US 11,772,313 B2 · Injection molding adaptive compensation method based on melt viscosity fluctuation

Abstract

An injection molding adaptive compensation method based on melt viscosity fluctuation comprising: initializing equipment; in a pre-calculation stage, introducing melt into a mold cavity at a constant rate, collecting pre-calculation parameters in each sampling period T, and obtaining a first injection work in the pre-calculation stage by using a first calculation formula; in a self-adaptation stage, introducing the melt into the mold cavity at a constant rate, collecting adaptive parameters in each sampling period T, and obtaining a second injection work in the self-adaptation stage by using a second calculation formula; calling the PVT characteristics of current processing raw materials to construct a PVT relation function, and obtaining an optimized V/P switching point by using a PVT weight control model; and according to the injection work at the pre-calculation stage and the injection work at the present stage, obtaining an optimized holding pressure according to an injection work adjustment model.

An injection molding adaptive compensation method based on melt viscosity fluctuation, characterized by comprising:

S1, initializing equipment, and setting an initial V/P switching point, an initial holding pressure and an initial barrel temperature;
S2, entering a pre-calculation stage, introducing melt into a mold cavity at a constant rate, and collecting pre-calculation parameters in each sampling period T, including injection pressure, screw displacement and melt temperature;
S3, according to the pre-calculation parameters, obtaining a first injection work in the pre-calculation stage by using a first calculation formula;
S4, entering a self-adaptation stage, introducing the melt into the mold cavity at a constant rate, and collecting adaptive parameters in each sampling period T, including injection pressure, screw displacement and melt temperature;
S5, according to the adaptive parameters, obtaining a second injection work in the self-adaptation stage by using a second calculation formula;
S6, calling the PVT characteristics of current processing raw materials to construct a PVT relation function, and obtaining an optimized V/P switching point by using a PVT weight control model;
and
S7, according to the injection work at the pre-calculation stage and the injection work at the present stage, obtaining an optimized holding pressure according to an injection work adjustment model;
in S3, the first calculation formula is:
W
0
=

K
*
∫
Xstart
Xswitch
⁢
pdx

=

K
*
∑
p
i
+
p
i
-
1
2
⁢
(
x
i
-
x
i
-
1
)

;
(
1
)
where W0 is the first injection work;
a pressure value at a starting point of the pre-calculation stage is set to be Pstart, and a screw displacement value is set to be Xstart;
a pressure at an end point of the pre-calculation stage is set to be Pswitch, and a screw displacement value is set to be Xswitch;
and pi and xi respectively represent the injection pressure and screw displacement in an ith sampling period T, and K is a material correction coefficient related to the material itself;
in S5, the second calculation formula is:
W
t
=

K
*
∫
Xstart
X
switch
*
⁢
pdx

=

K
*
∑
p
j
+
p
j
-
1
2
⁢
(
x
j
-
x
j
-
1
)

;
(
2
)
where Wt is the second injection work;
a pressure value at a starting point of the self-adaptation stage is set to be Pstart, a screw displacement value is set to be Xstart, and the displacement value is consistent with Xstart in the pre-calculation stage;
a pressure value at an end point of the self-adaptation stage is set to be P*switch, and a screw displacement value is set to be X*switch;
and pj and xj respectively represent the injection pressure and screw displacement in a jth sampling period T, and K is a material correction coefficient related to the material itself;
in S6, the PVT weight control model is:
x
t
=
x
0
*
V
⁡
(
T
t
,
P
t
)
V
⁡
(
T
0
,
P
0
)
;
(
3
)
where xt is an optimized V/P switching point position at the current stage, and x0 is an initial V/P switching point position;
V(T,P) is a PVT relation function of currently processed materials, T0 and Tt are melt temperature in the pre-calculation stage and the self-adaptation stage respectively, and P0 and Pt are the pressure values of characteristic points on injection pressure curves of the pre-calculation stage and the self-adaptation stage respectively;
and the characteristic point is a point on a collected injection pressure curve which is separated from the V/P switching point by a safe distance Xs;
V
⁡
(
T
,
P
)
=
[
b
1
+
b
2
(
T
-
b
5
)
]
⁢
{
1
-
C
⁢
ln
[
1
+
P
b
3
⁢
exp
[
-
b
4
(
T
-
b
5
)
]
]
}
;
(
5
)
where V(T,P) is the specific volume under temperature T and pressure P, C is a universal constant, and b1, b2, b3, b4, and b5 respectively represent the state constants of polymer materials in the molten state;
in S7, the injection work adjustment model is:
P
K
⁢
L
=
P
K
⁢
0
*
K
0
*
W
t
W
0
;
(
4
)
where PKL is an optimized holding pressure value of each mold, PK0 is an initial holding pressure, and K0 is a correction coefficient related to a material product.

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Injection molding adaptive compensation method based on melt viscosity fluctuation

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Injection molding adaptive compensation method based on melt viscosity fluctuation

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Abstract

Claims6