JP2983651B2 - Injection molding condition setting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding condition setting method, and more particularly, to an injection molding condition setting method capable of easily setting molding conditions capable of effectively preventing occurrence of burrs. It is about.

[0002]

2. Description of the Related Art Generally, what is called a burr is left on an edge of a molded product formed by an injection molded product. The prevention of such burrs has been made on a trial and error basis by a skilled technician or operator adjusting the molding conditions empirically or experimentally, or by improving the adhesion of the mating surfaces of the molds. .

Japanese Patent Application Laid-Open No. 1-285319 proposes a molding die configured to prevent the occurrence of such burrs by modifying the shape of the cavity. Japanese Patent Application Laid-Open No. 1-28841 discloses an automatic molding condition switching apparatus configured to set appropriate molding conditions following changes in environmental conditions such as room temperature and mold temperature.
No. 8 proposes this. This automatic molding condition switching apparatus sets molding conditions suitable for environmental conditions that change over time, stores the conditions, and automatically selects molding conditions according to time, thereby enabling a long period of time. The purpose is to properly supervise the continuously operated injection molding machine.

[0004]

However, such a conventional molding method or molding apparatus cannot cope with recent injection molding techniques in which molded articles have become thinner and larger.
At present, it is extremely difficult to form a good molded product without burrs using such a molding method or molding apparatus.

[0005] Further, the occurrence of burrs is caused by insufficient strength of the mold,
If it is due to structural inconvenience, it is difficult for the above-described molding method or molding apparatus to find the cause of burr generation, and therefore, burr generation cannot be prevented. The present invention has been made in view of such a point, and an object of the present invention is to provide an injection molding condition setting method capable of easily setting molding conditions that can effectively prevent occurrence of burrs. It is in.

[0006]

To achieve the above object, the present invention provides an injection molding condition setting method for injection molding a molded article using a resin, the method comprising: set the allowable value (t _0), obtains the correlation of (a) between the mold open distance and burr thickness upon molding using said resin mold during molding using said resin opening amount and the resin (B) with the injection pressure of the resin, and the correlation (C) between the amount of mold opening at the time of molding using the resin and the injection speed of the resin, and mold opening at the time of molding using the resin. A correlation (D) between the amount and the injection temperature of the resin is obtained, and from (A), a mold opening amount (δ) at which the generated burr thickness is equal to or less than the allowable value (t ₀ ) is obtained. from B), the maximum value of the injection pressure that causes the amount of opening the mold (δ) (P _max), further, the injection shortage Flip no minimum value of the injection pressure (P _min) and the maximum value (P _max), determine the proper range of the injection pressure (E), injection speed from said (C), causing the opening amount the type ([delta]) Maximum value (V _max )
From the minimum value (V _min ) and the maximum value (V _max ) of the injection speed that does not cause insufficient injection, and then determine the appropriate range (F) of the injection speed. The minimum value (T _min ) of the injection temperature that causes (δ) is obtained, and further, the injection temperature is determined from the maximum value (T _max ) of the injection temperature that can secure the desired viscosity and fluidity and the minimum value (T _min ). Is determined as the pressure, speed and temperature conditions at the time of injection with the resin, and the injection pressure (P) and the injection speed within the respective appropriate ranges (E), (F) and (G), respectively. (V) and an injection temperature (T) are selected.

[0007]

According to the above construction of the present invention, the conditions of the injection pressure, the injection speed, and the injection temperature are set so that the thickness of the burr generated on the molded product becomes equal to or less than the allowable amount. As a result, the thickness of the burr generated on the molded product is surely smaller than the allowable amount.

[0008]

[0009]

FIG. 1 is a longitudinal sectional view showing an injection molding die for performing an injection molding condition setting method according to the present invention in a mold-clamped state. In FIG. 1, a mold 1 includes a male mold 2 and a female mold 3. When the male mold 2 and the female mold 3 are clamped, the opposing surfaces of the male mold 2 and the female mold 3 partially adhere to each other to form mating surfaces 6, 7, 8. The surfaces of the male mold 2 and the female mold 3 that are separated from each other are formed in cavities 4 and 5 into which resin is injected from an injection gate (not shown).
Is defined. The cavities 4 and 5 are separated from each other by a mating surface 8, and burrs of a molded product are apt to occur on the mating surface 8 during injection molding.

