JP3469983B2 - Injection condition setting method for injection molding machine and screw protection device for injection molding machine - 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 condition setting method and a screw protection device for an in-line screw type injection molding machine using a servo motor as an injection drive source, and more particularly to a maximum injection speed and a maximum injection speed in a primary injection stroke. The present invention relates to a method for setting the injection pressure.

[0002]

2. Description of the Related Art In an in-line screw type injection molding machine, one shot of molten resin stored on the tip side of a screw in a measuring process is injected and filled in a mold by driving the screw forward. The primary injection stroke is performed, and subsequently, the screw performs a pressure-holding stroke in which pressure (holding pressure) is applied to the resin in the mold via the molten resin remaining on the tip side of the screw. ing.

In the above primary injection process, the injection speed and the injection pressure (resin pressure) depend on the resin material and the shape of the molded product.
And the set injection speed and the set injection pressure are values below the specification maximum injection speed V _MAX and specification maximum injection pressure P _MAX that the machine (injection molding machine) has as specifications. It was supposed to allow this in any combination.

Therefore, for example, the specified maximum injection speed V
_In a machine in which _MAX is 300 mm / sec and specification maximum injection pressure P _MAX is 2000 kgf / cm ² , the maximum injection speed V _X in the primary injection stroke is 300 mm / sec.
It was possible to set the maximum injection pressure P _X to 2000 kgf / cm ² .

[0005]

As described above, the maximum injection speed V _X and the maximum injection pressure P _X in the primary injection stroke are set.
Even if both are set to the specification maximum injection speed V _MAX and the specification maximum injection pressure P _MAX of the machine, there is no problem if the machine is operating normally. That is, even if the injection speed is preferentially controlled according to the set injection speed condition to perform the primary injection and the set maximum injection speed V _X is output, the machine is operating normally. Is 1
The actually measured injection pressure (resin pressure) of the next injection does not exceed the specified maximum injection pressure P _MAX which is the upper limit monitoring value.

However, when the die is clogged or the nozzle is clogged during the execution of the primary injection, the maximum injection speed and the maximum injection pressures V _X and P _X in the primary injection process are set as described above. When the specification maximum injection speed and the specification maximum injection pressures V _MAX and P _MAX are set, the measured injection pressure (resin pressure) of the primary injection rises sharply when the servo motor is used as the injection drive source. As a result, a high peak pressure is shown, and the maximum injection pressure P _MAX , which is the upper limit monitoring value, is greatly exceeded. That is, in the case of the servo motor drive, the inertia of the injection drive unit is large, so when the specification maximum injection pressure P _MAX that is the upper limit monitoring value is detected, control is performed to reduce the pressure by reducing the high-speed injection speed. However, since the deceleration time is required, the pressure reduction control cannot catch up and a high peak pressure rises. This is, of course, a remarkable phenomenon as the injection speed is higher.

As described above, the specified maximum injection pressure P _MAX at which the actually measured injection pressure (resin pressure) of the primary injection is the upper limit monitoring value.
If the value is much higher than the above, the screw will be loaded more than the buckling load, and the screw will be bent or broken, and the expensive screw must be replaced.

FIG. 5 shows that the specified maximum injection speed V _MAX is 300.
mm / sec, specification maximum injection pressure P _MAX is 2000 kg
In a machine with f / cm ² , the maximum injection speed V _X of the primary injection stroke is 300 mm / sec, and the maximum injection pressure P is
_{When X} is set to 2000 kgf / cm ² ,
It is a graph figure which shows the relationship between the measured injection speed 51 and the measured injection pressure 52, when a gate jam of a metal mold | die generate | occur | produces in the middle of a primary injection process, for example.

