Sydenham, P. H. (1969) Manual and automatice large-scale dimensional metrology. PhD thesis, University of Warwick.

PDF WRAP_THESIS_Sydenham_1969.pdf - Requires a PDF viewer. Download (10Mb)

Request Changes to record.

Abstract

Current techniques for manual and automated determination
of decametre-range are reviewed from information gained by extensive
literature search and from visits made to a wide cross section of
European establishments concerned with large-scale dimensional
measurements. The reviews, which contain nearly 200 references, provide
background information needed by systems designers.
A 12m steel measuring base is described which was length
stabilised to within 3 parts in 10 for periods in excess of 500 hours.
Temperature of the internal water flow is monitored by a contact
thermometer which controls the heat input.
The theory and practice of tensioned-wire dimensional
transducers are given which enables this new-class of dimensional
measuring instrument to be designed. Two distinct groups of instrument
described are those for transducing continuous length changes into
electrical signals with better than 5 parts in 10^6 error and those for
detecting changes of 1 part in 10^10 or smaller, of a nominally fixed
length.
Continuous subdivision transducers with 12m and 1m range are
reported which incorporate mechanical mechanisms for obtaining adjustable
absolute length, reduction of in-scale accuracy, errors, linear rotary
output, rapid following response and simple temperature compensation.
A method and practical apparatus are described which uses this type of
transducer for automatic control of the position of a workhea moved
on a cartesian-frame manipulator. Actual two-dimensional position
is measured on a trilateral basis, a technique which eliminates the need
for a massive framework when machining or inspecting large workpieces.
In-situ numerically-controlled machining is possible with this system.
A second frameless technique is described for automatically
recording roundness variations of large rings or spigots. Repeatability
of 5 parts in 10^6 or better has been proven to be possible with
inexpensive equipment. This method illustrates the use of deformation
wire-transducers for dynamic dimensional measurement. A similar type
of instrument was used for creep determination of invariwires and
carbon-fibres supported on the 12m base. Results are given which have
shown that 1 part in 10^8 length stability is attainable over considerable
periods.
It is shown that measurement of earth strains is possible with
an invar wire tensioned by a simple beam-balance. Details are given of
an experiment performed in a tunnel in which solid-earth tidal strains
are recorded within hours of installation.
Several other possible applications are discussed for which
tensioned-wire transducers seem suited.
The use of position-sensitive photocells in dimensional
metrology is outlined with particular reference to wire transducers
where linear and rotary movements may need monitoring. It is shown
that they are a simple and economic way to measure small displacements of
millimetre range.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QC Physics
Library of Congress Subject Headings (LCSH):	Metrology
Official Date:	May 1969
Dates:	Date Event May 1969 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Douce, John Leonard
Sponsors:	English Electric Company ; Science Research Council (Great Britain) (SRC) B/SR/5029
Extent:	vi, 131 leaves : ill., charts
Language:	eng

Request changes or add full text files to a record

Repository staff actions (login required)

View Item

Downloads