present invention belongs to the field of mechanical and electronic technology. Specifically, it simplifies the structure of traditional ball linear bearings and eliminates the steel ball retainer with a return channel. It not only greatly increases the load, but also allows the compound movement of axial rotation, generating a free bearing that can simultaneously meet the requirements of linear motion and axial rotation. [Background Technology]

[0002] Linear bearings are a type of linear motion system used for linear travel, used in conjunction with cylindrical or prismatic shafts. Its structure usually includes: steel balls, end caps, bearing sleeves, and (steel ball) retainers with steel ball return channels. When in use, the optical axis passes through the center holes of the end caps installed at both ends of the bearing sleeves, allowing it to slide back and forth along the optical axis. The steel balls continuously return to the axial steel ball retaining channel through the return channel of the retainer, cyclically. Linear bearings are widely used, and are commonly used in precision equipment such as tensile testing machines and digital three-dimensional coordinate measuring equipment. They are also widely used in industrial machinery such as multi-axis machine tools, punching machines, tool grinders, automatic gas cutting machines, printers, card sorting machines, and food packaging machines.

[0003] Pros and Cons Overview:

[0004] Advantages: Because the load-bearing steel ball is held by the steel ball retainer, a point contact mode is established between the column shaft and the bearing sleeve. Under the holding constraint of the axial holding channel of the retainer, the steel ball sandwiched in between matches the relative motion between the column shaft and the bearing sleeve in a rolling friction mode with minimum resistance; therefore, the linear bearing has the characteristics of low friction, stability, and resistance that does not change with the movement speed, and can obtain smooth linear motion with high sensitivity and high precision.

[0005] Disadvantages: 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. [Summary of the invention]

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and improve the existing linear bearings' poor anti-bearing impact and bearing capacity.

[0007] The invention has the following characteristics: compact structure, strong resistance to bearing impact and large load-bearing capacity, and the volume can be reduced.

[0008] 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.

[0009] Specific content of the invention:

[0010] A free bearing structure includes: a bearing sleeve, an end cover and a steel ball, and an additional steel ball retaining shield is allowed; the detailed structure of each component is as follows: the structure of the bearing sleeve includes two types, one is that the inner cylindrical surface of the bearing sleeve is divided into a load-bearing cylindrical surface and a return cylindrical surface; the gap between the load-bearing cylindrical surface and the cylindrical surface of the optical axis (after installation) just accommodates the diameter of the steel ball, which can form a supporting state of the steel ball; and the gap between the return cylindrical surface and the cylindrical surface of the optical axis is larger than the diameter of the steel ball, so there is no pressure on the cylindrical surface, and a return channel for the steel ball is formed; the area of ​​the load-bearing cylindrical surface is The sum of the areas of the return cylinder plus the area of ​​the guide slope is equal to the area of ​​the entire cylinder. The load-bearing cylinder and the return cylinder are adjacent to each other and arranged alternately; the guide slope is located in the intersection area between the load-bearing cylinder and the return cylinder, and gradually and smoothly connects the two surfaces; the circular holes of the two end covers are used for sliding through the optical axis; the guide surface helps to guide the steel balls to travel back and forth between the load-bearing cylinder and the return cylinder through the guide slope; the height transition between the load-bearing cylinder and the return cylinder on the inner surface of the bearing sleeve is a gradual transition of the slope, which makes the flow of the steel balls smooth.

[0011] Another type of free bearing is a bearing sleeve whose inner cylindrical surface is entirely load-bearing cylindrical surface, and the bearing sleeve has multiple return cylindrical surfaces, all of which are on the inner surface of the return hole on the end face of the bearing sleeve; the present invention does not limit the sum of the cross-sectional areas of the return holes; but it is smoothest when the sum of the cross-sectional areas of all the return holes is greater than or equal to the area enclosed by the surface of the load-bearing cylindrical surface and the surface of the optical axis; the return channel is the channel formed by the circular hole of the end cover and the return hole; in this way, the flow rate (translational speed) of the return steel balls can be less than or equal to the flow rate of the steel balls in contact with the load-bearing cylindrical surface; the circular hole of the end cover is also slidably fitted to the optical axis passing through it; the guide comb structure of the guide surface is similar to the streamlined shape of the bow, guiding the steel balls into and out of the return channel; when assembling the steel balls, the optical axis is drawn to the end face into the bearing sleeve, and the steel balls are loaded from the gap.

