WO2024007683A1 - 一种龙门加工中心横梁导轨的卸荷装置及卸荷方法 - Google Patents

一种龙门加工中心横梁导轨的卸荷装置及卸荷方法 Download PDF

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Publication number
WO2024007683A1
WO2024007683A1 PCT/CN2023/089659 CN2023089659W WO2024007683A1 WO 2024007683 A1 WO2024007683 A1 WO 2024007683A1 CN 2023089659 W CN2023089659 W CN 2023089659W WO 2024007683 A1 WO2024007683 A1 WO 2024007683A1
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WIPO (PCT)
Prior art keywords
guide rail
unloading
force
rail surface
worm gear
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PCT/CN2023/089659
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English (en)
French (fr)
Inventor
陈传海
刘志峰
郭劲言
陈尚
金桐彤
齐宝宝
杨兆军
龙珺琪
黎志杰
化春雷
张亮
严昊明
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吉林大学
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Application filed by 吉林大学 filed Critical 吉林大学
Priority to US18/346,876 priority Critical patent/US20230347465A1/en
Publication of WO2024007683A1 publication Critical patent/WO2024007683A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q1/00—Members which are comprised in the general build-up of a form of machine, particularly relatively large fixed members
    • B23Q1/01—Frames, beds, pillars or like members; Arrangement of ways
    • B23Q1/017—Arrangements of ways
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q11/00—Accessories fitted to machine tools for keeping tools or parts of the machine in good working condition or for cooling work; Safety devices specially combined with or arranged in, or specially adapted for use in connection with, machine tools
    • B23Q11/001—Arrangements compensating weight or flexion on parts of the machine

Definitions

  • the invention relates to the technical field of machine tool machining centers, and in particular to an unloading device and an unloading method for beam guide rails of a gantry machining center.
  • the crossbeam guide rail has an important impact on the machining quality, including its guiding accuracy, straightness, stiffness, and wear resistance. Because the crossbeam guide rail is affected by the gravity of the skateboard assembly, the general guide rail surface is subject to a large load, and wear becomes a key issue that must be considered in product design; the gravity of the skateboard assembly causes the crossbeam guide rail to overturn, and the straightness of the guide rail is also affected. Therefore, an unloading mechanism is usually involved to solve the problem of guide rail surface wear and ensure the straightness of the beam guide rail and the machining accuracy of the machine tool.
  • unloading methods for crossbeam guide rails include hydraulic unloading, mechanical unloading and pneumatic unloading.
  • the unloading force provided by the force-increasing mechanism often relies on engineering experience to design its numerical value, and for different types and structures of guide rail structures As for the unloading scheme, there is a lack of theoretical methods for analyzing the unloading force, and the evaluation and optimization of the unloading scheme are even more difficult to carry out.
  • the existing design method of unloading force is mainly based on the method described in the "Modern Practical Machine Tool Design Manual".
  • rough unloading factor a is given for different types of machine tools based on engineering experience. scope.
  • the patent CN103286625B unloading device for machine tools has an adjusting nut in the force-increasing mechanism of the unloading unit. By adjusting the nut, the deformation amount of the elastic member is changed, so that 80% of the dead weight of the sliding saddle is unloaded onto the steel guide rail in the middle of the crossbeam. .
  • this unloading scheme design method mainly relies on engineering experience, and its design results have a certain degree of ambiguity and randomness, and lack a scientific and reasonable theoretical basis; the method of solving the unloading force does not consider the impact of the sliding speed on the guide rail load. , there is a lack of unloading force solution method for specific moving speed working conditions; because the rigid beam guide rail has a large number of guide rail surfaces and complex stress conditions, the existing design method of the unloading scheme cannot quantify the actual load condition of each guide rail surface.
  • the present invention provides an unloading device and an unloading method for the beam guide rail of a gantry machining center to further ensure the straightness and load-bearing capacity of the beam guide rail.
  • first force-increasing mechanism includes a worm
  • the worm gear gland includes a worm
  • the worm gear shaft includes a worm
  • the worm gear includes a worm
  • the worm gear gland includes a worm
  • the worm gear shaft includes a worm
  • the worm gear includes a worm
  • the worm gear gland includes a worm
  • the worm gear shaft includes a worm
  • the worm gear shaft the worm gear
  • the baffle assembly includes a first mounting bracket and the first slide block.
  • the worm is horizontally rotatably connected to the sliding plate assembly
  • the worm gear gland is fixed to the sliding plate assembly.
  • the second force-increasing mechanism includes an unloading bolt, a second mounting bracket and a second slide block.
  • An unloading pressure plate is fixed on one side of the skateboard assembly.
  • the unloading bolt is connected with a horizontal thread.
  • the second mounting bracket is provided with a perforation, and one end of the unloading bolt is coaxially fixed with a shaft, and the shaft is adapted to be installed in the perforation.
  • the unloading bolt One end of the bolt is in contact with the second mounting bracket, the second sliding block is connected to the second mounting bracket, and the second sliding block is slidingly connected to the unloading guide rail elevation.
  • the gear sleeve assembly includes a worm gear sleeve and a disc spring
  • the worm gear shaft is a stepped shaft
  • the worm gear sleeve and the disc spring are respectively inserted into the outer peripheral side of the worm gear shaft
  • the worm gear sleeve is The top end is in contact with the shoulder of the worm gear shaft
  • the bottom end of the worm gear sleeve is in contact with the top end of the disc spring
  • the bottom end of the disc spring is in contact with the top surface of the first mounting bracket.
  • a mounting groove is provided at the bottom of one side of the unloading pressure plate, a threaded hole is horizontally provided on the bottom of the installation groove on the unloading pressure plate, and a round nut is connected to the unloading bolt. The round nut is in contact with the other side wall of the unloading pressure plate.
  • the bottom end of the unloading pressure plate is horizontally fixedly connected to a baffle
  • the second mounting bracket is slidably connected in the mounting groove
  • the bottom end of the second mounting bracket is slidably connected to the baffle.
  • the first slide block and the second slide block are rolling slide blocks for machine tools.
  • a fixed seat is fixedly connected to the outer wall of one end of the worm, and a plurality of screw holes are provided on the fixed seat.
  • the fixed seat is fixedly connected to the slide plate assembly through screws to limit the rotation of the worm,
  • One end of the worm is provided with an inner corner blind hole to facilitate the rotation of the worm.
  • the invention also discloses an unloading method for the beam guide rail of the gantry machining center, which uses an unloading device for the beam guide rail of the gantry machining center and includes the following steps:
  • Step 1 According to the actual project, the guide rail surface on the crossbeam guide rail is divided into upper guide rail surface, lower guide rail surface, unloading guide rail horizontal plane, unloading guide rail elevation and preload guide rail surface. Among them, the load only reaches the preload The guide rail surface that acts tightly and has no counteracting effect on the overturning tendency of the skateboard assembly is regarded as the preloaded guide rail surface.
  • the upper guide rail surface, lower guide rail surface, unloading guide rail horizontal plane, and unloading guide rail elevation are the main loaded guide rail surfaces. Establish a force balance equation for the main loaded guide rail surface;
  • Step 3 Divide the plane into multiple rectangular areas with the horizontal and vertical coordinates of the resultant force application points of each guide rail surface as boundaries. According to the overturning of the skateboard assembly in the opposite direction to the position of the cross beam, judge whether each guide rail will not overturn compared to the skateboard assembly. The increase and decrease trend of surface pressure is analyzed, and the change trend of surface pressure of each guide rail is analyzed when the rotation center is located in each rectangular area, and each rectangular area whose change trend is in line with the actual situation is screened out as the possible distribution area of the rotation center. For each possible distribution area Establish geometric equations and combine deformation coordination equations and equilibrium equations to establish mathematical models:
  • it also includes:
  • Step 4 Analyze the maximum pressure that each guide rail surface can withstand based on the maximum moving speed of the skateboard assembly, and calculate the maximum allowable pressure for each guide rail surface.
