For three years, Isaberg Rapid AB have acquired rivet pliers in their range of products, Rapid have seen a potential in developing rivet pliers and have therefor combined an exam work that will investigate the potential and attempt to find a solution to three given problem areas. The primary purpose of this study is to reduce the force needed when using rivet pliers for riveting, which is done to reduce injury on muscles and joints that can occur during heavy and repetitive work. The primary purpose has been given two subordinate purposes which are desired to be solved without violating the primary purpose. The first subordinate purpose is to reduce the number of re-grips that the plier needs to make about the rivet pin, the second subordinate problem is to reduce the gripping distance between the handles to encourage one hand usage.   To answer the research questions of this study, the work has been performed in three steps, which are problem identification, problem solving and lastly verification of solutions. The problem identification consisted of a pilot study and a product specification, which provided a foundation for the work, gave understanding and defined the problem. In the pilot study, an analysis of the products features and mechanics, a market research and a survey were conducted. The product specification was formulated based on the requirements provided by Rapid and from this a functional specification was created. The second step, problem identification, consisted of concept generation and concept selection. The concept generation method used was a variant of brainstorming, which was the basis for the subsequent concept selection phase. The concept selection was performed with Pahl’s and Beitz’s elimination matrix and this matrix was used to eliminate the concepts and indicated which concepts that supposedly meets the requirements for further development. The concepts that was not eliminated was designed further and was evaluated with Pughs decision matrix and Kesselring’s criterion weighting method. From these two, concepts were obtained that most advantageous meet the requirements. Further on, calculations were performed based on the theory of leverage principle on the concept and this was done in order to theoretically determine the force exchange. To enable a verification of the solution, 3D printed prototypes were made to provide feeling and a first confirmation that the solution has potential to solve the problem. Later, a prototype was made by a milling machine to enable a force measurement, which was not possible with the 3D-printed prototype. To answer the research questions, this study reports two concepts together with theories. One of the concepts has a solution that reduces the force needed to use the plier, increases the force exchange and reduces the grip distance based on theories.  According to the calculations that was performed, the increased force exchange shall result in a lowered force by 24 % that is needed by the user to perform riveting.  The measurements performed on the prototype made by the milling machine, showed a reduced force value, but these values did not match the calculated values. The reason to why the values didn’t match is thought to be the friction.  Further development was needed on the concept to enable a verification of the force and before this development it is considered not reasonable to reject the concept. The friction is thought to be lowered by designing an insert and a new fastener.  In the study it was also discovered that an increased force exchange to reduce the force needed by the user to perform, could result in a reduced stroke length. The second concept was created to reduce the number of re-grips that the plier needs to do about the rivet pin. This concept is considered a solution to the problem but could counteract the desired force reduction and is therefore considered not to qualify for further development as the previously mentioned concept. The three research questions cover three different problems and it was discovered that the solution to these counteracts each other.  The delimitations of this study were made to one of Rapid’s rivet pliers with non-rotating heads to enable focus on the mechanics and shape of the product. The potential improvements and development performed on one of Rapid’s rivet pliers are intended to be applicable to other rivet pliers with same features and function.

Bandställ används idag för att förvara och transportera stålband hos voestalpine Precision Strip AB. Bandställets uppgift är att på ett säkert sätt hålla fast de ihoprullade cylindrarna med bandsstål i en ram som möjliggör transport med gaffeltruck. Konstruktionen är flera decennier gammal har därmed aldrig CE-certifierats. Detta kan innebära att konstruktionen inte uppfyller alla säkerhetskrav. Konstruktionens metod att låsa fast stålbanden kan upplevas icke ergonomisk och håller inte alla band på ett homogent sätt. Låsningen medför dessutom alltid ett glapp då den endast kan justeras stegvis. Projektets mål är att generera och designa en idé på en nykonstruktion av bandställen som moderniserar låsningen och ökar fasthållningsförmågan av bandsstålen. Säkerheten och ergonomin är de viktigaste aspekterna inom projektet. Nykonstruktionen ska klara av att arbeta parallellt med dagens bandställ för att möjliggöra en implementering av nykonstruktionen under en lång tid. Detta på grund av att det idag finns ca 700st bandställ inom fabriken samt att man ej vill stoppa den värdeskapande produktionen. En förstudie genomförs för att skapa en bild om hur bandställen hanteras idag och hur operatörerna låser fast bandställen. En litteraturstudie inom området säkerhet genomförs. Många säkerhetsaspekter avklaras genom att helt enkelt följa Arbetsmiljöverkets dokument Maskiner 2008:3. Den slutgiltiga produkten blev en konstruktion med skivor emellan varje bandsstål som operatören trycker till rätt position. För att låsa skivorna i en position trycker operatören på en fotpedal som sänker ner skivorna så att de trycker emot en gummiduk och skapar friktion. Gummiduken används dessutom som vilostöd för stålbanden. För att låsa upp konstruktionen trycker operatören ytterligare en gång på pedalen. Detta släpper låsningen