花岗岩铣削刀具加工效能的系统研究

发布时间：2019-06-18 14:29

【摘要】：随着计算机技术在花岗岩铣削加工中的应用,使得花岗岩雕刻制品在实际生活中已得到了大量的应用,同时也具有着更广阔的应用前景。目前花岗岩加工机械设备技术已比较成熟,但刀具的使用效能成为了困扰花岗岩铣削加工的难题,其加工工艺参数一直使用经验的工艺参数,不适当的加工工艺参数经常导致刀具磨损,甚至断裂,缩短刀具使用寿命。而铣削力是影响刀具使用效能的关键因素,同时刀具的磨损也对加工效能有较大的影响。目前在花岗岩加工领域针对金刚石锯片的研究成果较多,为实际加工提供了参考和依据,但对花岗岩铣削加工刀具的研究较少,阻碍了花岗岩铣削技术的迅速发展和应用。因此,本文针对花岗岩铣削加工刀具加工效能关键因素进行了系统研究,所做的工作主要包括：(1)从压痕断裂理论入手,通过分析尖锐压头挤压花岗岩的接触应力及裂纹形成过程,研究花岗岩铣削加工的机理。运用ANSYS/LS-DYNA软件进行压痕仿真,模拟了金刚石颗粒在压入花岗岩时裂纹的产生及应力状态,通过不同进给速度的加载,获得了花岗岩和金刚石的最大应力,得出当切入深度一定时,金刚石的最大应力随进给速度的增加而增大。并利用尖锐压头进行了压痕实验,通过显微照片进一步对裂纹的构成和特征做了进一步描述和分析。(2)根据建立的加工模型,分析金刚石颗粒铣削花岗岩的几何学参数,推导了花岗岩铣削加工中工件与刀具相互作用弧长、平均切削厚度的理论公式。从切削前后切削体积相等入手,微观上分析了单颗粒金刚石的受力情况,理论上建立了相关的特征因素的计算公式。主要包括铣刀单位长度静态有效磨粒数N1、单位面积静态有效磨粒数Ns和动态有效磨粒数Nd。同时进行了系统的公式推导,从宏观理论上分析了一般铣削条件下的铣刀受力的情况,并结合实际花岗岩雕刻中的典型加工,建立了花岗岩雕刻的加工模型,推导花岗岩雕刻中铣削力公式。分析结果表明花岗岩铣削加工中铣削力大小与加工参数切削深度成比例增大,与进给速度成接近1/2的指数增长,与主轴转速成接近1/2的指数递减。(3)为了对理论分析结果进一步验证,同时为后续的预测分析提供建模样本数据,搭建了花岗岩铣削力在线检测的硬件系统,并利用VC++6.0软件开发了对应的检测系统软件,实现对加工过程中铣削力的动态检测。(4)在搭建的检测实验台上进行了花岗岩铣削力的实验,完成了金刚石铣刀加工花岗岩的单因素实验、正交实验和刀具断裂实验。重点考察加工工艺参数主轴转速n (r/min)、进给速度vf(mm/min)和切削深度αp (mm)对铣削力的影响。单因素实验测量出对应加工工艺参数下的100组实验样本；做正交实验并测量出对应加工工艺参数下的9组实验样本；做金刚石铣刀断裂实验并测出金刚石铣刀断裂时所受的最大铣削力,获得刀具断裂的临界铣削力。根据实验数据进行了相关分析,同时获得的实验数据也为后续的神经网络建模和验证提供了样本数据。(5)分别采用BP神经网络和RBF神经网络对花岗岩雕刻过程中的铣削力建立了预测模型,通过对MATLAB神经网络工具箱中相关函数的调用实现了网络设计、权值初始化和网络训练以及仿真等,通过实验数据验证了预测模型的可行性,使模型能够根据不同的加工参数比较准确的预测铣削力。并根据实验数据对两种神经网络的预测准确性做了比较。结果表明,利用BP神经网络预测的铣削力虽然能够保证其预测值的平均误差低于6%,但单体误差的波动较大,且与铣削力的理论计算值的平均误差较大；相比之下,利用RBF神经网络的预测模型预测的铣削力不仅平均误差低于BP神经网络,而且单体误差波动比较稳定,与铣削力的实验值平均误差为2.5173%,相比BP神经网络误差更小,更接近实际情况,切实可行,能根据加工工艺参数更准确的预测出花岗岩雕刻加工中金刚石铣刀的铣削力。(6)针对花岗岩加工中铣刀表面磨损情况进行了分析。从铣刀的磨损量和铣刀表面微观的磨损形式进行了研究。分析铣刀磨损量与加工工艺参数：主轴转速n(r/min)、进给速度vf (mm/min)和切削深度αp (mm)间的影响关系和规律；对铣刀表面微观形态进行观察分析研究其主要的磨损形式和对刀具寿命的影响。结合刀具的磨损情况,进行了新型刀具的探索实验,将等离子热喷涂技术引入到花岗岩加工刀具的制备中,并对制备的刀具进行了相关的刀具磨损实验,并对实验结果给出了较详细的分析。本文最后结合RBF神经网络预测模型、刀具断裂实验结果和刀具磨损分析,给出了花岗岩铣削加工过程中提高刀具加工效能,优选加工工艺参数的步骤,该方法在保证刀具可靠加工的情况下,通过优选加工参数提高材料去除率,从加工效率和刀具两方面降低产品成本,通过石材企业的实际应用验证了该方法的可行性。并给出了具体的应用实例,为花岗岩铣削加工中工艺参数的选择提供了参考的方法和依据。通过优选加工参数,对花岗岩铣削加工中降低生产成本、提高加工效率具有一定的指导意义。
[Abstract]:With the application of computer technology in the process of granite surface cutting, the granite carving product has been widely used in the actual life, and has a wider application prospect. At present, the technology of the granite processing and mechanical equipment has been relatively mature, but the use efficiency of the tool has become a difficult problem for the processing of the granite of the granite, the processing process parameters of the tool have been using the process parameters of the experience, and the improper machining process parameters often cause the tool to wear and even break, And the service life of the cutter is shortened. The cutting force is a key factor that affects the efficiency of the tool, and the wear of the tool has a great effect on the processing efficiency. At present, the research results of the diamond saw blade in the field of granite processing are much more, and the reference and the basis for the actual processing are provided. However, the research on the granite cutting and processing tool is less, and the rapid development and application of the granite cutting technology are hindered. In this paper, a systematic study on the key factors of the machining efficiency of the cutting tool for granite is carried out. The main work is as follows: (1) from the theory of indentation fracture, the contact stress and the crack formation process of the granite are analyzed by the analysis of the sharp pressure head. In this paper, the mechanism of granite cutting and processing is studied. By using the software of ANSYS/ LS-DYNA to simulate the indentation, the generation and stress state of the crack during the press-in of the granite by the diamond particles are simulated, the maximum stress of the granite and the diamond is obtained through the loading of different feeding speeds, and when the cut-in depth is fixed, The maximum stress of the diamond increases with the increase in the feed rate. The formation and characteristics of the crack were further described and analyzed by the micrographs. (2) According to the established machining model, the geometric parameters of the diamond particles and the granite are analyzed, and the theoretical formula of the interaction arc length and the average cutting thickness of the workpiece and the tool in the granite cutting process is derived. Starting from the cutting volume before and after cutting, the stress condition of single-grain diamond is analyzed, and the relevant characteristic factors are theoretically established. The static and effective abrasive grain number N1, the static effective abrasive grain number Ns and the dynamic effective abrasive grain number Nd of the unit area are mainly included, and the formula derivation of the system is also carried