Reverse supporting guide rail
By adopting a reverse bearing design in the guide rail, external force is transferred to the lower guide rail surface to achieve frictionless guidance, solving the problems of unstable motion and low positioning accuracy caused by friction by existing guide rails, and improving processing accuracy and manufacturing ease.
Patent Information
- Application Number
- CN202510361780.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-05-23
AI Technical Summary
When existing guide rails are subjected to external forces, they are unstable in motion due to friction, have low positioning accuracy and are difficult to manufacture, and insufficient friction damping leads to inertial impacts affecting processing accuracy.
The reverse-supported guide rail design is adopted to transfer external force to the lower guide rail surface through the magnet. The upper guide rail surface does not bear external force, achieving frictionless guidance. The lower guide rail surface is supported by rolling elements to bear external force, providing appropriate damping to balance inertial impact.
The frictionless guidance is achieved, the movement speed and positioning accuracy of the guide rails are improved, friction wear is reduced, manufacturing difficulty and cost are reduced, and sufficient damping is provided to balance the inertial impact, which improves the processing accuracy.
Smart Images
Figure CN120023655A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of mechanical manufacturing and relates to a reverse-supported guide rail, which is a new type of guide rail for numerically controlled machine tools. Background Art
[0002] The guide rail is one of the core components of high-end CNC machine tools and machining centers. It is a guiding mechanism for coordinate motion and also a load-bearing component. In the guide rail pair, the moving side is called the dynamic guide rail, and the stationary side is called the supporting guide rail. The supporting guide rail is connected to the base and does not move. It bears the vertical component of the gravity of the worktable and the workpiece mounted on the worktable and the cutting force. The dynamic guide rail can only have one degree of freedom relative to the supporting guide rail, usually linear motion or rotational motion.
[0003] The machine tool has very strict requirements on the guide rail. The main requirements are: high guiding accuracy, good accuracy retention, good stability of low-speed movement, large load-bearing capacity, high rigidity, high movement speed, and low friction loss.
[0004] There are three types of guide rails currently in use: sliding guide rails, rolling guide rails and hydrostatic guide rails. Since the supporting guide rails must bear the gravity of the workbench and workpiece and the cutting force of the vertical guide rail surface, there must be friction when the moving guide rail moves.
[0005] Sliding guides were the first to appear and were used the earliest. This type of guide has high guiding accuracy, large load-bearing capacity, and high rigidity. However, due to the friction between the guide surfaces, the friction loss is large, the movement speed is not large, and there is a creeping phenomenon at low speeds. After plastic is applied, the friction coefficient is reduced, the friction is reduced, and the performance is greatly improved.
[0006] Rolling guides and hydrostatic guides are designed to reduce friction. Because the friction coefficient is very small, the friction is small, the low-speed movement is smooth, the positioning accuracy is high, and high-speed movement is possible. However, rolling guides are not shock-resistant and vibrate. They have low contact stiffness (the steel ball is in point contact, and the roller is in line contact), low load-bearing capacity, and cannot be used on heavy and large machine tools. Rolling guides have a ball returner. When moving at high speed, the steel ball has a greater impact on the ball returner, which will cause vibration. Rotating objects have a gyroscopic effect. When the steel ball (or roller) rotates at high speed, there is also a gyroscopic effect. When the workbench needs to stop, the gyroscopic effect and the inertia of the moving parts cause the workbench to have a forward force. This affects the positioning accuracy. Since the friction of rolling guide rail is small, the friction damping is very small during movement. The disadvantage of small damping is that it cannot reduce the inertial impact of the worktable. When the worktable moves (especially high-speed movement) and stops, the inertia of the moving parts is very large, and the force of inertial forward rush needs to be balanced by resistance. The guide rail has no friction damping, and all the inertial force is borne by the ball screw or linear motor of the drive mechanism. The ball screw relies on its own deformation to balance the inertial force of the worktable. Therefore, the positioning accuracy of the machine tool worktable is affected.