The mating surface 8 is provided with a mold opening amount measuring device 10 for detecting the mold opening amount. The mold opening amount measuring device 10 includes a measuring element 11 slidably disposed in the male mold 2.
And a holder 12 connected to the tracing stylus 11 and a holder 12
And an output terminal 13 provided at the rear end. The tip surface of the tracing stylus 11 is in contact with the surface of the female mold 3 at the mating surface 8. The holder 12 urges the tracing stylus 11 toward the surface of the female mold 3, and is built in the holder 12 when the measuring stylus 11 is displaced toward the female mold 3 due to the occurrence of a gap in the mating surface 8. The detecting mechanism detects the displacement amount of the tracing stylus 11 as the mold opening amount of the mold 1. Further, the output terminal 13 is connected to a mold opening amount monitor 15 via a cord 14, and the displacement amount detected by the detection mechanism of the holder 12 is sent to the mold opening amount monitor 15 as a detection value of the mold opening amount. It is configured to be entered.

The cavity 4 is provided with an in-mold pressure sensor 20 for detecting a resin pressure in the cavity 4. The in-mold pressure sensor 20 includes a detection pin 21 facing the cavity 4 and a pressure detector 22 connected to an end of the detection pin 21. Resin pressure to pressure detector 2
2, and the detected value is input to the in-mold pressure monitor 25 via the code 24.

The opening amount monitor 15 and the in-mold pressure monitor 25 are connected to the pen recorder 3 via cords 16 and 26.
0, the pen recorder 30 records the mold opening amount and the in-mold pressure. FIG. 2 is a diagram showing a relationship between a mold opening amount and a thickness of a burr formed on a molded product.
FIG. 5 to FIG. 5 are diagrams each showing a relationship between a mold opening amount, an injection pressure, an injection speed, and a resin temperature.

FIG. 2 is a diagram showing the correlation between the mold opening amount of the mold 1 and the thickness of burrs for first and second resins having different characteristics, for example, polypropylene resin and ABS resin. As shown in FIG. 2, in both the first and second resins, the burr thickness t of the molded product increases as the mold opening amount δ increases. As indicated by the broken line for reference, when the mold alignment itself is poor, burrs are generated even though the mold opening amount is zero. Also, for the thickness t of the burr, an allowable value t set by a visual inspection of the molded product.
₀ (for example, 0.05 μm) is set as the threshold value, and the mold opening amounts δ ₁ , δ ₂ , δ ₃ that can suppress the thickness t of the burr to the threshold value t ₀ or less are determined by the first resin, This is set when the second resin and the mold matching are defective.

As shown in FIG. 3, the first resin and the second resin
The opening amount δ of the resin is determined by irradiating the resin to the cavity 4.
Outgoing pressure, that is, injection pressure P
As the injection pressure P of the resin increases, the mold 1
The mold opening amount δ increases. Mold opening amount δ₁, Δ_TwoCorrespond to
The injection pressure is the maximum value P of the injection pressure P_maxSet as
And the lower limit of injection pressure that does not cause insufficient resin injection
Value (for example, 30 to 40 kg / cm for the first resin)
^Two) Is the minimum value P of the injection pressure P_minSet as
You. Thus, for each of the first and second resins, the mold
Aperture δ₁, Δ _TwoIn relation to the maximum value P of the injection pressure P
_maxAnd the minimum value P_minCan be obtained.

As shown in FIG. 4, the opening amount δ of the first resin and the second resin has a certain correlation with the speed of the resin upon injection into the cavity 4, that is, the injection speed V. Thus, as the resin injection speed V increases, the mold opening amount δ of the mold 1 increases. The injection speeds V corresponding to the mold opening amounts δ ₁ , δ ₂ are respectively set as the maximum value V _max of the injection speed V, and the lower limit value of the injection speed at which insufficient resin injection does not occur (depending on the model of the injection molding machine). Different, for example, the first
0.5 cm / sec) is the injection speed V
_Is set as the minimum value _Vmin . Thus, for each of the first and second resins, the maximum value V _max and the minimum value V _min of the injection speed V can be obtained in relation to the mold opening amounts δ ₁ and δ ₂ .