  • the vertical pressure p on each horizontal guide rail surface is ⁇ 0.025MPa, and the vertical unloading ratio of the beam of the gantry machining center is less than or equal to 0.7, calculate the minimum pressure on each guide rail surface; combined with the allowable pressure range of each guide rail surface, solve for the unloading Allowable range;
  • Step 5 Integrate the solution results of all areas where the rotation center is distributed, and analyze the relationship between the load condition of each guide rail surface and the changes in the two sets of unloading forces F 1 and F 2 in the vertical and horizontal directions;
  • Step 6 The vertical unloading force takes the maximum value in the allowable range to minimize the vertical load on the lower guide rail surface to improve geometric accuracy
  • Step 7 Solve for the horizontal unloading force when the pressure on the upper and lower guide rail surfaces is the same, so that the life of the guide rail surfaces is the same and the overall life of the guide rail is maximized;
  • Step 8 Calculate the load condition of each guide rail surface and verify it through the limit load range of each guide rail surface
  • Step 9 Based on the selected unloading force and the number of force-increasing mechanisms arranged at the same position, calculate the component force provided by each force-increasing mechanism, and then complete the part design of the force-increasing mechanism.
  • S is the stress area of each guide rail surface.
  • the contact surface stiffness k is calculated as:
  • ⁇ is the pressure of the TSF soft belt under a specific thickness
  • ⁇ is the compression deformation of the TSF soft belt under this pressure
  • the load limit value of each plastic surface is calculated:
  • the unidirectional unloading force has a greater impact on the load on the guide rail in the same direction and has a smaller impact on the surface pressure of the different guide rails.
  • the unloading force only has two directions: vertical and horizontal directions, Conduct an independent analysis on the selection of the unloading force in the two directions; in step five, if the unloading mechanism has a situation where the angle between the direction of the unloading force and the horizontal plane is less than 90°, then the unloading force will be moved in the vertical direction. Decomposed with the horizontal direction, the functional relationship between the components in the two directions and the unloading force is obtained:
  • the results obtained by the method of the present invention are: first, the innovation of the mathematical model: the present invention classifies the guide rail surface into the main loaded guide rail surface and the preloaded guide rail surface, conducts independent force analysis on the main loaded guide rail surface, and introduces the overturning angle and the rotation center , combined with the stiffness and deformation of the plastic guide rail, a set of mathematical deformation coordination equations is established, and then a mathematical model is established.
  • this invention considers the interaction between the moving speed and the guide rail surface pressure, takes the maximum moving speed of the plastic guide rail as a constraint, and proposes an unloading force solution method that meets any target moving speed.
  • this invention uses the load distribution principle of small loads in the vertical direction of the guide rail, loads on the upper and lower main rail surfaces, etc., to solve the problem of reasonable load distribution on the main rail surface and ensuring the straightness of the lower guide rail.
  • the optimal solution of unloading force uses the load distribution principle of small loads in the vertical direction of the guide rail, loads on the upper and lower main rail surfaces, etc., to solve the problem of reasonable load distribution on the main rail surface and ensuring the straightness of the lower guide rail.
  • this invention selects the preload force according to a certain proportion, and by bringing in the optimal solution of the unloading force, the solution for the pressure and pressure on all guide rail surfaces is achieved.
  • the ultimate purpose of the present invention is to realize the rapid movement of the skateboard assembly at a specific speed and to reasonably distribute the load on each guide rail surface to meet the design requirements of the machining center, thereby ensuring the straightness of the crossbeam guide rail and improving the processing accuracy and guide rail life.
  • Figure 1 is a schematic diagram of the installation structure of the unloading device of the beam guide rail of a gantry machining center according to the present invention
  • Figure 2 is a schematic diagram of the assembly of the unloading device of the crossbeam guide rail of a gantry machining center according to the present invention and the crossbeam guide rail;
  • Figure 3 is a schematic diagram of the first force-increasing mechanism of the unloading device of the beam guide rail of a gantry machining center according to the present invention
  • Figure 4 is a schematic diagram of the second force-increasing mechanism of the unloading device of the beam guide rail of a gantry machining center according to the present invention
  • Figure 5 is a schematic diagram of the installation of the second force-increasing mechanism of the unloading device of the beam guide rail of a gantry machining center according to the present invention
  • Figure 6 is a schematic diagram of each rail surface of the beam guide rail of an unloading device of the beam guide rail of a gantry machining center according to the present invention
  • Figure 7 is a force analysis diagram of the slide plate assembly of the unloading device of the beam guide rail of a gantry machining center according to the present invention.
  • Figure 8 is an analysis diagram of the overturning state of the slide plate assembly of the unloading device of the beam guide rail of a gantry machining center according to the present invention.
  • Figure 9 is an analysis diagram of the pressure difference between the upper and lower main rails in an example of the unloading device of the beam guide rail of a gantry machining center of the present invention.
  • 1 skateboard assembly 2 beam guide rail, 21 upper guide rail surface, 22 lower guide rail surface, 23 unloading guide rail horizontal plane, 24 unloading guide rail elevation, 25 preload guide rail surface, 3 first force increasing mechanism, 31 worm, 32 worm gear Gland, 33 worm gear shaft, 34 worm gear, 35 block sleeve assembly, 351 worm gear sleeve, 352 disc spring, 36 first mounting bracket, 37 first slide block, 4 second force increasing mechanism, 41 unloading bolt, 42 No. 2 mounting brackets, 43 second slide blocks, 5 shafts, 6 mounting slots, 7 baffles, 8 round nuts, 9 inner corner blind holes.
  • an unloading device for the beam guide rail of a gantry machining center is installed on the skateboard assembly 1.
  • the skateboard assembly 1 is slidably connected to the beam guide rail 2 of the gantry machining center.
  • On the crossbeam guide rail 2 there are an upper guide rail surface 21, a lower guide rail surface 22, an unloading guide rail horizontal surface 23, an unloading guide rail elevation 24 and a preloading guide rail surface 25, which include:
  • the first force-increasing mechanism 3 includes a worm 31, a worm gear gland 32, a worm gear shaft 33, a worm gear 34, a baffle assembly 35, a first mounting bracket 36 and a first slider 37.
  • the worm 31 rotates horizontally.
  • the worm gear gland 32 is fixed on the skateboard assembly 1.
  • the worm gear gland 32 is provided with a screw hole, the top end of the worm gear shaft 33 is threadedly connected in the screw hole, and the worm gear 34 is fixed on the worm gear shaft 33. And engages with the helical teeth of the worm.
  • a shaft hole is provided on the first mounting bracket 36.
  • the first force-increasing mechanism uses a worm gear pair and a disc spring to adjust the unloading force in the vertical direction.
  • the worm rotates to drive the worm wheel to rotate, the worm wheel can generate axial displacement along the worm gear shaft, thereby compressing the disc spring, causing the disc spring to generate The unloading force acts on the rolling element bracket, pressing the first slide block against the horizontal plane of the unloading guide rail;
  • the second force-increasing mechanism 4 includes an unloading bolt 41, a second mounting bracket 42 and a second slider 43.
  • An unloading pressure plate 10 is fixed on one side of the skateboard assembly 1, and the unloading bolt 41 is horizontal. The thread is connected to the unloading pressure plate 10.
  • the second mounting bracket 42 is provided with a perforation. One end of the unloading bolt 41 is coaxially fixed with a shaft 5. The shaft 5 is installed in the perforation. One end of the unloading bolt is connected to the second The mounting bracket is in contact; the second sliding block 43 is connected to the second mounting bracket 42 , and the second sliding block 43 is slidingly connected to the unloading guide rail elevation 24 .
