The mold used in an injection molding process consists of a top half and a bottom half. Each half is 60 mm × 60 × mm × 20 mm and is constructed of metal ( ρ = 7800 kg/m 3 , c = 450 J/kg ⋅ K ). The cold mold ( l 00 ° C ) s to be heated w 2 00 ° C with pressurized water (available at 275 ° C and a total flow rate of 0.0 2 kg / s ) prior to injecting the thermoplastic material. The injection takes only a fraction of a second, and the hot mold ( 2 00 ° C ) is subsequently cooled with cold water (available at 25 ° C and a total flow rate of 0.0 2 kg / s ) prior to ejecting the molded part. After part ejection, which also takes a fraction of a second, the process is repeated. (a) In conventional mold design, straight cooling (healing) passages are bored through the mold in a location where the passages will not interfere with the molded part. Determine the initial heating rate and the initial cooling rate of the mold when five 5 − mm -diameter, 6 0 − mm -1ong passages are bored in each half of the mold (10 passages total). The velocity distribution of the water is fully developed at the entrance of each passage in the hot (or cold) mold (b) New additive manufacturing processes, known as selective freeform fabrication, or SFF, are used to construct molds that are configured with conformal cooling passages. Consider the same mold as before, but now a 5 − mm -diameter, coiled, conformal cooling passage is designed within each half of the SFF-manufactured mold. Each of the two coiled passages has N = 2 turns. The coiled passage does not interfere with the molded part. The conformal channels have a coil diameter C = 5 0 mm . The total water flow remains the same as in part (a) ( 0.0 1 kg / s per coil). Determine the initial heating rate and the initial cooling rate of the mold. (c) Compare the surface areas of the conventional and conformal cooling passages. Compare the rate at which the mold temperature changes for molds configured with the conventional and conformal healing and cooling passages. Which cooling passage, conventional or conformal, will enable production of more parts per day? Neglect the presence of the thermoplastic material.
The mold used in an injection molding process consists of a top half and a bottom half. Each half is 60 mm × 60 × mm × 20 mm and is constructed of metal ( ρ = 7800 kg/m 3 , c = 450 J/kg ⋅ K ). The cold mold ( l 00 ° C ) s to be heated w 2 00 ° C with pressurized water (available at 275 ° C and a total flow rate of 0.0 2 kg / s ) prior to injecting the thermoplastic material. The injection takes only a fraction of a second, and the hot mold ( 2 00 ° C ) is subsequently cooled with cold water (available at 25 ° C and a total flow rate of 0.0 2 kg / s ) prior to ejecting the molded part. After part ejection, which also takes a fraction of a second, the process is repeated. (a) In conventional mold design, straight cooling (healing) passages are bored through the mold in a location where the passages will not interfere with the molded part. Determine the initial heating rate and the initial cooling rate of the mold when five 5 − mm -diameter, 6 0 − mm -1ong passages are bored in each half of the mold (10 passages total). The velocity distribution of the water is fully developed at the entrance of each passage in the hot (or cold) mold (b) New additive manufacturing processes, known as selective freeform fabrication, or SFF, are used to construct molds that are configured with conformal cooling passages. Consider the same mold as before, but now a 5 − mm -diameter, coiled, conformal cooling passage is designed within each half of the SFF-manufactured mold. Each of the two coiled passages has N = 2 turns. The coiled passage does not interfere with the molded part. The conformal channels have a coil diameter C = 5 0 mm . The total water flow remains the same as in part (a) ( 0.0 1 kg / s per coil). Determine the initial heating rate and the initial cooling rate of the mold. (c) Compare the surface areas of the conventional and conformal cooling passages. Compare the rate at which the mold temperature changes for molds configured with the conventional and conformal healing and cooling passages. Which cooling passage, conventional or conformal, will enable production of more parts per day? Neglect the presence of the thermoplastic material.
Solution Summary: The author explains the initial heating rate and cooling rate of the mold. The specific heat of metal is c=450 J/kgK.
The mold used in an injection molding process consists of a top half and a bottom half. Each half is
60
mm
×
60
×
mm
×
20
mm
and is constructed of metal (
ρ
=
7800
kg/m
3
,
c
=
450
J/kg
⋅
K
). The cold mold (
l
00
°
C
) s to be heated w
2
00
°
C
with pressurized water (available at
275
°
C
and a total flow rate of
0.0
2 kg
/
s
) prior to injecting the thermoplastic material. The injection takes only a fraction of a second, and the hot mold (
2
00
°
C
) is subsequently cooled with cold water (available at
25
°
C
and a total flow rate of
0.0
2 kg
/
s
) prior to ejecting the molded part. After part ejection, which also takes a fraction of a second, the process is repeated.
(a) In conventional mold design, straight cooling (healing) passages are bored through the mold in a location where the passages will not interfere with the molded part. Determine the initial heating rate and the initial cooling rate of the mold when five
5
−
mm
-diameter,
6
0
−
mm
-1ong passages are bored in each half of the mold (10 passages total). The velocity distribution of the water is fully developed at the entrance of each passage in the hot (or cold) mold
(b) New additive manufacturing processes, known as selective freeform fabrication, or SFF, are used to construct molds that are configured with conformal cooling passages. Consider the same mold as before, but now a
5
−
mm
-diameter, coiled, conformal cooling passage is designed within each half of the SFF-manufactured mold. Each of the two coiled passages has N = 2 turns. The coiled passage does not interfere with the molded part. The conformal channels have a coil diameter
C
=
5
0
mm
. The total water flow remains the same as in part (a) (
0.0
1 kg
/
s
per coil). Determine the initial heating rate and the initial cooling rate of the mold.
(c) Compare the surface areas of the conventional and conformal cooling passages. Compare the rate at which the mold temperature changes for molds configured with the conventional and conformal healing and cooling passages. Which cooling passage, conventional or conformal, will enable production of more parts per day? Neglect the presence of the thermoplastic material.
1. A 40 lb. force is applied at point E. There are pins at
A, B, C, D, and F and a roller at A.
a. Draw a FBD of member EFC showing all the known and
unknown forces acting on it.
b. Draw a FBD of member ABF showing all the known and
unknown forces acting on it.
c. Draw a FBD of member BCD showing all the known and
unknown forces acting on it.
d. Draw a FBD of the entire assembly ADE showing all the
known and unknown forces acting on it.
e. Determine the reactions at A and D.
f. Determine the magnitude of the pin reaction at C.
40 lbs.
B
A
6 in.
4 in.
D
F
-5 in.4 in 4.
A crude oil of specific gravity0.85 flows upward at a volumetric rate of flow of 70litres per
second through
a vertical
venturimeter,with an inlet diameter of 250 mm and a throat
diameter of 150mm. The coefficient
of discharge of venturimeter is 0.96. The vertical
differences betwecen the pressure toppings is
350mm.
i)
Draw a well labeled diagram to represent the above in formation
i)
If the two pressure gauges are connected at the tapings such that they are
positioned at the levels of their corresponding tapping points,
determine the
difference of readings in N/CM² of the two pressure gauges
ii)
If a mercury differential
manometer
is connected in place of pressure gauges,
to the tappings such that the connecting tube up to mercury are filled with oil
determine the difference in the level of mercury column.
Can you solve it analytically using laplace transforms and with Matlab code as well please. Thank You
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Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning