Vibration Drilling Research Articles

Influence Axial Vibration on Lateral Bending Deformation of Twist Drill in Machining Small Hole

According to material mechanics theory and drilling practice, the equation of lateral bending deformation (LBD) of drill was built and the inclined angle of drill tip was solved when drilling small hole. And then the drilling test was done and the character of drilling force was analyzed. Based on this, the LBD of drill was studied. The result shows that, the rise of lateral force and thrust force will increase the inclined angle of drill tip in drilling process, and lateral force is the main factor of generating LBD. By choosing suitable axial vibration parameter, axial vibration drilling can reduce the LBD of drill and improve the dimensional accuracy of hole evidently.

Step Vibration Drilling for Micro Inclined Hole

In modern manufacturing industry, there are a great deal of micro inclined holes, which is a difficult problem to machining. A novel micro inclined hole drilling method, step vibration drilling, is adopted. The experiments are carried that 45 degrees inclined hole is drilled into the 45 steel workpiece with Φ0.5mm carbide drill bit. The notable result was obtained with the method of step vibration drilling for drilling 45 degrees inclined holes on 45 steel, which break the restriction of drill jig. The new approach is put forward for micro inclined hole.

Modeling of Self‐Vibratory Drilling Head‐Spindle System for Predictions of Bearings Lifespan

The machining of deep holes is limited due to inadequate chip evacuation, which induces tool breakage. To limit this drawback, retreat cycles and lubrication are used. An alternative response to the evacuation problem is based on high‐speed vibratory drilling. A specific tool holder induces axial self‐maintained vibration of the drill, which enables the chips to be split. The chips are thus of a small size and can be evacuated. To anticipate the potential risk of decreased spindle lifespan associated with these vibrations, a model of the behavior of the system (spindle—self‐vibrating drilling head—tool) is elaborated. In order to assess the dynamic behavior of the system, this study develops a rotor‐based finite element model, integrated with the modelling of component interfaces. The current results indicate that the simulations are consistent with the experimental measurements. The influence of spindle speed and feed rate on bearing lifespan is highlighted.

A Study on Chip Breakage in Mini-Pore Vibration Drilling for Hard-to-Cut Material of Austenitic Stainless Steel

This research aims to improve the method of Mini-pore Drilling superimposed an axis vibration for hard-to-cut material of Austenitic Stainless Steel 1Cr18Ni9Ti, as well as to make it easier for the chips to be discharged. A mathematical model of vibration drilling is presented, and the relationship between the vibration parameters and cutting parameters to generate little and short broken-chips in vibration drilling is investigated, analyzed and verified by experiments. The results show that when the processing parameters meet the conditions given in this article, stable and reliable chip-breaking can be achieved. The results provide a theoretical guidance to achieve chip-breaking in mini-pore vibration drilling for hard-to-cut material.

Drilling Characteristics of SiC Particle Reinforced Aluminum-Matrix Composites with Ultrasonic Vibration

With the rapid development of aviation at home, particle reinforced metal matrix composites (PRMMCs) has been widely applied recently. But at the same time, the difficult machining has gradually been one of the most outstanding bottle-necks that restrict the rapid enhancement of productivity. Here, in virtue of the self-developed ultrasonic drilling equipment, hole-making experiments of common and ultrasonic vibration drilling are performed on SiC particle reinforced aluminum-matrix composites （SiCp/Al）with different content of SiC by using two types of tungsten carbide drill. Drilling characteristics of machining composites with ultrasonic vibration are analyzed from such respects as the composites crush, drilling force, drill wear and hole surface quality. Studies show that, during the ultrasonic vibration drilling process, SiC particle in the composites is prone to break along the crystal connection boundary or suffer ductile fracture under the dynamic ultrasonic impulse, in which the cutting resistance could be reduced and the tool edge could be protected. Thereby, drilling locating precision and hole surface quality could be enhanced, wear of the drill chisel edge effectively improved, and the drilling torque reduced about 30%.

Design and Research of Amplitude Transformer in Ultrasonic Vibration Drilling System

The ultrasonic vibration drilling presents superior technology effect than common methods in small-diameter deep hole machining areas, and can improve the machining quality and efficiency remarkably. The amplitude transformer usually is designed by users according to the requirement of production. Thus the design and manufacturing of amplitude transformer and the realization of the resonance of device are key problems in ultrasonic vibration drilling system. In this paper, we firstly analyzed the structure of amplitude transformer in the axial ultrasonic vibration drilling, and then designed and manufactured the composite amplitude transformer for small-diameter deep holes in the ultrasonic vibration drilling. After we carried out the test in the sound vibration system, the result indicated that the resonance of the sound system could be satisfied and the demand of small-diameter deep hole drilling could be met.

Analysis of an assigned oscillatory trajectory of a vibratory drilling screen

A design for an assigned oscillatory trajectory of the frame of a vibratory drilling screen is defined in a Cartesian coordinate system. Algebraic equations presented are derived as sufficient limitations for differential motion equations of the vibratory drilling screen.

