Dissertations / Theses on the topic 'Sheep shearing'

Sheep entering the live export chain will experience increased handling, novel forms of feed, and novel environments before the journey on the export ship itself; all occurring over a period of around one month (Norris et al., 1989a). These factors can also cause stress (Kilgour & DeLangen, 1970; Hargreaves & Hutson, 1990a, 1990b; Doyle et al., 2010; Sanger et al., 2011), which could lead to a high incidence of inappetance and mortality (Norris & Richards, 1989b; Higgs et al., 1993). This study was conducted to determine whether the day of shearing could affect feeding and behaviour of sheep in the pre-embarkation period. Sheep were fitted with Radio Frequency Identification (RFID) tags that could be picked up by tracking antennae at all water and feed troughs in the pens when the sheep’s head was in such a position that the sheep was likely to be eating or drinking. The system then would record the total amount of time the sheep spent at the troughs per day. The sheep were shorn on either day 1, 2, 3, 4 or 5 and an ethogram was generated through analysis of 60-second video clips from footage of the sheep filmed one hour after shearing. There was no difference in time spent at feed troughs between any treatment groups on any day. There was a treatment effect, with the control (unshorn) group spending more time at the water trough; however, there were no difference between the other groups in time spent at water troughs or any behavioural states or events. The results suggest that shearing may occur on any day during the pre-embarkation feedlot period, and that current management practices do not disrupt time spent at the feed trough.

"The goal of this thesis was to evaluate high speed steel for use in the construction of sheep shearing combs, to determine if its use can be justified on a performance basis."
Master of Applied Science

"The goal of this thesis was to evaluate high speed steel for use in the construction of sheep shearing combs, to determine if its use can be justified on a performance basis."
Master of Applied Science

