Hydrostatic guide rail and manufacturing method thereof

Abstract

The invention relates to a hydrostatic guideway and a manufacturing method thereof. The hydrostatic guideway mainly comprises four structural components, namely a supporting component, a linear shaft moving component, an oil way channel component and a connecting component. The manufacturing method of the static pressure guide rail comprises the steps that firstly, plastic pasting is conducted on the installation positions of the static pressure plates on the bottom face of the stand column, then the plastic pasting faces are scraped manually to improve contact precision and geometric precision, then the upper end faces and the lower end faces of all the static pressure plates are ground to be consistent in thickness on a grinding machine, and the height difference is within 0.002 mm; finally, the static pressure plate is connected to the stand column bottom through a torque wrench through screws, and manufacturing of the static pressure guide rail pair is completed. The invention has the following advantages: 1) the process of firstly pasting plastic and then scraping and grinding is relatively simple, and the machinability is strong; 2) the modular manufacturing cost of the components is low, and subsequent assembly debugging, maintenance and replacement are facilitated; and 3) the oil sealing edge and the guide rail surface of the lathe bed are grinding surfaces, the oil film thickness is uniform after floating, the hydrodynamic performance is close to the theoretical performance, and the problems of leakage of the oil sealing edge, non-uniform floating and the like in the traditional method are solved.

Description

Technical Field

[0001] The invention belongs to the field of advanced manufacturing technology, is applicable to large and heavy precision CNC machine tools, and specifically relates to a hydrostatic guide rail and a manufacturing method thereof. Background Art

[0002] Liquid hydrostatics have stronger load-bearing capacity and better stiffness than gas hydrostatics, and are therefore widely used in large precision CNC machine tools. The collaborative mechanism of discrete manufacturing of parts and components and then combined operation has greatly guaranteed and improved the quality and efficiency of the research and development and production process of large, complex, high-end mechanical equipment. For hydrostatic guide pairs for linear motion, the shapes of the guide surfaces and oil chambers are mainly rectangular. The guide surfaces of the bed serve as fixed supports, and the oil chambers are opened on the moving parts. The hydraulic system achieves a balance between oil supply and oil return, and the sealing device effectively prevents lubricating oil leakage. The parametric design and manufacturing of the above-mentioned liquid hydrostatic guide assembly can quickly respond to the high load and high precision requirements of heavy CNC machine tools. It has the advantages of mass production, short customization cycle, strong interchangeability and controllable costs, and improves the utilization rate of the bed and guides in remanufacturing.

[0003] However, in the process of using liquid hydrostatic guide rails in large CNC machine tools, the existing technology often has the following problems:

[0004] 1) High-precision scraping and grinding of the guide rail surface is difficult: the common steel or cast iron guide rail surface is hard, and the scraping and grinding process is time-consuming and laborious. The fitter must reasonably choose the manual operation method, such as the direct push method, the direct push plus twist method, and the left-right twist method, so as to achieve the shaping cutting process control of different tool traces. Since it is a process of combined force, the scraping quality depends heavily on the operator's proficiency;

[0005] 2) Manual assembly and maintenance of guide rails are difficult: For large CNC machine tools, the bed and columns are long and heavy, and handling, positioning and installation must be done by special equipment and multiple people. It is relatively cumbersome to achieve accurate and precise adjustment of the position of parts during disassembly and reassembly. The oil circuit of the static pressure system is complex, and the layout of the oil chamber must ensure force balance and take into account the convenience of debugging and replacement;

[0006] 3) Oil leakage and uneven floating: Generally, the machining accuracy of the guide rail surface is obtained by manual scraping. The quality of the oil sealing edge depends on manual craftsmanship, and the quality fluctuation is relatively large. The surface flatness and finish directly affect the contact accuracy with the hydrostatic oil film, and change the uniformity of floating, causing the hydrodynamic performance of the hydrostatic guide rail to deviate a lot from the theoretical value. Fluctuations in oil supply pressure, improper design or aging of the oil return device and sealing structure may lead to unstable floating and even oil leakage. Summary of the invention

