Edge Grinding Research Articles

Experimental bison butchery using replica hafted Clovis fluted points and large handheld flakes

Late Pleistocene Clovis fluted points and stone flake tools have been found in association with bison at several archaeological sites in western North America. To gain insight into how these tools may have functioned in bison butchery, as well as to assess the assumptions or interpretations of these implements by archaeologists, we conducted a bison-processing experiment. We examined the relative efficacy in the butchering process of hafted fluted points versus handheld flakes and of different Clovis point forms; the types of tool breakage that might occur during butchering; cut-marks that might occur on bones; and, the effects of edge resharpening, both in terms of cutting efficiency and in the before/after form of the points and flake tools used in the process. We also recorded several unanticipated observations on, but not limited to, field-processor injury, the function of fluted point proximal-lateral edge grinding, and tool loss during the butchery event. Overall, our experiment emphasizes the prevalence of equifinality in archaeological interpretation, as it shows that numerous aspects of the Clovis archaeological record – as it is currently understood – can be equally explained by several distinct processes.

A Novel Vision-Based Outline Extraction Method for Hull Components in Shipbuilding

The diverse nature of hull components in shipbuilding has created a demand for intelligent robots capable of performing various tasks without pre-teaching or template-based programming. Visual perception of a target’s outline is crucial for path planning in robotic edge grinding and other processes. Providing the target’s outline from point cloud or image data is essential for autonomous programming, requiring a high-performance algorithm to handle large amounts of data in real-time construction while preserving geometric details. The high computational cost of triangulation has hindered real-time industrial applications, prompting efforts to improve efficiency. To address this, a new improvement called Directive Searching has been proposed to enhance search efficiency by directing the search towards the target triangle cell and avoiding redundant searches. Another improvement, Heritable Initial, reduces the search amount by inheriting the start position from the last search. Combining Directive Searching and Heritable Initial into a new method called DSHI has led to a significant efficiency advancement, with a calculation efficiency improvement of nearly 300–3000 times compared to the ordinary Bowyer–Watson method. In terms of outlines extraction, DSHI has improved the extraction efficiency by 4–16 times compared to the ordinary Bowyer–Watson methods, while ensuring stable outlines results, and has also increased the extraction efficiency by 2–4 times compared to PCL. The DSHI method is also applied to actual ship component edge-grinding equipment, and its effect meets the shipbuilding process requirements. It could be inferred that the new method has potential applications in shipbuilding and other industries, offering satisfying efficiency and robustness for tasks such as automatic edge grinding.

Influence of Hob Front Angle on Grinding Wheel Curved Shapes in Open Edge Grinding

When calculating the grinding wheel curved shapes, the hob front angle of hob is usually zero by default. In the actual production and processing, there are many hobs whose hob front angle is not zero. In this paper, when calculating the grinding wheel curved shapes, the parameter hob front angle is added to analyze its influence on the grinding wheel curved shapes according to the grinding wheel curved shapes calculated by different hob front angles.

Automatic Generation of Interference-Free and Posture-Smooth Toolpath for Robotic Belt Grinding of Complex Workpieces

Robotic belt grinding has shown great potential to achieve automatic machining of high-precision parts. However, its productivity in machining complex parts has been greatly limited by the problem that interference-free and posture-smooth toolpath planning is still a time-consuming and labor-intensive job. Therefore, this work presents a fully automatic and practical approach to facilitate interference-free and posture-smooth toolpath planning for robotic belt grinding of complex parts. With this approach, the interference correction spaces in two common belt grinding modes, namely, wheel face grinding and wheel edge grinding, are first established, where various types of interferences and their corresponding correction strategies are modeled. Then, two B-spline posture curves, which represent the rotational motion and translational motion of the workpiece for correcting interference throughout the entire cutter contact curve, are presented. With the two B-spline curves, a toolpath planning algorithm for robotic belt grinding of complex parts is further developed based on surface partitioning and iteratively correcting interference and smoothing grinding postures. The effectiveness and practicability of the proposed approach are validated by simulations and experimental studies, which demonstrates that the authors’ approach can significantly improve the toolpath planning efficiency and ground surface quality for complex parts as compared with the leading commercial computer-aided manufacturing (CAM) software.