  • the unloading bolt By rotating the unloading bolt, the unloading bolt undergoes axial displacement, thereby pushing the second mounting bracket horizontally toward the crossbeam guide rail, causing the second slide block to press against the crossbeam guide rail, thereby completing the unloading adjustment of the skateboard assembly.
  • the gear sleeve assembly 35 includes a worm gear sleeve 351 and a disc spring 352.
  • the worm gear shaft 33 is a stepped shaft.
  • the worm gear sleeve 351 and the disc spring 352 are respectively inserted into the outer peripheral side of the worm gear shaft 33.
  • the worm gear sleeve 351 is a stepped shaft. The top end of 351 is in contact with the shoulder of the worm gear shaft, the bottom end of the worm gear sleeve 351 is in contact with the top end of the disc spring, and the bottom end of the disc spring 352 is in contact with the top surface of the first mounting bracket 36 .
  • the axial displacement of the worm gear shaft pushes up the displacement of the worm gear sleeve, and then pushes up the disc spring, so that the unloading force generated by the disc spring acts on the first mounting bracket.
  • the disc spring can more stabilize the movement of the mechanism, with short stroke and large load. .
  • a mounting groove 6 is provided at the bottom of one side of the unloading pressure plate 10
  • a threaded hole is horizontally provided at the bottom of the unloading pressure plate 10 corresponding to the installation groove 6
  • a round nut 8 is connected to the unloading bolt 41 , the round nut 8 is in contact with the other side wall of the unloading pressure plate 10. The round nut can lock the unloading bolt and complete the locking after unloading adjustment.
  • the bottom end of the unloading pressure plate 10 is horizontally fixedly connected to the baffle 7
  • the second mounting bracket 42 is located in the mounting groove 6
  • the bottom end of the second mounting bracket 42 is slidingly connected to the baffle 7 .
  • the baffle ensures stable operation of the second mounting bracket.
  • both the first slide block 37 and the second slide block 43 are rolling slide blocks for machine tools. Multiple rollers are installed at the bottom of the slider.
  • a fixed seat is fixedly connected to the outer wall of one end of the worm 31 .
  • a plurality of screw holes are provided on the fixed seat.
  • the fixed seat is fixedly connected to the slide plate assembly 1 through screws to limit the rotation of the worm 31 .
  • One end is provided with an inner corner blind hole 9 that drives the worm to rotate.
  • the fixed seat is used for positioning the worm after adjustment.
  • the inner corner blind hole is convenient for using tools to rotate the worm.
  • Step 1 According to the actual engineering, the guide rail surface whose load only plays a pre-tightening role and has no resistance to the overturning tendency of the skateboard assembly is regarded as the pre-tensioning guide rail surface.
  • the remaining guide rail surfaces (excluding the unloading guide rail horizontal surface and unloading Guide rail elevation) is the main load-bearing guide rail surface.
  • the guide rail surface on the beam guide rail (2) is divided into an upper guide rail surface (21), a lower guide rail surface (22), an unloading guide rail horizontal surface (23), an unloading guide rail surface
  • the load-bearing guide rail facade (24) and the preload guide rail surface (25), through force analysis, the balance equation set to establish the support force for the main load-bearing guide rail surface () is:
  • the upper guide rail surface (21) is the upper vertical surface close to the side of the skateboard assembly.
  • the lower guide rail surface (22) includes a lower vertical surface and a lower horizontal plane.
  • the unloading guide rail horizontal plane (23) is the upper horizontal plane and the unloading guide rail elevation.
  • (24) is the facade arranged parallel to the vertical plane and the preload guide rail surface (25) is arranged parallel to the lower horizontal plane and lower vertical plane, and the lower vertical plane is arranged on one side of the smooth plate assembly;
  • S is the stress area of each guide rail surface.
  • the contact surface stiffness k is calculated as:
  • ⁇ is the pressure of the TSF soft belt under a specific thickness
  • ⁇ is the compression deformation of the TSF soft belt under this pressure
  • Step 3 Solve the mathematical model based on the boundary conditions, consider the physical meaning of each parameter, and obtain the boundary conditions as
  • the horizontal unloading force F 2 For the selection of the horizontal unloading force F 2 , by solving the mathematical model and analyzing the relationship between the pressure difference
  • Step 4 Substitute the selected values F 1 and F 2 of the two unloading forces into the mathematical model, calculate the load on the remaining guide rail surfaces, and compare the calculation results with the allowable pressure interval ⁇ i of each guide rail surface. When the design unloading force meets the limit load requirements under the maximum moving speed and the minimum pressure on the guide surface, it is judged that the selection of the unloading force meets the design requirements.
  • this CNC gantry five-sided machining center is used as an example to illustrate the selection of the unloading force and the calculation method of the load condition of the main loaded guide rail surface.
  • the limit pv value of the TSF plastic soft belt is 30MPa ⁇ m ⁇ min -1
  • the maximum moving speed of the skateboard v max 25m ⁇ min -1
  • S 4 130000mm 2
  • S 6 95000mm 2
  • Step 5 The first force-increasing mechanism uses a worm gear pair and a disc spring to adjust the unloading force in the vertical direction.
  • the worm gear shaft hole of the turbine cover plate has internal threads. When the worm rotates to drive the worm gear to rotate, the worm gear can move along the worm gear.
  • the shaft generates axial displacement, thereby compressing the disc spring, causing the unloading force generated by the disc spring to act on the first mounting bracket, pressing the first slide block against the horizontal plane of the unloading guide rail.
  • the second force-increasing mechanism is installed on the unloading pressure plate.
  • the unloading bolt and the pressure plate are connected through threads.
  • the unloading bolt is rotated to cause axial displacement.
  • the second mounting bracket is used to press the second slider against the unloading guide rail facade. Generate unloading force.
  • the transmission ratio i of the worm gear pair is initially selected, and the number of worm heads z 1 and the number of worm gear teeth z 2 are selected.
  • the internal thread of the worm gear shaft hole matches the worm gear shaft. According to the spatial structure size of the unloading device, find the thread nominal diameter D, pitch P, pitch diameter D′, thread surface angle ⁇ from the ordinary thread diameter and pitch series and basic dimensions (GB/T196-2003), and calculate the thread rise angle :
  • the torque T2 on the worm gear shaft can be calculated.
  • the worm gear pair Since the worm gear pair in the force-increasing mechanism does not maintain transmission motion for a long time, the worm gear pair is designed according to the U coefficient method.
  • the span L of the worm is obtained from the value range of the worm span L ⁇ (12+0.1z 2 )m and the size of the spatial structure.
  • the center distance of the worm gear can be calculated based on the design tooth width B2 .
  • the maximum axial working load on the worm gear shaft is determined by the thread lead angle and the torque on the worm gear.
  • the deformation amount s when the single disc spring is loaded F q is analyzed.
  • the adjustment of the unloading force from 0 is calculated using a single disc spring.
  • the number of revolutions of the worm reaches the target value, taking into account the sensitivity of the force-increasing mechanism to adjust the unloading force and the ideal shape of the spring compression, the design of the combined form of the disc spring is completed.
  • the bolt spacing needs to be checked. It is known from engineering experience that when the connection purpose is ordinary connection, the maximum allowable bolt spacing t 0 ⁇ 10d for bolted connections.
  • the stud spacing should also meet the requirements of the wrench space.
  • the spacing parameter A is determined by the wrench space size (JB/ZQ4005-1997). When the actual spacing between any two studs on the same pressure plate is t 0 ′>A, the bolt spacing is judged to meet the design requirements.