[0007] The purpose of the present invention is to solve the shortcomings of the prior art and provide a hydrostatic guide rail and a method for manufacturing the same to meet the requirements of high precision and high rigidity for large and heavy CNC machine tools during the linear motion of the column, thereby reducing the difficulty of the hydrostatic guide rail manufacturing process, solving the problems of manual assembly and maintenance operations of traditional hydrostatic guide rails, and further improving or eliminating the oil leakage and uneven floating during the movement of the hydrostatic guide rails between the column and the bed.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A hydrostatic guide rail comprises a supporting component, a linear axis moving component, an oil passage component and a connecting component; the supporting component is a bed 9; the linear axis moving component is a column 1; the oil passage component is composed of a hydrostatic plate 2, an oil inlet pipe 3, an oil baffle plate 4, an oil inlet chamber 6, an oil sealing edge 7 and an oil return chamber 8; the connecting component is composed of a plastic layer 5 and a screw 10.

[0010] A method for manufacturing a hydrostatic guide rail comprises the following steps:

[0011] Step 1) Plastic coating on the bottom surface of the column: A plurality of plastic coating areas are arranged at equal intervals on the bottom surface of the column of the large CNC machine tool. The plastic coating layer 5 is 2 mm thick and is a guide rail soft belt made of polytetrafluoroethylene. The upper end surface of the plastic coating layer 5 and the bottom surface of the column 1 are used as the bonding surface. After the surface is cleaned and dried, glue is applied to achieve tight bonding, and then uniform pressure is applied to solidify, and the excess periphery and chamfer of the plastic coating layer 5 are cut off;

[0012] Step 2) Scraping and grinding the plastic layer: After manually scraping the scraped surface of the plastic layer 5 with a scraper, evenly apply a colorant; using the grinding surface of the guide rail of the bed 9 as the matching reference surface, grind the scraped surface of the plastic layer 5 and the guide rail surface of the bed 9, and then scrape the high points shown in the contact spots on the scraped surface of the plastic layer 5, repeat the scraping and grinding process several times until the contact accuracy and geometric accuracy requirements of the scraped surface of the plastic layer 5 and the grinding surface of the guide rail of the bed 9 are met;

[0013] Step 3) Grinding of static pressure plates: Grinding the upper and lower end surfaces of all static pressure plates 2 using a grinder to ensure that the thickness of the static pressure plates 2 processed in batches is consistent, and the height difference is within 0.002 mm for qualified parts;

[0014] Step 4) The static pressure plate is connected to the column: According to the plastic-sticking area reserved at the bottom of the column 1, a corresponding number of static pressure plates 2 that meet the geometric accuracy requirements are selected, and then they are fixed to the plastic-sticking station at the bottom of the column 1 by multiple screws 10, and the mechanical assembly process is completed using a torque wrench to ensure the torque and position accuracy requirements of the static pressure plate 2 during installation;

[0015] Step 5) Lubricating oil flows in the oil chamber: The oil chamber is opened on the lower end surface of each static pressure plate to ensure that it is not exposed during the movement of the static pressure guide rail. Based on the effect of the static pressure oil film, the oil sealing edge 7 at the lower end of the static pressure plate 2 is separated from the grinding surface of the guide rail of the bed 9, and the floating amount is 0.03-0.06mm, which is in a pure liquid friction state. The lubricating oil is transported to the oil inlet chamber 6 through the oil inlet pipe 3 by an oil pump, so that the oil film thickness of the static pressure plate 2 and the column 1 is uniform after floating; when the lubricating oil flows out from the gap on the horizontal guide rail surface of the bed 9, it is promptly refluxed through the oil return chamber 8, or recovered to the oil tank.

[0016] When the guide rail length of the bed 9 is less than 2m, the number of oil chambers is 2 to 4; when the guide rail length of the bed 9 is more than 2m, the number of oil chambers is 5 to 6.

[0017] The oil baffle plate 4 is connected and fixed to the guide surface of the bed 9 near the outer edges on both sides by screws, thereby preventing the lubricating oil from leaking from the outside of the bed, and preventing impurities and cuttings from entering the oil chamber, keeping the guide surface and lubricating oil clean.

