Research on the peak prediction and intelligent computing of reversal error for the tilt feed system installed on the precision machine tools

To effectively predict the peak of reversal error of tilt feed system and reduce reversal error caused by friction and gravity components, a peak prediction method of reversal error for tilt feed system on the precision NC machine tool is proposed. According to the load, tilt angle, motion trajectory, maximum static friction torque and relevant dynamic characteristic information, the peak prediction formula of the reversal error for the tilt feed system is established by mathematical derivation based on the kinematics, dynamics and torque balance during the process of reversal. Thus, the peak of reversal error for the tilt feed system can be obtained. The experimental results show that this method can achieve a good prediction effect, and can predict the peak of reversal error before the machining. It provides a theoretical basis for the reversal error suppression.

Error correction technique for numerical control machine tools based on the simplex method

The objective of this research is to develop a novel correction mechanism to reduce the fluctuation range of tools in numerical control (NC) machining. Error compensation is an effective method to improve the machining accuracy of a machine tool. If the difference between two adjacent compensation data is too large, the fluctuation range of the tool will increase, which will seriously affect the surface quality of the machined parts in mechanical machining. The methodology used in compensation data processing is a simplex method of linear programming. This method reduces the fluctuation range of the tool and optimizes the tool path. The important aspect of software error compensation is to modify the initial compensation data by using an iterative method, and then the corrected tool path data are converted into actual compensated NC codes by using a postprocessor, which is implemented on the compensation module to ensure a smooth running path of the tool. The generated, calibrated, and amended NC codes were immediately fed to the machine tool controller. This technique was verified by using repeated measurements. The results of the experiments demonstrate efficient compensation and significant improvement in the machining accuracy of the NC machine tool.

The Measurement and Correction of the Spindle Squareness Error on Five-Axis Machine Tools

The present study aims to establish a measurement method for the squareness error between the machine spindle and the machine table plane. The contact-type touch trigger probe is installed on the spindle of machine tool. When the probe ball touches the rectangle box, a signal is sent to the CNC system to record the space position of the spindle in the machine coordinate system. What this design is to pass to adopt three views of the spindle to determine its spatial location. In the light of the front view and the side view of the spindle, the tilt angle can be identified. According to the projection data, the perpendicularity of the spindle to the horizontal plane is adjusted until the tilt angle error decrease to zero. To verify this method, the corresponding tests are performed on five-axis CNC machine tool. The experimental results show that vertical error of the spindle is reduced by about 60 percent after the tilt angle is adjusted. Therefore, the proposed measurement and calibration method is effective in NC machine tool.

TECHNOLOGICAL DESIGNING NC LATHES BASED ON REGIONAL MACHINERY AND DEVICE DATA BANK

The manufacturers of NC machine-tools pay little attention to the analysis of consumer requests that is to production and technological conditions typical to the majority of equipment customers. The work purpose consists in the optimization of NC lathe (NCL) technological potentialities based on the analysis of machinery and device characteristics. The scientific novelty of the work consists in a new approach to the substantiation of NC lathes parameters based on their interconnection with machinery characteristics, formation of original data bank on parts of the Uliyanovsk region companies (200,000 of items) presenting different branches of industry: aircraft manufacturing, shipbuilding, machine tool construction, automotive industry, instrument making et al. stage-by-stage parts grouping on the basis of ESKD classifier and the application of a cluster analysis. As a result of investigations there are revealed eight parts groups of revolution solids, design-technological characteristics which should be used as a technological basis for designing and choice of NC lathes (NCL). For all groups of parts there are developed complex parts (CP) generalizing all design-technological characteristics of group parts and group technological operations (GTO) for their production. The substantiation of GTO formation scheme was carried out according to shown costs Cmanuf. for machining a complex part. The design-technological characteristics and schemes of GTO formation are initial data for the definition of basic technological parameters of a new range of NCLs or the choice of the most suitable existing NCL. As a result there are substantiated NCL basic parameters for machining eight groups of parts. The design and production of all eight NCLs should be organized according to block-modular principle that is on a single common element base. To realize this principle there is substantiated a unified structure of functional units of the machine for the creation of all NCLs with different technological potentialities.