As shown in FIG. 5, when the mold is clogged in the gate during the primary injection process, the molten resin is injected and filled at a high speed, so the actually measured injection pressure 52 starts to rise rapidly. Maximum injection pressure P _X (20
00 kgf / cm ² ) is exceeded. When it is recognized at time t2 that the actually measured injection pressure 52 has reached the maximum injection pressure P _X , the servo motor is controlled to rapidly decelerate the screw in order to lower the actually measured injection pressure 52 from this time point, and the actually measured injection pressure 52 is measured. The injection speed 51 starts to drop sharply from a level of about 300 mm / sec. However, as described above, in the case of the servomotor drive, the inertia of the injection drive unit is large, so the maximum injection pressure P _X (2
000 kgf / cm ² ) is detected, even if control is performed so as to reduce the pressure by decelerating the high-speed injection speed,
Since the deceleration time is required, the pressure reduction control cannot catch up, and as shown in FIG. 5, for example, a high peak pressure of about 3300 kgf / cm ² rises. Like this, 3000k
When a large pressure exceeding gf / cm ² is generated, the screw is likely to be damaged depending on the screw diameter.

The present invention has been made in view of the above points,
The purpose is to prevent screw damage such as bending and breakage from occurring in the primary injection stroke even if the mold is clogged with nozzles or nozzles during the primary injection. It is to be able to properly set the maximum injection speed and the maximum injection pressure of.

[0011]

In order to achieve the above object, the present invention provides a method for setting an injection condition of an in-line screw type injection molding machine using a servo motor as an injection drive source. The maximum injection speed V _MAX from the specification maximum injection speed V _MAX that the injection molding machine has as a specification by limiting the combination of the maximum injection pressure V and the maximum injection pressure
_{When the} maximum injection speed V _X is set in a range up to a value smaller than _MAX by a predetermined amount, the upper limit value of the maximum injection pressure P _X that is set according to the set maximum injection speed V _X is injected. From the maximum injection pressure P _MAX that the molding machine has as specifications,
Up this specification maximum injection pressure P _MAX regulated to a value in the range below a predetermined amount, from the specifications maximum injection pressure P _MAX with injection molding machine as a specification, a range of the specification maximum injection pressure P _MAX to a predetermined amount below the value When the injection pressure P _X is set, the upper limit of the maximum injection speed V _X that is set according to the set maximum injection pressure P _X is the maximum injection speed V that the injection molding machine has as a specification. _The maximum injection speed V _MAX is regulated from _MAX to a value in the range below a predetermined amount.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a diagram showing a configuration of a main part of an inline screw type injection molding machine according to an embodiment of the present invention (hereinafter referred to as this example), and a mechanism and a control system show only an injection system. is there.

In FIG. 1, 1 is a heating cylinder, 2 is a screw arranged in the heating cylinder 1 so as to be rotatable and forward / backward, 3 is a servomotor as an injection drive source, 3a is a servomotor 3. The output pulley 4 is a belt for transmitting the rotation of the output pulley 3a to the pulley 5a of the linear-to-linear movement converting mechanism 5, and the reference numeral 5 is a ball screw mechanism for converting the rotational movement into the linear movement and transmitting the linear movement to the screw 2. → Linear motion conversion mechanism, 6 is an encoder for detecting the rotation of the servomotor 3, and 7 is a load cell for detecting the resin pressure (injection pressure) applied to the screw 2.

Reference numeral 8 denotes an injection condition setting storage unit embodied by a function of a microcomputer or the like, including a setting limit range determining unit 8a,
Primary injection condition setting storage 8b and pressure holding condition setting storage 8
c and. 9 is an injection feedback control unit, 10
Is a servo amplifier.

The primary injection condition setting storage unit 8b of the injection condition setting storage unit 8 rewritably stores the control conditions of the primary injection stroke. In this example, the control conditions according to the screw stroke from the injection start position are stored. The injection speed (the injection speed set in multiple stages) and the injection pressure (primary pressure) in the primary injection process are set and stored. The control conditions for the pressure-holding stroke subsequent to the injection stroke are rewritably stored in the pressure-holding condition setting storage unit 8c of the injection condition setting storage unit 8. In this example, the control conditions according to the time from the pressure holding switching point are stored. Holding pressure (holding pressure set in multiple stages) is set and stored.