No Brasil, a produção de ovinos é um fator de grande importância econômico-social, principalmente no estado do Rio Grande do Sul (RS). Um dos principais problemas enfrentados neste mercado são as perdas reprodutivas, representadas por baixa taxa de prenhes, baixa prolificidade e alta mortalidade perinatal de cordeiros. A deficiência de informações sobre as causas dessas perdas motivaram a realização dos experimentos aqui apresentados. No primeiro artigo dados sobre o peso (kg), condição corporal (CC) e nível sérico de beta-hidoxibutirato (BHB) foram estimados em um grupo (n=16) de ovelhas Corriedale prenhes, mantidas a campo no RS, pelo período de um ano. O grupo experimental foi tomado aleatoriamente de um rebanho de 60 ovelhas encarneiradas por monta natural no outono. Das 60 ovelhas do rebanho expostas a carneiros 53 (88,3%) foram detectadas prenhes ao exame de ultrassonografia e somente oito com partos gemelares (13,3%). O peso médio não mostrou variação estatística significativa durante o período de observação. O peso no pré-encarneiramento de 51,04kg (±1,2) mostrou um pequeno aumento até o início do encarneiramento. Esse peso sofreu um pequeno declínio entre o início e o meio da gestação. Entre o meio e o final da gestação houve um pequeno aumento de peso experimentando a partir dai um declínio, chegando ao seu menor valor de 47,93kg (±0,31), no início da lactação. A CC média das ovelhas aumentou entre o pré-encarneiramento e a início da gestação (p<0,05), sendo que a CC média de 2,9, observada no início da gestação foi a mais elevada durante o período de observação. Observou-se, por outro lado, um declínio no valor médio da CC do rebanho no meio, final da gestação e início da lactação, observando-se o valor mais baixo da CC, 2,03 (±0,11) (p<0,05), no início da lactação. Os valores séricos médios de BHB mantiveram-se estáveis durante o pré-encarneiramento e o início da gestação. A partir do meio da gestação observou-se um aumento no valor médio desse metabólito, tendo sido observado diferença significativa (p<0,05) entre o meio e o final da gestação. O valor mais elevado de 0,595 mmol/L (±0,10) foi detectado no início da lactação, sendo esse valor significativamente diferente (p<0,05) do observado no final da gestação, sugerindo um desbalanço energético. Conclui-se que o ganho de peso ou CC, observada no pré-encarneiramento foram aparentemente insuficientes para elevar a taxa de prenhez e a prolificidade do rebanho. No segundo artigo foi observado o efeito da esquila, no meio da gestação, sobre o peso ao nascer e perfil hematológico de cordeiro, peso da placenta, condição corporal das ovelhas no momento do parto, por dois anos reprodutivos consecutivos. O grupo experimental foi constituído de 41 ovelhas no primeiro ano (2010) e de 51 ovelhas no segundo ano (2011). As ovelhas, da raça Corriedale, foram mantidas em pastagem natural e cultivada durante a gestação. O encarneiramento (45 dias) foi feito por monta natura com 6-7% de carneiros reprodutivamente aptos, no outono (março/abril). Aos 50 dias da retirada dos carneiros foi realizado diagnóstico ultrassonográfico de gestação. A metade da cada grupo de ovelhas gestando, em cada ano, foi então submetida a esquila completa (grupo E). As ovelhas restantes forma mantidas com lã, constituindo o grupo NE. No ano de 2010, a esquila foi realizada aos 72 dias e em 2011 aos 74 dias de gestação, em média. Cada ovelha teve o parto acompanhado desde os primeiros sinais do trabalho até a expulsão completa do feto. Em 2010 realizou apenas a pesagem dos cordeiros, já em 2011 além da pesagem do cordeiro foi realizada a pesagem da placenta e coleta sanguínea do cordeiro recém-nascido para análise bioquímica e hematológica. O peso ao nascer dos cordeiros do grupo de ovelhas E e NE foram de 5,56kg (±1,2) e 4,84kg (±0,9) no ano de 2010 e de 5,57kg (±1,07) e 4,32kg (±1,1) para o ano de 2011 (p<0,05), nos dois anos. O peso médio da placenta do grupo de ovelhas E e NE foi de 497,5g (±98,2) e 380g (±133,5), respectivamente (p<0,05). Foi também observado, que o valor médio do hematócrito do grupo de cordeiros provenientes de ovelhas do grupo E foi menor (43%) que o valor médio dos cordeiros nascidos de ovelhas do grupo NE (46%) (p<0,05). Não foram observadas diferenças entre os níveis médios de lactado de cordeiros nascidos dois grupos. Finalmente, os dados aqui obtidos mostraram não haver diferença (p>0,05) entre o escore de CC das ovelhas, no momento do parto, com o peso ao nascer dos cordeiros nos dois grupos, durante os dois anos de experimento.
In Brazil, the sheep industry is an important social and economic sector; mainly in the state of Rio Grande do Sul (RS). One of the most pressing problem faced by the industry are the reproductive losses, caused by a low pregnancy rate, low prolificity and high perinatal mortality. The lack of information about the causes of these reproductive waists led to the conduction of two experiments here presented. In the first paper, data on body live weight (kg) (BLW), body condition score (BC) and serum level of beta-hydroxybutirate (BHB) were estimated in a group (n=16) of pregnant Corriedale ewes, grazed on natural pasture of Rio Grande do Sul (RS) state, during one year observation period. The experimental group was taking randomly from a flock of 60 ewes exposed to rams during the autumn. Of the 60 original flock ewes only 53 (88,3%) were detected pregnant at scanning and only 13% show multiple pregnancy. The BLW did not show statistics difference during the observation periods. However the BLW of 51,04kg (±1,2) showed a little increase on the pre-tupping time period. Then a small lost of BLW was observed between the beginning and middle of gestation period. From then to the final of gestation period a small increase of BLW was detected. The minor BLW of 47,93kg (±0,31) was detected at the beginning of the lactation period. The BC mean increased during the pre-tupping time and beginning of pregnancy (p<0,05), being the BC of 2.9, observed on the beginning of gestation period, the most elevated value detected. On the other hand, a decrease of the BC mean was observed starting on the middle of gestation until the beginning of lactation periods, when the lower value (2.03 ±0,11) (p<0,05) was detected. The serum values of BHB were stable on the pre-tupping and beginning of gestation periods. An increase statistically significant (p<0,05) of the metabolic was then detected between the middle and final of gestation periods. The highest value observed of 0,595 mmol/L (±0,10mmol/L) occurred at the beginning of lactation (p<0,05) when compared with the final of gestation suggesting an energetic disbalance. Finally, the information obtained in this paper suggested that the gain in BLW and BC observed in the pre-tupping time period was not enough to increase the pregnancy and prolificacy rates of the flock. In the second paper, the medium gestation shearing effect on the birth weight and haematocrit value of lambs, placental weight and body score condition (SC) of ewes at parturition, during two reproductive years was observed. The experimental group was constituted of 41 ewes on the first year (2010) and 51 ewes on the second year (2011) . The Corriedale ewes were grazed on natural and cultivated pasture during the gestation period. The ewes were exposed (45days) to 6-7% fertile rams in the autumn (March and April). The scanning was performed in all ewes fifty days after the ram’s removal. Each year one half of the pregnant ewes were sheared (S group) and the remain left unsheared (US). The sharing was performed at days 72 and 74 of gestation period on years 2010 and 2011, respectively. At the lambing time the ewes were observed during the entering labour time. In the 2010 lambing time only the lamb birth weight was taken. On the other hand, in 2011 beyond the birth weight of lambs, placental weight and lamb blood samples were collected for haematological analyses. The mean birth weight of the lambs from groups S and US observed were 5,56kg (±1,2) and 4,84kg (±0,9) in 2010 and 5,57kg (±1,07) and 4,32kg (±1,1) in 2011 (p<0,05). The placental mean weight from ewes of groups S and US were 497,5g (±98,2) and 380g (±133,5), respectively (p<0,05).The haematocrit mean value of lambs from S ewes was lower (43%) than the lambs from the US ewes (46%) (p<0,05). The lactate blood level from lambs born from S an US ewes did not show any significance difference. Finally, the data did not show any correlation (p>0,05) between the SC of ewes at lambing time and lamb birth weight in both groups on the two consecutive observation years.