[0007] Liquid hydrostatic guides have a very small friction coefficient, very small guide friction, and a large load-bearing capacity, and are mostly used on heavy and large machine tools. However, they are difficult to manufacture and costly, and the thickness of the oil film changes due to changes in external forces, affecting the processing accuracy. Since the friction damping is very small, the positioning accuracy is also affected by the inertia force of the moving parts.
[0008] The above three guide rails all have advantages and disadvantages. The problems with the guide rails are all caused by the load-bearing of the guide rail surface. If the guide rail surface does not bear load, all problems can be solved. However, there must be external forces (the gravity of the workbench, workpiece, and cutting force). If the external forces are borne by the lower guide rail surface of the supporting guide rail, there will be no positive pressure on the upper guide rail surface, and the problem can be solved. This guide rail is the reverse supporting guide rail of the present invention. It has the advantages of large load-bearing capacity and good rigidity of the sliding guide rail, as well as the advantages of small friction of the rolling guide rail and the hydrostatic guide rail, and can provide damping to balance the motion inertia of the workbench. Summary of the invention
[0009] The functions of the guide surfaces of the guide rails used in existing machine tools and CNC machine tools are to bear weight and guide. The supporting guide surface bears all external forces (the weight of the workbench, the workpiece and the cutting force in the vertical direction). Therefore, under the action of external forces, friction will definitely be generated when the moving guide rail moves. In order to reduce the friction of the guide rail, rolling guides and hydrostatic guides have appeared. The guide rails are complicated and the manufacturing difficulty and cost are increased. If the guide surface of the supporting guide rail does not bear weight and is only used for guiding, the guide rail will have no friction and rolling guides and hydrostatic guides may not be needed. Therefore, the present invention provides a reverse-supported guide rail to transfer the external force to the lower guide surface of the supporting guide rail. The upper and lower guide surfaces work together to eliminate the friction of the upper guide rail, improve the movement speed of the guide rail, the guiding accuracy and the machining accuracy of the machine tool.
[0010] Since permanent magnets and electromagnets can generate forces without contacting relatively moving parts, the present invention uses the attractive force generated by permanent magnets or electromagnets to support the downward force of the moving guide rail. External forces (the gravity of the workbench, the workpiece, and the vertical cutting force) are supported by magnets. The supporting guide rail has two guide rail surfaces. The upper guide rail surface and the lower guide rail surface, the lower guide rail surface is parallel to the movement direction of the workbench and perpendicular to the external force. Connecting plates are installed on both sides of the workbench. The lower guide rail surface of the supporting guide rail contacts the rolling body (such as a bearing) on the rolling body bracket installed on the connecting plate, and the rolling body and the lower guide rail surface have a pre-pressure, and the pre-pressure keeps the guide rail surfaces of the supporting guide rail and the moving guide rail in contact. The magnetic force of the magnet installed on the connecting plate gives the connecting plate an upward force, which is opposite to the direction of the external force. The magnetic force must be greater than or equal to the sum of the external force and the pre-pressure, and cannot be less than this sum. The magnetic force can be set at the sum of the maximum external force and the pre-tightening force on the workbench, so that the supporting guide rail surface is not subjected to force. The magnetic force can remain unchanged. When the external force is less than the maximum value, the excess magnetic force can increase the pre-load force of the rolling element, and the upper guide surface is still not subjected to force. In this way, the guide rail is guaranteed to be frictionless, and the friction force is transferred to the lower guide surface. The friction on the lower guide surface of the supporting guide rail is rolling friction, and the friction force is very small, because the pre-load force is much smaller than the external force, and the greater the external force, the smaller the friction force.
[0011] The technical solution of the present invention is as follows:
[0012] A reverse-supported guide rail comprises a supporting guide rail, a connecting plate, a rolling body, a rolling body supporting device and a magnet device.
[0013] The supporting guide rail includes an upper guide rail surface and a lower guide rail surface located on the base. The upper guide rail surface cooperates with the moving guide rail surface on the workbench. The lower guide rail surface is a plane and parallel to the direction of movement of the guide rail. A bearing plate is provided on the lower guide rail surface, which serves as the guide rail surface of the rolling body, and a magnetic isolation plate is installed between the bearing plate and the base; there is a space below the lower guide rail surface for accommodating the magnet device, rolling body and rolling body support device installed on the connecting plate.