The injection feedback control unit 9 sets the setting data stored in the primary injection condition setting storage unit 8b and the pressure holding condition setting storage unit 8c, the measured speed data obtained by appropriately converting the output of the encoder 6, and Based on the measured pressure data obtained by appropriately converting the output of the load cell 7, a control signal is generated and output to the servo amplifier 10, and the servo motor 3 is drive-controlled. That is, in the primary injection stroke, the injection feedback control unit 9
The servomotor 3 is drive-controlled via the servo amplifier 10 so that the measured speed data matches the injection speed setting data stored in the primary injection condition setting storage section 8b. The servomotor 3 is drive-controlled via the servo amplifier 10 so that the actually measured pressure data matches the holding pressure setting data stored in the condition setting storage section 8c.

The rotation of the servo motor 3 is controlled by the output pulley 3
a, rotation via belt 4 → linear motion conversion mechanism 5
Is transmitted to the pulley 5a, and the rotational movement is converted into the linear movement by the rotation → linear movement converting mechanism 5 and transmitted to the screw 2. As a result, in the primary injection stroke, the screw 2 is driven forward by feedback control so as to follow the set injection speed, and the molten resin stored on the tip side of the screw 2 in the known measurement stroke is transferred to the metal mold. It is injected and filled in the mold. Further, in the pressure-holding process, the pressure following the set pressure-holding pressure is applied to the screw 2
The forward pressure of the screw 2 is controlled by feedback control so that it is applied to the resin in the mold via the.

Here, in this example, the combination of the maximum injection speed and the maximum injection pressure set in the above-mentioned primary injection stroke is limited, and the maximum injection speed input by the operator (multistage setting is performed. Whether the combination of the maximum one in the injection speed) and the maximum injection pressure (here, the constant primary pressure) can be set (whether the setting is permissible) is determined by the injection condition. The setting limit range determination unit 8a of the setting storage unit 8 makes a determination.

[0019] That is, setting limits determination unit 8a, the specification maximum injection speed V _MAX with machine (injection molding machine) as a specification, below a predetermined amount the specification maximum injection speed V _MAX (e.g., 15-25%) When the maximum injection speed V _X is set within the range up to the value, the set maximum injection speed V _X
The maximum injection pressure P _X (primary pressure here) that is set according to the value of _X is set from the maximum injection pressure P _MAX that the machine has as a specification to a predetermined maximum injection pressure P _MAX . regulated to a value in the range below, and the maximum injection pressure in the range from the specification maximum injection pressure P _MAX with machine as specifications, until a predetermined amount of this specification maximum injection pressure P _MAX (e.g., 10-20%) lower than the value When P _X (here, the primary pressure) is set, the injection molding machine has the upper limit of the maximum injection speed V _X that is set according to the value of the set maximum injection pressure P _X. From the specification maximum injection speed V _MAX ,
The specification maximum injection speed V _MAX is regulated to a value in a range below a predetermined amount.

Further, the setting limit range determining unit 8a is configured to allow the maximum injection speed V _X and the maximum injection pressure P _X input by the operator.
And both are values in a range that regulates the other upper limit value, the maximum injection pressure P _X is given priority and automatically set in the primary injection condition setting storage unit 8b, and the maximum injection speed V _X is calculated according to the value of the set maximum injection pressure P _X, specifications from the maximum injection speed V _MAX, the range of values of this specification maximum injection speed V _MAX below a predetermined amount, which first injection molding condition setting storage unit 8b is automatically set.

FIG. 2 is a diagram showing an example of a combination range of the maximum injection speed and the maximum injection pressure which can be set in the primary injection stroke according to the present example, and here, the maximum specification injection speed V _{MAX of the} machine is shown. Is 300 mm / sec, and the specified maximum injection pressure P _MAX is 2000 kgf / cm ² .