As shown in FIG. 5, the opening amount δ of the first resin and the second resin has a certain correlation with the temperature of the resin when the resin is injected into the cavity 4, ie, the injection temperature T. As the injection temperature T of the resin increases, the opening amount δ of the mold 1 decreases. The injection temperatures corresponding to the mold opening amounts δ ₁ and δ ₂ are respectively set as the minimum value T _min of the injection temperature T, and the maximum injection of the resin which can secure desired resin characteristics, for example, desired viscosity and fluidity. Each temperature is set as the maximum value _Tmax of the injection temperature T. Thus, the first
And For each of the second resin, the mold opening amount [delta] _1, in conjunction with [delta] _2, it is possible to obtain the maximum value T _max and the minimum value T _min of the injection temperature T.

The maximum value P _max and the minimum value P _min of the injection pressure P obtained in this manner, the maximum value V _max of the injection speed V
The injection pressure P, the injection speed V, and the injection temperature T, which are defined by the minimum value V _min and the maximum value T _max and the minimum value T _min of the injection temperature T, respectively, are indicated by shadow lines in FIGS. Indicated by The injection pressure P, the injection speed V, and the injection temperature T set in the range of this region are defined by the mold opening amount δ ₁ or δ ₂ and the burr thickness threshold value t ₀ shown in FIG. Since an arbitrary mold opening amount δ is generated in the region (indicated by a shadow line in FIG. 2), in order to suppress the thickness t of the burr to be within an appropriate range, it is indicated by a shadow line in FIGS. What is necessary is just to select the injection pressure P, the injection speed V, and the injection temperature T in the region, that is, the appropriate region.

FIG. 6 shows the pressure P in the mold during injection molding.
FIG. 7 is a diagram showing the change over time of i, and FIG.
FIG. 7 is a diagram showing a correlation between a peak pressure Pm of the above and a mold opening amount δ. FIG. 8 is an explanatory view showing a method of reinforcing the mold 1. As shown in FIG. 6, the in-mold pressure Pi in the cavity 4 exhibits a maximum value at a certain point in time, and this maximum value, that is,
The peak pressure Pm has a certain correlation with the mold opening amount δ.
As shown in FIG. 7, with respect to the first and second resins, the mold opening amount δ tends to increase as the peak pressure Pi in the mold increases, so that the mold opening amount δ is changed to the mold opening amount δ _1. , Δ ₂
In order to suppress the pressure below, the peak pressures Pi of the first and second resins are set to the respective peak pressures Pm at which these resins cannot be injected.
_min (for example, 100 to 150 kg for the first resin)
/ Cm ² ) or more and not more than the peak pressure Pm _max corresponding to each of the mold opening amounts δ ₁ and δ ₂ . However, since the peak pressure Pi greatly affects the degree of filling of the resin in the cavity 4,
Until excessively reduce the peak pressure Pm _max, it is not preferable to set the value of the pressure in the region shown in FIG. For this reason,
In this example, in order to suppress the mold opening amount δ, the peak pressure Pm _{ma
When x} must be excessively reduced, the strength calculation of the mold 1 is corrected, or as shown in FIG. 8, a reinforcing pin 9b is added in addition to the support pins 9a, 9a that support the mold 1 in the middle. By doing so, the mold 1 is reinforced and the characteristic of changing the opening amount is changed. Thus, the desired peak pressure P
m can be maintained, and an opening amount δ of not more than the opening amounts δ ₁ and δ ₂ can be obtained.

Thus, in the above embodiment, the mold 1
Find the correlation between the opening amount δ and the thickness t of the burr,
Thickness t₀The mold opening that can suppress the thickness t of the burr below
δ₁, Δ _TwoAnd the mold opening δ and the injection pressure
Determine the correlation with the force P, the injection speed V or the injection temperature T,
Appropriate regions for these molding conditions are set. Furthermore, mold opening
The amount of opening δ of the mold 1 is detected by the
The thickness t of the mold is indirectly detected, and the mold opening amount δ is
Based on the relationship₁, Δ_TwoExceeds
Injection pressure P, injection speed
The degree V or the injection temperature T is set. Thus, the injection
According to the shape condition setting method, burr generation can be
This can be effectively prevented.