Grinding edge machining process on small-sized lens module components in a mobile phone.

The periscope phone lens has a bright application prospect; however, the problem of a large chipping size in the grinding process for the periscope phone lens module components seriously limits its development. We address the problem of the large edge chipping size in the grinding process of small-sized module components of periscope mobile phone cameras by investigating the influence of the grinding speed, feed speed, and grinding depth on the chipping size through theoretical simulation analysis and single-factor variable experimental verification. The optimal grinding process parameters were preferred, and yield experiments were conducted using the preferred process parameters. The results show that increasing the grinding speed and decreasing the feed speed and grinding depth can effectively suppress the chipping size of the component grinding edge.

Alumina abrasive wheel wear in ultrasonic vibration-assisted creep-feed grinding of Inconel 718 nickel-based superalloy

Blade root with a special fir-tree shape is a critical connection part in an aero-engine. This part has high requirements on the surface finish and geometrical accuracy. At present, the tangential ultrasonic vibration-assisted profile grinding (UVAPG) is an effective method for machining the blade roots. During UVAPG, the wheel wear degrades the surface finish and geometrical accuracy. However, the characteristics of the wheel wear in UVAPG are not fully revealed. This study proposes an analytical wear model by considering the intermittent grinding behavior of a grinding edge, the number of active grinding edges, and the effects of wheel profile on the tool wear. The model is experimentally demonstrated to be applicable to predicting the wear volume in UVAPG with a maximum error of 4.2 %. Based on the model, the tangential ultrasonic vibration increases the average unchanged chip thickness and the number of active grinding edges. UVAPG causes an approximately 22 % increase in wear volume at the steady wear stage compared with the conventional grinding. The wear speeds vary at different regions of a profile wheel. The convex regions represent higher wear speeds than the concave regions on the wheel.

Research on the method of skateboard edge grinding by combination of robot and pneumatic constant force grinding device

The paper presents a method of robot skateboard edging grinding based on pneumatic constant force device. To solve the problem of modeling and complex algorithm of robot end active compliance control during the grinding process, a hybrid position/force control is proposed by controlling position and force separately. That is, a kind of 2 degrees of freedom pneumatic constant force grinding device is designed to realize the constant force control in the horizontal and vertical directions, while a robot is used only for position control. Then a fuzzy PID control algorithm is proposed for smooth grinding based on the dynamic modeling of the grinding device. Experiments show that the use of fuzzy PID can effectively improve the dynamic adjustment performance of the pneumatic constant force grinding system and reduce the steady-state error. Compared with normal PID, fuzzy PID reduces the step response adjustment time of the grinding system from 400ms to within 200ms. In addition, when the constant force control is disturbed, the response adjustment time is less than 100ms and there is no oscillation, and the standard deviation of the grinding force is within 1N, which has good robustness and fulfills the requirements of edging control.

Edge Grinding Characteristics of Display Glass Substrate

Display glass substrate as a brittle material is very challenging to machine due to its excellent physical, mechanical, electrical, and optical properties such as high hardness, high strength, high wear resistance, good fracture toughness, good chemical stability, and good thermal stability. On the basis of Griffith fracture mechanics, our theoretical analysis indicated that edge grinding of the display glass substrate is under brittle mode when grinding with the given conditions, which was verified by the experimental studies of ground glass edge surface topography and fractured surface obtained. Grinding force (Fy) in the vertical direction was much larger than grinding force (Fx) in the horizontal direction, causing a large compressive stress acting on the grinding glass edge. Grinding torque was slightly increased with the increase of grinding speed. Grinding temperature was very high when measured under dry grinding compared with measurement under high-pressure coolant. Grinding of glass substrate edge was performed partially under ductile mode machining in the experimental conditions, which can be attributed to and contributed by those micro cutting edges generated by the fractured diamond grit on the grinding wheel surface.