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Abstract

一种龙门加工中心横梁导轨的卸荷装置，用以安装在滑板装配体(1)上，滑板装配体(1)滑动连接在龙门加工中心的横梁导轨(2)上，包括第一增力机构（3）及第二增力机构（4），第一增力机构（3）利用蜗轮蜗杆副与挡套组件（35）实现竖直方向卸荷力的调节，在蜗杆（31）旋转带动蜗轮（34）转动时，使蜗轮能够沿蜗轮轴（33）产生轴向位移，推顶挡套组件（35），产生的卸荷力作用在第一安装支架（36）上；第二增力机构（4）的卸荷螺栓（41）与压板（10）通过螺纹连接，转动卸荷螺栓（41）使其产生轴向位移，通过第二安装支架（42）使第二滑块（43）压紧卸荷导轨立面（24），产生卸荷力。卸荷装置实现滑板装配体以特定速度快速移动，并使各导轨面载荷分布合理，提高加工精度与导轨的寿命。还包括一种龙门加工中心横梁导轨的卸荷方法。

Description

一种龙门加工中心横梁导轨的卸荷装置及卸荷方法 技术领域
本发明涉及机床加工中心技术领域，具体涉及一种龙门加工中心横梁导轨的卸荷装置及卸荷方法。
背景技术
大型龙门加工中心在工业制造领域具有重要的地位，尤其是近几年我国装备制造业快速发展，市场上对这一类机床的需求和技术要求越来越高。横梁导轨作为保证龙门加工中心加工精度的关键部件，其导向精度、直线度、刚度、耐磨性都对加工质量有着重要影响。因横梁导轨受滑板装配体重力作用，一般导轨面受载较大，磨损成为产品设计必须考量的关键问题；滑板装配体的重力使横梁导轨形成倾覆趋势，导轨直线度同样收到影响。因此，通常涉及卸荷机构来解决导轨面磨损问题、保证横梁导轨的直线度与机床加工精度。
横梁导轨的卸荷方式常见的有液压卸荷、机械卸荷和气动卸荷，增力机构所提供的卸荷力往往依靠工程经验来设计其数值大小，而对于不同种类、不同结构的导轨结构与卸荷方案而言，缺乏对于卸荷力进行分析的理论方法，而卸荷方案的评价与优化更加难以进行。
现有卸荷力的设计方法主要依据《现代实用机床设计手册》所述方法，为避免卸荷比例过大而产生运动件的漂浮，根据工程经验对不同类型机床给出卸荷因数a的粗略范围。如专利CN103286625B机床用卸荷装置，其在卸荷单元增力机构中设置调节螺母，通过调节该螺母改变弹性件的变形量，使滑鞍自重的80％卸荷到横梁中部的镶钢导轨上。
但此种卸荷方案设计方法主要依靠工程经验，其设计结果具有一定的模糊性和随机性，且缺乏科学合理的理论依据；卸荷力的求解方法未考虑滑板移动速度对导轨受载的影响，缺乏针对特定移动速度工作条件的卸荷力求解方法；由于硬式横梁导轨的导轨面数量较多、受力情况复杂，现有卸荷方案的设计方法无法量化各导轨面的实际受载情况。
因此，如何提供一种能保证横梁导轨直线度，提高机床加工精度的龙门加工中心横梁导轨卸荷装置及卸荷方法是本领域技术人员亟需解决的问题。
发明内容
有鉴于此，本发明提供了一种龙门加工中心横梁导轨的卸荷装置及卸荷方法，进一步保证横梁导轨的直线度和承载能力。
为了达到上述目的，本发明采用如下技术方案：一种龙门加工中心横梁导轨的卸荷装置，用以安装在滑板装配体上，滑板装配体滑动连接在龙门加工中心的横梁导轨上，所述横梁导轨上设有上导轨面、下导轨面、卸荷导轨水平面、卸荷导轨立面及预紧导轨面，其特征在于，包括：第一增力机构，所述第一增力机构包括蜗杆、蜗轮压盖、蜗轮轴、蜗轮、挡套组件、第一安装支架及第一滑块，所述蜗杆水平转动连接在所述滑板装配体上，所述蜗轮压盖固定在所述滑板装配体上，所述蜗轮压盖上设有螺孔，所述蜗轮轴的顶端螺纹连接在所述螺孔内，所述蜗轮固定在所述蜗轮轴上且与蜗杆的螺旋齿啮合，所述第一安装支架上开设有轴孔，所述蜗轮轴的底端滑动连接在所述轴孔内，所述挡套组件套接在所述蜗轮轴上，所述挡套组件与所述第一安装支架抵接，所述第一滑块安装在所述第一安装支架上，所述第一滑块与所述卸荷导轨水平面滑动连接；
第二增力机构，所述第二增力机构包括卸荷螺栓、第二安装支架及第二滑块，所述滑板装配体的一侧固定有卸荷压板，所述卸荷螺栓水平螺纹连接在所述卸荷压板上，所述第二安装支架上开设有穿孔，所述卸荷螺栓的一端同轴固定有轴杆，所述轴杆适配安装在所述穿孔内，所述卸荷螺栓的一端与第二安装支架抵接，所述第二滑块连接在所述第二安装支架上，所述第二滑块与所述卸荷导轨立面滑动连接。
本发明的有益效果是：第一增力机构利用蜗轮蜗杆副与挡套组件实现竖直方向卸荷力的调节，其中蜗杆的转动，使得蜗杆上螺旋齿带动蜗轮转动，由于蜗轮轴是螺纹连接在蜗轮盖板上的，蜗轮盖板与滑板装配体固定，则蜗轮轴的转动会发生轴向位移，进而推顶挡套组件，挡套组件产生的卸荷力作用在第一安装支架上，使第一滑块下压卸荷导轨水平面；第二增力机构安装在卸荷压板上，卸荷螺栓与卸荷压板螺纹连接，卸荷螺栓的转动发生水平方 向的轴向位移，卸荷螺栓推顶第二安装支架，使得第二滑块水平压向卸荷导轨立面，产生卸荷力。
优选的，所述挡套组件包括蜗轮挡套及碟簧，所述蜗轮轴为阶梯轴，所述蜗轮挡套及碟簧分别穿套在所述蜗轮轴的外周侧，所述蜗轮挡套的顶端与蜗轮轴的轴肩抵接，所述蜗轮挡套的底端与碟簧的顶端抵接，所述碟簧的底端与所述第一安装支架的顶端面抵接。
优选的，所述卸荷压板的一侧底部开设有安装槽，所述卸荷压板上对应所述安装槽的槽底水平开设有螺纹孔，所述卸荷螺栓上连接有圆螺母，所述圆螺母与所述卸荷压板的另一侧壁抵接。
优选的，所述卸荷压板的底端水平固定连接有挡板，所述第二安装支架滑动连接在所述安装槽内，所述第二安装支架的底端与所述挡板滑动连接。
优选的，所述第一滑块及第二滑块均为机床用滚动滑块。
优选的，所述蜗杆的一端外侧壁上固定连接有固定座，所述固定座上开设有多个螺钉孔，所述固定座通过螺钉与所述滑板装配体固定连接限制所述蜗杆的转动，所述蜗杆的一端开设有便于带动蜗杆转动的内角盲孔。
本发明还公开了一种龙门加工中心横梁导轨的卸荷方法，使用了龙门加工中心横梁导轨的卸荷装置，其包括以下步骤：
步骤一：根据工程实际，将横梁导轨上的导轨面划分为上导轨面、下导轨面、卸荷导轨水平面、卸荷导轨立面及预紧导轨面，其中，将所受载荷只起到预紧作用且对滑板装配体倾覆趋势无对抗作用的导轨面视为预紧导轨面，所述上导轨面、下导轨面、卸荷导轨水平面、卸荷导轨立面为主要受载导轨面，对主要受载导轨面建立受力平衡方程；
步骤二：引入滑板装配体受倾覆作用形成的转角α、贴塑面垂直方向变形量δ及旋转中心坐标，划分旋转中心分布区域，结合主要受载导轨面受力面积S，得到变形协调方程；
δ＝cosβαl   \*MERGEFORMAT (2)
F＝cosβαlkS   \*MERGEFORMAT (3)
