CNC Grinding Machine Research Articles

A practical optimization design of helical geometry drill point and its grinding process

Drill with helical geometry drill point was developed to avoid the disadvantages of planar drill. For the visualization design and optimization of helical drill, a numerical modeling and simulation CAD system has been developed based on the mathematical models of helical drill. The characteristics of helical drill, such as lip clearance angle along cutting lip, heel clearance angle along flank surface, cutting edge inclination angle, rake angle, and so on, are described. Therefore, drill geometric parameters are modified reasonably according to different drilling requirements by the aid of the developed CAD simulation system. Besides, grinding parameters are obtained to guide the flank grinding process of helical drill. A case has been given to demonstrate the function of the system. And the calculated grinding parameters in the above case have been applied on a five-axis CNC grinding machine RollomΛtic 620XS with an assistant fixture to accomplish the flank grinding process. Drill geometry of ground drill shows good agreement with the simulative one, which validates the accuracy of proposed model method and relative CAD system.

Determination of the relative position between grinding wheel and a cylindrical workpiece on a 7 axis grinding machine by acoustic emission

The contact between grinding wheel and workpiece in the grinding process is recognized by acoustic emission (AE). Two acoustic emission monitoring systems (MS) were integrated into a 3 axis CNC grinding machine. A laptop allows the signal acquisition and visualization. The acquired AERMS signals from the contact between tool and workpiece are analyzed permitting to establish the most suitable AE monitoring system to recognize the contact in a particular grinding machine. In a second experimental setup the selected MS was installed on a 7 axis tool grinding machine at an industrial partner. At this partner, the relative position between grinding wheel and workpiece was previously determined manually. This procedure has a direct influence on the results depending on the technical skills of the operator. The automation of this activity supported by acoustic emission has led to satisfactory results regarding the relative position between grinding wheel and workpiece and contributed to the setup time reduction.

A Time-Domain Surface Grinding Model for Dynamic Simulation

The quality of a workpiece resulting from a grinding process is strongly influenced by the static and dynamic behavior of the mechanical system, composed by machine tool, wheel, fixture and workpiece. In particular, the dynamic compliance may cause vibrations leading to poor surface quality. In order to evaluate in advance the process performance in terms of surface quality, a simulation model for surface grinding has been developed, based on workpiece discretization by means of a z-buffer approach. The volume engaged by the wheel is associated to the grinding force by means of a variable specific energy that is a function of the equivalent chip thickness. The model is able to provide static and dynamic grinding force components taking into account the following aspects: nonlinearity of the grinding force with respect to cutting parameters, grinding damping effect, contact stiffness, machine-workpiece dynamics in all the relevant degrees of freedom (radial and tangential both for wheel and workpiece). The implementation in Matlab/Simulink™ environment allows an easy connection with any given mechatronic models of the grinding machine. Stable surface grinding tests with force measurements have been performed on a commercial CNC grinding machine for identifying the model parameters; then, the validation was extended to the dynamic case by introducing an artificial wheel unbalance.

The Static and Dynamic Characteristics Analysis of a CNC Grinding Machine Bed Made from Artificial Granite

The machine tool bed is an important fundamental unit of the Machine tool, and its static and dynamic characteristics directly influence the precision of the Machine tool’s process. The precise composite B2-K3000 CNC grinding machine bed is made from artificial granite. Through entity modeling, adding the boundary conditions and stress conditions to the bed, this article analyses the static stiffness, natural frequency, vibration mode and harmonic response of the grinding machine bed, and masters the natural characteristics and preponderant natural frequency.On the basic of the bed’s structure characteristics and stiffness requirements, the original bed’s structure gets partial improvements. By increasing the number of ribs and using the cross-shaped ribs, the improved result indicates that the bed’s static stiffness can be enhanced obviously and the bed’s static and dynamic characteristics can be more excellent.

