A new method for roadheader pick arrangement based on meshing pick spatial position and rock cutting verification

This paper proposes a cutting head optimization method based on meshing the spatial position of the picks. According to the expanded shape of the spatial mesh composed of four adjacent picks on the plane, a standard mesh shape analysis method can be established with mesh skewness, mesh symmetry, and mesh area ratio as the indicators. The traversal algorithm is used to calculate the theoretical meshing rate, pick rotation coefficient, and the variation of cutting load for the longitudinal cutting head with 2, 3, and 4 helices. The results show that the 3-helix longitudinal cutting head has better performance. By using the traversal result with maximum theoretical meshing rate as the design parameter, the longitudinal cutting head CH51 with 51 picks was designed and analyzed. The prediction model of pick consumption is established based on cutting speed, direct rock cutting volume of each pick, pick rotation coefficient, uniaxial compressive strength, and CERCHAR abrasivity index. And the rock with normal distribution characteristics of Uniaxial Compressive Strength is used for the specific energy calculating. The artificial rock wall cutting test results show that the reduction in height loss suppresses the increase in pick equivalent loss caused by the increase in mass loss, and the pick consumption in this test is only 0.037–0.054 picks/m3. In addition, the correlation between the actual pick consumption and the prediction model, and the correlation between the actual cutting specific energy and the theoretical calculation value are also analyzed. The research results show that the pick arrangement design method based on meshing pick tip spatial position can effectively reduce pick consumption and improve the rock cutting performance.

Cell Wall Fracture Mechanism in Ultrasonic Assisted Cutting of Honeycomb Materials

Revealing the ultrasonic cutting mechanism of honeycomb composite is important for determining the acoustic parameters of the ultrasonic system and selecting the parameters of the cutting process. Understanding more details of the stress on the cell wall from ultrasonic vibrating tool and the conditions for cell wall breakage is essential to study the machining mechanism. According to the evolution of contact state between the straight edge cutter and the honeycomb cell wall in a cycle, the cutting force acting on the cell wall is divided into three stages: transverse cutting load action, longitudinal cutting load action, and no cutting load action. The cell wall deflection and stress equations under transverse cutting load were established by applying elastic thin plate small deflection theory. The deformation and fracture characteristics of the honeycomb cell wall were analyzed by combining the analytical and the finite element model. The results showed that the ultrasonic vibration of the cutter greatly improved the stiffening effect of the cell wall and its fracture was caused by the deflection under the transverse cutting load, which exceeded the maximum allowable deformation after local stiffening. In addition, with only longitudinal cutting load, it was difficult to break the critical buckling state that leads to cell wall fracture.

Optimization of the cutting planning process in cardboard and paper production

Improving the production efficiency is one of the main management tasks for the pulp and paper industry. This can be achieved through the use of automated planning systems, designed to take into account the features and limitations of particular production. Such systems allow, on the basis of orders received from consumers, a voluminous production schedule to be made to take into account the needs for raw materials, the productivity of paper or cardboard machines, and the optimal cutting of the canvas on longitudinal cutting machines. Linear programming method for solving optimization problems. Computer simulation using optimized packages to compare the results with the options used in production. Cutting planning processes were optimized on the basis of standard orders for rolled products of an enterprise in the Kyiv region. The problem of optimizing the cutting planning process and criteria for increasing the production efficiency is formalized. The target function is to increase the profit of production by minimizing material losses in planning the cutting of the master rill and minimizing the storage of related products in production warehouses. To solve the optimization problem, it is proposed to use our own method of calculating the optimal cutting patterns for the manufacture of finished products on a longitudinal cutting machine. The MS Office SOLVER package was used for the calculations. Different cutting options were compared via the target function. Important criteria for this inspection are the fulfillment of the entire order, the availability and storage of related products outside the order, and the minimization of time for the reconfiguration of machines. Longitudinal cutting machines of this production can be adjusted only manually, and it takes a long time. Also, technological restrictions on the allowable width of the edge are an important requirement for cutting patterns. All patterns that do not meet these restrictions cannot be compared. There are three options for comparison. An option is made according to the proposed method and with an optimization package using the Simplex method and a number of technological limitations inherent in this production. An option is selected by the production planner manually taking into account previous experience. And the variant of cutting orders is made by the production management system, which accompanies the process of planning and transfer of tasks for longitudinal cutting machines. The function takes the maximum value in the option offered by the production scheduler. But this option is not optimal, because a person adds rolls to the satellite to improve the cutting map to fulfill all orders. This in turn leads to overfulfillment of orders and production of additional products in a warehouse where they can be stored for years until the expiration date. The option offered by the automotive system does not require the use of accompanying rolls but unfortunately does not meet the requirements for optimal cutting of the material. Automatic cutting leaves a large edge that is already within the maximum allowable limitations of the machines and, moreover, does not lead to the execution of the entire order. This violates the basic requirement for production such as full execution of the order. Therefore, this option cannot be used either. The optimal cut for profit maximization is the option obtained using the roll planning technique. This technique allows the average weight of the roll to be obtained through the use of production history. The estimated weight is used to convert the order from tons to the number of pieces. Cutting patterns for the production of the order in this way are presented and, taking into account the technological limitations of production, can be calculated on the basis of the Simplex method in optimization packages. Such cutting patterns have no satellites and allow the fulfilment of all orders. The roll planning technique reduces the number of clippings and avoids overproduction. The analysed cutting plans show that the use of satellites reduces the profitability of the enterprise and does not always minimize material costs.