设旋转中心与主要受载导轨面所受合力F作用点距离为l，旋转中心至卸荷导轨立面与其对应的卸荷作用点连线与水平方向的夹角为β，接触面刚度为k；
步骤三：以各导轨面合力作用点横、纵坐标为边界将平面划分为多个矩形区域，按照滑板装配体向横梁所在位置的反方向倾覆，判断相比滑板装配体不发生倾覆时各导轨面压力的增大减小趋势，并分析当旋转中心位于各矩形区域时各导轨面压力变化趋势，筛选出变化趋势符合实际情况的各个矩形区域作为旋转中心的可能分布区域，对各个可能分布区域建立几何方程，结合变形协调方程、平衡方程建立数学模型：
优选的，还包括：
步骤四：根据滑板装配体最大移动速度分析各导轨面能承受的最大压强，计算各导轨面许用最大压力，为避免卸荷量过大，运动部件漂浮导致加工精度降低的问题，卸荷后各水平导轨面所受竖直方向压强p≥0.025MPa，且龙门加工中心横梁竖直方向卸荷比例小于等于0.7，计算各导轨面的最小压力；结合各导轨面许用压力范围，求解卸荷力许用区间；
步骤五：将旋转中心分布的全部区域求解结果整合，分析各导轨面受载情况与竖直方向、水平方向两组卸荷力F1、F2变化的关系；
步骤六：竖直方向卸荷力取许用区间中的极大值，以使下导轨面竖直方向受载尽量小来提高几何精度；
步骤七：求解上下导轨面压强相同时的水平方向卸荷力，以使导轨面寿命相同，导轨整体寿命达到最大；
步骤八：计算各导轨面受载情况，通过各导轨面极限受载区间加以验证；
步骤九：根据选定卸荷力大小与同一位置所布置增力机构的数量，计算每个增力机构所提供的分力大小，进而完成对增力机构进行零件设计。
优选的，所述步骤二中，S为各导轨面受力面积，根据特定厚度的TSF软带变形—载荷特性曲线，计算接触面刚度k为：
其中，Δσ为特定厚度下TSF软带所受压强，Δδ为在此压强下TSF软带压缩形变量；
在所述步骤三中，通过划分旋转中心的分布区域，建立旋转中心处于各区域时的几何关系方程组：
通过上述公式，建立旋转中心位于不同区域时的数学模型；
在所述步骤四中，根据滑板Y轴最大移动速度vmax与软带材料极限pv值，计算得到各贴塑面的受载极限值：
当主要受载导轨面存在对立预紧导轨面时，因主要受载导轨面上合力F的实际值为理论值与对应预紧导轨面所受预紧力之和，按照预紧力不超过0.2倍极限压强的设计原则，得到主要受载导轨面的所受压力：
Fmax＝(1-0.2)F′max   \*MERGEFORMAT (17)
综上得到各导轨面压力Fi的许用区间Φi。
优选的，所述步骤五中，单方向卸荷力对同方向导轨受载影响程度大，对异向导轨面压力影响程度小，当卸荷力仅有竖直方向和水平方向两种时， 对两种方向卸荷力的选取进行独立分析；在所述步骤五中，若卸荷机构存在卸荷力方向与水平面夹角小于90°的情况，则将此种卸荷力进行竖直方向与水平方向分解，得到两方向分量与此种卸荷力的函数关系：
将Fsx、Fsy作为不同方向的两个卸荷力，按照相同方法建立数学模型，进一步完成对卸荷力的设计。
本发明方法获得效果是：首先，数学模型的创新：本发明对导轨面分类为主要受载导轨面与预紧导轨面并对主要受载导轨面独立进行受力分析，引入倾覆角与旋转中心，结合塑料导轨刚度与变形量，建立数学变形协调方程组，进而建立数学模型。
其次，计算满足滑板装配体最大移动速度的创新：本发明考虑移动速度与导轨面压强相互影响关系，将塑料导轨最大移动速度作为约束条件，提出满足任意目标移动速度的卸荷力求解方法。
再次，卸荷力最优解选取的创新：本发明按下导轨竖直方向小负载、上下主导轨面载荷等分配的载荷分配原则，求解满足主导轨面受载分布合理、保证下导轨直线度的卸荷力最优解。
最后，量化各导轨面受载情况的创新：本发明按一定比例对预紧力进行选取，通过带入卸荷力最优解，实现对全部导轨面所受压力与压强的求解。本发明最终目的是实现滑板装配体以特定速度快速移动，并使各导轨面载荷分布合理，以满足加工中心的设计要求，从而保证横梁导轨的直线度，提高加工精度与导轨寿命。
附图说明
图1为本发明一种龙门加工中心横梁导轨的卸荷装置的安装结构示意图；
图2为本发明一种龙门加工中心横梁导轨的卸荷装置的与横梁导轨装配示意图；
图3为本发明一种龙门加工中心横梁导轨的卸荷装置的第一增力机构示意图；
图4为本发明一种龙门加工中心横梁导轨的卸荷装置的第二增力机构示意图；
图5为本发明一种龙门加工中心横梁导轨的卸荷装置的第二增力机构安装示意图；
图6为本发明一种龙门加工中心横梁导轨的卸荷装置的横梁导轨各个轨面示意图；
图7为本发明一种龙门加工中心横梁导轨的卸荷装置的滑板装配体受力分析图；
图8为本发明一种龙门加工中心横梁导轨的卸荷装置的滑板装配体倾覆状态分析图。
图9为本发明一种龙门加工中心横梁导轨的卸荷装置的列举实例中上下主导轨压强差分析图。
1滑板装配体、2横梁导轨、21上导轨面、22下导轨面、23卸荷导轨水平面、24卸荷导轨立面、25预紧导轨面、3第一增力机构、31蜗杆、32蜗轮压盖、33蜗轮轴、34蜗轮、35挡套组件、351蜗轮挡套、352碟簧、36第一安装支架、37第一滑块、4第二增力机构、41卸荷螺栓、42第二安装支架、43第二滑块、5轴杆、6安装槽、7挡板、8圆螺母、9内角盲孔。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
参阅本发明附图1至8，根据本发明实施例一种龙门加工中心横梁导轨的卸荷装置，用以安装在滑板装配体1上，滑板装配体1滑动连接在龙门加工中心的横梁导轨2上，横梁导轨2上设有上导轨面21、下导轨面22、卸荷导轨水平面23、卸荷导轨立面24及预紧导轨面25，其包括：
第一增力机构3，第一增力机构3包括蜗杆31、蜗轮压盖32、蜗轮轴33、蜗轮34、挡套组件35、第一安装支架36及第一滑块37，蜗杆31水平转动连接在滑板装配体1上，蜗轮压盖32固定在滑板装配体1上，蜗轮压盖32上设有螺孔，蜗轮轴33的顶端螺纹连接在螺孔内，蜗轮34固定在蜗轮轴33上且与蜗杆的螺旋齿啮合，第一安装支架36上开设有轴孔，蜗轮轴33的底端 滑动连接在轴孔内，挡套组件35套接在蜗轮轴33上，挡套组件35与第一安装支架36抵接，第一滑块37安装在第一安装支架36上，第一滑块37与卸荷导轨水平面23滑动连接；
第一增力机构利用蜗轮蜗杆副与碟簧实现竖直方向卸荷力的调节，在蜗杆旋转带动蜗轮转动时，使蜗轮能够沿蜗轮轴产生轴向位移，进而压缩碟簧，使碟簧产生的卸荷力作用在滚动体支架上，将第一滑块压紧卸荷导轨水平面；