[0014] The connecting plate is an L-shaped plate, the upper part of which is a vertical part fixed to the side of the workbench, and a gasket is provided between the workbench and the connecting plate for adjusting the horizontal position of the connecting plate. The lower part of the connecting plate is a horizontal part parallel to the lower guide rail surface. A square space is formed between the horizontal part of the connecting plate and the bearing plate on the lower guide rail surface of the supporting guide rail for installing the magnet device, the rolling body and the rolling body support device.
[0015] The rolling body supporting device installed on each connecting plate comprises two rolling body brackets and two rolling body supporting shafts; the two rolling bodies are installed on the rolling body brackets through the rolling body supporting shafts; the two rolling body brackets are fixed at both ends of the horizontal part of the L-shaped connecting plate.
[0016] The magnet device on each connecting plate is fixed on the horizontal part of each L-shaped connecting plate and is located between two rolling body brackets; a group of magnet devices is installed on each connecting plate.
[0017] An air gap of less than 1 mm is left between the magnet device and the bearing plate, and the rolling body mounted on the rolling body bracket is ensured to be pressed against the lower surface of the bearing plate; by adjusting the upper and lower positions of the connecting plate, the pre-pressure of the rolling body on the rolling body bracket on the bearing plate can be adjusted.
[0018] The upper guide rail surface is a convex double triangle guide rail, a concave double triangle guide rail or other forms of non-inlaid guide rails.
[0019] The length of the horizontal portion of the connecting plate should be slightly greater than or equal to the sum of the length of the two rolling element supports and the length of the magnet device.
[0020] The lengths of the bearing plate and the magnetic isolation plate are the same as the length of the supporting guide rail.
[0021] The lower guide rail surface is on the left and right outer sides or inner sides of the bed.
[0022] Each group of magnet devices is one or more permanent magnets or electromagnets.
[0023] According to the force balance condition, the two sides of the workbench can be assembled symmetrically, and one or more connecting plates can be set on each side of the workbench.
[0024] The bearing plate is made of a magnetically conductive and quenchable material.
[0025] The magnetic isolation plate is made of non-magnetic conductive material, such as stainless steel.
[0026] The bearing plate and the magnetic conductive plate are integrated or separated structures.
[0027] The rolling body is a bearing, a rolling guide block or other rolling bodies.
[0028] The supporting guide rail is a guide rail for linear motion or a circular guide rail for rotational motion.
[0029] The supporting guide rail is a machine tool guide rail or a guide rail for other mechanical movements.
[0030] The present invention mainly has the following characteristics:
[0031] (1) The upper guide rail surface does not bear external force, and the external force is borne by the lower guide rail surface of the supporting guide rail through magnetic force.
[0032] (2) The upper guide surface constrains five degrees of freedom and can provide precise guidance.
[0033] (3) There is no external force on the upper guide surface and no friction or wear.
[0034] (4) The force direction of the lower guide surface of the supporting guide rail is opposite to the external force direction. When the external force is large, the force on the lower guide surface can be reduced. Therefore, the magnetic force must be greater than the sum of the external force and the pre-compression force of the rolling element on the bearing plate to ensure that the upper guide surface is frictionless. When the positive and negative forces are equal, it is a critical state. A slight increase in the external force can cause friction on the upper guide surface.
[0035] (5) The lower guide surface and the rolling element are rolling friction. The rolling element can be a bearing or other rolling unit and can run at high speed. The lower guide surface is also the air gap surface of the electromagnet. The bearing surface of the rolling element and the air gap surface of the electromagnet can be one surface or two surfaces. It depends on the overall structure of the machine tool.
[0036] (6) The guide rail of the present invention is preferably a double triangular guide rail, which can be a convex-convex, convex-flat, concave-concave, or concave-flat combination. This guide rail has high guiding accuracy and no inlay friction.