Population fluctuation of fruit fly Anastrepha spp. (Diptera: Tephritidae) in guava (Psidium guajava L.) accesses produced in organic system

Guava (Psidium guajava L.) presented prominence among the tropical fruit. Guava exports are still unimpressive, because of the quarantine pests, among them the fruit flies. The present research had as objective to evaluate the population fluctuation of fruit flies Anastrepha spp. and the fruits infestation caused in guava accesses cultivated in organic system, and study the possible correlations between this pest and meteorological factors. To estimate population fluctuation, 20 yellow sticky traps were used. The reviews were initiated in April 2013, for 378 days. The traps were kept in the field for the entire duration of the experiment, and they were reviewed every 14 days in most cases, during replacement of traps for new ones. With the data, simple correlations were calculated between the fruit flies of the genus Anastrepha spp., the temperature, and precipitation. Nine fruits per accession, at the stage of maturation, were taken to the laboratory and evaluated for fruit fly infestation by the longitudinal cutting of fruit. The averages were compared by the Scott-Knott test at 5% probability. The genus Anastrepha was found in greater quantity, and there is no correlation between the meteorological factors and population fluctuation of Anastrepha. Also was found some individuals of the species Ceratitis capitata. Most of the fruits of the evaluated accesses presented high infestations by fruit flies. Accesses IAC – 4 – Cica noteworthy for not presenting any infested fruit, without differing from accesses Taquaritinga Comum, both red. The accesses Torrão de Ouro, Supreme BA, L2P4, and Supreme, also showed low numbers of fruit attacked.

Comparing procedures for performing tetrazolium test on carrot seeds

ABSTRACT The tetrazolium (TZ) test is one of the main methods to estimate vitality or viability and seed vigor. The aim of this study was to improve the methodology and reduce the execution time of tetrazolium test on carrot seeds, considering two existing references on this subject. Eight lots of ‘Brasilia’ carrot seeds were used. The hydration, during the pre-conditioning of the seeds, was done in two ways: directly in water during 18 hours and in rolls of filter paper during 2 hours. Seed color was analyzed through combinations between cutting types, concentration, period and temperature used during contact with the TZ solution. Three types of longitudinal cutting were used, before immersion in the tetrazolium solution: a) lateral and as distant as possible from the embryo distal to the embryo; b) partial, in the distal region opposite to the embryo, on about 1/3 of seed length; c) lateral and near the embryo, without reaching it. The used TZ concentrations were 0.1; 0.5 and 1.0%; periods of contact of the seeds with TZ solution were 1, 2, 6 and 24 h and temperatures were 30 and 35°C. The experimental design was completely randomized, with 5 replicates of 20 seeds per lot, per procedure. The results obtained through TZ test were compared with the results obtained in germination and seedling emergence tests. We could make hydration period shorter, from 18 to 2 hours, and staining from 24 to 2 hours. The lateral cutting as close as possible to the embryo, without reaching it, used in preparing the staining, should be emphasized for making execution and interpretation easy. The combination of higher efficiency used for hydration rolls of filter paper during 2 hours and, for staining lateral cutting as close as possible to the embryo, without reaching it, with the development of staining during 2 hours in 0.1% TZ solution at 35ºC. Thus, the reduction of the maximum tetrazolium test time, considering hydration (18 hours) and staining (24 hours), was from 42 to 4 hours and showed to be a feasible and reliable alternative.

In-Plane Longitudinal Cutting in Single-Crystal Silicon Wafer Surface Micromachining

The current concept of grinding or abrasive machining involves the formation and removal of segmented strips of material termed chips from the surface of the solid. A novel cutting mechanism is hereby presented in this research study that suggests that the generation of chips from the surface does not occur but only a shearing process that splits material creating added surface features and textures in the silicon surface. This arises from the unique set of factors of abrasive grit size, thrust force, polishing speed, and polishing time that lead to phase transformations in the surface layers of the silicon wafers. Statistical analysis of the factor effects yielded results that show the surface roughness values, Ra and Rz, increasing without any appreciable change in the thickness of the silicon wafers. This can be attributed to the proposed cutting mechanism indicating that only in-plane surface shearing occurred due to the change of the silicon crystal structure from exhibiting brittle behavior to that of ductile mode of deformation. Moreover, experimental quantities of the specific energy for surface machining of silicon was calculated with an overall mean of 50.5 GPa. This is about 33% less than the currently accepted value and can be considered further evidence that polymorphic transitions to a softer material occurred rendering the surface layers more susceptible to longitudinal cutting deformation and fracture. A model based on the inverted spherical cap or spherical bottom geometry for the individual abrasive particle is also proposed, verified by a finite element method analysis simulation, that can mathematically describe this particular micromachining process.

The Longitudinal Cutting on Hollow Glass Cylinders

This paper presents experimental data and discussions concerning “Elastic Working” which exploits the cutting of hollow glass cylinders at the longitudinal section. Here, “Elastic Working” indicates the cutting method for glass or ceramics using natural cracks occurring at the fracture points of brittle materials. “Elastic Working” has the significant characteristics that the amount of energy required is very small, the time required is very short, and so on. Hollow cylinders made of Pyrex glass were used in the cutting experiment. Using the presented cutting method, the hollow cylinders could be cut instantaneously at the desired longitudinal section. The experiment to examine the cutting load of the hollow cylinder was tried using brittle plaster material as well as glass. It was found that the cutting load of the hollow cylinder was consistent with the load determined from the radial crushing strength on “Sintered metal bearing”.