[0018] The beneficial effects of the present invention are:

[0019] The manufacturing method of the hydrostatic guide rail of the present invention mainly includes four major structural components: a supporting component, a linear axis motion component, an oil channel component and a connecting component. First, plastic is applied to the installation position of the hydrostatic plate on the bottom surface of the column, and then the plastic surface is manually scraped to improve the contact accuracy and geometric accuracy. Then, the upper and lower end surfaces of all the hydrostatic plates are ground on a grinder to a uniform thickness (within a height difference of 0.002 mm), and finally, the hydrostatic plate is screwed to the bottom of the column using a torque wrench to complete the manufacturing of the hydrostatic guide rail pair.

[0020] The present invention has the following advantages: 1) The process of first plasticizing and then scraping and grinding is relatively simple and has strong machinability; 2) The modular manufacturing cost of the components is low, which is convenient for subsequent assembly, debugging, maintenance and replacement; 3) The oil sealing edge and the bed guide surface are both ground surfaces, and the oil film thickness is uniform after floating, and the fluid dynamics performance is close to the theory, which overcomes the problems of oil sealing edge leakage, uneven floating and the like existing in the traditional method. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0022] Figure 1 It is a schematic diagram of the overall structure of a static pressure guide rail pair embodiment.

[0023] Figure 2 This is a structural schematic diagram of the grinding process of the plastic layer and the bed guide surface.

[0024] Figure 3It is a structural schematic diagram of the screw connection method between the static pressure plate and the column.

[0025] Figure 4 The figure shows the position of the static pressure plate in the guide rail and a cross-sectional view of its internal structure.

[0026] Figure 5 This is the working status diagram of the oil chamber.

[0027] In the figure: 1. Column; 2. Static pressure plate; 3. Oil inlet pipe; 4. Oil baffle plate; 5. Plastic layer; 6. Oil inlet chamber; 7. Oil sealing edge; 8. Oil return chamber; 9. Bed; 10. Screws. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that these descriptions are only illustrative and exemplary and should not be construed as limiting the scope of protection of the present invention.

[0029] Embodiment 1

[0030] A hydrostatic guide rail comprises a supporting component, a linear axis moving component, an oil passage component and a connecting component; the supporting component is a bed 9; the linear axis moving component is a column 1; the oil passage component is composed of a hydrostatic plate 2, an oil inlet pipe 3, an oil baffle plate 4, an oil inlet chamber 6, an oil sealing edge 7 and an oil return chamber 8; the connecting component is composed of a plastic layer 5 and a screw 10.

[0031] Embodiment 2

[0032] A method for manufacturing a hydrostatic guide rail comprises the following steps:

[0033] Step 1) Plastic coating on the bottom surface of the column: A plurality of plastic coating areas are arranged at equal intervals on the bottom surface of the column of the large CNC machine tool. The plastic coating layer 5 is 2 mm thick and is a guide rail soft belt made of polytetrafluoroethylene. The upper end surface of the plastic coating layer 5 and the bottom surface of the column 1 are used as the bonding surface. After the surface is cleaned and dried, glue is applied to achieve tight bonding, and then uniform pressure is applied to solidify, and the excess periphery and chamfer of the plastic coating layer 5 are cut off;

[0034] Step 2) Scraping and grinding the plastic layer: After manually scraping the scraped surface of the plastic layer 5 with a scraper, evenly apply a colorant; using the grinding surface of the guide rail of the bed 9 as the matching reference surface, grind the scraped surface of the plastic layer 5 and the guide rail surface of the bed 9, and then scrape the high points shown in the contact spots on the scraped surface of the plastic layer 5, repeat the scraping and grinding process several times until the contact accuracy and geometric accuracy requirements of the scraped surface of the plastic layer 5 and the grinding surface of the guide rail of the bed 9 are met;

[0035] Step 3) Grinding of static pressure plates: Grinding the upper and lower end surfaces of all static pressure plates 2 using a grinder to ensure that the thickness of the static pressure plates 2 processed in batches is consistent, and the height difference is within 0.002 mm for qualified parts;

