1. NOVEL HIGH TEMPERATURE VACUUM
FURNACE FOR IN SITU NEUTRON-
SCATTERING STRESS MEASUREMENTS
15MPD101 Group Design Project Portfolio
Charles Brooker
Christopher Davies
Katrina Duncumb
Michael Greenhough
Yannis Kouparitsas
Anthony Smith
2. CURRENT RIG This portfolio follows
the design process of
the 15MPD101 Group
Design Project. Ac-
companying this port-
folio is a report with
full justifications for
all design, material and
manufacturing decisions
made throughout the
course of the project.
The project looked at de-
signing a high tempera-
ture vacuum furnace for
use in situ with a 100kN
stress testing rig on the
ENGIN-X beamline at the
ISIS Facility in the Ruther-
ford Appleton Laboratory,
Oxfordshire. From examin-
ing the current furnace, and
consulting the team who in-
teract with it, requirements
were generated for the new
design. The main design re-
quirements were:
- To be able to test samples at
1600°C
- To be able to test in a vacuum
environment
- Reduce the amount of time
taken to set up the furnace for
testing
Images of the current high
temperature furnace for
the ENGIN-X beamline
Temperature produced by
four infrared heaters
situated around the
sample
Reaches a maximum
temperature of 1100°C
Has some inert
atmosphere capabilities
Side view of the furnace
3. 2-3
Instron 100kN Stress Testing Rig
Front and side views
of the current furnace
positioned on the rig
4. INITIAL CONCEPTS
Tube furnace concepts struggled with
the small volume of space available
to fit all of the necessary components
5. 4-5
Initial concepts were devised for
the design of the rig were based
on the notion of a small tube
containing the vacuum atmos-
phere. This premise involved
looking at connections to the
test rig sample holders, as
shown on the right, cooling of
the sample holders and at-
tachment of necessary water
and pumps, as shown on the
left.
Although a tube vacuum
would have been a smaller
area to pump down and
heat up, there were too
many components that
needed to be within close
proximity to the sample
(such as the induction
heater and thermocou-
ples) to make this idea
feasible. Designs based
on a larger chamber
were then investigated.
Possible bellows attachment
methods for tube furnace
Sample holder to
bellows concept
for tube furnace
6. INITIAL CONCEPTS
In contrast to the tube
vacuum, a chamber
vacuum was proposed,
with several ideas put
forward. Gull-wing, egg,
and top hat designs were
suggested, encompassing
the whole rig, but these
were identified as having
issues with portability
and vacuum compatibility.
From these designs, a ver-
tical cylindrical option was
considered most appro-
priate to be taken forward,
as the shape would have
minimal stress concentra-
tors, and with proper sealing,
would be able to sit on/with-
in the test rig.
Significant work was put into
determining a good shape
for the vacuum chamber, pri-
or to proceeding forward with
chamber design, and this can be
found in Section 5.5.7 of the ac-
companying report.
Egg concept with
hinged top
Gull wing concept -
hinged door with the
test rig situated inside
Top hat concept similar to those
used in other high temperature
vacuum furnaces
7. 6-7
One issue of the furnace cur-
rently in place on the ENGIN-X
beamline was the ability to
change heaters quickly whilst
the furnace was on the rig, as
infrared heaters have short
lives. The current furnace did
not address this, requiring
several components to be
removed to replace a heat-
ing unit. Options proposed
to solve this issue includ-
ed: an “X-Wing” concept,
where the heaters would
fold down to be removed
from either side; a con-
cept that was top and
bottom hinged, where
heaters would fold up to
be removed; and a slider
concept, which could be
removed as a whole and
heaters slotted in. The
slider design showed
most promise, and was
developed further.
Slider concept with clip
in heating elements
top and bottom hinged concept
- would require significant space
for folding away
Star Wars “X-Wing” style concept
would involve attaching around
sample in an unspecified way
9. 8-9
Further development was carried
out on the initial concepts to
produce a final design. The vac-
uum chamber, being a pressure
vessel, was discussed at length
in terms of shape, size, neutron
compatibility, windows, seal-
ing, and door design. Several
door types were looked into,
though a fully separated door
was preferred over a hinged
door to make sealing easier.
Methods of closing the door,
and sealing it to withstand
negative pressure were re-
searched and options were
designed for the chamber.