[0012] Working principle of free bearing:

[0013] When the optical axis (cylindrical) makes pure rotation relative to the bearing sleeve, the steel balls between the load-bearing cylindrical surface of the inner cylindrical surface of the bearing sleeve and the cylindrical surface of the optical axis will also make circular motion around the axis; for non-"full-area" free bearings, the steel balls continuously cross the load-bearing cylindrical surface area and enter the low-lying return cylindrical surface area (the steel balls are not clamped in this area, and there is no pressure between the two cylinders), repeating the cycle; and for "full-area" free bearings, the steel balls continuously make circular motion around the axis along the load-bearing cylindrical surface, repeating the cycle; and the existing steel balls in the return channel do not move.

[0014] When the optical axis makes a pure linear reciprocating motion along the axial direction relative to the bearing sleeve, the steel balls clamped between the load-bearing cylindrical surface of the inner cylindrical surface of the bearing sleeve and the cylindrical surface of the optical axis will also make a linear reciprocating motion along the axial direction; the load-bearing cylindrical surface pushes the steel balls to move, and at the same time, it will also drive the steel balls in the return cylindrical area to move (the steel balls in this area are not clamped and there is no pressure from the cylinder), and all the steel balls circulate continuously.

[0015] The complex motion of the optical axis can be decomposed into a compound motion of pure rotation and pure axial sliding, so it can meet the complex motion of the free bearing.

[0016] Further: For non-full-area free bearings, the two end covers and the bearing sleeves can be processed as an integrated unit in addition to being processed separately.

[0017] Further: the contact part between the end cover and the steel ball can be a plane maintained perpendicular to the axis, or protrudes along the axial direction in the area corresponding to the return cylinder, and the highest point of the protrusion is located in the central area of ​​the return cylinder.

[0018] The technical progress of the present invention is as follows: the existing linear bearings have poor resistance to bearing impact and poor load-bearing capacity, and the structure is compact, the bearing resistance is strong and the load-bearing capacity is large, and the volume can be reduced; and a composite bearing that can adapt to both linear and rotational applications is provided. [Drawings]

[0019] The present invention will be further described below with reference to the accompanying drawings with regard to preferred embodiments of the present invention:

[0020] [ Figure 1 ] Schematic diagram of the overall and characteristic cross-section of the free bearing.

[0021] [ Figure 2 ] Schematic diagram of the axial cooperation between the bearing sleeve 1 of the free bearing and the optical axis.

[0022] [ Figure 3}Auxiliary schematic diagram of the assembly relationship of the free bearing.

[0023] [ Figure 4 ] Schematic diagram of the free bearing shape and shaft cross-section that bears full-area pressure.

[0024] [ Figure 5 ] Schematic diagram of the explosion of a full-area pressure-free bearing.

[0025] Description of the numbers in the figure:

[0026] 1Bearing sleeve 1

[0027] 1-1 Load-bearing column 1

[0028] 1-2 Return cylinder 1

[0029] 1-3 Guide slope 1

[0030] 2 End cap 1

[0031] 2-1 Guide surface 1

[0032] 2-2 round hole 1

[0033] 2-3 Guide protrusion

[0034] 3 End cap 2

[0035] 3-1 Guide surface 2

[0036] 3-2 round hole 2

[0037] 3-3 Guidance Structure

[0038] 4 bearing sleeve 2

[0039] 4-1 Load-bearing column 2

[0040] 4-2 Return cylinder 2

[0041] 4-3 Guide slope 2

[0042] 4-4 return hole

[0043] 4-5 Return hole wall

[0044] 5 optical axes

[0045] 6 steel balls

[0046] 7 axis

[0047] 8 Gap

[0048] 9. Zoom in Figure 1

[0049] 10. Zoom in Figure 2

[0050] 11 Overall view

[0051] 12 Selection Section

[0052] 13 Bearing sleeve internal space diagram

[0053] 14 Axis cross section

[0054] [Implementation Case]