Shearing is the process where sheet metal is mechanically cut between two tools. Various shearing technologies are commonly used in the sheet metal industry, for example, in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material. The constant development of sheet metals toward higher strength and formability leads to increased forces on the shearing equipment and tools. Shearing of new sheet materials imply new suitable shearing parameters. Investigations of the shearing parameters through live tests in the production are expensive and separate experiments are time consuming and requires specialized equipment. Studies involving a large number of parameters and coupled effects are therefore preferably performed by finite element based simulations. Accurate experimental data is still a prerequisite to validate such simulations. There is, however, a shortage of accurate experimental data to validate such simulations. In industrial shearing processes, measured forces are always larger than the actual forces acting on the sheet, due to friction losses. Shearing also generates a force that attempts to separate the two tools with changed shearing conditions through increased clearance between the tools as result. Tool clearance is also the most common shearing parameter to adjust, depending on material grade and sheet thickness, to moderate the required force and to control the final sheared edge geometry. In this work, an experimental procedure that provides a stable tool clearance together with accurate measurements of tool forces and tool displacements, was designed, built and evaluated. Important shearing parameters and demands on the experimental set-up were identified in a sensitivity analysis performed with finite element simulations under the assumption of plane strain. With respect to large tool clearance stability and accurate force measurements, a symmetric experiment with two simultaneous shears and internal balancing of forces attempting to separate the tools was constructed. Steel sheets of different strength levels were sheared using the above mentioned experimental set-up, with various tool clearances, sheet clamping and rake angles. Results showed that tool penetration before fracture decreased with increased material strength. When one side of the sheet was left unclamped and free to move, the required shearing force decreased but instead the force attempting to separate the two tools increased. Further, the maximum shearing force decreased and the rollover increased with increased tool clearance. Digital image correlation was applied to measure strains on the sheet surface. The obtained strain fields, together with a material model, were used to compute the stress state in the sheet. A comparison, up to crack initiation, of these experimental results with corresponding results from finite element simulations in three dimensions and at a plane strain approximation showed that effective strains on the surface are representative also for the bulk material. A simple model was successfully applied to calculate the tool forces in shearing with angled tools from forces measured with parallel tools. These results suggest that, with respect to tool forces, a plane strain approximation is valid also at angled tools, at least for small rake angles. In general terms, this study provide a stable symmetric experimental set-up with internal balancing of lateral forces, for accurate measurements of tool forces, tool displacements, and sheet deformations, to study the effects of important shearing parameters. The results give further insight to the strain and stress conditions at crack initiation during shearing, and can also be used to validate models of the shearing process.