As the maximum injection speed V _{X in the} primary injection stroke,
300mm / sec (= specification maximum injection speed V _MAX ) ~ 2
40mm / sec (= specification maximum injection speed V _MAX is 20%
When the range of (lower value) is input by the operator, according to the value of the input maximum injection speed V _X ,
The upper limit of the settable maximum injection pressure P _X (primary pressure here) is calculated, and the upper limit of the maximum injection pressure P _X is set to 2000.
kgf / cm ² (= specification maximum injection pressure P _MAX ) ~ 170
0kgf / cm ² (= maximum specified injection pressure P _MAX is 15%
(Lower value). That is, for example, when 300 mm / sec is set as the maximum injection speed V _X , the upper limit of the maximum injection pressure P _X is 1700 kgf / cm.
Restricted to ² , maximum injection speed V _X 270 mm / se
When c is set, the upper limit of the maximum injection pressure P _X is restricted to about 1850 kgf / cm ² , and the maximum injection speed V _{X is set.}
When 240 mm / sec is set, the upper limit of the maximum injection pressure P _X is set to 2000 kgf / cm ² (= specification maximum injection pressure P _MAX ).

The maximum injection pressure P _{X in the} primary injection stroke
(Primary pressure in this case) 2000 kgf / cm ²
(= Specification maximum injection pressure P _MAX ) ~ 1700kgf / cm
² If the range of (= specification maximum injection pressure P _MAX of less than 15% value) is entered by the operator, depending on the value of the maximum injection pressure P _X to the input, the maximum settable injection speed V _X Of the maximum injection speed V _X , and the upper limit of the maximum injection speed V _X is calculated as 300 mm / sec (= the specified maximum injection speed V
_MAX ) ~ 240mm / sec (= Specification maximum injection speed V
_The value is 20% below _MAX ). That is, for example, when 2000 kgf / cm ² is set as the maximum injection pressure P _X , the upper limit of the maximum injection speed V _X is set to 24
Restricted to 0 mm / sec, maximum injection pressure P _X is 18
When 50 kgf / cm ² is set, the upper limit value of the maximum injection speed V _X is restricted to about 270 mm / sec, and when 1700 kgf / cm ² is set as the maximum injection pressure P _X , the maximum injection speed is set. The upper limit of V _X is 300 mm /
and sec (= specification maximum injection speed V _{MA X).}

In FIG. 2, the hatched area 21 is a combination range (settable range) of the maximum injection speed and the maximum injection pressure that can be set in the primary injection stroke, and the doted area 22 is. , This is an area where setting is prohibited.

[0025] In the example described above, the range of the specification maximum injection speed V _MAX values below the specification maximum injection speed V _MAX 20%, and, below 15% specification maximum injection pressure P _MAX from the specification maximum injection pressure P _MAX in the range of values, but so as to regulate the upper limit of the mating of the maximum injection speed V _X or maximum injection pressure P _X, the extent below much of the specification maximum injection speed V _MAX or specification maximum injection pressure P _MAX ,
It is arbitrary to set the upper limit value of the other side (speed or pressure) as a range, and the appropriate range is determined according to screw design such as L / D (length / diameter).

FIG. 3 is a diagram showing an example of the injection setting screen called on the display device (not shown) in this example.
When the operator operates a key input device (not shown), the injection setting screen is displayed on the display device, and by interactively inputting numerical values into each setting item column, the injection conditions can be changed. Is set.

In the primary injection condition setting field 31 shown in FIG. 3, the operator sets 2000 kgf / cm ² (= specification maximum injection pressure P _MAX ) as the maximum injection pressure P _X (primary pressure in this case) of the primary injection stroke. Is input and 300 mm / sec (= specification maximum injection speed V _MAX ) is input as the maximum injection speed V _{X in} the primary injection stroke, the setting limit range determination unit 8a causes the maximum injection pressure P _X (= 2000 kgf /
cm ² ) is preferentially automatically set in the primary injection condition setting storage section 8b, and the maximum injection speed V _X is 240 mm / s.
ec is calculated and automatically set in the primary injection condition setting storage unit 8b. In FIG. 3, the maximum injection speed setting unit 31a of the primary injection condition setting field 31 is set to 300 mm / se.
It is shown that c is rewritten to 240 mm / sec and that the window display unit 32 displays an alarm to the operator that the processing has been performed in this manner.