[0036] Step 4) The static pressure plate is connected to the column: According to the plastic-sticking area reserved at the bottom of the column 1, a corresponding number of static pressure plates 2 that meet the geometric accuracy requirements are selected, and then they are fixed to the plastic-sticking station at the bottom of the column 1 by multiple screws 10, and the mechanical assembly process is completed using a torque wrench to ensure the torque and position accuracy requirements of the static pressure plate 2 during installation;

[0037] Step 5) Lubricating oil flows in the oil chamber: The oil chamber is opened on the lower end surface of each static pressure plate to ensure that it is not exposed during the movement of the static pressure guide rail. Based on the effect of the static pressure oil film, the oil sealing edge 7 at the lower end of the static pressure plate 2 is separated from the grinding surface of the guide rail of the bed 9, and the floating amount is 0.03-0.06mm, which is in a pure liquid friction state. The lubricating oil is transported to the oil inlet chamber 6 through the oil inlet pipe 3 by an oil pump, so that the oil film thickness of the static pressure plate 2 and the column 1 is uniform after floating; when the lubricating oil flows out from the gap on the horizontal guide rail surface of the bed 9, it is promptly refluxed through the oil return chamber 8, or recovered to the oil tank.

[0038] When the guide rail length of the bed 9 is less than 2m, the number of oil chambers is 2 to 4; when the guide rail length of the bed 9 is more than 2m, the number of oil chambers is 5 to 6.

[0039] The oil baffle plate 4 is connected and fixed to the guide surface of the bed 9 near the outer edges on both sides by screws, thereby preventing the lubricating oil from leaking from the outside of the bed, and preventing impurities and cuttings from entering the oil chamber, keeping the guide surface and lubricating oil clean.

[0040] Figure 1 It is a schematic diagram of the overall structure of an embodiment of a hydrostatic guide pair, which mainly includes four major components: the bed 9 is a supporting component; the column 1 is a linear axis motion component; the static pressure plate 2, the oil inlet pipe 3, the oil baffle plate 4, the oil inlet chamber 6, the oil sealing edge 7 and the oil return chamber 8 are oil passage components; the plastic layer 5 and the screw 10 are connecting components.

[0041] Figure 2The figure is a structural diagram of the grinding process of the plastic coating layer and the guide rail surface of the bed. The bottom of the column 1 of a large CNC machine tool is generally several meters long, and the plastic coating areas are evenly arranged at equal intervals, corresponding to the actual installation positions of each static pressure plate 2 of the same specification. The thickness of the plastic coating layer 5 is about 2mm, and a guide rail soft tape with a base material such as polytetrafluoroethylene that is wear-resistant, high-temperature-resistant and has good vibration reduction characteristics is usually selected. Check that the plastic coating area of ​​the column 1 has completed the threaded hole processing, and the flatness and roughness meet the standards, and wipe it clean with acetone or the like. The upper end face of the plastic coating layer 5 and the bottom surface of the column 1 are used as the bonding surface. After the soft tape is soaked, dried, cut, degreased and cleaned, the two end faces are tightly bonded by gluing, and uniform pressure is applied to achieve the curing effect of the plastic coating layer 5 and the bottom of the column 1, and the excess periphery of the plastic coating layer 5 is cut off and chamfered. Manually scrape and grind the lower end surface of the plastic layer 5, repeat the cycle of first flat scraping and then grinding to ensure that the scraped surface of the plastic layer 5 and the grinding surface of the guide rail of the bed 9 can achieve full and uniform contact. First, use a scraper to complete the manual scraping of the plastic layer 5, and evenly apply colorant on the scraped surface, and then use the grinding surface of the guide rail of the bed 9 as the matching reference surface to grind the scraped surface of the plastic layer 5 and the guide rail surface of the bed 9, observe the contact spots on the scraped surface of the plastic layer 5, scrape the high points displayed, and repeat grinding and scraping for multiple times.