This master’s thesis presents a proposal for the technology of manufacturing sheet metal part, which is a part of a bicycle wall bracket. The component is made of steel sheet ČSN 11 325 with subsequent surface treatment by galvanizing. Due to the chosen method of manufacturing with a progressive stamping die, the research part is focused on the technology of shearing and bending. Technological calculations were performed for the most suitable production variant, on the basis of which a mechanical press ANDRITZ Metals with the designation KSTU 2000-20-4G-PSE was chosen. Furthermore, the design of the tool itself is presented, which is substantiated by drawing documentation. At the end of the work, a technical and economic evaluation of the produced series of 300 000 workpieces per year is calculated.

The thesis proposes a concept of manufacturing the folding meter lock. The part is made from DC01+LC steel of 0,3 mm thickness. The series size is 100 000 pcs/year. A forming in a progressive combination tool combining shearing, bending and stamping was chosen for the production, based on the analysis of possible solutions. The tool, designed on the basis of literary research of used technologies, produces the part in eleven steps exerting maximal force of 38,5 kN. The production will take place on an eccentric press LEN 40 C. The market price of 3,38 Kč for one piece was established by the technical and economic evaluation.

The thesis deals with the design of a technological process for the production a rotationally symmetrical component, which is part of the body for the chassis ball joint of a passenger car. Thesis was developed on request and in cooperation with THK RHYTHM Automotive Czech a.s. On the basis of a literary study, a technological process consisting of 10 operations was designed and elaborated. For the prototype production of the component, a four-column hydraulic press SHPFS 250, with a nominal force 2500 kN, was selected and price offer were prepared. For each of ten operations a prototype tool was designed and prepared assembly drawings. To reduce costs, a single die set was designed to allow all tools to be clamped. The total cost of acquisition of the prototype hydraulic press and tools was set at CZK 2,672,950.

This master’s thesis focuses on the concept of large-lot manufacturing of sheet metal component made from DC01 steel. Based on forethought, the method of compound tool combining shearing and bending was chosen. The theoretical part analyses used technologies in detail. In the next part specific course of manufacture was created and supplied with technological calculations. Based on all needed facts the tool was designed and after that forming machine, LDC 160 crank press, was chosen. At the end the usability of designed concept was confirmed with economical calculations.

A steel slitting process is simulated using FEM (Finite Element Method) in order to see potential defects along the edge in a steel sheet after it has been cut. The model's results were compared to microscope images of the steel sheet in order to verify accuracy. The purpose is conceptual and to find a model that successfully simulates a steel cutting process and (hopefully) how the edge depends on different parameters. The model developed seems to achieve this task, and a more thorough calibration of the model could result in (more) optimal parameters for the machine to use.

This master’s thesis is focused on the design of the technology to produce a part of the TV bracket. The part is made of steel sheet with a thickness of 2.5 mm. The structural steel S235JR was chosen as the most suitable material with following powder coating. From the possible variants, the production by progressive forming tool was chosen with respect to production requirements and a series size of 30 000 pieces by year. The part will be made in seven steps in designed tool and the total required force is 1013 kN. The production will take place on a mechanical press PCK12 from Bliss-Bret with a maximum force of 1250 kN. The final price of the part is 39.4 Kč.

The thesis focuses on the production concept of component Cage ECR 10 12, which is used as assembly element together with a nut during the bus production. Sheet metal part is made from 11 321 steel 1,5 mm thick in production 10 000 parts per year. Technology of production in progressive tool was selected based on literature study. Progressive tool combines technology of shearing and bending. Tool was designed after the technological calculations. Forming machine was selected after the stamping force calculation. Eccentric press LEN 63 C with 630 kN forming force was selected for production.

The project drawn up within engineering studies, field N2307-00, presents a design for processing a single part – the part is made of sheet steel number S235JRG1 by shearing and bending. On the basis of literary study was design compound tool which is working in three steps. The tool is fixed in eccentric press LEN 40 C (producer TOMA Industries, s.r.o.) with nominal force 400 kN. Blanking punch and blanking die are made from tool steel 19 436 according the drawing documentation.