out, Combining with the typical processing in the granite carving, the processing model of the granite carving is established, and the formula of the cutting force in the granite carving is derived. The results show that the size of the cutting force of the granite in the cutting process is increased in proportion to the cutting depth of the machining parameter, and the index with the feeding speed close to 1/2 is increased, and the index with the rotation speed of the main shaft is close to 1/2 is decreased. and (3) in order to further verify the theoretical analysis result, the data is provided for subsequent prediction analysis, a hardware system for on-line detection of the granite cutting force is built, and a corresponding detection system software is developed by using the VC ++ 6.0, And the dynamic detection of the cutting force in the machining process is realized. (4) The experiment of granite shearing force was carried out on the built-up test bench, and the single-factor experiment, the orthogonal experiment and the tool fracture experiment of the diamond cutter-processed granite were completed. The influence of the spindle speed n (r/ min), the feeding speed vf (mm/ min) and the cutting depth (p (mm) on the cutting force of the machining process parameters is mainly studied. a single-factor experiment is used to measure 100 groups of experimental samples corresponding to the processing process parameters, And the critical cutting force of the tool fracture is obtained. The relevant analysis is carried out according to the experimental data, and the obtained experimental data also provides the sample data for subsequent neural network modeling and verification. and (5) using the BP neural network and the RBF neural network to set up a prediction model for the cutting force in the granite carving process, and the network design, the weight initialization and the network training and the simulation are realized through the call of the related functions in the MATLAB neural network toolbox, The feasibility of the prediction model is verified by the experimental data, so that the model can accurately predict the cutting force according to different machining parameters. And the prediction accuracy of the two neural networks is compared according to the experimental data. The results show that the average error of the predicted value is lower than 6% by using the BP neural network, but the fluctuation of the monomer error is large, and the average error of the theoretical calculation value of the cutting force is large; in contrast, The prediction model of the RBF neural network not only has the average error lower than that of the BP neural network, but also the fluctuation of the monomer error is relatively stable, the average error of the experimental value with the cutting force is 2.5173%, and the error of the BP neural network is smaller and closer to the actual situation. The cutting force of the diamond cutting knife in the granite carving process can be predicted more accurately according to the processing process parameters. (6) The wear of the surface of the granite in the process of granite processing is analyzed. The wear and wear of the blade surface were studied. The influence relation and law of the wear and processing parameters of the cutting tool, the main shaft speed n (r/ min), the feeding speed vf (mm/ min) and the cutting depth (p (mm) were analyzed, and the main wear pattern and the influence on the life of the tool were studied. Combined with the wear of the tool, the new tool's exploration experiment is carried out, the plasma thermal spraying technology is introduced into the preparation of the granite processing tool, and the related tool wear experiment is carried out on the prepared tool, and the detailed analysis is given to the experimental results. In this paper, based on the prediction model of the RBF neural network, the experimental results of the tool fracture and the analysis of the wear of the tool, the step of improving the machining efficiency of the tool in the processing of the granite is given, and the process parameters are preferably processed. The material removal rate is improved by the preferred processing parameters, the product cost is reduced from the processing efficiency and the cutting tool, and the feasibility of the method is verified through the practical application of the stone enterprise. The specific application examples are given, and the reference method and the basis for the selection of the process parameters in the granite cutting process are provided. By optimizing the processing parameters, the production cost is reduced, and the processing efficiency is improved.
【学位授予单位】：东北大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG714

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