[0037] (7) The connecting plate is installed on both sides of the workbench, and the space formed by the connecting plate and the lower guide surface of the supporting guide is used to install the magnet device, rolling element bracket and rolling element. The connecting plate can be moved up and down to adjust the pre-tightening force of the rolling element on the lower guide surface. After adjustment, it is fixed with screws and pins.
[0038] (8) The lower surface of the bearing plate is the lower guide surface of the supporting guide rail and should be made of a material with good magnetic conductivity and can be quenched.
[0039] (9) There is a magnetic isolation plate under the load-bearing plate and the supporting guide rail.
[0040] Beneficial effects of the present invention:
[0041] (1) The guide rail of the present invention eliminates the pressure acting on the upper guide rail surface, eliminates the friction when the movable guide rail moves, and eliminates all adverse consequences caused by the friction of the guide rail.
[0042] (2) The present invention is a structural form of a sliding guide rail, which has the advantages of a sliding guide rail: large load-bearing capacity, good rigidity, good shock resistance, high guiding accuracy, smooth movement, simple structure, easy manufacturing and low cost. Also, because there is no friction, the disadvantages of the sliding guide rail, such as large friction and wear, creeping at low speed, inability to run at high speed and low positioning accuracy, are overcome.
[0043] (3) Compared with rolling guides, the present invention has the advantages of low friction and wear, flexible movement, high positioning accuracy, and high-speed operation. However, rolling guides have the disadvantages of vibration, poor vibration resistance, low rigidity, complex structure, high manufacturing difficulty, high cost, geometric error, assembly error, etc.
[0044] (4) Compared with the liquid hydrostatic guide rail, the present invention has the advantages of less friction and wear, no disadvantages of oil film thickness variation, and no complicated hydraulic system.
[0045] In summary, compared with the three existing guide rails, the guide rail of the present invention has the advantages of the three guide rails without their disadvantages. It is a more rational guide rail that can replace the three guide rails. The various indicators of the guide rail itself are very superior, and can reach sub-micron level error. The positioning accuracy, repeated positioning accuracy and processing accuracy of the machine tool can be improved. Due to the lack of friction, the operating speed of the workbench can reach the international advanced level. BRIEF DESCRIPTION OF THE DRAWINGS
[0046] Figure 1 and Figure 2 It is a schematic diagram of the rolling element support device (the installation method of the first connecting plate is different).
[0047] Figure 3 and Figure 4 It is a schematic diagram of the magnet device (the installation method of the first connecting plate is different).
[0048] Figure 5 It is a left side structural diagram of two reverse-supported guide rails of the present invention arranged side by side.
[0049] Figure 6 It is a right side structural diagram of two reverse-supported guide rails of the present invention arranged side by side.
[0050] Figure 7 It is a schematic diagram of the overall structure of the reverse-supported guide rail of the present invention.
[0051] In the figure: 1 first connecting plate, 2 screw a, 3 first rolling element bracket, 4 first rolling element, 5 first rolling element support shaft, 6 screw b, 7 first bearing plate, 8 first magnetic isolation plate, 9 screw c, 10 screw d, 11 first gasket, 12 workbench, 13 base, 14 workbench drive mechanism (can be a ball screw or a linear motor), 15 screw e, 16 first magnet, 17 screw f, 18 second rolling element bracket, 19 screw g, 20 second rolling element support shaft, 21 second rolling element, 22, third rolling element bracket, 23 screw h, 24 third rolling element support shaft, 25 third rolling element, 26 screw i, 27 second magnet, 28 screw j, 29 second connecting plate, 30 screw k, 31 fourth rolling element bracket, 32 fourth rolling element support shaft, 33 fourth rolling element, 3 4 positioning pin a, 35 screw l, 36 positioning pin b, 37 positioning pin c, 38 positioning pin d, 39 second gasket, 40 screw m, 41 screw n, 42 second magnetic isolation plate, 43 second bearing plate, 44 third magnet, 45 third connecting plate, 46 screw o, 47 screw p, 48 fifth rolling element, 49 fifth rolling element support shaft, 50 fifth rolling element bracket, 51 screw q, 52 sixth rolling element bracket, 53 screw i, 54 sixth rolling element support shaft, 55 sixth rolling element, 56 seventh rolling element bracket, 57 screw s, 58 seventh rolling element support shaft, 59 seventh rolling element, 60 screw t, 61 fourth magnet, 62 fourth connecting plate, 63 screw u, 64 eighth rolling element bracket, 65 eighth rolling element support shaft, 66 eighth rolling element, 67 screw, 68 pin a, 69 pin b. DETAILED DESCRIPTION
[0052] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.