FIG. 4 shows that the specified maximum injection speed V _MAX is 300.
mm / sec, specification maximum injection pressure P _MAX is 2000 kg
In the machine with f / cm ² , the maximum injection pressure P _X in the primary injection stroke is set to 2000 kgf / cm ² , and the maximum injection speed V _X is 240 m by the above-mentioned upper limit value limiting method.
FIG. 6 is a graph showing a relationship between an actually measured injection speed 41 and an actually measured injection pressure 42 when, for example, a die is clogged during a primary injection process when m / sec is set.

As shown in FIG. 4, when the mold is clogged during the primary injection stroke, the maximum injection speed V of the specified maximum is reached.
_Although the value is not as high as _MAX (300 mm / sec), since the molten resin is injected and filled at a high speed, the measured injection pressure 42 starts to rise rapidly, and the maximum injection pressure P _X (2000 kgf) that is the upper limit monitoring value. / Cm ² ). When it is recognized at time t1 that the actually measured injection pressure 42 reaches the maximum injection pressure P _X , the servo motor 3 is controlled to rapidly decelerate the screw 2 from this time point in order to lower the actually measured injection pressure 42. , The measured injection speed 41 is approximately 240 mm
It begins to fall sharply from the level of / sec. At this time, unlike the case shown in FIG. 5, the pressure is not rapidly decelerated from approximately 300 mm / sec, but is rapidly decelerated from 240 mm / sec at most, so that the pressure reduction control by decelerating the injection speed is relatively good. Effectively, the peak pressure of the actually measured injection pressure 42 is about 2750 kgf / cm ² . Therefore, compared with the case of FIG. 5, the peak pressure becomes smaller, and the occurrence of screw damage can be suppressed as much as possible, regardless of the screw diameter and the like.

Although not shown, the specification maximum injection speed V _MAX is 300 mm / sec and the specification maximum injection pressure P is
_On a machine with a _MAX of 2000 kgf / cm ² ,
Maximum injection pressure P _X in the primary injection stroke is 1700 kgf / c
m ² and set the maximum injection speed V _X to 300 mm / sec
If, for example, a die gate is clogged during the primary injection stroke when the setting is set to 0, the servo motor 3 starts to operate when the maximum injection pressure P _X (1700 kgf / cm ² ) which is the upper limit monitoring value is exceeded. Since the screw is controlled so as to be rapidly decelerated in order to lower the measured injection pressure, the peak pressure of the measured injection pressure is smaller than that in the case of FIG. 5 also in this case.

In other words, in the present invention, the peak pressure of the actually measured injection pressure generated when the die is clogged with the gate or the nozzle is clogged during the primary injection stroke so that the screw is not damaged. , The maximum injection speed V _X and the maximum injection pressure P _X are limited, and it goes without saying that the peak pressure at a level that does not cause screw damage varies depending on the screw design and the like. Yes.

In the above-mentioned example, the maximum injection pressure P _X is a constant primary pressure during the primary injection stroke, but when the injection pressure is set in multiple stages in the primary injection stroke, the injection pressure is set. The largest of them is the maximum injection pressure P _X.

In the above example, if the maximum injection speed V _X and the maximum injection pressure P _X input by the operator are both within the range that regulates the upper limit of the other, the maximum injection is performed. The pressure P _X is prioritized and automatically set. However, when the maximum injection speed V _X and the maximum injection pressure P _X input by the operator are both values within a range that regulates the other upper limit value. May display an alarm to prompt the operator to re-input.

[0034]

As described above, according to the present invention, even when the die is clogged with the nozzle or the nozzle is clogged during the execution of the primary injection, the screw may be damaged such as bending or breaking. The maximum injection speed and maximum injection pressure in the primary injection stroke can be set easily and reliably without any risk of erroneous input, and even if the range is limited, the degree of freedom of the combination range of pressure and speed is high. You can secure enough.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main configuration of an inline screw type injection molding machine according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a combination range of the maximum injection speed and the maximum injection pressure that can be set in the primary injection stroke according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of an injection setting screen according to the embodiment of the present invention.