[0055] like Figure 1 , Figure 2 , Figure 3 Shown:

[0056] The overall diagram (11) shows the appearance of the present invention, combined with the inner hollow diagram of the bearing sleeve (13) and Figure 2From the axial schematic diagram of the matching of the bearing sleeve 1 and the optical axis (with the end cover removed and viewed along the axis), it can be seen that: the gap between the load-bearing cylindrical surface 1 (1-1) of the bearing sleeve 1 (1) and the cylindrical surface of the optical axis (5) just accommodates the diameter of the steel ball (6), forming a supporting relationship through the steel ball (6); while the gap between the return cylindrical surface 1 (1-2) and the cylindrical surface of the steel ball (6) is larger than the diameter of the steel ball (6), and there is no pressure on the cylindrical surface, forming a return channel for the steel ball; the sum of the area of ​​the load-bearing cylindrical surface 1 (1-1) and the area of ​​the return cylindrical surface 1 (1-2) plus the area of ​​the guide slope surface (1-3) is equal to the area of ​​the entire cylindrical surface, and the load-bearing cylindrical surface 1 (1-1) and the return cylindrical surface 1 (1-2) are equal to the area of ​​the entire cylindrical surface. The travel cylinders 1 (1-2) are adjacent to each other and arranged in a staggered manner; the guide slope (1-3) is located in the intersection area between the load-bearing cylinder 1 (1-1) and the return cylinder 1 (1-2), and is gradually and smoothly connected to the two surfaces; the circular holes 1 (2-2) of the two end covers 1 (2) are used for sliding through the optical axis (5); the guide surface 1 (2-1) is helpful to guide the steel ball to travel back and forth between the load-bearing cylinder 1 (1-1) and the return cylinder 1 (1-2) through the guide slope (1-3); the height transition between the load-bearing cylinder 1 (1-1) and the return cylinder 1 (1-2) on the inner surface of the bearing sleeve 1 (1) is a gradual transition, that is, a slope transition, so that the flow of the steel ball is smooth.

[0057] Working principle of free bearing: It can be seen from the selected cross-sectional view (12) that when the optical axis (5) rotates relative to the bearing sleeve 1 (1), the steel ball between the load-bearing cylindrical surface 1 (1-1) of the inner cylindrical surface of the bearing sleeve 1 (1) and the optical axis cylindrical surface will also make a circular motion around the axis (7), such as Figure 1 A partial enlargement of point B in the middle Figure 2 As shown in (10), the steel ball is in contact with the two cylinders and there is no gap; Figure 1 A local enlargement of the middle Figure 1 The steel balls between the load-bearing cylindrical surface 1 (1-1) and the optical axis cylindrical surface at (9) are in a free state without being compressed, and there is a gap (8) between the steel balls and the cylindrical surface; for non-"full-area" free bearings, the steel balls continuously cross the load-bearing cylindrical surface 1 (1-1) area and enter the low-lying return cylindrical surface 1 (1-2) area, cyclically; while for "full-area" free bearings, the steel balls continuously make circular motions around the axis along the load-bearing cylindrical surface, cyclically; and the existing steel balls in the return channel do not move. The guide protrusion (2-3) is a selective structure, which is used to make the flow of steel balls smoother, and it can also operate without this structure;

[0058] like Figure 4 , Figure 5 Shown:

[0059] The axial cross-section (14) passing through the axis (7) shows that: the area of ​​the load-bearing cylindrical surface 2 (4-1) of the full-area free bearing is the entire cylindrical surface; the return cylindrical surface 2 (4-2) of the bearing sleeve 2 has multiple return cylindrical surfaces 2 (4-2), which are part of the inner surface of the return hole (4-4); the sum of the cross-sectional areas of all return holes (4-4) is greater than or equal to the area enclosed by the surface of the load-bearing cylindrical surface 2 (4-1) and the optical axis (5); the return channel is the circular hole 2 (3-2) and the return hole (4-4) of the end cover 2, and the guide slope surface 2 (4- 3) constitutes a channel (a channel connecting the load-bearing cylinder and the return cylinder); in this way, the flow velocity (translation velocity) of the return steel ball can be less than or equal to the flow velocity of the steel ball (6) in contact with the load-bearing cylinder 2 (4-1); the circular hole 2 (3-2) of the end cover 2 (3) is also slidably matched to the optical axis (5) passing through; the guiding structure of the guide surface 2 (3-1) is similar to the streamline shape of the bow, guiding the steel ball to enter and exit the return channel, and the return hole wall (4-5) can be thinned to increase the return area to reduce the resistance to the steel ball.