[0042] Figure 3 It is a structural diagram of the screw connection method between the static pressure plate and the column. After completing the plastic coating and scraping of the plastic coating layer 5 at the bottom of the column 1 in sequence, the upper and lower end surfaces of all static pressure plates 2 are ground by a grinder, and the thickness after processing is required to be consistent, and the height difference is within 0.002mm for qualified parts; according to the multiple plastic coating area installation stations evenly arranged at equal length intervals along the bottom of the column 1, a corresponding number of static pressure plates 2 that meet the geometric accuracy requirements are selected, and then fixed to the plastic coating area position at the bottom of the column 1 by multiple screws 10. In the process of using a torque wrench to complete the above-mentioned mechanical assembly, the torque value of the torque wrench must be determined and preset first, the screws must be aligned with the hole position without interference from debris, and then the torque wrench must be slowly rotated and tightened until a "click" sound is heard and the operation is stopped, and the tightness of the above-mentioned screws must be confirmed to ensure uniform force.

[0043] Figure 4The position of the static pressure plate in the guide rail and the cross-sectional view of its internal structure. The oil sealing edge 7 at the lower end of the static pressure plate 2 is in contact with the guide rail surface of the bed 9 in the non-working mode, and is separated by the static pressure oil film in the working mode. Large CNC machine tools usually use liquid static pressure guide rails. From the perspective of oil supply, compared with the constant pressure type, the advantage of using the quantitative type is that there is no need for a throttle, thereby avoiding the problem of throttle blockage, and the heating phenomenon is not significant. Since the oil supply flow rate of each oil chamber remains unchanged, when the external load increases, the column 1 and the static pressure plate 2 will produce a downward displacement, the oil film thickness will decrease, the return oil resistance will increase, and the oil pressure in the oil chamber will increase, thereby achieving external load balance. When an open static pressure guide rail is selected, the column 1 relies on its own weight or load to remain connected to the guide rail surface of the bed 9, has a strong positive load-bearing capacity, is conducive to structural design, processing, assembly and maintenance, and its oil chamber pressure depends almost only on the load size. When the pressure of the lubricating oil in the oil chamber is greater than the load-bearing capacity of the guide surface of the bed 9, considering the effect of the static pressure oil film, the lower end surface of the static pressure plate 2 is separated from the guide surface of the bed 9, and the floating amount is 0.03 to 0.06 mm, which corresponds to the engineering experience recommended range of the static pressure oil film thickness of heavy machine tools and is in a pure liquid friction state.

[0044] Figure 5 The figure is the working state diagram of the oil chamber. For the linear motion guide pair, the oil chamber should be opened on the guide surface of the moving part, corresponding to the lower end surface of the static pressure plate 2 connected to the bottom of the column 1. When determining the number of oil chambers, if the guide length is less than 2m, take 2 to 4; if the guide length is more than 2m, it should not exceed 5 to 6. When using quantitative oil supply, one is to use distributed oil supply, that is, to equip each oil chamber with an independent oil pump; the other is centralized oil supply, that is, each oil chamber is equipped with an independent flow regulating valve and shares an oil pump. The oil pump delivers the lubricating oil to the oil inlet chamber 6 through the oil inlet pipe 3. Since the oil sealing edge 7 and the guide surface of the bed 9 are both ground surfaces, it is easy to ensure that the oil film thickness is uniform after the static pressure plate 2 and the column 1 float, and the fluid dynamics performance is close to the theoretical state; for the horizontally placed static pressure guide rail, when the lubricating oil flows out from the gap on the guide surface of the bed 9, it will be promptly refluxed through the return oil chamber 8 and recovered to the oil tank, thereby improving the utilization rate of the lubricating oil; the structures on both sides of the liquid static pressure guide rail pair are symmetrical, and the oil baffle plate 4 is connected and fixed to the guide surface of the bed 9 by screws, which can effectively avoid the leakage of lubricating oil from both sides of the bed 9; in addition, the oil baffle plate 4 also has a protective function to prevent impurities and cuttings from entering the oil chamber, thereby keeping the guide surface and lubricating oil clean.