第二增力机构4，第二增力机构4包括卸荷螺栓41、第二安装支架42及第二滑块43，滑板装配体1的一侧固定有卸荷压板10，卸荷螺栓41水平螺纹连接在卸荷压板10上，第二安装支架42上开设有穿孔，卸荷螺栓41的一端同轴固定有轴杆5，轴杆5穿设在穿孔内，卸荷螺栓的一端与第二安装支架抵接；第二滑块43连接在第二安装支架42上，第二滑块43与卸荷导轨立面24滑动连接。通过转动卸荷螺栓，使得卸荷螺栓发生轴向位移，进而推动第二安装支架水平方向趋近横梁导轨，使得第二滑块压向横梁导轨，完成滑板装配体的卸荷调节。
在另一些实施例中，挡套组件35包括蜗轮挡套351及碟簧352，蜗轮轴33为阶梯轴，蜗轮挡套351及碟簧352分别穿套在蜗轮轴33的外周侧，蜗轮挡套351的顶端与蜗轮轴的轴肩抵接，蜗轮挡套351的底端与碟簧的顶端抵接，碟簧352的底端与第一安装支架36的顶端面抵接。蜗轮轴的轴向位移推顶蜗轮挡套位移，进而推顶碟簧，使碟簧产生的卸荷力作用在第一安装支架上，碟簧能更加的稳定机构的运动，行程短，负荷大。
在另一些具体实施例中，卸荷压板10的一侧底部开设有安装槽6，卸荷压板10上对应安装槽6的槽底水平开设有螺纹孔，卸荷螺栓41上连接有圆螺母8，圆螺母8与卸荷压板10的另一侧壁抵接。圆螺母能锁紧卸荷螺栓，完成卸荷调节后的锁紧。
在其他一些实施例中，卸荷压板10的底端水平固定连接有挡板7，第二安装支架42位于在安装槽6内，第二安装支架42的底端与挡板7滑动连接。挡板能保证第二安装支架的稳定运行。
具体的，第一滑块37及第二滑块43均为机床用滚动滑块。滑块的底部安装多个滚子。
在另一些实施例中，蜗杆31的一端外侧壁上固定连接有固定座，固定座上开设有多个螺钉孔，固定座通过螺钉与滑板装配体1固定连接限制蜗杆31的转动，蜗杆31的一端开设有带动蜗杆转动的内角盲孔9，固定座用于蜗杆调节完成后的定位，内角盲孔方便使用工具转动蜗杆。
一种龙门加工中心横梁导轨的卸荷方法：
通过引入滑板装配体转角、旋转中心与导轨面刚度，建立求解各未知参数的数学模型，按下导轨竖直方向小负载、上下导轨面载荷等分配的载荷分配原则，结合对滑板装配体最大移动速度的分析，实现对卸荷力的求解，其最终目的是实现滑板装配体以特定速度快速移动，并使各导轨面载荷分布合理，以满足加工中心的设计要求，从而提高加工精度与导轨寿命。
旋转中心的确定方法：
1、把旋转前后重合的点看成是两图的对应点。
2、找出两组对应点，分别连接每组对应点并作连线的垂直平分线，交点就是旋转中心。
首先建立数学模型
步骤1：根据工程实际，将所受载荷只起到预紧作用且对滑板装配体倾覆趋势无对抗作用的导轨面视为预紧导轨面，其余导轨面(不包括卸荷导轨水平面和卸荷导轨立面)作为主要受载导轨面，如图6所示横梁导轨(2)上的导轨面划分为上导轨面(21)、下导轨面(22)、卸荷导轨水平面(23)、卸荷导轨立面(24)及预紧导轨面(25)，通过受力分析对主要受载导轨面()建立支持力的平衡方程组为：
上导轨面(21)为靠近滑板装配体一侧的上竖直面，下导轨面(22)包括下竖直面和下水平面、卸荷导轨水平面(23)为上水平面、卸荷导轨立面(24)为与竖直面平行布置的立面及预紧导轨面(25)为与下水平面和下竖直面平行布置，下竖直面平滑板装配体一侧布置；
令滑板装配体受倾覆作用形成的转角为α、贴塑面法向的变形量为δ，设旋转中心与各导轨面所受合力F作用点距离为l，作用点连线与水平方向的夹角为β，转角朝向滑板转配体的倾覆方向，得到变形协调方程为：
δ＝cosβαl
F＝cosβαlkS
其中，S为各导轨面受力面积，根据特定厚度的TSF软带变形—载荷特性曲线，计算接触面刚度k为：
其中，Δσ为特定厚度下TSF软带所受压强，Δδ为在此压强下TSF软带压缩形变量。
通过划分旋转中心的分布区域，建立旋转中心处于各区域时的几何关系方程组：
通过上述公式，建立旋转中心位于不同区域时的数学模型。
滑板最大移动速度分析
步骤2：根据滑板装配体Y轴最大移动速度vmax与软带材料极限pv值，计算得到各贴塑面的受载极限值：
当主要受载导轨面存在对立预紧导轨面时，因主要受载导轨面上合力F的实际值为理论值与对应预紧导轨面所受预紧力之和，按照预紧力不超过0.2倍极限压强的设计原则，得到主要受载导轨面的所受压力：
Fmax＝(1-0.2)F′max
根据《现代实用机床设计手册》，为避免卸荷量过大、运动部件漂浮导致加工精度降低的问题，卸荷后各水平导轨面所受竖直方向压强p≥0.025MPa，且龙门加工中心横梁竖直方向卸荷比例小于等于0.7，由此计算各导轨面的最小压力。
综上所述，可以得到各导轨面压力Fi的许用区间Φi。
卸荷力最优值求解
步骤3：结合边界条件对数学模型进行求解，考虑各参数的物理含义，得到边界条件为
α，li，βi＞0
将满足边界条件的全部区域的求解结果进行整合，分析各导轨面受载情况与两卸荷力F1、F2变化的关系，可知，由于特定卸荷力对同方向导轨的受载情况影响较大，对不同方向的导轨面压力影响较小，所以对两方向的卸荷力进行单独求解。
对于竖直方向卸荷力F1的选取，可根据平衡方程∑FY＝0计算得到：
F1＝G-F3
根据F3的许用区间Φ3计算竖直方向卸荷力F1的许用区间Φ1，取许用区间的极大值F1′作为竖直方向卸荷力的选取值，其原因是龙门加工中心的加工精度受下导轨直线度的影响更大，应使下导轨在竖直方向上的受力F3尽量小，以提高导轨几何精度。
对于水平方向卸荷力F2的选取，通过对数学模型求解分析上下主导轨面所受压强差|P3-P6|与水平方向卸荷力F2之间的变化关系，将竖直方向卸荷力F1取一固定值，则当上下导轨面压强差|P3-P6|趋于极小值时，求解得到的水平方向卸荷力F2′即为所取值。在此情况下，上下主导轨面塑料软带所受压强相同，从而保证两主导轨面寿命相同，导轨整体寿命达到最大。
计算各导轨面受载
步骤4：将两卸荷力的选取值F1、F2代入数学模型，计算其余各导轨面的受载，并将计算结果与各导轨面压力许用区间Φi进行比较。当设计卸荷力满足最大移动速度与导轨面最小压强下的极限载荷要求时，判断卸荷力的选取满足设计要求。
以此数控龙门五面加工中心实际计算为实例，说明此卸荷力选取与主要受载导轨面受载情况计算方法。由已知条件，滑板装配体重力G＝63700N，TSF塑料软带极限pv值为30MPa·m·min-1，滑板最大移动速度vmax＝25m·min-1，各导轨面受力面积：
S3＝49000mm2
S4＝130000mm2
S6＝95000mm2
计算各主要受载导轨面作用力的许用极大值：
F1max＝0.7G＝44590N


由各导轨面所受竖直方向压强p≥0.025MPa，计算F3许用极小值：
F3min＝pmin·S3＝1225N
进而得到得到各导轨面压力Fi的许用区间Φi：
Φ3＝[1225，47040N]
Φ4＝[0，124800N]
Φ6＝[0，91200N]
对于竖直方向卸荷力F1的选取，根据平衡方程∑FY＝0计算得到：
16660≤F1＝G-F3≤62475
