Utjecaj konstrukcijskih i radnih veličina na učinak lančane sjekačice

doctoral thesis

• Title: Utjecaj konstrukcijskih i radnih veličina na učinak lančane sjekačice : doktorski rad
• Title (english): Influence of constructional and operational parameters on chain saw performance : doctoral thesis
• Author: Tomislav Korman
• Mentor: Trpimir Kujundžić (mentor)
• Committee member: Gordan Bedeković (predsjednik povjerenstva)
• Committee member: Trpimir Kujundžić (član povjerenstva)
• Committee member: Petar Hrženjak (član povjerenstva)
• Committee member: Dalibor Kuhinek (član povjerenstva)
• Committee member: Josip Mesec (član povjerenstva); MBZ: 123530
• Granter: University of Zagreb; Faculty of Mining, Geology and Petroleum Engineering; Zagreb
• Defense date and country: 2014-11-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mining, Petroleum and Geology Engineering; Mining
• Universal decimal classification (UDC): 622 - Mining

Abstract

Lančane sjekačice se koriste za izradu vertikalnih ili horizontalnih rezova, a primjenu
su našle u površinskoj i podzemnoj eksploataciji arhitektonsko-građevnog kamena.
Učinkovitost sjekačica može se izraziti kroz učinak, potrošnju reznih elemenata i utrošak
energije. Glavni čimbenici koji utječu na učinkovitost sjekačice su: konstrukcija sjekačice,
radne veličine, fizikalno - mehaničke značajke stijenske mase i stupanj istrošenosti reznih
elemenata. Radne veličine kojima upravlja rukovatelj sjekačice su brzina posmaka sjekačice i
brzina lanca. Vrijednosti radnih veličina temelje se na preporuci proizvođača i/ili iskustvu
rukovatelja sjekačice. Konstrukcijom sjekačice određene su geometrijske veličine reznih
pločica odnosno položaj reznih pločica na lancu sjekačice, koje se razlikuju ovisno o
proizvođaču.
Cilj ovog istraživanja je na znanstveno utemeljenom pristupu analizirati utjecaj radnih
i konstrukcijskih veličina na učinak lančane sjekačice. Istraživanja su provedena sa svrhom
definiranja smjernica za povećanje učinkovitosti lančanih sjekačica. U skladu s predmetom i
ciljem istraživanja postavljena je hipoteza da se primjenom uređaja za pravolinijsko rezanje
može simulirati proces rezanja stijena lančanom sjekačicom, a na temelju analize dobivenih
rezultata moguće je optimizirati radne i konstrukcijske veličine sjekačice. Utjecaj radnih
veličina na učinak sjekačice određen je terenskim ispitivanjima, a utjecaj konstrukcijskih
veličina laboratorijskim ispitivanjima. Terenska ispitivanja uključivala su mjerenje učinka i
energije utrošene na rezanje pri različitim brzinama reznog lanca i posmaka sjekačice.
Laboratorijskim ispitivanjima, pomoću uređaja za pravolinijsko rezanje stijena simuliran je
proces rezanja lančane sjekačice. Na temelju rezultata ispitivanja analiziran je utjecaj širine,
dubine reza te napadnih kutova reznih pločica na sile i energiju rezanja. Kako bi se ispitala
postavljena hipoteza, komparirane su vrijednosti specifične energije dobivene laboratorijskim
i terenskim ispitivanjima.
Provedenim istraživanjima dobiveni su precizniji pokazatelji o utjecaju radnih i
konstrukcijskih veličina na učinak sjekačice. Analizom rezultata ustanovljeno je da je moguće
smanjiti specifičnu energiju rezanja bez utjecaja na učinak sjekačice, ukoliko se smanji brzina
lanca. Pored navedenog, u radu su prikazani modeli za određivanje minimalne brzine lanca i
sila na maču sjekačice. Također su date smjernice za poboljšanje konstrukcije reznog lanca u
pogledu smanjena specifične energije rezanja.

Abstract (english)

Chain saw machines are used for cutting vertical or horizontal cuts in underground and
surface exploitation of dimension stone. Efficiency of a chain saw can be expressed through
cutting rate, consumption of cutting tools and energy consumption. Cutting performance of a
chain saw is mainly dependent on machine design, physico-mechanical properties of rock
mass, operational parameters and tool wear rate. The operational parameters which the
operator must arrange on a chain saw are chain speed and cart speed movement. Operational
parameters are based on manufacturer's recommendations and/or the operator experience. The
main objective of this research is to analyze the relationship between operational parameters,
chain design and chainsaw performance. The major hypothesis of this study was that cutting
action of chain saw machines can be successfully simulated by linear rock cutting test. For
this purpose in this work small-scale and full-scale rock cutting experiments were performed.
The operational parameters of chain saw are studied by performing full-scale field studies on
chain saw. A portable data acquisition system, using a laptop computer, was developed to
monitor cutting energy of chain saw. Specific energy was calculated as the amount of energy
required to cut a unit volume of rock.
The second hypothesis stated that the operational and constructional parameters can be
optimized based on experimental studies of linear cutting test. The constructional parameters
of cutting chain are studied by performing small scale tests on laboratory rock cutting
machine. The Linear cutting machine is a modified shaping machine equipped with a triaxial
dynamometer attached to the cutter head. The dynamometer resolves the instantaneous force
on a cutting tool into three mutually orthogonal components, each measured by a straingauged
bridge circuit. Linear cutting test were carried out with the sequence of cutting
patterns same as on chain saw. The specific cutting energy, which represents the energy
required to remove a unit volume of work-material, is calculated from the cutting force,
length of cut and volume of cut rock. The major hypothesis was tested by comparing the
specific cutting energy obtained from laboratory test and field measurement.
Thus, linear cutting machine test can be used not only for measurement of cutter
forces, but also to select the most suitable cutter in order to achieve the most efficient cutting.
This means different cutter geometry design with different chain patterns. The experimental
results based on statistical analysis show that the specific energy of material is reduced
considerably as depth of cut increases. The depth of cutting is affected by transverse speed of
chain saw and the chain speed. It can be increased by increasing transverse speed or
decreasing speed of chain. Maximum transverse speed of chain saw is limited due the forces
acting on a chain. Minimum chain speed depends on volume of loose cuttings. In this work,
model for estimating minimum chain speed and cutting forces acting on the cutting bar has
been developed. The paper also presents suggestions for improving design of the cutting
chain.

• Keywords: arhitektonsko-građevni kamen; lančana sjekačica; konstrukcijske veličine; radne veličine; specifična energija rezanja; sila rezanja.
• Keywords (english): dimension stone; chain saw; constructional parameters; operational parameters; specific cutting energy; cutting force.
• Language: croatian
• URN:NBN: urn:nbn:hr:169:838373
• Promotion: 2015-07-12
• Study programme: Title: Applied Geosciences, Mining and Petroleum Engineering; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor znanosti/doktorica znanosti (doktor znanosti/doktorica znanosti)
• Catalog URL: http://katalog.nsk.hr/F/?func=direct&CON_LNG=ZAG&local_base=ZAG01_WEB&doc_number=000588519
• Type of resource: Text
• Extent: 135 str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-11-22 15:38:16