likt funktionen av en kulspetspenna. Konstruktionen uppfyller alla krav specificerade i kravspecifikationen och nästan alla önskemål. De högprioriterade önskemålen är uppfyllda. Det läggs märke till att konstruktionen har utvecklingsmöjligheter i from av bland annat dess hävarm för fastlåsning av glidskivor. Kraften som operatören måste trycka emot pedalen är relativt hög och andra alternativ på hävarmar kan studeras. / Strip-carriers are today used to store and transport precision strips at voestalpine Precision Strip AB. The Strip-carriers main task is to in a securely and in a stable manner hold the rolledup cylinders of precision strips securely to a frame which allows for transportation with a forklift. The construction is many decades old and has therefore never been CE-certified. This could mean that the construction does not meet some requirements for safety. The designs method for holding the precisions strips can be described as un-ergonomic and does not hold the strips in a homogeneous way. The method of locking the precision strips can also only be locked gradually which always results in some play in the precision strips. The projects goal is to generate and design an idea for a new construction of the strip-carrier which shall modernise the method of locking and increase the clamping force of the precision strips. Safety and ergonomics are of key aspects in this project. The new design shall be able to operate in parallel with todays strip carrier to enable the possibility of implementing the strip-carriers over a long period of time. The reason being that the factory has about 700 stripcarriers in their factory and to not have to stop the value generating production. A pilot study is performed to understand how the strip carriers are manoeuvred today and how the operator locks the precision strips. A literature study is performed in the field of safety. Many safety aspects can be achieved by simply by following the guidelines of Maskiner 2008:3 by Arbetsmiljöverket. The final design is a construction where plates separate each precision strip. The operator can slide these plates to their desired position. To lock the plates in position the operator steps on a pedal with force which lowers the plates against a rubber mat which creates friction. The rubber mat also is used as rest supports for the precision strips. To unlock the plates and free the precision strips the operator steps on the pedal again. The unlocking works with the same principle as a ball-pen locking mechanism. The final design fulfils all the requirements specified in the requirement specification and almost all the requests. All the highly prioritised requests are fulfilled. It is noticed that the design has potential for continued development. An example is the lever for the locking of the plates. The force needed to operate the locking mechanism through the pedal is relatively high and could be further developed.

Detta kandidatexamensarbete syftar till att finna felmoder på Scanias kopplingssystem för framtida självkörande lastbilar. Detta görs genom att fokusera på ECA (Electronic Clutch Actuator), hävarm och lager. FMEA är en riskanalys som används för att kartlägga felmoder, felorsaker och deras feleffekter. Med en 10-gradig skala görs en bedömning med avseende på tre parametrar: felsannolikhet, allvarlighetsgrad och upptäckbarhet. Ett riskprioteringstal, RPN, fås genom att multiplicera dessa. Metoder som vi använt i vår studie är ett studiebesök på SCANIA, litteraturstudier och FEM-analys av hävarmen. De sex vanligaste felmoder som identifierats för lagret är utmattning, nötning (adhesiv och abrasiv), korrosion, plastisk deformation, elektrisk korrosion och sprickbildning/brott. De vanligaste orsakerna till lagerfel kan klassificeras till områdena smörjning, montering, hantering, design och driftförhållanden. Där innefattas bl.a. främmande partiklar (smuts, nötningspartiklar), monteringsfel, linjeringsfel, otillräcklig smörjning och överbelastning. All hantering av lager är viktig då lagerfel är en kombination av flera orsaker. Enligt experter är hävarmen välkonstruerad med hög säkerhetsfaktor. Den största orsaken till fel är på grund av intilliggande komponenter som exempelvis lager och ECA. Hög temperatur ökar spänningar och deformationer väsentligt. Bristande smörjmedel i lagren vid hävarmen har identifieras som en huvudorsak till funktionsfel. Enligt experterna från reparationsverkstaden fungerar ECA enheten smidigt med väldigt lågt fel sannolikhet. / This bachelor thesis aims at finding the failure modes at Scania's clutch system for future selfdriving trucks. The examined components are the ECA (Electronic Clutch Actuator), the fork and the release bearings. The FMEA- tool was used for the mapping the failure modes, their causes and effects. This assessment is made using a 10-grade scale with respect to three parameters: occurrence, degree of severity and detectability. A risk priority number RPN, is calculated by multiplying the aforementioned numbers. The methods that we used are a study trip to SCANIA's facilities, the relevant literature on the subject, and the FEM-analyses of the fork. The six most frequent failure modes identified at the release bearing are (fatigue), wear (adhesive and abrasive), corrosion, plastic deformation, electrically induced corrosion and fractures/crack formation. The most common causes for release bearing failures are classified into smearing, assembly, handling, design and runtime circumstances. They include among others exogenous particles (dirt, wear particles), assembly errors, misalignment, insufficient (grease) and excessive loads. All handling of the release bearings is important because release bearing errors have several causes. According to experts, the clutch fork is well-designd with a high safety factor. The most common failure mode causes are a result of interactions with neighbouring components e.g. release bearing and ECA. High temperatures increase the stresses and the deformation of the components substantially. Insufficient amount of lubricant in the release bearing is identified as the main reason of failure. According to experts from the repair workshop, the ECA unit works smoothly and with a low probability of error.