进而得到竖直方向卸荷力F1的许用区间Φ1：
Φ1＝[16660，44590N]
按下导轨竖直方向小负载原则，取：
F1＝44590N
根据平衡方程∑FY＝0计算得到：
F3＝G-F1＝62475
将计算得到的F1和F3代入方程组，将卸荷力F2以20000N为步长在[40000，100000N]区间上通过数学模型求解各参数值，按照上下主导轨面载荷等分配的载荷分配原则，分析上下主导轨面压强差|P4-P6|对卸荷力F2的变化关系，如图所示，当F2趋近于60000N时，|P4-P6|趋于极小值，因此通过不断减小F2求解区间与步长，最终当求解步长为1N时，选取|P4-P6|达到极小值时的水平方向卸荷力：
F2＝58625N
将求解出的两卸荷力F1、F2和F3代入方程组，求解其余导轨面受力：
F4＝33946.1N
F6＝24678.9N
增力机构设计与校核
步骤5：第一增力机构利用蜗轮蜗杆副与碟簧实现竖直方向卸荷力的调节，其中涡轮盖板的蜗轮轴孔有内螺纹，在蜗杆旋转带动蜗轮转动时，使蜗轮能够沿蜗轮轴产生轴向位移，进而压缩碟簧，使碟簧产生的卸荷力作用在第一安装支架上，将第一滑块压紧卸荷导轨水平面。
第二增力机构安装在卸荷压板上，卸荷螺栓与压板通过螺纹连接，转动卸荷螺栓使其产生轴向位移，通过第二安装支架使第二滑块压紧卸荷导轨立面，产生卸荷力。
蜗轮蜗杆副设计与校核
对于蜗轮蜗杆副的设计，初选蜗轮蜗杆副的传动比i、选择蜗杆头数z1与蜗轮齿数z2。
蜗轮轴孔内螺纹与蜗轮轴相配合。根据卸荷装置空间结构尺寸，由普通螺纹直径与螺距系列及基本尺寸(GB/T196-2003)查取螺纹公称直径D，螺距P，中径D′，螺纹面夹角α，计算螺纹升角：
确定所选蜗轮材料的接触强度安全系数SH，载荷系数K，根据接触疲劳极限应力σHlim，计算许用接触应力：
当确定增力机构轴向夹紧力Fq、当量摩擦角取承托表面摩擦因数f1，初选蜗轮内径D1、外径D2后，可计算得到承托表面摩擦力矩的力臂：
根据螺旋增力机构夹紧力的计算公式，可计算蜗轮轴所受转矩T2。
由于增力机构中的蜗轮蜗杆副并非长期保持传动运动，故按照U系数法对蜗轮蜗杆副进行设计。已知U系数法校核计算公式。
U＝KAFt2m/b2≤UP＝Ulim/SFmin
计算蜗轮圆周力：Ft2＝T2/d2
推导蜗轮参数设计计算公式，并根据圆柱蜗杆传动基本参数GB10085-2018选取蜗轮模数m、分度圆直径d2与蜗杆分度圆直径d1，计算蜗轮齿数z2＝d2/m，由蜗杆跨度取值范围L≥(12+0.1z2)m以及空间结构尺寸得到蜗杆的跨度L。
d2b2m≥KAT2SFlim/Ulim
根据设计齿宽B2可计算得到蜗轮蜗杆的中心距。
进而，对第一增力机构的蜗轮轴外螺纹与蜗轮蜗杆进行校核：
由螺纹升角与蜗轮所受转矩确定蜗轮轴所受的轴向最大工作载荷
按控制预紧力确定安全系数S，计算螺纹的许用应力[σ]＝σs/S，
由强度条件计算螺纹的最小直径
由普通螺纹直径与螺距系列及基本尺寸(GB/T196-2003)，当所选螺纹小径d1＜d1min，蜗轮轴外螺纹满足强度要求。
碟簧选型
对于第一增力机构中碟簧的选型，根据碟形弹簧的特性曲线，为满足特性线趋近于直线，取
因碟簧直径比C＝D/d≈1.7时，碟簧单位体积材料的变形量最大，而C值过大会导致碟簧外径过大，因此取C＝1.7～2。
随着碟簧变形量与最大形变行程比值s/h0增大，实际杠杆臂缩短，弹簧实际承载能力与计算值的差值增大，当时，该差值已十分明显。根据GB/T1872规定smax/h0＝0.75，当时，I点可能出现裂纹。因此所选弹簧应在0.20＜s/h0＜0.60时满足受载条件。
已知同一方向上增力机构个数为n，每个增力机构上的载荷为根据各家厂商提供的产品参数，结合上述选型原则，完成水平方向和竖直方向上增力机构中碟簧的选型。
结合单片碟簧的受载变形曲线，分析单片碟簧受载Fq时变形量s，通过螺纹升角与传动比的推导，计算使用单片碟簧的情况下调整卸荷力从0到目标值蜗杆的回转次数，考虑增力机构调整卸荷力的灵敏度和弹簧压缩的理想形程，完成碟簧的组合形式的设计。
通过上述的计算和校核，可实现龙门加工中心横梁导轨卸荷力的求解和设计方案的校核。
第二增力机构螺栓设计与校核
对于第二增力机中螺栓设计，因其常处于受变载荷、振动、冲击载荷的工作环境，且作为微调机构要具备调整功能，可选用普通粗牙螺纹的螺柱进行连接。
根据螺栓数z，计算每个螺栓所受的最大工作载荷按控制预紧力确定安全系数S，计算螺栓的许用应力由公式计算螺栓的最小直径d1min。
由普通螺纹直径与螺距系列及基本尺寸(GB/T196-2003)，当所选螺纹小径d1＜d1min，第二增力机构的螺栓满足强度要求。
螺栓间距校核
当同一压板上使用多个卸荷螺栓时，需要对螺栓间距进行校核。由工程经验得知，连接用途为普通连接时，螺栓连接允许的螺栓最大间距t0≤10d。螺柱间距还应满足扳手空间的要求，由扳手空间尺寸(JB/ZQ4005-1997)确定间距参数A，当同一压板任意两螺柱实际间距t0′＞A时，判断螺栓间距满足设计要求。
对于实施例公开的装置和使用方法而言，由于其与实施例公开的方法相对应，所以描述的比较简单，相关之处参见方法部分说明即可。
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

Claims (10)

  1. 一种龙门加工中心横梁导轨的卸荷装置，用以安装在滑板装配体(1)上，所述滑板装配体(1)滑动连接在龙门加工中心的横梁导轨(2)上，所述横梁导轨(2)上具有上导轨面(21)、下导轨面(22)、卸荷导轨水平面(23)、卸荷导轨立面(24)及预紧导轨面(25)，其特征在于，包括：第一增力机构(3)，所述第一增力机构(3)包括蜗杆(31)、蜗轮压盖(32)、蜗轮轴(33)、蜗轮(34)、挡套组件(35)、第一安装支架(36)及第一滑块(37)，所述蜗杆(31)水平转动连接在所述滑板装配体(1)上，所述蜗轮压盖(32)固定在所述滑板装配体(1)上，所述蜗轮压盖(32)上设有螺孔，所述蜗轮轴(33)的顶端螺纹连接在所述螺孔内，所述蜗轮(34)固定在所述蜗轮轴(33)上且与蜗杆的螺旋齿啮合，所述第一安装支架(36)上开设有轴孔，所述蜗轮轴(33)的底端滑动连接在所述轴孔内，所述挡套组件(35)套接在所述蜗轮轴(33)的底端边缘，所述挡套组件(35)底端与所述第一安装支架(36)抵接，所述第一滑块(37)安装在所述第一安装支架(36)底端，所述第一滑块(37)底端与所述卸荷导轨水平面(23)滑动连接；
