1,721,173 research outputs found
Dīzeļdzinēju kloķvārpstu gultņu kakliņu virsmas apstrādes pētījumi
No full textIzvēlētā promocijas darba tēma "Dīzeļdzinēju kloķvārpstu gultņu kakliņu virsmas apstrādes pētījumi" ir cieši saistīta ar Latvijas ražošanai svarīgu nozari - kuģu būvi un kuģu remontu. Veicot kuģu dīzeļdzinēju remontu, kloķvārpstu gultņu kakliņu virsmas ir jāatjauno, ievērojot ļoti augstas ģeometriskās un virsmas raupjuma prasības. Šobrīd kuģu remonta uzņēmumos pieejamās tehnoloģijas nodrošina šo prasību ievērošanu, bet ir laikietilpīgas un dārgas. Tādēļ nepieciešams veikt kuģu dīzeļdzinēju kloķvārpstu gultņu kakliņu virsmu apstrādes pētījumus, uzlabojot tehnoloģiskos procesus, nosakot atbilstošus virsmas raupjuma parametrus un sniedzot adekvātas tehnoloģiskās rekomendācijas. Pie kam gultņu kakliņu virsmas jāaplūko kā trīs dimensiju objekts, definējot reālajai virsmai atbilstošus mikrotopogrāfiskos raupjuma parametrus. Apkopojot pieejamos zinātniskajos pētījumus, konstatēts, ka līdz šim nav analizēta slīpēšanas tehnoloģisko režīmu ietekme uz kuģu dzinēju kloķvārpstu gultņu kakliņu mikrotopogrāfiju. Ņemot vērā iepriekš minētos apsvērumus, promocijas darbā tiek izmantota jauna tehnoloģiskā pieeja, kas ievērojami atvieglo tehnoloģisko apstrādi un ļauj veikt kloķvārpstas kakliņu slīpēšanu, neizņemot to no dzinēja, proti, apstrādi veicot dzinēja karterī. Šī tehnoloģija ļauj ietaupīt ievērojamus līdzekļus, kā arī krietni samazina dzinēja remonta laiku. Promocijas darba tēmā ir ietverts aktuāls ražošanas uzdevums ar praktisku pielietojumu. Atrisinot ar virsmas precizitāti saistītās problēmas, iespējams būtiski uzlabot kloķvārpstu apstrādi, kā arī remonta operācijas veikt daudz lētāk un augstākā kvalitātē
Laser Cladding Device for In-Situ Repairs of Marine Crankshafts
No full textThis paper presents the development and design of the laser cladding machine for marine diesel engine crankshaft in-situ repairs. The described technology and device is designed to perform crankpin journal build-up operations directly in the engine housing, without removing the crankshaft from the engine. Furthermore, this technology could be successful-ly combined with the subsequent final machining operation – grinding. There is already equipment and technology in place for in-situ crankpin grinding operations. Both technological platforms can be combined to deliver the most appropriate output. For the very first time, this paper outlines the novel, in-situ concept of applying laser cladding to marine crankshafts. The principal design of the in-situ laser clad-ding machine is provided and is accompanied with a de-tailed description of the in-situ laser cladding machine construction. The proposed device and method satisfy ship-board crankshaft surface renovation needs and opens up an entirely new dimension for the industrial application of laser cladding technologies
The Application of Laser Cladding to Mechanical Component Repair, Renovation and Regeneration
No full textThanks to shifting social paradigms and economic pressure, the repair and refurbishment sector of production engineering is currently booming. This chapter describes laser cladding technology, which is being increasingly applied in the repair and reconditioning of all kinds of mechanical components. We have sought here to describe the use of laser cladding technology and its basic principles. Its comparative advantages over other build-up technologies include better overall quality of coating, minimal dilution and distortion and customised surface parameters. The methods for applying additive material to the repaired surface are detailed, together with the three main types of lasers.
The current stage of laser cladding technology implementation and trends for its industrial application are outlined with emphasis to the repair sector, including relevant equipment and powder delivery nozzles. An illustrative case study is included in the chapter to demonstrate how laser cladding could be effectively applied to in-situ marine crankshaft repairs. This includes an assessment of previous studies in the field, the sampling of laser-cladding machine designs and lessons learned. It is then possible to evaluate the advantages and disadvantages of laser cladding. Here we have defined the challenges to be addressed and summarized the emerging overall trends of this technology. It is noted that laser cladding is only in its early stages of implementation and commercialization. Finally we offer a brief overview of the relevant issues to be considered by engineering educators and policy makers
Damage characterisation of tantalum ion source electrodes and reconditioning by wire- and powder-based laser metal deposition
Full text linkThe internal ion source of the Advanced Molecular Image Technologies (AMIT) superconducting cyclotron uses cathodes made of pure tantalum to generate high energy H− ion beams for the production of isotopes for positron emission tomography. During service, the cathodes are impacted by high-energy ions from the plasma. The resulting erosion creates craters that reduce the current density of the extracted beam. The cathodes eventually
need to be replaced when the ion source can no longer be activated. This research explores the possibility of repairing the tantalum cathodes used in the AMIT cyclotron through laser metal deposition additive manufacturing. The damaged parts were first characterised by 3D imaging, scanning electron microscopy, and Vickers microhardness to understand the damage mechanisms occurring during service and quantify the extent of the damage. Different repair strategies were then tested employing both high-purity tantalum wire and
powder feedstocks and the properties of the reconditioned electrodes were determined. The ability of laser metal deposition to restore the damaged cathodes for use in the AMIT cyclotron has been demonstrated
Non-Standard Approach Can Help, when Sticking in Distributed Parameters
No full textThe author has developed a non-standard
approach yielding a remarkable progress in investigation of oscillatory instability. In such a
way it is possible to obtain some simple approximate but reliable enough solution considering
oscillatory variations. The solution enables the comparison with experimental data. The
report reflects the basic principles of method, shows the diagrams demonstrating the
interrelations between oscillating variables, the loci of phasors determining the stability
conditions and some remarkable conclusions made on such basis
The Necessity for Exploitation of Novel Technologies in Order to Secure a Sustainable Development of Ship Repairs in Latvia
No full textThe necessity for exploitation of novel technologies in order to secure a sustainable development of ship repairs in Latvia
Study of the Durability of Materials Used in Turnout Crossings
No full textStudies of the durability of heavily loaded crossings in Latvian Railway provide information about the use of innovative materials and the impact of geometric improvements on their design. An empiric connection has been found on the basis of experimental results which enables making forecasts as to the service life of crossings. The experience thus acquired enables railway infrastructure to select crossings of the proper design more efficiently, thereby reducing life-cycle costs
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Development of the New Chair Milling Technology
No full textThis article is devoted to a specialized wood milling equipment which is made for production of the back cuts of chair bottoms. Its application into the chair production segment in the wood-processing company is described as well. Furthermore technological challenges related with the introduction of the above mentioned equipment into the small-scale production facility are discussed too. Practical solutions which could resolve these problems are offered
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