[0045] It should be noted that the oil supply method in this embodiment can also be constant pressure oil supply. In this case, a throttle must be configured for each oil chamber, so that the constant pressure lubricating oil supplied by the oil pump can be delivered to the oil chamber through the throttle.

[0046] The above-described embodiments are only descriptions of preferred implementations of the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A hydrostatic guide rail, characterized in that: The invention comprises a supporting component, a linear axis moving component, an oil passage component and a connecting component; the supporting component is a bed (9); the linear axis moving component is a column (1); the oil passage component is composed of a static pressure plate (2), an oil inlet pipe (3), an oil baffle plate (4), an oil inlet chamber (6), an oil sealing edge (7) and an oil return chamber (8); and the connecting component is composed of a plastic coating layer (5) and a screw (10).

2. The method for manufacturing a hydrostatic guide rail according to claim 1, characterized in that: The steps include: Step 1) Plastic coating on the bottom surface of the column: a plurality of plastic coating areas are arranged at equal intervals on the bottom surface of the column of the large CNC machine tool, and the plastic coating layer (5) is 2 mm thick and is a guide rail soft belt made of polytetrafluoroethylene substrate; the upper end surface of the plastic coating layer (5) and the bottom surface of the column (1) are used as the bonding surface, and after the surface is cleaned and dried, glue is applied to achieve tight bonding, and then uniform pressure is applied to solidify, and the excess periphery and chamfer of the plastic coating layer (5) are cut off; Step 2) scraping and grinding the plastic layer: after manually scraping the scraped surface of the plastic layer (5) with a scraper, evenly apply a colorant; using the grinding surface of the guide rail of the bed (9) as a matching reference surface, grind the scraped surface of the plastic layer (5) and the guide rail surface of the bed (9), and then scrape the high points shown in the contact spots on the scraped surface of the plastic layer (5), and repeat the scraping and grinding process for several times until the contact accuracy and geometric accuracy requirements of the scraped surface of the plastic layer (5) and the grinding surface of the guide rail of the bed (9) are achieved; Step 3) Grinding of static pressure plates: Grinding the upper and lower end surfaces of all static pressure plates (2) using a grinder to ensure that the thickness of the static pressure plates (2) processed in batches is consistent, and the height difference is within 0.002 mm to be a qualified part; Step 4) connecting the static pressure plate to the column: according to the plastic-coating area reserved at the bottom of the column (1), select a corresponding number of static pressure plates (2) that meet the geometric accuracy requirements, and then fix them to the plastic-coating station at the bottom of the column (1) through multiple screws (10), and use a torque wrench to complete the mechanical assembly process to ensure that the torque and position accuracy requirements of the static pressure plate (2) are met; Step 5) Lubricating oil flows in the oil chamber: The oil chamber is opened on the lower end surface of each static pressure plate to ensure that it is not exposed during the movement of the static pressure guide rail. Based on the effect of the static pressure oil film, the oil sealing edge (7) at the lower end of the static pressure plate (2) is separated from the grinding surface of the guide rail of the bed (9), and the floating amount is 0.03-0.06mm, which is in a pure liquid friction state. The lubricating oil is transported to the oil inlet chamber (6) through the oil inlet pipe (3) by an oil pump, so that the oil film thickness of the static pressure plate (2) and the column (1) is uniform after floating; when the lubricating oil flows out from the gap on the horizontal guide rail surface of the bed (9), it is promptly refluxed through the oil return chamber (8) or recovered to the oil tank.

3. The method according to claim 2, characterized in that: When the guide rail length of the bed (9) is less than 2 m, the number of oil chambers is 2 to 4; when the guide rail length of the bed (9) is more than 2 m, the number of oil chambers is 5 to 6.

4. The method according to claim 2, characterized in that: The oil baffle plate (4) is connected and fixed to the guide rail surface of the bed (9) near the outer edges on both sides by screws, thereby preventing the lubricating oil from leaking from the outside of the bed, and preventing impurities and cuttings from entering the oil cavity, thereby keeping the guide rail surface and the lubricating oil clean.

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