The project elaborated in frame of engineering studies branch 2303T002. The project is submitting design of technology production of the part from the deep drawing sheet iron 11 320.30. Pursuant to of the literary pursuit a problem of the shearing, bending and calculation was designed manufacturing in transfer combined die, which is set on the eccentric press LEXN 100 C (producer TOMA INDUSTRIES s.r.o. Trnava), with nominal force 1000 kN. Functional parts of tool are produced of tool steel 19 436.3.

The wall clamp is used for attaching columns or pillars to a concrete foundation. It is made from structural steel 11 375 in the form of sheets with a thickness of 4 mm in the production run of 150 000 pcs/year. A combination of shearing and bending technologies in a progressive forming tool was selected from various options as the most appropriate. On the basis of structural and technological calculations, an instrument was designed, for which the technical documentation was elaborated. Due to the total forming force and work, the forming machine LDO 800 A/S from Šmeral Brno a.s. was selected as the manufacturing machine. The production cost per one part 53.66 CZK was determined using economic evaluation; based on the break even point, the production becomes profitable for the production run with the minimum number of 13 065 pcs.

The project, which has been elaborated within the framework of Master's Degree in Manufacturing Technology (2303T002), processes a technology proposal for the production of stamped part čelo from DD14 material, with a thickness 4 mm, with production quantities of 100 000 pieces per year, in cooperation with the company UNIRON Ltd. Based on the literature study of deep drawing without thinning of the walls and calculations, production of the part of simple single-function drawing tools was proposed. The first three operations performed on a PYE 100 S/1 hydraulic press and the last calibration operation carried out on a LEK 250 eccentric press. The semi-finished product is blank with a diameter of 195 mm, produced in a simple cutting die. The cutting die is designed for both the material in the form of a sheet metal strip in coils and cut strips of metal sheet, which is associated with the use of two eccentric presses of the LEK 250 and LE 400C types. The proposed manufacturing process was simulated in the PAM-Stamp 2G software, in which the influence of the radius the functional parts of tools to change the thickness of the material is further simulated. The part of the project is a technical and economic evaluation, in which the price of one piece of the product and production quantity at which production becomes profitable was rated.

The project drawn up within engineering studies, field M-STG, presents a design for processing a single part – the part is made of sheet steel number S195T by shearing and bending. On the basis of literary study was design compound tool which is working in three steps. The tool is fixed in eccentric press LE 250 with nominal force 25000 kN. Blanking punch and blanking die are made from tool steel 1.2379 according the drawing documentation.

In this master's thesis the proposal of the production technology of component – solar collector anchor element from steel 1.0038 (11 375) quality, 5 mm thickness is solved. For the manufacturing of the assigned part the shearing and bending technology and a progressive forming tool including a suitable forming machine of 8,000 kN rated power is selected. The proposed method of production is laid down by a technical-economic evaluation with respect to the production series of 150,000 units per year. The solar collector anchor element serves to hold the frame for the solar vacuum tube collector. In the scope of this master's thesis, an assessment of the current production method, including the selection of a suitable semi-finished product for production, was also carried out and their optimization was proposed.

Copy of author's previously published work inserted.
xii, 138, [51] leaves, [29] leaves of plates.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
The aim of this thesis is to investigate the process of applying the plasma immersion ion implantation (PIII) to shearing tools and to test surface modified tools in a sheep shearing environment. Detailed observations are made of the microstructural changes occurring near the surface of a Cr-Mo-V alloy tool steel rod subjected to nitrogen ion implantation at 350oC by the Australian Nuclear Science and Technology Organization (ANSTO)
Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1996

The air found in a shearing shed environment is normally contaminated with many different airborne substances. These contaminants include dust (predominantly organic), bioaerosols (fungi and bacteria), and gases (ammonia and carbon monoxide). Respiratory disorders have been associated with exposure to the types of contaminants found in a normal sheep shearing environment. Twenty nine shearing sheds in the state of New South Wales in Eastern Australia were sampled for concentrations of airborne contaminants. Based on the results of this study the following recommendations are made for the shearing industry: under the current dust and bioaerosol exposure standards there are no requirements to investigate mechanical ventilation to reduce airborne contaminants and there is no need for respiratory protection in any of the monitored sheds. However, it is recommended that if a person has a known predisposition to respiratory illness/stress they should be closely monitored while working in a shearing shed. There are issues raised in this thesis that require further research including the need for an epidemiological study on the health of people working in shearing sheds in relation to their respiratory health. The monitoring of shearing sheds in other regions of Australia needs to be undertaken and based on available literature similar studies are also needed in other livestock industries in Australia.
Doctor of Philosophy (PhD)

