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Cold isostatic press has undergone a spiral
process of development from one with single
medium to one with double media and again
from one with double media to one with
single medium, indicating a technological
progress and rise, facilitating further
perfection of the equipment to meet the need
of the user. A brief development process has
been described as follows:
I. Single medium (water or emulsion) cold
isostatic press (Drawing 1)
Principle and structure: Pressurization and
pressure release are realized with the help
of water medium. The big piston of the
intensifier drives the emulsion (or oil) to
the main cylinder from the cavity after
pressurization to facilitate formation of
the work piece.
Advantage: 1. The nominal or effective
cylinder stem may help effective utilization
of the space in the main cylinder.
Shortcomings: 1. The ultra high-pressure
water containing impurities may damage the
mouth of the valve during pressure release,
often resulting in the problems of slow or
non-pressure increase followed by frequent
repairing.
2. Fast injection of liquid during low
pressure cannot be accomplished with water
supply by double medium intensifier while
80% of the task for formation of work piece
needs to be completed during low pressure,
thus prolonging the time for formation of
the work piece.
3. With the adoption of double medium
intensifier, the ultra high-pressure water
may be mixed with oil easily.
II. Radial isolation double medium cold
isostatic press (Drawing 2)
Principle and structure: Put a rubber sleeve
in the main cylinder to separate the oil out
of the bucket and water in the bucket. The
intensifier may inject the ultra high
pressure oil to the outside of the
separating sleeve and realize formation of
the work piece by pressing the water with
the rubber sleeve.
Advantages: 1. The sleeve separates oil and
water. Water containing impurities is kept
in the sleeve. The oil out of the sleeve
will not damage the valve during pressure
release, resulting in long working hours of
the equipment.
2. Fast pressurization of oil may be
achieved during low pressure, saving time
for formation of work piece, which is about
30%゛60% comparing with the time for
formation of work piece by single medium
equipment.
Shortcomings: 1. Effective volume for
pressurization is reduced 40%゛50% with the
addition of the separating sleeve.
2. Any inadequate calculation of the
pressing capacity or placement of the work
piece etc may enable the sleeve to press
onto the work piece to result in breakage
and pollution of the entire oil system.
3. Incident relating to the mixing of water
in the rubber sleeve and oil out of it is
unavoidable.
4. Ineffective liquid will increase to cause
higher consumption of energy, which is above
30%.
III. Radial Isolation single medium
pressurization and double medium pressure
release cold isostatic press (Drawing 3)
Principle and structure: A bowl type rubber
cover or a 2-direction equal pressure
sealing board is laid above the bottom of
the main cylinder. Prior to pressurization,
oil or water pump of low pressure and small
volume pushed up their rise to fill in the
cavity while the double medium intensifier
will motivate the ultra high pressure water
to run through the bottom of the cylinder by
the oil cavity into the upper part of the
water cavity to press the work piece. After
completion of pressurization, there will be
a release of oil followed by the falling of
the separating board or the bowl type cover,
the pressure of the main cylinder down to
zero, return of the lid and bottom of the
cylinder, coming out of the frame and
uncovering of the cylinder.
Advantages:? 1. Nominal cylinder stem is the
effective cylinder stem, without waste of
volume or energy.
2. Pressurization is realized with the help
of water and pressure release by oil (or
water), ensuring long normal operation of
the pressure release valve.
3. Pollution of the system owing to breakage
of the separator is completely avoided.
4. Oil (or water) used for pressure release
is less, hence the smaller volume of the oil
(water) tank for pleasure release. In
addition, the volume of pressurization of
the main cylinder is not big either.
Shortcomings:? 1. Fast pressurization is not
possible.
2. Double medium intensifier may cause
mixing of oil and water.
TPY has conducted the following technical
innovations on the basis of the available
patent so as to overcome the existing
shortcomings described in above article III.
Adoption of hydraulic intensifier system
featured by fast and pre-pressurization
(patent).
Adoption of double medium intensifier,
eliminating the problem relating to mixture
of oil and water.
The cold isostatic press of a new type
manufactured by TPY has already come into
emergence, starting its normal operation in
some factories. It has shown more
advantageous economic and technical features
comparing with the previous double medium
cold isostatic press used the rubber cover
for separation purpose, indicating a fresh
contribution to the technological
development of cold isostatic press. |