[0053] A reverse-supported guide rail of the present invention may be a symmetrical structure, comprising a supporting guide rail, a connecting plate, a rolling body, a rolling body supporting device and a magnet device.
[0054] The supporting guide rail includes an upper guide rail surface and a lower guide rail surface located on the base. The upper guide rail surface can be a convex double triangle guide rail or a concave double triangle guide rail or other forms of non-inlaid guide rails. The upper guide rail surface cooperates with the moving guide rail surface on the workbench. The lower guide rail surface is a plane, parallel to the direction of movement of the guide rail, and perpendicular to the direction of the positive pressure acting on the guide rail surface. It is the bearing surface of the reverse force and also the guide rail surface of the rolling body. The lower guide rail surface bears external force through the magnetic force of the magnet. In order to resist wear and pressure, the lower guide rail surface can be an inlaid steel structure. The inlaid steel plate is a bearing plate. The bearing plate is a magnetic conductive material. Its width can close the magnetic lines of force of the magnet. In order to prevent the supporting guide rail and the base from being magnetized, a magnetic isolation plate is installed between the bearing plate and the base. There is a space below the lower guide rail surface to accommodate the magnet device, rolling body and rolling body support device installed on the connecting plate.
[0055] The connecting plate is an L-shaped plate, the upper part of which is fixed to the side of the workbench, and the horizontal part of the connecting plate is used to install the rolling element support, the rolling element and the magnet device. A square space is formed between the connecting plate and the bearing plate on the lower rail surface of the support rail, which is used to install the magnet device, the rolling element and the rolling element support device. According to the force balance condition, the two sides of the workbench can be assembled symmetrically. According to the needs of the machine tool, there can be 1, 2, 3 or more connecting plates on each side. And a gasket is provided between the workbench and the connecting plate to adjust the horizontal position of the connecting plate. A square space is formed between the horizontal part of each L-shaped connecting plate and the bearing plate on the lower rail surface of the support rail. Two rolling element supports and the rolling elements mounted thereon, and a group of magnet devices (permanent magnets or electromagnets) can be accommodated in this square space. The rolling element supports are screwed to the two ends of the horizontal part of the L-shaped connecting plate, and the magnets are screwed to the connecting plate in the middle of the two rolling element supports. There is an air gap of less than 1 mm between the magnet and the bearing plate, and it is ensured that the rolling element mounted on the rolling element support is pressed against the lower surface of the bearing plate. By adjusting the up and down position of the connecting plate, the pre-pressure of the rolling body on the rolling body bracket on the bearing plate can be adjusted.
[0056] A guide rail of a reverse support of this embodiment, such as Figures 1 to 7 As shown, it includes a supporting guide rail on the base 13 and a moving guide rail on the workbench 12, a connecting plate, a rolling body, a rolling body supporting device and a magnet device.
[0057] In this embodiment, two sets of guide rails are used in conjunction with the workbench 12, and the specific structure is described as follows:
[0058] The support rail on the base 13 consists of two parts: upper rail surfaces A and B and lower rail surfaces C and D (the lower surfaces of the first bearing plate 7 and the second bearing plate 43). The upper rail surfaces A and B do not bear force and play a guiding role. The lower rail surfaces C and D are parallel to the direction of movement of the workbench and perpendicular to the direction of the positive pressure. They are the air gap surfaces of the magnets, bearing the suction of the magnets, and are also the guide rails of the rolling elements on the rolling element brackets.