Failure Mechanism of Twist Drill in Vibration Drilling of Duralumin

Based on experiments of common drilling and vibration drilling on duralumin (2A12), the failure mode and failure reason of twist drill are studied theoretically and experimentally. The result shows that, compared with common drilling, the wear of clearance face and rake face decreases evidently during vibration drilling, and the wear of chisel edge and marginal point of twist drill hardly happens. Moreover the probability of drill breakage is very low during vibration drilling. However, if amplitude is bigger, the tipping of chisel edge often appears.

Effects of Ultrasonic Vibration on Machining Accuracy in Drilling

Generally in the drilling of micro and small hole such as nozzle, problems frequently occur in terms of burr formation at the cutter exit, breakage of the drills and degradation of machining accuracy. A recent and promising method to overcome these technological constraints is the use of ultrasonic vibration drilling. This paper presents the design of an ultrasonically vibrated tool based on tailstock of lathe and the experimental investigation of ultrasonically assisted drilling of 3J1 stainless steel. The location accuracy of entering drilling and linear of drill were measured and compared. The obtained results show that the application of ultrasonic vibration can improve the machining accuracy considerably.

Study on the Kinematics of the Lips of the Twist Drill on the Axial Vibration Part 2: Theoretical Chip Length and Dynamic Angles of the Drill

In vibratory drilling, the chip lengths and working angles alter respectively, and play important part in the process for the quality, efficiency, and chip breakage. The length of the edge movement in real drilling is just the theoretical length of the chip as the distance between the adjacent entering point and detaching point. It is revealed that from the condition of hm=0, the chip breaks automatically in the disjunction vibratory drilling pattern. Change of the dynamic angles was researched and based on the finding that the dynamic angle change undulates cyclically versus vibratory phase angle as well as the axial velocity in magnitude and direction of the drill, generated from the input of vibratory signals, the best performance of the drill in work may be pursued with the optimal working angle and clearance angle obtained by selecting the input vibratory parameters and selecting other drilling parameters in proper order.

Study on the Kinematics of the Lips of the Twist Drill on the Axial Vibration Part 1: Axial Locus and Vibration Pattern

Loci were studied of the lips movement with axial vibration for both non-disjunction and dis-junction pattern of the twist drill, with the proof that for the dis-junction pattern the chip might be broken by the special loci of the lips without any additional external forces. Positions of the same two points on the two major cutting edges were presented in detail with the rotation angle between the two points, 180 deg. Difference of the two loci, h, was the chip thickness that altered instantly and when it was zero the chip broke. Minimum difference hmin was taken as a criterion for vibration drilling pattern. Non-disjunction pattern of vibratory drilling came out when hmin ＞0 and disjunction pattern arrived otherwise. Expressions for the two patterns showed that vibratory parameters and cutting parameters have influenced h considerably.

Drilling Force of SiC Particle Reinforced Aluminum-Matrix Composites with Ultrasonic Vibration

In recent years, particle reinforced metal matrix composites (PRMMCs）has been widely applied because of its excellent mechanical performances. But the machining is very difficult due to the rigidity of reinforced phase in it, thus the popularization of PRMMCs is restricted much. Here, a method of ultrasonic vibration drilling is presented to the hole-making of Aluminum-matrix composites based on cutting force analysis between common and vibration machining. In virtue of the self-developed ultrasonic drilling equipment, experiments of common and ultrasonic vibration drilling are performed on SiC particle reinforced Aluminum-matrix composites with different content of SiC by using two types of tungsten carbide twist drill. Since the tool life can be represented directly by drilling force, especially the torque, the study of drilling force is very important for the surface roughness, the design and life of drill. Drilling force and its variation in the machining process are analyzed by comparison of common and vibration drilling. It shows that the eviction of drilling chips can be meliorated to some extent, and the drilling torque can be reduced about 30% during the ultrasonic vibration drilling process.

Identification of thrust force models for vibratory drilling

Among the scientific problems in drilling, determining thrust forces for any drill geometry and any workmaterial remains an issue. This question is especially critical in the context of the self-vibratory drilling (SVD) technology, since thrust force governs the trajectory of cutting lips. In order to predict the dynamical behaviour of the self-vibratory drilling head (SVDH), a numerical simulator has been developed in the laboratory. In order to predict the relevant behaviour of the SVD operations, a good accuracy of the thrust force model is highly necessary. The aim of the paper is to propose an experimental methodology to identify a thrust force model for one pair “drill–workmaterial” depending on the uncut chip thickness. This methodology proposes to divide cutting edges into several parts in order to define the local contribution of this part to the macroscopic thrust force. Local models are identified during the penetration of the drill. From a limited number of experiments with various feeds, it becomes possible to identify all the coefficients of an accurate thrust force model.