Accuracy Analysis of Grinding Indexable Inserts Related to the Centrifugal Force of High Speed Abrasive Wheel

When grinding the carbide insert with the abrasive wheel at high rotating speed, the accuracy of inserts is impacted by the changed size of abrasive wheel by the centrifugal force. This paper proposes a computing model of grinding location for insert, and giving an analysis of dynamic simulation of the abrasive wheel at high rotating speed. The analysis showed which the diameter of wheel is enlarged, and its axial size is indented. According to the result, some geometrical parameters offsets were afforded to realize to grind inserts accurately in the CNC grinding machine tool.

Static and Dynamic Characteristics Analysis of Precise Composite CNC Grinding Machine

The parameters of joint parts must be included in the finite element model of a whole grinding machine. The subject investigated in this paper is B2-K3000 high-precision composite flexible grinding machine. Through finite element modeling, the joint part parameters are integrated into the whole grinding machine model to establish a dynamic model and then analyze its static and dynamic characteristics. The result shows that the whole grinding machine possesses good features, but it still needs to be improved. This paper gives suggestions for its structure development and application.

A Quick-Test Method to Determine the Grinding Wheel Topography Based on Acoustic Emission

A quick-test method for the determination of the topographic characteristics of a CBN grinding wheel is developed based on acoustic emission technology. For implementing the strategy, an acoustic emission (AE) monitoring system was integrated into a 3 axis CNC grinding machine. A computer with specific software allows the signal acquisition and visualization of the AERMSsignals, which are originated through interferences between the grinding wheel and dressing tool in a range of a few micrometers. The acquired AERMSsignals from these interferences are used in order to establish an on-line map from the grinding wheel periphery, indicating the active cutting grains during the contact amid grinding wheel and dressing tool. The implementation of such activity supported by AE has led to satisfactory results regarding the required time to evaluate the strategy as well as the verified correlation with different grinding topographies caused by changes in the dressing parameters.

Development of CAD/CAM system and profile measuring device for CNC grinding machine to obtain an optimal grinding speed

Cam mechanics is one of the most popular devices for generating irregular motions and is widely used in automatic equipment, such as textile machines, internal combustion engines, and other automatic devices. In order to obtain a positive motion from the follower using a rotating cam, its shape should be correctly designed and manufactured. The development of an adequate CAD/CAM system for a cam profile CNC grinding machine is necessary to manufacture high-precision cams. The purpose of this study is the development of a CAD/CAM system and profile measuring device for a CNC grinding machine to obtain an optimal grinding speed with a constant surface roughness. Three types of disk cams were manufactured using the proposed algorithm and procedures to verify effectiveness of the developed CAD/CAM system.

Dynamic Characteristics Analysis of Precision Linear Rolling Guide CNC Grinding Machine Tool’s Bed

Bed is a main component of a large precision linear rolling guide CNC grinding machine tool Its dynamic characteristics impact on machine tool’s machining precision and stability directly. In this paper, boundary conditions on the bed of a machine tool factory’s production are analyzed. By using FEA method, the bed finite element models for dynamic analysis model are established and calculated. It provides guidance in investigating the effect factors of machining precision, the machine tool’s structure optimization and error compensation.

An Analysis of Thermal-Structural Characteristics for Precision Linear Rolling Guide CNC Grinding Machine Tool’s Bed

The bed is a main component of the large precision linear rolling guide CNC grinding machine tool. Its thermal-structure characteristics affect on machine tool’s machining precision and stability directly. In this paper, boundary conditions on the bed of a machine tool factory’s production are analyzed; using FEA method, the bed finite element models for thermal-structure coupling analysis are established and then calculated. By analysis, the simulation of the CNC machine tool operating conditions can effectively obtain the distributions of the bed temperature, thermal deformation and thermal stress; and the results are closed to the true situation.