A robotic belt grinding approach based on easy-to-grind region partitioning

For workpieces featured with complex shapes, it is difficult to plan their toolpaths for robotic belt grinding by off-line programming (OLP) owing to frequent gouges between the workpiece and contact wheels. Hence, this work presents a region-based robotic belt grinding approach to facilitate avoiding such gouges for toolpath generation. With the approach, gouge analysis algorithms for two main belt grinding modes, namely wheel face grinding and wheel edge grinding respectively, are proposed. Machinability analyses of these two modes in machining various types of surfaces are then conducted. A concept, namely ‘easy-to-grind region’, is proposed so that the surface to be ground can be partitioned into different regions, and then by imitating the behavior of experienced workers in manual grinding to avoid gouges, the algorithm to select compatible belt grinding mode for partitioned regions is presented. Experimental studies are conducted and show that the proposed approach can significantly decrease the complexity in generating a gouge-avoidance toolpath for belt grinding such complex workpieces.

Corner Transition Toolpath Generation Based on Velocity-Blending Algorithm for Glass Edge Grinding

Sharp corners usually are used on glass contours to meet the highly increasing demand for personalized products, but they result in a broken wheel center toolpath in edge grinding. To ensure that the whole wheel center toolpath is of G1 continuity and that the grinding depth is controllable at the corners, a transition toolpath generation method based on a velocity-blending algorithm is proposed. Taking the grinding depth into consideration, the sharp-corner grinding process is planned, and a velocity-blending algorithm is introduced. With the constraints, such as traverse displacement and grinding depth, the sharp-corner transition toolpath is generated with a three-phase motion arrangement and with confirmations of the acceleration/deceleration positions. A piece of glass with three sharp corners is ground on a three-axis numerical-control glass grinding equipment. The experimental results demonstrate that the proposed algorithm can protect the sharp corners from breakage efficiently and achieve satisfactory shape accuracy. This research proposed a toolpath generation method based on a velocity-blending algorithm for the manufacturing of personalized glass products, which generates the transition toolpath as needed around a sharp corner in real time.

Effect of Hydrogen-Ion-Implantation on Self-Separation of Free-Standing Gallium Nitride Wafers Grown By Hvpe

