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滚珠丝杆的安装过程

来源:http://www.jngongrun.com/ 日期:2020-11-04 发布人:admin

滚珠丝杆的安装过程是非常严谨的,因为如果安装不到位将会对它的使用效率造成很大的困扰,所以每一个步骤都需要小心的。

I ball screw installation process is very rigorous, because if it is not installed in place, it will cause great trouble to its efficiency, so every step needs to be careful.
滚珠丝杠副作为数控机床的进给传动链,其装配形式和精度决定了数控机床的定位精度,也影响着进给轴插补运行的平稳性。
As the feed transmission chain of CNC machine tool, the assembly form and precision of ball screw pair determine the positioning accuracy of CNC machine tool, and also affect the stability of feed shaft interpolation operation.
一、tbi滚珠丝杠副安装形式及受力
1、 Installation form and force of TBI ball screw
控机床进给轴常见的丝杠支撑有如下几种形式:
The common screw supports for the feed shaft of control machine tools are as follows:
1、一端固定——一端自由
1. One end fixed - one end free
丝杠一端固定,另一端自由。固定端轴承同时承受轴向力和径向力,这种支承方式用于行程小的短丝杠或者用于全闭环的机床,因为这种结构的机械定位精度是更不可靠的,特别是对于长径比大的丝杠(滚珠丝杠相对细长),热变性是很明显的,1.5m长的丝杠在冷、热的不同环境下变化0.05~0.10mm是很正常的。但是由于他的结构简单,安装调试方便,许多高精度机床仍然采用这种结构,但是必须加装光栅,采用全闭环反馈。
One end of the screw is fixed and the other is free. The fixed end bearing bears both axial force and radial force. This support method is used for short lead screw with small stroke or full closed-loop machine tool, because the mechanical positioning accuracy of this structure is the most unreliable, especially for the lead screw with large length diameter ratio (ball screw is relatively slender), the thermal denaturation is obvious. The 1.5m long lead screw changes by 0.05 ~ 0.10mm under different cold and hot conditions It's normal. However, because of its simple structure and convenient installation and debugging, many high-precision machine tools still use this structure, but it must be equipped with grating and adopt full closed-loop feedback.
2、一端固定——另一端支承
2. Fixed at one end - supported at the other end
丝杠一端固定,另一端支承。固定端同时承受轴向力和径向力;支承端只承受径向力,而且能作微量的轴向浮动,可以减少或避免因丝杠自重而出现的弯曲,同时丝杠热变形可以自由的向一端伸长。这种结构使用更广泛,目前国内中小型数控车床、立式加工等均采用这种结构。
One end of the screw is fixed and the other end is supported. The fixed end can bear both axial force and radial force; the supporting end only bears radial force and can make a small amount of axial floating, which can reduce or avoid the bending due to the self weight of the lead screw. At the same time, the thermal deformation of the screw can freely extend to one end. This structure is the most widely used structure, which is widely used in domestic small and medium-sized CNC lathes and vertical machining centers.

导轨丝杠
3、两端固定
3. Fixed at both ends
丝杆两端均固定。固定端轴承都可以同时承受轴向力,这种支承方式,可以对丝杠施加适当的预紧力,提高丝杠支承刚度,可以部分补偿丝杠的热变形。
Both ends of the screw rod are fixed. The fixed end bearing can bear the axial force at the same time. This kind of bearing can exert appropriate pre tightening force on the lead screw, improve the supporting stiffness of the screw, and partially compensate the thermal deformation of the screw.
对于大型机床、重型机床以及高精度镗铣床常采用此种方案。但是,这种丝杠的调整比较繁琐,如果两端的预紧力过大,将会导致丝杠更终的行程比设计行程要长,螺距也要比设计螺距大。如果两端锁母的预紧力不够,会导致相反的结果,并容易引起机床震动,精度降低。所以,这类丝杠在拆装时一定要按照原厂商说明书调整,或借助仪器(双频激光测量仪)调整。
For large machine tools, heavy machine tools and high-precision boring and milling machines, this scheme is often used. However, the adjustment of this kind of screw is complicated. If the preload at both ends is too large, the final stroke of the lead screw will be longer than the designed stroke, and the pitch will be larger than the designed pitch. If the pre tightening force of the lock nut at both ends is not enough, it will lead to the opposite result, and it is easy to cause vibration of the machine tool and reduce the accuracy. Therefore, this kind of screw must be adjusted according to the original manufacturer's instructions or with the help of the instrument (dual frequency laser measuring instrument).
二、滚珠丝杠轴承的排列与命名
2、 Arrangement and nomenclature of ball screw bearings
首先我们了解典型的进给轴传动链,更终支撑滚珠丝杠的是近端支承轴承和远端支承轴承,这两组轴承通过相互的作用,将轴向力顶住,也就是丝杠轴成巧妙地运用了“角接触轴承”即可以承受径向力,又可以承受轴向力的双向受力特点。
First of all, we understand the typical feed shaft drive chain. The final support of the ball screw is the near end support bearing and the far end support bearing. These two groups of bearings can resist the axial force through the interaction, that is, the screw shaft skillfully uses the "angular contact bearing" which can bear both radial force and axial force.
当轴承内挡圈和外挡圈受到一组相反方向的作用力时,轴承钢珠承受着一对互为相反的作用力,从静力学的角度上看,当物体静止时,这一对作用力大小相等,方向相反。
When the inner and outer rings of the bearing are subjected to a group of forces in the opposite direction, the bearing steel balls bear a pair of opposite forces. From the static point of view, when the object is stationary, the force is equal and the direction is opposite.
作为机床丝杠传动,来自工作台的轴向力是作用在轴承的内圈上,如果我们约束丝杠不窜动,只要在轴承外圈上作用一个方向相反、大小相等的力即可,这样轴向受力是平衡的。又由于内、外圈之间是滚动摩擦,因而保证了丝杠灵活的转动。
As a machine tool lead screw drive, the axial force from the working table acts on the inner ring of the bearing. If we restrict the lead screw from moving, we only need to apply a force of opposite direction and equal size on the outer ring of the bearing, so that the axial force is balanced. Because of the rolling friction between the inner and outer rings, the flexible rotation of the lead screw is ensured.
对于数控机床丝杠传动,需要根据不同的情况控制轴承的游隙(钢珠与内外环之间的间隙),对于低速大转矩的传动,需要这一游隙是过盈的,即要使钢珠在滚到内受挤压变形,从配合角度讲,间隙是负值。而对于高速小一点的负载,则需要游隙大一点,预留出高速运行后钢珠和内圈的热膨胀系数。
For the screw drive of CNC machine tools, it is necessary to control the clearance of the bearing (the clearance between the ball and the inner and outer ring) according to different conditions. For the transmission with low speed and high torque, this clearance is required to be interference, that is, to make the steel ball be extruded and deformed from the rolling to the inside. From the perspective of matching, the clearance is negative. For the load with small speed, the clearance should be larger, and the coefficient of thermal expansion of steel ball and inner ring should be reserved after high speed operation.
丝杠的约束是通过近端轴承及远端轴承的轴向和径向约束来完成,不同安装形式下的丝杠受力情况以及滚珠丝杠轴承安装形式,对于今后日常维护,特别是传动链的精度调整有所帮助。
The constraint of the lead screw is accomplished by the axial and radial constraints of the near end bearing and the far end bearing. The force condition of the lead screw under different installation forms and the installation form of the ball screw bearing are helpful for the daily maintenance in the future, especially for the accuracy adjustment of the transmission chain.

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