Some methods of attach-
ment included bolting,
clamping and clipping,
with quick release style
clips being favoured.
Rubber seals were able
to be used between
the chamber and door
flanges to prevent leak-
age with a clip system.
10. CONCEPT
DEVELOPMENT
Even with a chamber
vacuum, the temper-
ature requirements of
the sample holders were
still significantly higher
than those of the current
rig. The development of
the sample holders there-
fore primarily looked at
cooling methods, converg-
ing towards a spiral water
channel design. Research
conducted on the material
requirements also necessi-
tated the addition of sam-
ple holder extensions for the
highest temperature ranges,
which would allow the remov-
al of more heat before reaching
the cooled sample holders.
Sample holder extension
for very high temperatures
to reduce heat transferred
to sample holders and rig
11. 10-11
The slider was chosen as a sim-
ple concept for inserting/re-
moving infrared heaters, but it
also allowed induction heating
to be used when the design
was turned into a frame, as
the centre could be used for
any pipes or cables that were
needed for heating or cool-
ing. The simplicity of the
design allowed it to be in-
tegrated into the vacuum
chamber easily with rails
top and bottom, and re-
moving a broken infrared
heater would be as sim-
ple as disconnecting the
pipes/cables, sliding the
module out, and unclip-
ping it, with replacement
simply being the re-
verse.
Slider concept pulled back
to a skeletal frame for easier
manufacturing, also allowing
induction heating elements
to be connected through
the module
Solid piece slider concept
would be difficult to manu-
facture and require signifi-
cant machining of holes
Connection to the vacuum
chamber through a protruding
rail on the slider module and
a holding rail in the vacuum
chamber
A clip system would allow
the infrared heaters to be
quickly inserted or removed
from the module
12. FINAL
CONCEPT
The final design con-
sisted of four main
components: the vac-
uum chamber; the
chamber door; the
sample holders; and
the slider mechanism.
The chamber and door,
as shown on the right,
will fit between the
two Instron stress rig
bars, and allow enough
room in when closed for
both methods of heating,
sensors, and the sam-
ple and sample holders.
There were many changes
made after the final con-
cept drawing of the vacuum
chamber, including the ad-
dition of handles and hoists,
these can be seen in the CAD
images and drawings on pag-
es 16 – 21.
Thea sample holders, shown
on the left, will screw into the
Instron stress rig arms, and be
attached to sets of bellows to
allow for the movement of the
arms during testing. The inter-
nal cooling channels will be hel-
ical, and at higher temperatures
extensions will reduce the heat
being transmitted to the sample
holders.
Sample holder extension for
very high temperatures
sample holder with bellows connections
shown to vacuum chamber
13. 12-13
Sample holder entry holes were positioned in
the middle of the chamber, with test rig rails
holes ouside of the chamber
Flanges located on both door and
chamber for vacuum sealing
Quick release clip points positioned
around the chamber and door
Neutron entry and exit
windows positioned for
diffraction detection
14. FINAL
CONCEPT Around the edge of the
vacuum chamber and
door, several clips will
secure the position and
seal the chamber shut,
as shown on the left.
These clips are quick
release and will improve
the time it takes to set up
on the Instron stress rig
for testing.
There will be two slider
modules for the vacuum
chamber, top and bottom,
which will house the infra-
red heaters and the induc-
tion coil as two methods of
heating the sample. Cooling
and power will be supplied
to the modules through the
roof of the chamber, and uti-
lising the space in the centre
of the module to direct these
tubes and cables to the correct
heating method. The infrared
heaters clip in and out of the
slider module, to allow for quick
changing if one is not function-
ing correctly.
Approximate placement of the
quick attachment mechanisms
on the door and chamber
16. COMPUTER
AIDED DESIGN
From the concept devel-
opment stage, Computer
Aided Design (CAD) soft-
ware was used to create a
3D representation of the
chamber, sample hold-
ers and sliders. The use
of CAD aided the group in
making design decisions
throughout the project, as
the software creates mod-
els to scale, which can be
used for prototyping; allows
manipulation of viewpoint,
to aid in visualisation of the
product; and can create as-
semblies to check for any in-
terference between the compo-
nents.
CAD model iterations
Full assembly model
Open door assembly
Slider module
Chamber door
Vacuum chamber
