<p>This study focuses on the wear of piston rings in a hydraulic radial piston motor. The piston ring has to satisfy increasing demands for reliability and longer service life. It has two contacting surfaces, the face and the flank, and operates under a boundary lubrication state.</p><p>This first part of the project aimed to detect and characterise piston ring wear. Measurement by weighing gives an overall value for wear defined as loss of mass. Two-dimensional form and surface roughness measurements show the distribution of wear on the piston ring face in contact with the cylinder bore and the piston ring flank in contact with the piston groove. Three-dimensional analyses, both quantitative and qualitative, allow the wear mechanisms to be identified.</p><p>The wear of piston rings from an actual hydraulic motor was characterised. As well, rig testing was performed in two different test rig set-ups, one simulating the sliding movement of the piston ring and the other the tilting movement at the end of the strokes. Wear during the running-in period was investigated, and the findings indicate that the period when this takes place is of short duration. In the long term, mild wear makes the surfaces smoother than they were when new, resulting in a very low wear coefficient. Significant levels of wear were measured on both contacting surfaces of the piston ring. In cases in which the flank exhibits more wear than the face, the wear on the flank can be reduced by proper design of the piston groove.</p><p>The second part of the project aimed to evaluate use of a textured surface for the cylinder bore counter surface and a coated surface for the piston ring. Three modelling experiments were performed to characterise the friction and wear properties under lean boundary lubrication conditions. Under such conditions, textured surfaces have the advantage of retaining more lubricant and supplying it over a longer time. Stable friction was also a distinctive feature of the textured surface. Use of a coating could also possibly reduce the amount of wear. Though a smooth surface, like a polished one, is hard to beat for a working texture, a coated surface is far ahead of a smooth uncoated one. Different manufactured and commonly used cylinder bore surfaces, including textured ones, were evaluated in the sliding movement test rig. That allowed favourable wear properties, such as lowest wear coefficient, to be determined with the use of a roller burnished surface.</p><p>A final part of the research involved simulating wear on the piston ring face throughout the entire service life of a hydraulic motor. This allowed us to determine the roles of surface roughness and coating in prolonging service life and achieving acceptable and secure piston ring operation. The model is simple and realistic, but still needs to be refined so as to correspond even better to reality.</p>

No description available.

This study focuses on the wear of piston rings in a hydraulic radial piston motor. The piston ring has to satisfy increasing demands for reliability and longer service life. It has two contacting surfaces, the face and the flank, and operates under a boundary lubrication state. This first part of the project aimed to detect and characterise piston ring wear. Measurement by weighing gives an overall value for wear defined as loss of mass. Two-dimensional form and surface roughness measurements show the distribution of wear on the piston ring face in contact with the cylinder bore and the piston ring flank in contact with the piston groove. Three-dimensional analyses, both quantitative and qualitative, allow the wear mechanisms to be identified. The wear of piston rings from an actual hydraulic motor was characterised. As well, rig testing was performed in two different test rig set-ups, one simulating the sliding movement of the piston ring and the other the tilting movement at the end of the strokes. Wear during the running-in period was investigated, and the findings indicate that the period when this takes place is of short duration. In the long term, mild wear makes the surfaces smoother than they were when new, resulting in a very low wear coefficient. Significant levels of wear were measured on both contacting surfaces of the piston ring. In cases in which the flank exhibits more wear than the face, the wear on the flank can be reduced by proper design of the piston groove. The second part of the project aimed to evaluate use of a textured surface for the cylinder bore counter surface and a coated surface for the piston ring. Three modelling experiments were performed to characterise the friction and wear properties under lean boundary lubrication conditions. Under such conditions, textured surfaces have the advantage of retaining more lubricant and supplying it over a longer time. Stable friction was also a distinctive feature of the textured surface. Use of a coating could also possibly reduce the amount of wear. Though a smooth surface, like a polished one, is hard to beat for a working texture, a coated surface is far ahead of a smooth uncoated one. Different manufactured and commonly used cylinder bore surfaces, including textured ones, were evaluated in the sliding movement test rig. That allowed favourable wear properties, such as lowest wear coefficient, to be determined with the use of a roller burnished surface. A final part of the research involved simulating wear on the piston ring face throughout the entire service life of a hydraulic motor. This allowed us to determine the roles of surface roughness and coating in prolonging service life and achieving acceptable and secure piston ring operation. The model is simple and realistic, but still needs to be refined so as to correspond even better to reality. / QC 20101007