In recent years, free-standing Gallium Nitride (FS-GaN) wafers were utilized as substrates for high-brightness light-emitting-diodes (HB-LED), LASER diodes (LD) and power devices due to their characteristics, such as 3 times higher thermal conductivity than sapphire substrates and higher breakdown voltage than conventional Si substrates. The FS-GaN wafers grown by hydride vapor phase epitaxy (HVPE) demonstrated lower dislocation density (DD) than that of GaN wafers grown by metal-organic chemical vapor deposition (MOCVD) on sapphire substrates (template GaN wafer). However, one of big challenges for their commercializing is the crack free FS-GaN wafers during the HVPE GaN growth, which resulted in lowering the productivity and increasing the fabrication cost. The main cause of the cracking is the stress induced by the differences in thermal expansion coefficients (TEC) and lattice constants of sapphire and GaN. To overcome this issue, the design of GaN growth process with self-separation is the key technology. The self-separation technique consists of two key points, one is separation enhancement and the other is blocking edge-poly-GaN growth. In this study, we investigated the effect of hydrogen-ion-implantation on self-separation of FS-GaN wafers. In addition, the blocking effect of edge grinding of template GaN wafers was also investigated. Two-inch-diameter template GaN wafers with the GaN layer thickness of 5 μm were prepared and the hydrogen-ions were implanted with various dose conditions to enhance self-separation of FS-GaN wafers from the sapphires. The edges of the implanted template GaN wafers were then ground to eliminate the polished edge surfaces to deter the poly-GaN growth. 800-μm-thick GaN layers were grown by HVPE on the template GaN wafers, and the FS-GaN wafers were successfully self-separated during the cool-down process. Fig. 1 shows the edge images of the GaN on sapphire substrates after 300-μm-thick GaN layer was grown on the template GaN substrates. When the edge-grinding was utilized to template GaN substrate, the poly-GaN was grown less than that of the substrate without edge-grinding. Also, the poly-GaN was easily removed at the edge of the substrate by edge-grinding without additional process. Fig. 2 shows the hydrogen-ion-band inside the MOCVD-GaN layer with three different hydrogen-ion dose conditions. The sample with hydrogen-ion dose of 2.25 E17 H+/cm2 showed larger size of the hydrogen cavity than the samples with hydrogen-ion dose of 1.75 E17 and 2.0 E17 H+/cm2. Fig. 3 shows the wafer images after 800-μm-thick GaN grown on the edge-ground template GaN with three different hydrogen-ion-implantation conditions. The FS-GaN wafers with hydrogen-ion dose of 1.75 E17 and 2.0 E17 H+/cm2 were successfully self-separated from the sapphire substrates, while the sample with hydrogen-ion-dose of 2.25 E17 H+/cm2 was self-separated around 63% of the area. In our presentation, we will report how we achieved the self-separation of FS-GaN wafers without cracking by hydrogen-ion-implantation into the template GaN substrates, and discuss about the crystal quality of the grown FS-GaN samples. * This work was financially supported by the Brain Korea 21 Plus Program in 2018. Figure 1

Study of Grinding Edge on Tempered Glass Using Electroplated Diamond Abrasive Belts

Abstract This study aims at improving the grinding quality and efficiency of the grinding edges on tempered glass using electroplated diamond abrasive belts. Firstly, the most suitable diamond type and composition of metal coating were selected in the first experiment. Secondly, the structure parameters of abrasive belts, such as diamond grain size (dgs), chip clearance (chc), matrix thickness (mt), and coating thickness ratio (ctr), were optimized through an L9 (34) orthogonal experiment. Finally, the influences of the process parameters on the grinding effect were investigated, which are optimized by an L9 (33) orthogonal experiment. The results show the following: (1) the abrasive belt with the diamond type of SMD40 and metal coating of 90 % nickel, 5 % cobalt, 5 % copper (Ni90%-Co5%-Cu5%) weight percentage (wt.%) of the total weight of the coating metal possesses the best grinding performance for the grinding edges on tempered glass. (2) The best grinding quality can be achieved under the conditions of the 230/270 US mesh (63-53 μm) in dgs, 1.5 mm in chc, 1.2 mm in mt, and 2/3 in ctr. (3) The roughness decreases first and then increases with the increase of dgs and ctr, decreases with the increase of chc, and increases with the increase of mt. (4) With the increase of the grinding pressure (gp), the roughness increases, and the material removal rate increases first and then decreases; with the increase of belt linear velocity (blv), the roughness first descends and then tends to stability, and the material removal rate increases first and then decreases; with the increase of the belt tensioning force (btf), the roughness decreases, and the material removal rate increases first and then tends to be stable. (5) The best grinding performance can be achieved under gp of 18 N, blv of 30 m/s, and btf of 55 N.

NURBS toolpath planning for glass sharp corner edge grinding

In this paper, a transition toolpath planning algorithm is proposed to achieve sharp corner edge grinding in personalized glass products manufacturing. The developed algorithm is based on a segmented conic NURBS curve with parameterized knot and weight sequences. First, the requirements for glass sharp corner grinding are given, and a transition velocity constraint is derived based on a grinding forces model. Moreover, considering the grinding depth and velocity control around the tips, a segmented NURBS transition toolpath is created to connect the broken wheel center trajectory. Afterwards, the application methods for the proposed NURBS curve in different commercial CNC systems are summarized and presented. An experimental study was carried out to validate the proposed method.