FIG. 4 is a graph showing a relationship between an actually measured injection speed and an actually measured injection pressure when the die is clogged during the primary injection process according to the first embodiment of the present invention.

FIG. 5 is a graph showing a relationship between an actually measured injection speed and an actually measured injection pressure when a mold gate is clogged during a primary injection process according to a conventional technique.

[Explanation of symbols]

1 heating cylinder 2 screws 3 Servo motor 3a Output pulley 4 belts 5 rotation → linear motion conversion mechanism 5a pulley 6 encoder 7 load cell 8 Injection condition setting storage section 8a Setting limit range determination unit 8b Primary injection condition setting storage unit 8c Holding pressure condition setting storage 9 Injection feedback controller 10 Servo amplifier

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A 61-249734 (JP, A) JP-A 6-246801 (JP, A) JP-A 5-169505 (JP, A) JP-A 6- 23813 (JP, A) JP-A-2-43021 (JP, A) International Publication 87/4388 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45 / 50,45 / 76 B29C 45 / 77,45 / 84

Claims (3)

(57) [Claims] 1. A servomotor is used as an injection drive source,
In the injection molding machine that transmits the rotation of this servo motor to the screw in the heating cylinder via the rotation-> linear motion conversion mechanism and injects the molten resin into the mold by the forward movement of the screw, the maximum injection speed in the primary injection stroke By limiting the combination of the maximum injection pressure and the maximum injection pressure, the maximum injection speed V _X can be set within a range from the maximum injection speed V _MAX specified by the injection molding machine to a value lower than the maximum injection speed V _MAX by a predetermined amount. If set, the upper limit of the maximum injection pressure P _X that is set according to the set maximum injection speed V _X is set from the specification maximum injection pressure P _MAX that the injection molding machine has as a specification. Maximum injection pressure P
_The maximum injection pressure P _X is set within a range from the specified maximum injection pressure P _MAX that the injection molding machine has as a specification to a value that is below the specified maximum injection pressure P _MAX by limiting the value to a value below the specified amount. In this case, the upper limit of the maximum injection speed V _X that is set according to the set maximum injection pressure P _X is set from the specification maximum injection speed V _MAX that the injection molding machine has as a specification to this specification maximum. Injection speed V
An injection condition setting method for an injection molding machine, characterized in that the value is regulated to a value within a predetermined amount less than _MAX . 2. The maximum injection pressure according to claim 1, when the maximum injection speed V _X and the maximum injection pressure P _X input by the operator are both within a range that regulates the upper limit of the other. P _X has priority and is set automatically,
The maximum injection speed V _X is automatically set to a value in the range below the specified maximum injection speed V _MAX from the specified maximum injection speed V _MAX according to the value of the set maximum injection pressure P _X. A method for setting injection conditions for an injection molding machine, characterized in that 3. A servomotor is used as an injection drive source,
In the injection molding machine that transmits the rotation of this servo motor to the screw in the heating cylinder via the rotation-> linear motion conversion mechanism and injects the molten resin into the mold by the forward movement of the screw, the maximum injection speed in the primary injection stroke By limiting the combination of the maximum injection pressure and the maximum injection pressure, the maximum injection speed V _X can be set within a range from the maximum injection speed V _MAX specified by the injection molding machine to a value lower than the maximum injection speed V _MAX by a predetermined amount. If set, the upper limit of the maximum injection pressure P _X that is set according to the set maximum injection speed V _X is set from the specification maximum injection pressure P _MAX that the injection molding machine has as a specification. Maximum injection pressure P
_The maximum injection pressure P _X is set within a range from the specified maximum injection pressure P _MAX that the injection molding machine has as a specification to a value that is below the specified maximum injection pressure P _MAX by limiting the value to a value below the specified amount. In this case, the upper limit of the maximum injection speed V _X that is set according to the set maximum injection pressure P _X is set from the specification maximum injection speed V _MAX that the injection molding machine has as a specification to this specification maximum. Injection speed V
A screw protection device for an injection molding machine, which is designed to prevent damage to the screw by limiting the value to a value below _MAX by a predetermined amount.