The air found in a shearing shed environment is normally contaminated with many different airborne substances. These contaminants include dust (predominantly organic), bioaerosols (fungi and bacteria), and gases (ammonia and carbon monoxide). Respiratory disorders have been associated with exposure to the types of contaminants found in a normal sheep shearing environment. Twenty nine shearing sheds in the state of New South Wales in Eastern Australia were sampled for concentrations of airborne contaminants. Based on the results of this study the following recommendations are made for the shearing industry: under the current dust and bioaerosol exposure standards there are no requirements to investigate mechanical ventilation to reduce airborne contaminants and there is no need for respiratory protection in any of the monitored sheds. However, it is recommended that if a person has a known predisposition to respiratory illness/stress they should be closely monitored while working in a shearing shed. There are issues raised in this thesis that require further research including the need for an epidemiological study on the health of people working in shearing sheds in relation to their respiratory health. The monitoring of shearing sheds in other regions of Australia needs to be undertaken and based on available literature similar studies are also needed in other livestock industries in Australia.

Choice of shearing time is one of the major management decisions for a wool-producing Merino flock and affects many aspects of wool production and sheep health. Previous studies have investigated the effect of shearing on only a few of these factors at a time, so that there is little objective information at the flock level for making rational decisions on shearing time. This is particularly the case for flocks that lamb in spring, the preferred time in south-eastern Australia.
A trial was conducted in a self-replacing, fine wool Merino flock in western Victoria, from January 1999 to May 2004, comparing ewes shorn annually in December, March or May. Within each of these shearing times, progeny were shorn in one of two different patterns, aligning them with their adult shearing group by 15–27 months of age.
Time of shearing did not consistently improve the staple strength of wool. December-shorn ewes produced significantly lighter and finer fleeces (average 19.1 μm, 3.0 kg clean weight), whereas fleeces from March-shorn ewes were heavier and coarser (19.4 μm, 3.1 kg). Fleeces from ewes shorn in May were of similar weight to fleeces from March-shorn ewes (3.1 kg), but they were of significantly broader diameter (19.7 μm). In young sheep, beneficial changes in some wool characteristics for each shearing group were offset by undesirable changes in others.
Shearing ewes in March or May, and weaners in March, May or June, significantly increased the risk of post-shearing mortality about three- and four-fold, respectively, compared to unshorn sheep. Substantial, highly significant associations in young sheep between post-weaning mortality, bodyweight and growth rate were also quantified using various survival analysis techniques. For example, the lightest 20% of weaners at weaning contributed 31% of all deaths in the year following weaning, and increasing average growth rate over summer and autumn from 250 to 500 g/month reduced the risk of death by 74%. These results could be used to develop supplementary feeding systems that efficiently reduce weaner mortality, which is a significant animal welfare issue in many Australian Merino flocks.
Mortality effects were incorporated into estimates of the total value of wool produced by the different shearing times between birth and culling at 6¼ years of age. Using median historical (1991–2006) wool prices, shearing ewes in March and their progeny first in June, or October (weaner)-December (ewe) shearing produced the greatest total value of wool ($111/head). March (weaners)-March (ewes) shearing had a wool value of $107/head and December (weaners)-December (adults) shearing $103/head. May-shorn ewes produced the smallest value of wool, irrespective of whether their progeny were first shorn in May or July ($93–96/head).
No shearing time consistently improved all animal health measures. May-shorn ewes had significantly more fleece rot in late autumn than the other shearing groups (odds ratio 2.5) and were up to 0.4 condition score lighter during winter, although they had a lower cost of dag (average $0.64/head) and significantly less breech strike risk in spring, compared to December-shorn ewes (odds ratio 0.18). December-shorn ewes had the greatest cost of dag ($1.50/head). March-shorn ewes had an intermediate cost of dag ($1.03/head) but significantly less breech strike than May-shorn ewes (odds ratio 0.38).Overall, December and March shearing were shown to be appropriate alternatives for a self-replacing Merino flock in south-eastern Australia, whereas May was an undesirable shearing time.