Ductile to brittle transition in ultra-micro-grinding (UMG) of hard brittle crystal material

In this study, ductile to brittle transition in ultra-micro-grinding (UMG) of hard brittle material is investigated. The characteristics of UMG process are studied, and differences between UMG and micro-grinding (MG) are investigated. The grain penetration depth considering rotary deviation is calculated, grain invalid cutting phenomenon is discussed, and the critical condition for grain invalid cutting is given. In order to reveal the mechanism of material removal and study the special characteristics of UMG, a fracture energy model considering the energy consumption ways is built. A series of UMG and MG experiments are performed, and rotary deviation during the experiment is measured. The relationship between rotary deviation and machining parameters is revealed, and the variation process of edge fracture size with the changing parameter is discussed. The disappearance of the general law that fracture size on down grinding edge bigger than up grinding edge is observed, and the weakened twice fracture size soaring phenomenon is also found. Penetration depth 0.67 nm is found to be the critical value for ductile to brittle transition in UMG, which is 0.67 times of the critical value in MG. Besides, parameters for condition when extra energy Ee is completely used to remove the material, and when Ee is used to extend the contour of the slot are experimentally obtained, the experiment result proves the effectiveness of the fracture energy model. The fracture model in this study is not only anticipated to be practical to provide a deeper understanding of the UMG process but also expected to be meaningful to optimize the grinding parameters in UMG.

Verification of available glass mechanical properties against recommendation by the draft Eurocode design practice

Glass as a structural material has strongly evolved in modern architecture. Wide windows, glass facades and even load-bearing structures make buildings appear transparent and more integrated in the surrounding environment. According to the ongoing effort by the European Committee for Electrotechnical Standardisation, only recently the notice “Eurocode on glass in construction” has been issued. This will make applicable the binding design practice in the EU starting from the next decade. This design practice will include, among others, the required properties of material and products, application fields, respective failure potential and failure consequences, safety and reliability approaches, principles of design, design and calculation rules for primary members, joints, connections and supports. This standard will be binding in all European countries, therefore, until then every member state should adapt these guidelines in order to make safe design practices for glass structures. At present, in Latvia there is no enforced regulation for glass-bearing structural design and a scattered view on the mechanical properties of the available glass applied for load-carrying designs. In the present verification study, laboratory testings were performed to characterise glass mechanical properties such as stiffness and bending strength of the set of specimens provided by national distributers. For this reason, a series of samples has been tested by a 4-point bending with two different geometrical settings 360 ´ 1100 mm (EN 1228-3) and short beam tests of 50 ´ 200 mm. The current research has shown that compared with the Eurocode reference values, these test results show a lower strength of the internally available raw glass panels. The cause should be merged with edge grinding technology and studied in more detail in the further analysis.DOI: http://dx.doi.org/10.5755/j01.ct.68.1.18872

Sharp corner transitional trajectory planning based on arc splines in glass edge grinding

The sharp corners on final contours in flat glass grinding can cause broken wheel center trajectories. A corner transitional trajectory planning algorithm based on arc splines is proposed in this paper to control the wheel center trajectory G1 continuity and the grinding depth at a corner. The radii of arc splines are derived first to meet design requirements based on the geometrical features of a sharp corner. A three-phase feedrate planning scheme is introduced to generate the arc splines. Corner classification and treatment are presented to make the proposed algorithm flexible, and steps for algorithm application are summarized. Experimental results demonstrate that the proposed algorithm can achieve satisfactory shape accuracy at corners without any breakage, rounding, or flattening.

Experimental Evaluation of Respirable Dust and Crystalline Silica Controls During Simulated Performance of Stone Countertop Fabrication Tasks With Powered Hand Tools.

