3D roll-forming of hat-profile with variable depth and width

The use of roll-formed products in automotive, furniture, buildings etc. increases every year due to the low part-production cost and the complicated cross-sections that can be produced. The limitation with roll-forming until recent years is that one could only produce profiles with a constant cross-section in the longitudinal direction. About eight years ago ORTIC AB [1] developed a machine in which it was possible to produce profiles with a variable width (“3D roll-forming”) for the building industry. Experimental equipment was recently built for research and prototyping of profiles with variable cross-section in both width and depth for the automotive industry. The objective with the current study is to investigate the new tooling concept that makes it possible to roll-form hat-profiles, made of ultra high strength steel, with variable cross-section in depth and width. The result shows that it is possible to produce 3D roll-formed profiles with close tolerances.

Experimental and computational investigation of the roll forming process

One of the first questions to consider when designing a new roll forming line is the number of forming steps required to produce a profile. The number depends on material properties, the cross-section geometry and tolerance requirements, but the tool designer also wants to minimize the number of forming steps in order to reduce the investment costs for the customer. There are several computer aided engineering systems on the market that can assist the tool designing process. These include more or less simple formulas to predict deformation during forming as well as the number of forming steps. In recent years it has also become possible to use finite element analysis for the design of roll forming processes. The objective of the work presented in this thesis was to answer the following question: How should the roll forming process be designed for complex geometries and/or high strength steels? The work approach included both literature studies as well as experimental and modelling work. The experimental part gave direct insight into the process and was also used to develop and validate models of the process. Starting with simple geometries and standard steels the work progressed to more complex profiles of variable depth and width, made of high strength steels. The results obtained are published in seven papers appended to this thesis. In the first study (see paper 1) a finite element model for investigating the roll forming of a U-profile was built. It was used to investigate the effect on longitudinal peak membrane strain and deformation length when yield strength increases, see paper 2 and 3. The simulations showed that the peak strain decreases whereas the deformation length increases when the yield strength increases. The studies described in paper 4 and 5 measured roll load, roll torque, springback and strain history during the U-profile forming process. The measurement results were used to validate the finite element model in paper 1. The results presented in paper 6 shows that the formability of stainless steel (e.g. AISI 301), that in the cold rolled condition has a large martensite fraction, can be substantially increased by heating the bending zone. The heated area will then become austenitic and ductile before the roll forming. Thanks to the phenomenon of strain induced martensite formation, the steel will regain the martensite content and its strength during the subsequent plastic straining. Finally, a new tooling concept for profiles with variable cross-sections is presented in paper 7. The overall conclusions of the present work are that today, it is possible to successfully develop profiles of complex geometries (3D roll forming) in high strength steels and that finite element simulation can be a useful tool in the design of the roll forming process.

Kvinnans tillit till amning : En enkätstudie på BB och Eftervårdsmottagningen i Värmland

Amningsfrekvensen i Värmland sjunker och är låg jämfört med riket. En bidragande faktor till den sjunkande amningsfrekvensen är bristen på tillit till amning. Det är viktigt att kunna identifiera kvinnor med låg tillit till amning för att vända den sjunkande amningsfrekvensen och stärka kvinnan i rollen som moder. Syfte: Syftet med denna studie var att undersöka kvinnors tillit till amning på Barnbördshuset (BB) och Eftervårdsmottagningen i Värmland. Med enkäten BSES-SF identifieras kvinnor med låg tillit till amning och kvinnor som behöver ett ökat amningsstöd efter förlossning. Design/Metod: Studien utfördes med kvantitativ ansats. Data inhämtades från enkäten BSES-SF som besvarats av 70 kvinnor på BB och Eftervårdsmottagningen i Värmland. All data analyserades genom SPSS. Resultat: De flesta kvinnor ansåg att det var mycket viktigt med en fungerande amning och när kvinnorna skattade amningens betydelse framkom ett medelvärde på 8,66 där 0=inte alls viktigt och 10=mycket viktigt. Kvinnor som ammat tidigare skattade sin upplevda amningserfarenhet som mycket god. Varje enskild fråga på BSES-SF jämfördes mellan kvinnorna som vårdats på BB och Eftervårdsmottagningen. Det framkom en skillnad på åtta frågor där kvinnorna på Eftervårdsmottagningen skattade en högre tillit till amning jämfört med kvinnorna på BB. Utifrån totalsumman på BSES-SF med ett poängintervall mellan 14-70, framkom det att tilliten till amning skattades högre hos kvinnorna på Eftervårdsmottagningen (M=56,54) än på BB (M=49,88). Slutsats och klinisk tillämpbarhet: BSES-SF kan utifrån studiens resultat vara ett användbart verktyg, framförallt på BB där kvinnorna skattat en lägre tillit till amning. Förstföderskor och omföderskor som upplevt en komplicerad förlossning kan vara i behov av större insatser av amningsstöd. Studiens resultat kan medföra att barnmorskan blir extra uppmärksam på de kvinnor vars amning inte fungerar och där extra stöd behövs för att öka tilliten.

Women's acceptability of misoprostol treatment for incomplete abortion by midwives and physicians : secondary outcome analysis from a randomized controlled equivalence trial at district level in Uganda

OBJECTIVE: This study aimed to assess women´s acceptability of diagnosis and treatment of incomplete abortion with misoprostol by midwives, compared with physicians. METHODS: This was an analysis of secondary outcomes from a multi-centre randomized controlled equivalence trial at district level in Uganda. Women with first trimester incomplete abortion were randomly allocated to clinical assessment and treatment with misoprostol by a physician or a midwife. The randomisation (1:1) was done in blocks of 12 and stratified for health care facility. Acceptability was measured in expectations and satisfaction at a follow up visit 14-28 days following treatment. Analysis of women's overall acceptability was done using a generalized linear mixed-effects model with an equivalence range of -4% to 4%. The study was not masked. The trial is registered at ClinicalTrials.org, NCT 01844024. RESULTS: From April 2013 to June 2014, 1108 women were assessed for eligibility of which 1010 were randomized (506 to midwife and 504 to physician). 953 women were successfully followed up and included in the acceptability analysis. 95% (904) of the participants found the treatment satisfactory and overall acceptability was found to be equivalent between the two study groups. Treatment failure, not feeling calm and safe following treatment, experiencing severe abdominal pain or heavy bleeding following treatment, were significantly associated with non-satisfaction. No serious adverse events were recorded. CONCLUSIONS: Treatment of incomplete abortion with misoprostol by midwives and physician was highly, and equally, acceptable to women. TRIAL REGISTRATION: ClinicalTrials.gov NCT01844024.