The “Effective Region” Characteristic of the Tool Life in Vibration Drilling

There are different opinions on whether the tool life could be improved by the vibration drilling or not. The factors which affect the drill life during micro hole drilling were analysed, and the vibration drilling has the effective region characteristic for drill life. That is to say, the vibration drilling can extend the tool life significantly within the certain range of the hole depth (or depth-diameter ratio). The stainless micro hole drilling experiments were done, and the results showed that the life advantage for vibration drilling was represented on certain region, that is effective region phenomenon

The “Effective Region” Characteristic of the Tool Life in Vibration Drilling

There are different opinions on whether the tool life could be improved by the vibration drilling or not. The factors which affect the drill life during micro hole drilling were analysed, and the vibration drilling has the effective region characteristic for drill life. That is to say, the vibration drilling can extend the tool life significantly within the certain range of the hole depth (or depth-diameter ratio). The stainless micro hole drilling experiments were done, and the results showed that the life advantage for vibration drilling was represented on certain region, that is effective region phenomenon

Application of Minimum Quantity Lubricant in Vibration Drilling

In order to make full use of good cooling and lubricating performance of minimum quantity lubrication (MQL) cutting fluid in drilling,MQL is combined with vibration drilling and its application effect is studied theoretically and experimentally.The maximum thrust force and surface roughness in the machining process is measured.The results show that,contrast with common drilling,vibration drilling can improve the action effect of MQL effectively.Through rational selection of parameters,vibration drilling can make maximum thrust force decrease evidently and improve surface roughness significantly.Moreover,increasing amplitude is a good way for improving the action effect of MQL,which can reduce surface roughness and improve machining quality.

Influence of the ploughing effect on the vibratory drilling behaviour

The poor removal of chips in deep drilling of small diameter is often the cause of tool breakage and poor quality surface. The vibratory drilling enables the chip to be split thanks to the axial vibrations of the drill, self-maintained by the cutting energy. Thus, chips are then evacuated easily. The authors developed a specific tool holder with an adapted axial stiffness. The cutting conditions are chosen to be inside the instable domain and with the chatter phenomenon the lip jump out of the material. The parameters of the Self-Vibrating Drilling Head (SVDH) and the cutting conditions are conditioned by the presence of ploughing effect that dumps the vibrations. The objectives of this paper are (i) to model the cutting and ploughing forces, the dynamical behaviour of the SVDH and the material removal and (ii) to foresee the influence of ploughing on the shape of the chip. A numerical simulator makes it possible to validate the cutting conditions, in particular the influence of the ploughing effect. The simulated results are validated by an experimental protocol.

Influence of the ploughing effect on the dynamic behaviour of the self-vibratory drilling head

The vibratory drilling process enables the chip to be split into small elements thanks to axial vibrations of the drill self-maintained by the cutting energy. The vibrations should remain stable when machining, and damping be removed or very limited—particularly the ploughing force induced by the chisel edge and the flank face. To predict the behaviour of the self-vibratory drilling head, a new ploughing model has been developed. In this model, the interaction of the tool flank face with the machined material can be perceived as a virtual cutting edge that produces an additional thrust force and an additional removal of material. This model improves the cutting force models and is integrated into a numerical vibratory drilling simulator. The model shows a good correlation with experimental results.

A numerical simulator to predict the dynamical behavior of the self-vibratory drilling head

The manufacturing of deep holes has to face problems to evacuate chips, especially for small diameters. Such problems induce frequent tool breakage and poor surface quality. The vibratory drilling enables the chip to be split into small elements thanks to the axial vibrations of the drill, self-maintained by the cutting energy. Thus, chips are easily evacuated from the hole. A specific tool holder with an adapted axial stiffness has been developed in order to investigate this drilling process. The cutting conditions are predetermined in order to lead to axial vibrations with a stable frequency and amplitude. During a period, the amplitude of the vibrations is higher than the feed per revolution, which enables the cutting edges to jump out of the work material. The vibrations are self-maintained and remain stable if some disturbances are absent or very limited such as the friction of the drill against the work material along its margins, the ploughing force induced by the chisel edge, the ploughing force induced by clearance face, etc. The objectives of this paper are (i) to model the dynamical behavior of the self-vibrating drilling head, the cutting and ploughing forces, and the material removal, (ii) to foresee with a numerical simulator the cutting conditions which generate good vibrations, (iii) to validate the numerical simulator with a experimental round of test. This work has also shown that the productivity of the drilling is improved by the use of the vibratory drilling. Deep hole (ratio deep/drill diameter > 20 ) can be drilled with this new technology without any coolant and any retreat cycle with the same quality as a conventional drilling operation.

Simulation du phénomène de talonnage en perçage vibratoire auto-entretenu

The increase of productivity of the drilling operations is a major problem that exists for long time in production. The poor removal of chips in deep drilling of small diameter is often the cause of tool breakage and poor quality surface. The vibratory drilling enables the chip to be split thanks to the axial vibrations of the drill, self-maintained by the cutting energy. Thus chips are evacuated easily. A specific tool holder with an adapted axial stiffness has been developed. The cutting conditions are chosen to be inside the instable domain and with the chatter phenomenon the lip jumps out of the material. The parameters of the self-vibrating drilling head and the cutting conditions are conditioned by the presence of ploughing effect that dumps the vibrations. In order to foresee the behaviour of the drilling head, a numerical simulator that integrates the different forces models has been created. This simulator gives some information about the thrust force generated during the machining, the amplitude of the vibrations, the chip thickness and gives the possibility to study the influence of the cutting parameters on the vibrations. Some experiments have been made to validate the simulator.