[0059] The first connecting plate 1, the second connecting plate 29, the third connecting plate 45 and the fourth connecting plate 62 are respectively installed on the left and right sides of the front and rear ends of the workbench 12. The first connecting plate 1 and the second connecting plate 29 are installed on the left side of the workbench 12, and the third connecting plate 45 and the fourth connecting plate 62 are installed on the right side. The four connecting plates have the same structure, and the rolling body brackets and magnet devices with rolling bodies installed thereon are the same. A total of eight rolling body brackets with rolling bodies and four magnet devices (which can be permanent bridge magnets or electromagnets) are installed on the four connecting plates. The rolling bodies on the rolling body brackets are respectively pressed against the lower guide rail surfaces C and D, and an air gap of less than 1 mm is left between the suction surface of the magnet device and the lower guide rail surfaces C and D.
[0060] The first connecting plate 1, the second connecting plate 29, the third connecting plate 45 and the fourth connecting plate 62 are reverse-supported force-bearing plates, which transmit the suction force of the magnet to the workbench so that the magnetic force in the opposite direction to the external force G perpendicular to the workbench surface can offset the positive pressure acting on the guide rail.
[0061] Take the first connecting plate 1 as an example to explain its structure and working principle: the first bearing plate 7 is horizontally fixed on the lower guide surface by screws c9, which serves as the guide surface of the rolling body, and the first magnetic isolation plate 8 is also installed between the first bearing plate 7 and the base 13. The first rolling body bracket 3 and the second rolling body bracket 18 are installed at both ends of the bottom of the first connecting plate 1 parallel to the lower guide surface C. The bottom surface of the first rolling body bracket 3 is fixed to the bottom surface of the first connecting plate 1 by screws a2, and the side surface is fixed to the inner vertical surface of the first connecting plate 1 by screws b6. The first rolling body 4 is installed on the first rolling body bracket 3 through the first rolling body support shaft 5. The upper surface of the first rolling body 4 should be higher than the upper surface of the first rolling body bracket 3, so that the upper surface of the first rolling body bracket 3 cannot contact the lower guide surface C of the supporting guide. The second rolling body bracket 18, the second rolling body 21 and the second rolling body support shaft 20 are also installed in the above-mentioned way. The first magnet 16 (which can be a permanent magnet or an electromagnet) is installed between the first rolling body bracket 3 and the second rolling body bracket 18. The base of the first magnet 16 is fixed to the horizontal part of the first connecting plate 1 by screws e15 and f17. The upper surface of the first magnet 16 should be about 1 mm lower than the upper surface of the first rolling body 4 and the second rolling body 21 to ensure that there is an air gap of about 1 mm between the surface of the magnet and the lower guide surface C of the supporting guide rail. The suction force P of the first magnet 16 is 1 The direction is opposite to the external force G.
[0062] After the first magnet 16, the first rolling element bracket 3, the first rolling element 4, the first rolling element support shaft 5, the second rolling element bracket 18, the second rolling element 21, and the second rolling element support shaft 20 are installed on the first connecting plate 1, the first connecting plate 1 is installed to the left front end of the workbench 12 with a plurality of screws such as screw d 10, and a first gasket 11 is provided between the workbench 12 and the first connecting plate 1. During installation, the first rolling element 4 and the second rolling element 21 are pressed against the lower guide rail surface C of the supporting guide rail, and a preload F is generated respectively. 1 and F 2 After installation, use positioning pins c37 and d38 to position.
[0063] Using the same structure, the second connecting plate 29, the third connecting plate 45 and the fourth connecting plate 62 are installed on both sides of the workbench 12 according to the positions shown in the figure.
[0064] The attraction force P of the first magnet 16 1 , the attraction force P of the second magnet 272 , the attraction force P of the third magnet 44 3 and the attraction force P of the fourth magnet 61 4 The sum of the reverse supporting forces supports the workbench 12 in the reverse direction and offsets the positive pressure of the external force G on the guide surfaces A and B. The sum of the reverse supporting forces is greater than the external force G, and the excess is borne by the rolling elements on the 8 rolling element brackets.
