Rotary Cutting with Ultrasonic Vibration of Hardened Steel

We propose ultrasonic rotary cutting, in which ultrasonic vibrations are imparted to a rotating cemented carbide cylindrical tool to cut hardened steel to reduce the cutting resistance and improve the properties of the machined surface, and investigate the machining characteristics. Machining experiments were conducted under dry and wet conditions to verify the effects of the ultrasonic vibrations. The surface produced via ultrasonic rotary cutting was intermittently machined, which is characteristic of ultrasonic cutting. In dry machining, the cutting resistance was reduced by approximately 20%, and the surface roughness of the machined surface was reduced by approximately 30% when the cutting speed was below the critical speed. We also demonstrated that the surface roughness was improved by ultrasonic vibrations when the cutting speed was equal to or above the critical speed. A similar tendency was observed in wet machining with longer cutting lengths. We then applied ultrasonic rotary cutting to machine a straight R groove in hardened steel and showed that the cutting resistance was reduced, and the tool engagement was improved.

Clinical Application of a Modified Bone Cement Pusher in Percutaneous Vertebroplasty Combined with Multi-Target Negative Pressure Rotary-Cutting Technique in Puncture Biopsy for Bone Tumors

Purpose To assess the efficiency and safety of a modified bone cement pusher in percutaneous vertebroplasty (PVP) combined with a multi-target negative pressure rotary-cutting technique in puncture biopsy of bone tumors. Methods The biopsy performed with the modified bone cement pusher commonly used in PVP, and a multi-target negative pressure rotary-cutting technique. A total of 120 patients with spinal and pelvic tumors undergoing needle biopsy in our department were recruited and assigned to new biopsy device group (group A, n=60) or and conventional biopsy device group (group B, n=60). The puncture time, positive rate, consistency rate, and dependence rate between group A and B were compared to assess the efficiency and safety of the new device. Results No biopsy-related complications were reported in both groups. The puncture time (39.44±8.885 min vs. 61.61±9.880 min), positive rate (96.67% vs. 61.67%), consistency rate (96.55% vs. 81.8%), and dependence rate (100% vs. 83.33%) were significantly superb in group A compared with those in group B (all P<0.05). Patients in group A did not require repeated biopsies, and sufficient samples were obtained through the needle trajectory in PVP. All patients with a definite diagnosis were managed with appropriate treatments. Conclusions Featuring high safety, positive rate and consistency rate, the new device can be performed to collect sufficient pathological samples from multiple angles. Wide clinical replication can be expected considering its evident diagnostic efficiency for bone tumor.

Verification of Monolithic Rotary Cutting Tool For Active Driven Rotation Machining

Forced rotation turning appears to be an effective machining method due to higher tool life, time efficiency and acceptable quality. Several studies have been carried out to investigate the basic characteristics of forced rotation machining. So far, tools are used whose design included several components. However, such tools may generate vibrations, which are undesirable in the process. In engineering practice, most vibration problems are solved by reducing the cutting parameters (cutting speed and feed rate), which reduces machining productivity. For this reason, a new type of monolithic rotary tool has been designed that eliminates the design complexity and high assembly accuracy requirements of current rotary tools. The presented solution fundamentally validates the new monolithic tool for forced rotation technology and defines its application for different machining materials.

Ways to improve the methods of rotary cutting

Methods for improving rotary cutting are developed on the basis of self-organization in tribological coupling using algorithmic procedures of artificial intelligence are developed. For these purposes, a tool with a regular microrelief and lubricating-cooling media are used. Keywords: rotary cutting, regular microrelief, lubricating and cooling media. [email protected]

INVESTIGATION OF QUALITATIVE INDICATORS OF FRONTALLY SUSPENDED HICK-COLLECTING MACHINE DURING OSCILLATIONS IN THE LONGITUDINAL-VERTICAL PLANE

