| With market economy diversity requirements for the manufacturing，machinery spareparts and products are in the form of high efficiency and low cost.As an significent part ofmanufacturing, deep-hole drilling technology is faced with small batch, many varieties,heterotypic deep-hole, new materialse, high difficulty and the challenge of more and morehigh precision requirement. Because of its special environment in BTA deep-hole drillingprocessing, how to obtain high precision holes in size, parallelism, straightness and surfaceroughness has been the most concern of the researchers from all over the world. It will changestraightness error dramatically in deep-hole drilling processing that deep-hole axis deviationto a certain extent. The availability of various approaches such as improve the accuracy ofmachine tool, tooling and cutting tool and stiffness for solving the straightness error ofdeep-hole drilling that there is no universally accepted opinion on this point. Therefore,based on hydrodynamic lubrication theory, the influence factors of deep-hole straightness wasstudied in terms of deep-hole drilling cutting fluid hydrodynamic characteristics, cutting fluiddynamic interference of BTA drill bar, cutting fluid inlet pressure characteristics, andmeasurement of deep-hole drilling straightness error in the paper. The main results are asfollows:Firstly, the equation of deep-hole straightness error was established by using of cuttingfluid reynolds equation，drill bar bending deformation theory and drill bar angle equation,which revealed relationships between cutting fluid inlet pressure, drill rotation, whirl,squeezing feed and deep-hole straightness. In the condition of cutting stability, reducing the cutting fluid inlet pressure, increasing the drill rotation speed or decreasing drill whirl speedand extrusion speed can improve the straightness error of deep-hole was pointed out.Secondly, in the process of deep-hole drilling, the working parameters of deep-holenegative pressure structure had a great influence, including injection coefficient, chip removalof cross-sectional area ratio, discharge pressure, negative pressure number, etc. Injectioncoefficient had the non-linear proportional relationship with chip removal of cross-sectionalarea ratio, with the increasing incidence of negative pressure discharge pressure increases, aswell as, increasing negative pressure number to improve chip removal had a good effect.Movement patterns of cutting fluid was simulated, energy loss of cutting fluid in the flow wasstudied, finded curved edge nozzle has better negative effects than straight edge nozzle. Theeffect of negative pressure pumping crumbs was analyzed, the injection process of pumpcrumbs structure was simulated, and the form of the fluid motion in negative pressure nozzlewas obtained based on Fluent, which had a good guide for the actual production andmachining. And multi-level negative pressure structure is superior to the single-stage negativepressure structure.Thirdly, a new type of multi-injection structure was designed, which could effectivelyreduce the deep-hole straightness error, through the additional shunt cavity and injectionseries to reduce the inlet pressure. SFD-squeeze film damper was designed, and it was usedof oil film resistance decreases extruded deep-hole drill bar whirl and extrusion, to improvethe deep-hole straightness error. Tested deep-hole straightness error under the action of themulti-stage injection structure and SFD, and drill in the lower cutting fluid inlet pressure andsmall whirl and extrusion have a better deep-hole drilling straightness was verified. New ideasand designed scheme was given to control the deep-hole processing straightness error.Findly, based on the principle of photoelectric, an accurate method accorded to thechanging rule of the output voltage was builted to measure the deep-hole straightness. Someanalytical work was done to find the changed rule of the actual deep-hole center when thephotodetector had translational and rotational movements. Based on the least squares principle，the relationship between the deep-hole straightness and the output voltage wasdeduced，which provided the theoretical foundation for deep-hole straightness photoelectricmeasurement; Accorded to the photoelectric measurement theory, a self-positioning, real-timedisplay deep-hole straightness deviation measurement structure was designed, which couldeffectively achieved automatic and non-destructive detection for the challenges of deep-holestraightness error measurement. |
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