[0065] Figures 1 to 7 The reverse support device shown in the figure has four sets of reverse support mechanisms with the same structure. Four connecting plates, four magnets and eight rolling bodies respectively mounted on the rolling body brackets. These eight rolling bodies are respectively pressed on the lower guide rail surfaces C and D of the supporting guide rails. The preload is F 1 , F 2 , F 3 , F 4 , F 5 , F 6 , F 7 , F 8 .
[0066] The preload force should not be too large. Depending on the size of the machine tool, it can be tens of Newtons to hundreds of Newtons. The deformation of the rolling element caused by this preload force cannot exceed a few microns. The preload force F generated by these eight rolling elements 1 ~F 8 , so that the upper guide rail surfaces A and B are in close contact. When the four electromagnets are energized, they can generate four electromagnetic forces P in the opposite direction to the external force G. 1 , P 2 , P 3 , P 4 These four electromagnetic forces act on the workbench 12 through the connecting plate to offset the external force G.
[0067] The sum of the electromagnetic forces generated by the electromagnet should satisfy the following formula:
[0068] P 1 +P 2 +P 3 +P 4 ≧G+F 1 +F 2 +F 3 +F 4 +F 5 +F 6 +F 7 +F 8 (1)
[0069] Where: G - external force (the gravity of the worktable, workpiece and the cutting force perpendicular to the table)
[0070] F 1 ~F 8——Preload force of eight rolling elements
[0071] From formula (1), it can be seen that the electromagnetic force acting on the lower guide surface C and D bears the force acting on the upper guide surface A and B, so that there is no positive pressure on the upper guide surface A and B. 1 ~F 8 The function is to keep the upper and lower surfaces of the upper guide rail surfaces A and B in contact, thus maintaining a good guiding function.
[0072] If the left side of formula (1) is greater than the right side, the electromagnetic force not only offsets the external force G, but also causes the rolling element to generate an additional pressure on the lower guide surfaces C and D. This additional pressure only adds a little burden to the rolling element, while the guide surfaces A and B are not subjected to force. The friction on the lower guide surfaces C and D is rolling friction, which is much smaller than the friction of the rolling guide.
[0073] The upper guide surfaces A and B are not subjected to force and only play a guiding role; the lower guide surfaces C and D bear the external force G on the workbench, making the performance of the guide rail more perfect. It solves all the adverse consequences caused by friction in the previous guide rails and enables the machining accuracy of the machine tool to reach above sub-micron.
[0074] The weight that the workbench of each machine tool can bear is specified. Take the maximum value of G within the specified range, make the left and right sides of equation (1) equal, and determine P 1 ~P 4 Value. Usually P 1 =P 2 =P 3 =P 4 .
[0075] Since the load-bearing weight takes the maximum value, when processing a light workpiece, it is not necessary to adjust P. 1 ~P 4 This will simplify the control of the electromagnet and will not increase the friction of the guide surfaces A and B.
[0076] When the sum of the four magnetic forces is greater than the sum of the external force G and the eight preload forces, the upper guide surfaces A and B are not subjected to force, and the workbench is supported on the lower guide surfaces C and D, achieving reverse support. The advantage of reverse support is that there is no friction and wear on the upper guide surfaces A and B, only a guiding effect, and there is rolling friction of eight rolling elements on the lower guide surfaces C and D. The clamping force F on these eight rolling elements is the preload force plus the electromagnetic force minus the external force G.
[0077] That is: F = (F 1 +F 2 +F 3 +F 4 +F 5 +F 6 +F7 +F 8 )+(P 1 +P 2 +P 3 +P 4 )-G(2)
[0078] Friction force of rolling element f = μF = (0.001 to 0.0015) F
[0079] From formula (2), we can see that: 1 +P 2 +P 3 +P 4 )=G, the rolling element is only subjected to the preload force. At this time, the pressure on the upper guide surface A and B is equal to the preload force, but in the opposite direction. There is friction between the upper guide surface A and B. If the upper guide surface is free of friction, the electromagnetic force (P 1 +P 2 +P 3 +P 4 ) must satisfy the requirements of formula (1).