Among the problems of mechanized harvesting of sugar beet, the most important is the cutting of the bud from the heads of root crops that are in the soil. Based on the analysis of numerous design developments and research, a two-phase method of performing this technological operation is promising at this time. Thus as a result of performance of the first phase the continuous copyless cut of all green massif of a top, its collecting and transportation is carried out and the following phase - clearing of heads of root crops of the remains of a top or additional pruning of heads. The effectiveness of this method of harvesting hyphae is obvious, because the cut green mass of sugar beet hyphae can be used as animal feed or to produce biogas. A rotary cutting device with a horizontal drive shaft can be used as a cutting device. The collection of the hitch from the entire width of the coverage of the hitch-harvesting machine can be effectively carried out by means of an auger conveyor, and the loading of the cut hitch into the vehicle - by means of a loading device of the throwing type. In the course of the research a new three-row hook-harvesting machine was developed, which implements the above principles of work. The hitch harvester is aggregated by frontal attachment to a wheeled tractor of traction class 1.4, equipped with a front PTO shaft. We conducted field experimental studies to determine the performance of this hitchhiking machine. For this purpose, a program and methodology for conducting such experimental studies were developed, the results of which were processed by statistical methods on a PC using the basic methods of regression and correlation analysis. As a result of the analysis of the obtained values it was found that the rational values of the speed of the hitch harvester are 1.5… 2.0 m ∙ s – 1 at the height of the cut of the hitch, which is equal to 0.02 m and the rotor speed of 1000 rpm-1. The operational indicators are obtained: productivity when aggregating with a wheeled tractor of class 1.4 - 2.15 ha • year – 1; specific fuel consumption - 3.02 kg • ha – 1; specific investments - UAH 291.33 • ha – 1; reduced operating costs - UAH 441.18 • ha – 1. The obtained results of researches of operational indicators of the developed three-row hook-harvesting machine turned out to be 1.5… 1.8 times better in comparison with serial hook-harvesting machines.

Cutting Mechanical Study of Pick Cutting Coal Seams with Coal and Rock Interface

Shearer provide an effect solution for mining coal, and the cutting performance of pick largely accouts for the ability of a shearer and mining performance. We conducted pick cutting coal experiments in different seam forms on the coal and rock cutting teasted. According to the rotary cutting mechanical model of single pick cutting coal seam, combined with the strength condition of coal seam and coal-rock interface, the rotary cutting mechanical model of pick cutting coal seam with coal-rock interface is established. The stress strain and strength condition of the area in and around the interface are analyzed based on the coal-rock interface crushing theory, which provides basis for further research on the cutting mechanical model of single pick crossing the coal-rock interface. According to the analysis on the ampulitude domain, the phenomenon that force increment between the pick cutting rock and uniform coal seam linearly increases with the increase of compressive strength difference between coal seam and coal-rock interface, and the load fluctuation keep a positive correlation with the compressive strength. Analysis on the signals of the pick cutting coal seam with coal and rock interface at different conditions shows that some basic properties of the cutting load changes over times. In addition, the coal seam with coal-rock interface appears larger impact load and other time-domain characteristics.

MATHEMATICAL MODELING OF VERTICAL OSCILLATIONS OF A CUTTING MACHINE FRONTLY MOUNTED ON AN ARABLE-TILL TRACTOR

Experimental studies and production experience show that the most productive and high-quality collection of sugar beet haulms without soil impurities, is possible only when a continuous, carbonless cut of its main mass at the root is carried out. However, the use of haulm toppers with rotary haulm cutters, which are carried out without a guide cut, frontally mounted on energy resources, as well as a significant increase in the working speeds of harvesting, cause intense vibrations of these haulm toppers in the longitudinal-vertical plane, which not only reduces the quality of trimming the heads of root crops, but causes, in general, significant losses of tops. Therefore, there is a need for an analytical determination of the influence of the kinematic and design parameters of a topper, frontally mounted on a wheeled tractor, on the magnitude of the amplitude of oscillations in the longitudinal-vertical plane of its haulm topper. Taking this need into account, in this work we have constructed a computational mathematical model of the movement of a topper front-mounted on a wheeled tractor, based on the use of the original equation of dynamics in the form of Lagrange of the second kind. According to the developed equivalent circuit and the implementation of the necessary mathematical transformations, a nonlinear differential equation was obtained, which describes the oscillations of the rotary cutting device of the topper in the longitudinal-vertical plane when its pneumatic gauge wheels move over the unevenness of the soil surface. According to the compiled program and the numerical solution on the PC of the specified differential equation, rational constructive and kinematic parameters of the topper frontally mounted on the tractor have been determined which reduce the indicated oscillations. So, with the forward speed of movement of the topping unit equal to = 3,0 m∙ s–1, the vibration amplitude of the topper rotor decreases 1,2 ... 1,5 times in comparison with the height of the field surface irregularities, equal to = ± 0.04 m. With the vibration amplitude of the lower ends of the knives of the rotary cutting apparatus up to 4 cm, the loss of haulms does not increase significantly. However, with an increase in the amplitude of these fluctuations to 7 cm and more, the loss of tops increases significantly, the maximum values of which exceed 12%.