碩士
國立高雄科技大學
模具工程系
107
Blanking of the sheet metal or sheet plastic is one of the most frequently used processes in the washer industry. The punch is exposed to high stress and requires better resistance against wear. The quality of tool affects the quality of washers and causes some surface defects. The results show that the burrs occurs in three different materials, include 301-EH stainless steel, bakelite, and Polyslider. Besides, the misalignment of the bakelite washer was also observed. The AlCrN coated punch was used in 301-EH stainless steel washer. The surface hardness of the AlCrN coated punch was increased 68.6%. The cost of the defective products was decreased 71.4% and the repairing cost of the punch and mold was reduced 72.8%.

碩士
國立交通大學
工學院碩士在職專班精密與自動化工程學程
92
During fine blanking process, many factors affect shearing surface quality of the products. Major factors include machines and tools equipment, material properties and thickness, punch and die clearance, cutting tools radii, blank-holder type and loading, counter punch pressure and lubricant properties. In this study a medium carbon steel sheet (JIS S45C/AISI 1045) was selected as the blanking material, series of blanking parameter combinations organized by Taguchi method and experiments conducted. According to the result of experiments, small punch and die clearance and large blank-holder load would be advantageous to reduce the percentage of fracture portion and the squareness of the shearing surface. However, the counter punch pressure seems only affect the surface deflection of the product. In this study, the variations of the cutting tools radii do not show any significant effect on the shearing surface quality.

碩士
國立虎尾科技大學
創意工程與精密科技研究所
97
In this current study, finite element method (FEM) software and stamping die design theories were employed to investigate the stamping processes and die design of the immoveable spring chip in CD-ROM. The shearing and the bending were analyzed by finite element method software and then the accuracy of sheets forming simulated through CAE was tested. In the shearing analysis, focuses were mainly on the effects of clearance and pressure on the shearing surface quality, while in the bending analysis, the effects of die clearance, strip hold pressure, and shearing-bending velocity on sheets forming was explored. In addition, stamping die design theories were employed to investigate the die design system of sheets metal punching-bending for the immoveable spring chip in CD-ROM. Through the development processes, such as products assessment, stamping analysis, blank development, strip layout, process parameters calculation, die overall designs, and part design of dies, the development and design system for sheets metal punching-bending was constructed. In this study, a complete database for the SUS304 sheets metal detail properties was also constructed through the tensile test. Results of the study showed that the size values of the rollover plane and the fracture plane decrease as the die clearance decreases, but the burnish plane increases as the die clearance decreases. However, when the strip hold pressure increases, the size values of rollover plane and the fracture plane decrease accordingly, and the size of burnish plane increases as the strip hold pressure increases. In the aspect of bending analysis, the major parameters affecting the dimensions accuracy and the springback were the die clearance and strip hold pressure, while the die clearance and shearing-bending velocity were the main parameters which influenced the sheets metal strain. In the design of the strip, attention should be paid to the relations and continuity between the strip designs, such as strip design, strip feeding, force balance, and springback. Then, the overall solid progressive die was constructed after the press stroke, blank lifting height, punch length and stripper travel distances had been determined. The feasibility of the simulation and the dies deign was confirmed by dies manufacturing, erection and experiment. Furthermore, dimensions accuracy, springback and shearing-bending section of the immoveable spring chip in CD-ROM were examined. The results showed that the numerical values agree with the simulation ones with a reasonable accuracy, which further confirmed the feasibility and reliability of the application of FEM software for the sheets metal shearing-bending process. Harnessing both FEM and stamping die design software has been proved not only to save the time for, and the cost of, the die development, but also to raise the quality and precision of the products. When the current trend of industrial development is product miniaturization, the exploitation of scientific methods surely will be the core to the satisfaction of the purpose. The results found in the current study will shed some lights on the research and development of sheets metal shearing-bending process for the academia and industry.