Claims

1. A free bearing, comprising: Bearing sleeve, end cover and steel balls; bearing sleeve; working principle of free bearing: when the cylindrical optical axis makes pure rotation relative to the bearing sleeve, the steel balls between the load-bearing cylindrical surface of the inner cylindrical surface of the bearing sleeve and the cylindrical surface of the optical axis will also make circular motion around the axis; for non-full-area free bearings, the steel balls continuously cross the load-bearing cylindrical surface area and enter the low-lying return cylindrical surface area, in which the steel balls are not clamped, and circulate back and forth; while for full-area free bearings, the steel balls continuously make circular motion around the axis along the load-bearing cylindrical surface, and circulate back and forth; the stock steel balls in the return channel do not move; when the optical axis makes pure linear reciprocating motion relative to the bearing sleeve along the axis direction, the steel balls clamped between the load-bearing cylindrical surface of the inner cylindrical surface of the bearing sleeve and the cylindrical surface of the optical axis will also make linear reciprocating motion along the axis direction; The load-bearing cylinder pushes the steel balls to move, and at the same time, it also drives the steel balls in the return cylinder area to move. In this area, the steel balls are not clamped and there is no pressure from the cylinder, so all the steel balls keep returning in a continuous cycle. The complex motion of the optical axis can be decomposed into a compound motion of pure rotation and pure axial sliding, so it can meet the complex motion of the free bearing. That The characteristics are: There are two types of bearing sleeve structures: one structure is that the inner surface cylindrical surface of the bearing sleeve is divided into a load-bearing cylindrical surface and a return cylindrical surface. The load-bearing cylindrical surface is a cylindrical surface, and the gap between the load-bearing cylindrical surface and the optical axis cylindrical surface after installation is equal to the diameter of the steel ball; while the gap between the return cylindrical surface and the optical axis cylindrical surface is larger than the diameter of the steel ball, and the transition between the load-bearing cylindrical surface and the return cylindrical surface is a gradual slope transition; the guide slope is located in the intersection area between the load-bearing cylindrical surface and the return cylindrical surface, and gradually and smoothly connects the two surfaces; the gap between the return cylindrical surface and the optical axis cylindrical surface forms a return channel for the steel ball; the surface of the load-bearing cylindrical surface The sum of the area of ​​the load-bearing cylinder and the area of ​​the return cylinder plus the area of ​​the guide slope is equal to the area of ​​the entire cylinder. The load-bearing cylinder and the return cylinder are adjacent to each other and arranged alternately; the circular holes of the two end covers are used for sliding through the optical axis; the guide surface helps to guide the steel balls to travel back and forth between the load-bearing cylinder and the return cylinder through the guide slope; another structure is: the inner cylindrical surfaces of the bearing sleeve are all load-bearing cylinders, and the return cylinders of the bearing sleeve have multiple and all are on the inner surface of the return hole on the end face of the bearing sleeve; the guide comb structure of the guide surface is similar to the sharp streamline shape of the bow, guiding the steel balls into and out of the return channel.

2. The end cover and bearing sleeve according to claim 1, characterized in that: The two end covers and the bearing sleeves can be processed as a whole in addition to being processed separately.

3. The end cap and the steel ball according to claim 1, characterized in that: The contact part between the inner wall of the end cover and the steel ball can be a plane maintained perpendicular to the axis, or protrudes along the axial direction in the area corresponding to the return cylinder, and the highest point of the protrusion is located in the central area of ​​the return cylinder.

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