The aim of the masterâs thesis is to design a hydraulically controlled dozer for nonhomogeneous materials. The proposed dozer of non-homogeneous materials is attached to a telehandler. The thesis is divided into a theoretical and practical part. In the theoretical part contains a summary of similar machinery, a description of a telehandler and a summary of possible non-homogeneous materials. The practical part deals with the structural design of the proposed dozer. The design includes selection and justification of the chosen concept, important technical calculations, a scheme of the hydraulic circuit, strength check calculations, and drawing documentation.

In blast hole drilling, it is desirable to be able to drill as close as possible to the edge of the tunnel. The minimum distance from the edge is defined by the radial size of the rockdrill. Most of the rock drills used today have a rotation motor that rotates an axel parallel to the shank, which further rotates the shank through a gear set. Thus making the rock drill bulky. This thesis project carried out at Atlas Copco Rock Drills AB, Örebro, deals with the rotation mechanism of a rock drill. The main task of the project was to develop alternate concepts for rotation mechanism that would use the shank as a part of rotation mechanism and reduce the bulkiness of the rock drill. In order to find a suitable alternative, eight different concepts for hydraulic motor (with or without transmission) were generated and evaluated against each other. Two concepts, 1) multi-cam vane motor concept and 2) strain wave hydraulic gear motor concept, were selected for further functional design. Both concepts were designed at ideal conditions (100% efficiency) to achieve the required displacement. For the multi-cam vane motor, various design improvements were performed and the effect of different design parameters were also analyzed. Different variants of the motor were developed and analyzed. A rough design was performed for the strain wave hydraulic gear motor concept which was chosen for its novelty. CAD models for both the concepts and the related variants were developed for suggesting assembly layouts and valve mechanisms. The two concept designs would reduce the bulkiness of the rock drill. The benefits and drawbacks of the different variants have been discussed. The concepts must be further developed for implementation into a rockdrill. / Vid spränghålsborrning är det önskvärt att borra så nära tunnels periferi som möjligt. Det minsta avståndet från kanten definieras av borrmaskinens radie. Majoriteten av dagens borrmaskiner har en rotationsmotor som roterar en axel parallell till nackadaptern, vilket i sin tur roterar nackadaptern genom en drevuppsättning. Detta gör borrmaskinen otymplig. Detta examensarbete, som utfördes på Atlas Copco Rock Drills AB, Örebro, undersöker rotationsmekanismen hos en borrmaskin. Projektets huvuduppgift var att utveckla alternativa koncept till rotationsmekanismen som använder nackadaptern som en del av rotationsmekanismen och reducerar borrmaskinens otymplighet. För att hitta ett lämpligt alternativ genererades åtta olika koncept för en hydraulisk motor (med och utan transmission) som sedan utvärderades. Två koncept, 1) ”multi-kam vingmotor” och 2) ”hydrauliskt driven töjningsvåg-växel”, valdes för ytterligare funktionell konstruktion. Båda koncepten konstruerades under ideala förhållanden (100% effektivitet) för att uppnå det deplacement som krävs.För ”multi-kam vingmotor” utfördes ett flertal konstruktionsförbättringar och effekten av olika konstruktionsparametrar analyserades. Olika varianter av motorn togs fram samt analyserades. En grov design genomfördes för ”hydrauliskt driven töjningsvåg-växel”, vilken valdes på grund av att designen inte förekommit I någon litteratur. CAD-modeller för båda koncepten samt relaterade varianter togs fram för att föreslå monteringslayouter och ventilmekanismer. De två koncepten skulle reducera otympligheten hos borrmaskinen. För –och nackdelarna hos de olika varianterna har diskuterats. Koncepten måste utvecklas ytterligare för att kunna implementeras i en borrmaskin.