Design of CNC Grinding Machine Especially for C.V Joint Inner Race Spherical Raceway Processing

This dissertation introduces the reform function of CNC grinding machine specially for automobile c.v joint inner race spherical processing. By analyzing the work piece machining accuracy requirements. In this paper, the overall reform program design and main components of structure were described. In addition, a simple structure, high productivity and high automatically CNC grinding wheel dressing spherical was precisely proposed.

Machining Behavior of Green RBSC Body Prepared by Gel-Casting

In this paper, the green RBSC was prepared by gel casting process. The influences of the monomer content (MBAM and AM) and monomer ratio (MBAM to AM) on the flexural strength were investigated. The results indicated the flexural strength of green body was up to 8MPa and the micro- structures were homogeneous. The green RBSC bodies were machined by CNC grinding machine with diamond-coated grinding tools. Machining tests showed the green component could be machined without appended defects. It was found that green machining as a ‘top-down’ approach was a potential alternative for the rapid fabrication of complex-shaped ceramics, especially for some one-of-a-kind products.

An Expert Based Methodology for Cost Oriented Analysis of Machine Tool Reliability

This paper proposes an improved methodology for machine tool reliability analysis. The overall objective of the proposed methodology is to provide the machine tool manufacturers with the approach that will help them in making cost driven decisions while improving the performance of their machines in the field. The methodology consists of three parts viz., modified fault tree diagram, simulation based data analysis and cost based Failure Modes and Effects Analysis (FMEA). Modified fault tree diagram found useful in providing better insight into the failures and their impact. The simulation based approach helps in obtaining time to failure distribution parameters for each failure events using expert's judgements. The effect of uncertainty in the experts' judgements is also quantified in terms of 90 per cent confidence interval values of the parameters. Finally, the cost based FMEA proposed in this paper will help the manufacturer in identifying the critical failure events based on actual cost of failures to the users. The methodology is illustrated with the help of an example of a CNC grinding machine.

Application of the Minimum Quantity Lubrication (MQL) technique in the plunge cylindrical grinding operation

Precision cylindrical grinding is used extensively in the manufacture of precision components in the metal-mechanical industry in general. Modern CNC grinding machines have improved this process with respect to the positioning and rigidity of the machine-workpiece-tool system, allowing the production of high precision parts with low dimensional tolerances. Besides the difficulties inherent to the process, awareness has grown in recent years regarding the environmental issues of cutting fluids. As a response, the industry has begun to seek alternative lubrication and cooling methods. Among the various existing techniques, Minimum Quantity Lubrication (MQL) has been considered as an alternative. This technique can be understood as a combination of conventional lubrication and cooling methods and dry machining, in which a small quantity of lubricating oil mixed with compressed air flow is delivered in the wheel-workpiece interface. The MQL technique is already widely employed in machining processes with tools of defined geometry (e.g. turning), in which produces very satisfactory results. However, the MQL technique has been little explored in grinding processes (non-defined tool geometry), in which the really effective heat removal methods are required due to the frictional heat generation in the grinding zone. Consequently, the aim of this study was to evaluate the plunge cylindrical internal grinding operation when using the MQL technique and the conventional cooling method. Roughness and roundness were the outputparameters. As a result, it was found that the best values of roughness Ra were obtained with the conventional lubrication method. The MQL technique applied as proposed was not able to flush the chips away from the grinding zone, leading to the highest Ra values. No significant differences were detected among the cooling methods when analyzing the roundness results. The workpiece fixture method selected was responsible for the overall unsatisfactory results.

Jig Grinding, an Effective Method in Ball Lock Punches Production

Ball lock punches with non-circular sections, as a cutting tool in carbide dies, are widely used in car manufacturing industries. In this paper a simple method to produce non-circular cutting punches is presented. From this point of view, first of all, all the methods are analyzed and among them jig grinding as the best one is introduced. In continuation, the attachments of this method like grinding tool selection, mechanical attachments to CNC grinding machine is analyzed. Finally, the simple Visual Software to create motion codes is programmed.