In the above embodiment, when the peak pressure Pm of the in-mold pressure Pi must be excessively reduced in order to suppress the mold opening amount δ, the mold 1 is reinforced to obtain a desired peak pressure. With Pm secured, the mold opening amounts δ ₁ and δ ₂ or less are obtained. Therefore, by detecting the peak pressure Pm of the in-mold pressure Pi by the in-mold pressure sensor 20, the necessity of reinforcement of the mold 1 and the reduction of the peak pressure Pm are selectively determined. It is possible to prevent the occurrence of thick burrs while securing the strength and the peak pressure Pm.

Although the preferred embodiment has been described in detail above, the present invention is not limited to the above-described embodiment, and various changes or modifications can be made, and the invention is described in the claims. It is needless to say that the present invention is included within the scope of the present invention. For example, in the above embodiment, the injection pressure P, the injection speed V, and the injection temperature T are exemplified as the molding conditions, but instead of these molding conditions,
Or, in addition to these conditions, other molding conditions, for example,
The correlation between the molding conditions and the mold opening amount may be obtained by using the resin holding pressure during injection molding and / or the measured value of the resin in the injection machine.

[0022]

According to the above configuration of the present invention, it is possible to provide an injection molding condition setting method capable of easily setting the injection molding conditions capable of effectively preventing the occurrence of burrs.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an injection molding die for performing an injection molding condition setting method according to the present invention, in a clamped state.

FIG. 2 is a diagram showing a relationship between a mold opening amount and a thickness of a burr formed on a molded product.

FIG. 3 is a diagram showing a relationship between a mold opening amount and an injection pressure.

FIG. 4 is a diagram showing a relationship between a mold opening amount and an injection speed.

FIG. 5 is a diagram showing a relationship between a mold opening amount and a resin temperature.

FIG. 6 is a diagram showing a temporal change of an in-mold pressure during injection molding.

FIG. 7 is a diagram showing a correlation between a peak pressure of an in-mold pressure and a mold opening amount.

FIG. 8 is an explanatory view showing a method of reinforcing a mold.

[Brief description of reference numerals]

 REFERENCE SIGNS LIST 1 mold 2 male mold 3 female mold 4 cavity 5 cavity 6 mating surface 7 mating surface 8 mating surface 10 mold opening measuring device 11 measuring element 12 holder 13 output terminal 20 in-mold pressure sensor 21 detection pin 22 pressure detector

Claims (1)

(57) [Claims] 1. An injection molding condition setting method for injection-molding a molded article using a resin, wherein an allowable value (t ₀ ) of a burr thickness of the molded article is set, and the resin is used. The correlation (A) between the mold opening amount at the time of molding and the burr thickness is determined, the correlation (B) between the mold opening amount at the time of molding using the resin and the injection pressure of the resin is determined, The correlation (C) between the mold opening amount at the time of molding to be used and the injection speed of the resin is obtained, and the correlation (D) between the mold opening amount at the time of molding using the resin and the injection temperature of the resin is obtained. From (A), the mold opening amount (δ) at which the thickness of the generated burr is equal to or less than the allowable value (t ₀ ) is determined, and from (B), the injection pressure for producing the mold opening amount (δ). The maximum value (P _max ) of the injection pressure is determined, and the minimum value (P _min ) of the injection pressure that does not cause insufficient injection and the maximum value (P _min ) P _max ), the injection pressure proper range (E) is obtained, and from the above (C), the maximum value (V _max ) of the injection speed that causes the mold opening amount (δ) is obtained. From the minimum value (V _min ) and the maximum value (V _max ) of the injection speed, a proper range (F) of the injection speed is obtained. From the above (D), the injection temperature for generating the mold opening amount (δ) is determined. the minimum value (T _min) the determined, further, the maximum value of the injection temperature which can ensure the desired viscosity and fluidity (T _max) and the minimum value (T _min), the proper range of the injection temperature (G)
The injection pressure (P), the injection speed (V), and the injection temperature within the appropriate ranges (E), (F), and (G), respectively, as the pressure, speed, and temperature conditions at the time of injection by the resin. An injection molding condition setting method, wherein (T) is selected.