In a world with high energy cost, the efficiency of motors becomes increasingly important. Thereby, the understanding of loss mechanics is of great significance and having accurate simulation models for the efficiency of motors is crucial.    Bosch Rexroth Mellansel has developed a new radial piston hydraulic motor with high power, capable of operating at high torque and speed. In this master thesis the newly developed motor will be examined and undergo a lab test to determine its efficiency. The results from this will then be used to improve the current simulation model and aim for a physical model that align with the efficiency results. Furthermore, the loss mechanics of the motor is important and will be studied during this thesis. The loss mechanics in a motor can be split into two parts, hydro-mechanical and volumetric losses. Hydro-mechanical losses refer to the losses due to both friction and hydraulic flow. The losses in the fluid flow are in turn divided into two parts, the major losses and the minor losses which are the friction losses in the fluid and the losses due to geometric changes in the channels respectively. The volumetric losses are on the other hand the losses from internal and external leakage of the hydraulic fluid, and compression flow which is the extra flow that occurs when the fluid changes density.  In order to determine efficiency values from a radial piston hydraulic motor, a test specification was written containing the information needed to perform the test, including two different methods, the pressure and torque method, and the sensors needed to measure the different parameters. For the hydro-mechanical efficiency the uncertainty is 0.1% for the pressure method and 0.15% for the torque method. The test was performed for several different rotational speeds and different pressure points. An improved model was developed from the test results by testing and optimization, and it was found that having the losses due to geometric changes in the channels, depend on Reynolds number agreed better with the test result. However, the improved simulation model does not align as well with the test result for all measured points. Hence a further investigation on the friction model and the dependence on pressure might improve the model further. However, it was found that for a specific sub test, the new model had a mean difference from the pressure method test result of 10^-3. While the mean difference for the unaltered simulation model was 10^-2, hence the new simulation model is an improvement. Therefore, the outcome of this master thesis is an improved simulation model for the newly developed radial piston hydraulic motor QMp 560-560 but also for future motors to come.

The master’s thesis is focused on the proposal of working part of the hydraulic circuit for the hydraulic press with a press force 400 kN. The thesis contains justifiable structural design of the linear hydraulic motor, which includes material choices, necessary calculations and simulations of material strength characteristics and the choice of the individual components. The thesis also includes a proposal of “heel valve” including the choice of individual components and basic function calculation of the hydraulic circuit of the hydraulic press.

Bosch Rexroth in Mellansel is manufacturing hydraulic motors and constantly trying to improve their products to reduce downtime for their customers. An important thing to get a reliable system is to know the condition. In a hydraulic motor, it is crucial to determine the particle contamination of the oil to determine the condition. To do so many particle sensors have been tested by Bosch Rexroth but also other related companies during the past years. To this point, no sensor has been performing good enough to replace the ordinary magnetic plug for the laboratory tests at Bosch Rexroth.  The ordinary magnetic plug is based on an openable lid that has a magnet attached to it. The lid is opened to review the particle contamination of the system. To open the lid the motor has to be stopped and a competent person needs to be present to review the particles.To ease the work for the laboratory personal and also getting one step closer to a reliable condition monitoring solution a new idea was coined by employees at Bosch Rexroth. The idea was to use a magnet outside a glass disc and by that be able to detect the particles from outside the motor. Initial testing of the idea had been performed with promising results but more development was needed. The idea has therefore been investigated and developed further in this project. This has been done in parallel with an investigation of state-of-the-art techniques available on the market. The testing showed that the new type of magnet/glass solution was performing well and was able to detect particles of different sizes. Some other interesting options were also found during the investigation of other techniques but the new magnet/glass idea was the most prominent.

This master’s thesis with product design forks for handling logs as attachments for tractors Zetor Forterra the specified load capacity 1200 kg. The work is mainly focused on the design frame and fork clamps, the necessary calculations and ultimately strength check of designed structures. The work is also addressed in detail the linear hydraulic motor used for the rotational movement of the jaws, including the calculation of fork. Then there are the design calculations and stress analysis of journals. It also checked the stability of the machine. Stress analysis is performed for different load conditions and the jaw frame finite elements. As another part is making all the drawings.

No description available.