Manufacturing models for design and NC grinding of truncated-cone ball-end cutters

This paper presents a set of mathematical models for the design and manufacture of the helical flute and cutting-edge curve of a pair of truncated-cone ball-end cutters. The section profile and relative feeding velocities of the grinding wheel in NC machining of the cutter are deduced. In addition, the deviation of the cutting-edge curve, residual material and the land lack caused by the modified radial feeding velocity are taken into consideration. In order to finish the residual material and rebuild the land of the cutter, the technique for compensation has been developed in this research. The accuracy of the theoretical models is verified by means of an experimental machining test using a WALTER CNC grinding machine. The experimental results are in good agreement with those predicted theoretically, thereby confirming the accuracy and reliability of the proposed models. This study serves as a valuable reference for researchers investigating the NC machining of cutters with special forms.

Design and Realization of Control Software of the CNC Grinding Machine Tool for the Radome

Design and Realization of Control Software of the CNC Grinding Machine Tool for the Radome

Study on Balancing Technology of Hybrid CNC Grinding Machine

Good balancing is very important to improve the moving performance of grinding machine. General balancing technology of grinders was analyzed. The structure features of a new type of hybrid CNC grinding machine were introduced. The necessity of obtaining good balance of the hybrid grinder was demonstrated. Based on simulation and calculation of the distribution law of potential energy over the grinder, a solution for obtaining partial balance of the machine was worked out. An optimal parameter value of the designed balance unit was reached through optimization calculation with optimal balancing effect as target function. The max actuating force of balanced machine accounts for only 13.7% of the force of un-balanced. The balancing unit is of features of simple structure and good balancing effect.

Geometric modeling and grinder design for toroid-cone shaped cutters

This paper presents a set of mathematical models for the design and manufacture of the helical flute and cutting-edge curve of a toroid-cone shaped revolving cutter. The study not only considers the section profile and relative feeding velocities of the grinding wheel used in the NC machining of the cutter, but also addresses the deviation of the cutting-edge curve, the residual material which exists between adjacent flutes, and the lack of cutter land. Through a process of numerical simulation, a compensation technique is developed which reduces the residual material and rebuilds the missing land. The accuracy of the theoretical models is verified by means of an experimental machining test using a WALTER CNC grinding machine. The experimental results are in good agreement with those predicted theoretically, thereby confirming the accuracy and reliability of the proposed models. This study serves as a valuable reference for researchers investigating the NC machining of cutters with special forms.

An experimental investigation on dynamic analysis of high speed carbon–epoxy shaft in aerostatic conical journal bearings

Advanced composite materials are being increasingly used in aerospace and aircraft industry where high stiffness and strength to weight ratios are important. Most of the components usually designed are static components and often non-load bearing components. But focus by designers is now shifted to critically loaded structural components such as discs, blades, etc. In early stages composite shafts were operated in the sub critical region, therefore the research was directed towards the problem associated with their sub critical operation. However, the recent trend in design of high performance rotating machinery is towards higher operating speeds leading inevitably to supercritical operation of such shafts that gives rise to issues of vibration, stability and stress. As composite material like carbon–epoxy exhibits excellent properties for structures owing to high specific modulus, high damping and low thermal expansions and therefore composite shaft made of carbon–epoxy has been made for the high speed CNC grinding machines and the centrifuges. For the analysis purpose the one step composite shaft made of carbon–fibers in epoxy matrix has been manufactured with 16 layers having stacking angles [0°/90°/45°/−45°] 2s using filament winding process. The experimental set up has been designed to investigate static and dynamic analysis and performance characteristics of the carbon–epoxy shaft in aerostatic conical journal bearing at high speeds in the range of 10,000–65,000 rpm. The vibration spectrum analysis has been observed and studied for the same. Comparison of amplitude of vibration decides the maximum operational speed of the shaft with low vibration in aerostatic conical bearings.