[0080] Since the upper guide surfaces A and B of the reverse support guide rail are frictionless, the pressure F exerted by the eight rolling elements on the lower guide surfaces C and D is much smaller than the external force G. Therefore, this guide rail has the advantages of sliding guides, rolling guides and hydrostatic guides without their disadvantages.
Claims
1. A guide rail with reverse support, characterized in that: The reverse-supported guide rail comprises a supporting guide rail, a connecting plate, a rolling body, a rolling body supporting device and a magnet device; The supporting guide rail comprises an upper guide rail surface and a lower guide rail surface located on the base, the upper guide rail surface cooperates with the moving guide rail surface on the workbench, the lower guide rail surface is a plane parallel to the moving direction of the guide rail, a bearing plate is provided on the lower guide rail surface as the guide rail surface of the rolling body, and a magnetic isolation plate is installed between the bearing plate and the base; there is a space below the lower guide rail surface for accommodating the magnet device, the rolling body and the rolling body support device installed on the connecting plate; The connecting plate is an L-shaped plate, the upper part of the vertical part of which is fixed to the side of the workbench, and a gasket is provided between the workbench and the connecting plate for adjusting the horizontal position of the connecting plate, and the lower part of the connecting plate is a horizontal part parallel to the lower guide rail surface; a square space is formed between the horizontal part of the connecting plate and the bearing plate on the lower guide rail surface of the supporting guide rail, which is used to install the magnet device, the rolling body and the rolling body supporting device; each connecting plate is provided with two rolling body brackets equipped with rolling bodies, and a group of magnet devices is provided between the two rolling body brackets; The rolling body support device installed on each connecting plate includes two rolling body brackets and two rolling body support shafts; the two rolling bodies are installed on the rolling body brackets through the rolling body support shafts; the two rolling body brackets are fixed at both ends of the horizontal part of the L-shaped connecting plate; The magnet device is fixed to the horizontal part of each L-shaped connecting plate, located between the two rolling body brackets, and each connecting plate is equipped with a set of magnet devices; An air gap of less than 1 mm is left between the magnet device and the bearing plate, and the rolling body mounted on the rolling body bracket is pressed against the lower surface of the bearing plate; the pre-pressure of the rolling body on the rolling body bracket on the bearing plate is adjusted by adjusting the upper and lower positions of the connecting plate.
2. A reverse-supported guide rail according to claim 1, characterized in that: The upper guide rail surface is a convex double triangle guide rail, a concave double triangle guide rail or other forms of non-inlaid guide rails.
3. A reverse-supported guide rail according to claim 1, characterized in that: The length of the horizontal portion of the connecting plate is slightly greater than or equal to the sum of the lengths of the two rolling element supports and the length of the magnet device, and the lengths of the bearing plate and the magnetic isolation plate are the same as the length of the supporting guide rail.
4. A reverse-supported guide rail according to claim 1, characterized in that: Each group of magnet devices is one or more permanent magnets or electromagnets.
5. A reverse-supported guide rail according to claim 1, characterized in that: According to the force balance condition, the two sides of the workbench can be assembled symmetrically, and one or more connecting plates are set on each side of the workbench.
6. A reverse-supported guide rail according to claim 1, characterized in that: The bearing plate is made of a magnetically conductive and quenchable material; the magnetic isolation plate is made of a non-magnetic conductive material; the bearing plate and the magnetically conductive plate are an integrated or split structure.
7. A reverse-supported guide rail according to claim 1, characterized in that: The lower guide rail surface is on the left and right outer sides or inner sides of the bed.
8. A reverse-supported guide rail according to claim 1, characterized in that: The rolling body is a bearing, a rolling guide block or other rolling bodies.
9. A reverse-supported guide rail according to claim 1, characterized in that: The support guides are guides for linear motion or circular guides for rotational motion.