Workers who fabricate stone countertops using hand tools are at risk of silicosis from overexposure to respirable crystalline silica. This study explored the efficacy of simple engineering controls that can be used for dust suppression during use of hand tools by stone countertop fabricators. Controlled experiments were conducted to measure whether wet methods and on-tool local exhaust ventilation (LEV) reduced respirable dust (RD) exposures during use of various powered hand tools on quartz-rich engineered stone. RD samples collected during edge grinding with a diamond cup wheel and a silicon carbide abrasive wheel were analyzed gravimetrically as well as by X-ray diffraction to determine silica content. A personal optical aerosol monitor was used simultaneously with the RD samples and also for rapid assessment of controls for polishing, blade cutting, and core drilling. On-tool LEV and sheet-flow-wetting were effective in reducing exposures, especially when used in combination. Sheet-flow-wetting with LEV reduced geometric mean exposures by as much as 95%. However, typical water-spray-wetting on a grinding cup was less effective when combined with LEV than without LEV. Mean silica content of RD samples from grinding operations was 53%, and respirable mass and silica mass were very highly correlated (r = 0.980). Optical concentration measures were moderately well correlated with gravimetric measures (r = 0.817), but on average the optical measures during a single trial using the factory calibration were only one-fifth the simultaneous gravimetric measures. Sheet-flow-wetting combined with on-tool LEV is an effective engineering control for reducing RD exposures during engineered stone edge grinding and blade cutting. On the other hand, addition of LEV to some water-spray-wetted tools may reduce the effectiveness of the wet method.

Abrasive cylindrical brush behaviour in surface processing

Mechanical disintegration of glass surface layers by the action of composite filaments of a cylindrical brush is a new and unique technology for flat glass frosting. So far, similar tools have been used for metal treatment, e.g. for tool edge grinding or for surface treatment of stainless metal sheets. The technology has a high application potential, and facilitates the creation of new types of products for use in the fields of interior glass, domestic architecture, furniture, and lighting. Firstly, the paper describes the theoretical solutions of the new principle of frosting, and how the acquired knowledge can have a wider applicability in the fields of deburring, grinding of surfaces and edges of metal materials etc. Then, it presents a simulation of the kinetics of a separate filament brush, including an evaluation of the marks formed. Subsequently, the results are verified by laboratory experiments. In the conclusion, we recommend technical conditions for implementing the process of surface frosting.

Research on Casting Edge Grinding Machine of Tracking Type

This article analyzes the present situation of the casting edge grinding and cleaning, it introduces the main structure of tracking type casting edge grinding machine. We turn the 3D electronic picture into a edge grinding figure in order to store it into the edge grinding machine control system, then the control system will convert the edge grinding figure automatically into G code, and grinding head controlled by the G code makes edge grinding in according to the casting boundary, and in order to avoid the damage that made by the oversized grinding depth to the large number of grinding machines, the visual system should identify the boundary shape of casting boundary, controlling the grinding head to automatically withdraw the tool when the casting is oversize, and the grinding head grinds workpiece according to the maximum grinding depth in the same time.

The CAD drawing as a source of data for robot programming purposes – a review

Industrial robots are widely used in mass production, successfully replacing the workers during repetitive tasks. The lack of direct human participation in the production process involves the necessity of programming of the machines, which is mostly the time-consuming process. Most of the operations are well described in the process documentation, but some actions require the use of complicated paths, like for example welding, laser or water cutting, edge grinding, application of liquid sealants or films of paint etc. All of the mentioned activities need the precise movements of robot’s effector and this is - in many cases - connected with the necessity of entering of many points that approximate the path. One of the ways to solve this problem is the possibility of generating the complex path automatically, using the information from the technical documentation. This paper presents such approach that uses the CAD drawings as a data source. The available literature presents this problem mainly in the aspects of large software applications, but this paper was focused on presenting the problems of the proper analysis of the drawing and how to process the data to the form that can be used during robot programming.