    第二增力机构(4)，所述第二增力机构(4)包括卸荷螺栓(41)、第二安装支架(42)及第二滑块(43)，所述滑板装配体(1)的一侧固定有卸荷压板(10)，所述卸荷螺栓(41)水平螺纹连接在所述卸荷压板(10)上，所述第二安装支架(42)上开设有穿孔，所述卸荷螺栓(41)的一端同轴固定有轴杆(5)，所述轴杆(5)转动连接在所述穿孔内，所述卸荷螺栓(41)的一端与第二安装支架(42)抵接，所述第二滑块(43)固定连接在所述第二安装支架(42)远离所述卸荷螺栓(41)一侧，所述第二滑块(43)与所述卸荷导轨立面(24)滑动连接。
  2. 根据权利要求1所述的一种龙门加工中心横梁导轨的卸荷装置，其特征在于，所述挡套组件(35)包括蜗轮挡套(351)及碟簧(352)，所述蜗轮轴(33)为阶梯轴，所述蜗轮挡套(351)及碟簧(352)分别穿套在所述蜗轮轴(33)的外周侧，所述蜗轮挡套(351)的顶端与蜗轮轴的轴肩抵接，所述蜗轮挡套(351)的底端与碟簧的顶端抵接，所述碟簧(352)的底端与所述第一安装支架(36)的顶端面抵接。
  3. 根据权利要求2所述的一种龙门加工中心横梁导轨的卸荷装置，其特征在于，所述卸荷压板(10)的一侧底部开设有安装槽(6)，所述卸荷压板(10)上对应所述安装槽(6)的槽底水平开设有螺纹孔，所述卸荷螺栓(41)上连接有圆螺母(8)，所述圆螺母(8)与所述卸荷压板(10)的另一侧壁抵接。
  4. 根据权利要求3所述的一种龙门加工中心横梁导轨的卸荷装置，其特征在于，所述卸荷压板(10)的底端水平固定连接有挡板(7)，所述第二安装支架(42)滑动连接在所述安装槽(6)内，所述第二安装支架(42)的底端与所述挡板(7)滑动连接。
  5. 根据权利要求4所述的一种龙门加工中心横梁导轨的卸荷装置，其特征在于，所述第一滑块(37)及第二滑块(43)均为机床用滚动滑块。
  6. 根据权利要求1所述的一种龙门加工中心横梁导轨的卸荷装置，其特征在于，所述蜗杆(31)的一端外侧壁上固定连接有固定座，所述固定座上开设有多个螺钉孔，所述固定座通过螺钉与所述滑板装配体(1)固定连接限制所述蜗杆(31)的转动，所述蜗杆(31)的一端开设有内角盲孔(9)。
  7. 一种龙门加工中心横梁导轨的卸荷方法，其特征在于，包括以下步骤：
    步骤一：根据工程实际，将横梁导轨(2)上的导轨面划分为上导轨面(21)、下导轨面(22)、卸荷导轨水平面(23)、卸荷导轨立面(24)及预紧导轨面(25)，其中，将所受载荷只起到预紧作用且对滑板装配体倾覆趋势无对抗作用的导轨面视为预紧导轨面，所述上导轨面(21)、下导轨面(22)、卸荷导轨水平面(23)、卸荷导轨立面(24)为主要受载导轨面，对主要受载导轨面建立受力平衡方程；
    步骤二：引入滑板装配体(1)受倾覆作用形成的转角α、旋转中心至卸荷导轨立面(24)与其对应的卸荷作用点连线与水平方向的夹角为β、贴塑面垂直方向变形量δ及旋转中心坐标，结合主要受载导轨面受力面积S，得到变形协调方程；
    δ＝cosβαl\*MERGEFORMAT(2)
    F＝cosβαlkS\*MERGEFORMAT(3)
    设旋转中心与主要受载导轨面所受合力F作用点距离为l，接触面刚度为k；
    步骤三：以各导轨面合力作用点横、纵坐标为边界将平面划分为多个矩形区域，按照滑板装配体(1)向横梁所在位置的反方向倾覆，判断相比滑板装配体(1)不发生倾覆时各导轨面压力的增大减小趋势，并分析当旋转中心位于各矩形区域时各导轨面压力变化趋势，筛选出变化趋势符合实际情况的各个矩形区域作为旋转中心的可能分布区域，对各个可能分布区域建立几何方程，结合变形协调方程、平衡方程建立数学模型。
  8. 根据权利要求7所述的一种龙门加工中心横梁导轨的卸荷方法，其特征在于，还包括：
    步骤四：根据滑板装配体最大移动速度分析各导轨面能承受的最大压强，计算各导轨面许用最大压力，为避免卸荷量过大，运动部件漂浮导致加工精度降低的问题，卸荷后各水平导轨面所受竖直方向压强p≥0.025MPa，且龙门加工中心横梁竖直方向卸荷比例小于等于0.7，计算各导轨面的最小压力；结合各导轨面许用压力范围，求解卸荷力许用区间；
    步骤五：将旋转中心分布的全部区域求解结果整合，分析各导轨面受载情况与竖直方向、水平方向两组卸荷力F1、F2变化的关系；
    步骤六：竖直方向卸荷力取许用区间中的极大值，以使下导轨面竖直方向受载尽量小来提高几何精度；
    步骤七：求解上下导轨面压强相同时的水平方向卸荷力，以使导轨面寿命相同，导轨整体寿命达到最大；
    步骤八：计算各导轨面受载情况，通过各导轨面极限受载区间加以验证；
    步骤九：根据选定卸荷力大小与同一位置所布置增力机构的数量，计算每个增力机构所提供的分力大小，进而完成对增力机构进行零件设计。
  9. 根据权利要求8所述的一种龙门加工中心横梁导轨的卸荷方法，其特征在于，所述步骤二中，S为各导轨面受力面积，根据特定厚度的TSF软带变形—载荷特性曲线，计算接触面刚度k为：
    其中，Δσ为特定厚度下TSF软带所受压强，Δδ为在此压强下TSF软带压缩形变量；
    在所述步骤三中，主要受载导轨面总个数为n，Ai表示各导轨面所受合力作用点，O表示旋转中心，根据向量相加的三角形法则，建立旋转中心处于各区域时关于各主要受载导轨面的向量方程组，为使最终建立的数学模型为静定问题，方程组所含方程个数为n-1：
    将向量向x、y坐标轴投影，a，b分别为两导轨面合力作用点距离在y，x轴上投影，根据式(6)建立几何关系方程组：
    通过上述公式，建立旋转中心位于不同区域时的数学模型；
    在所述步骤四中，根据滑板Y轴最大移动速度vmax与软带材料极限pv值，计算得到各贴塑面的受载极限值：
    当主要受载导轨面存在对立预紧导轨面时，因主要受载导轨面上合力F的实际值为理论值与对应预紧导轨面所受预紧力之和，按照预紧力不超过0.2倍极限压强的设计原则，得到主要受载导轨面的所受压力：
    Fmax＝(1-0.2)F′max\*MERGEFORMAT(10)
    综上得到各导轨面压力Fi的许用区间Φi。
  10. 根据权利要求9所述的一种龙门加工中心横梁导轨的卸荷方法，其特征在于，所述步骤五中，单方向卸荷力对同方向导轨受载影响程度大，对异向导轨面压力影响程度小，当卸荷力仅有竖直方向和水平方向两种时，对两种方向卸荷力的选取进行独立分析；在所述步骤五中，若卸荷机构存在卸荷力方向与水平面夹角小于90°的情况，则将此种卸荷力进行竖直方向与水平方向分解：
    将Fsx、Fsy作为不同方向的两个卸荷力，按照相同方法建立数学模型。
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