JP5367736B2 - Resin temperature control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of controlling the temperature of molten resin just injected from an injection nozzle to an appropriate temperature. <P>SOLUTION: The molten resin generates heat by friction and shearing when injected from the injection nozzle (17) and its temperature becomes higher than that of before-injected molten resin in a heating cylinder (13). It is supposed that it is injected with the injection nozzle (17) separated from a die, and an injection pressure (P<SB POS="POST">0</SB>) measured at that time is lost and is changed to heat energy. Thus, a temperature rise amount(&Delta;T) of the molten resin by heat generation can be estimated. A target temperature (Tt) on the exit side of the injection nozzle (17) is determined. A pre-injection target temperature (Tk) of the temperature of the molten resin in the heating cylinder (13) is determined by subtracting the temperature rise amount (&Delta;T) from the injection nozzle exit side target temperature (Tt). <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention provides a heating cylinder in which a heater is provided on the outer peripheral portion and a nozzle is provided on the tip portion, a screw provided in the heating cylinder so as to be driven in the rotational direction and the axial direction, or driven in the axial direction. The present invention relates to a temperature control method for controlling the temperature of a molten resin in an injection molding machine provided with an injection device comprising a plunger provided as possible.

  As is conventionally known, an injection molding machine is composed of a pair of molds, a mold clamping device that clamps these molds, an injection device that melts and injects a resin material, and the like. The heating cylinder is composed of a screw driven in the rotation direction and the axial direction in the heating cylinder. The heating cylinder is provided with a band heater at the outer periphery and an injection nozzle at the tip, and the tip of the injection nozzle touches the sprue of the mold. Therefore, when the heating cylinder is heated by the band heater and the screw is driven to rotate and the resin material is supplied to the heating cylinder in a predetermined amount, the resin material is heated by the heat from the band heater and the friction / shearing action caused by the rotation of the screw. Melt and weigh at the tip of the cylinder. After weighing, when the screw is driven in the axial direction, the molten resin is injected from the injection nozzle and injected into and filled in the mold cavity that has been clamped. When the mold is opened after cooling and solidification, a molded product is obtained.

JP 2009-233892 A Japanese Patent Laid-Open No. 05-77301 JP 2002-331558 A

  It is important to control the temperature of the molten resin in injection molding, and an injection molding machine in which a temperature sensor is provided in a heating cylinder or an injection nozzle is well known. As such an injection molding machine, for example, Patent Document 1 proposes an injection molding machine in which a temperature sensor is provided in an injection nozzle. In this injection molding machine, the temperature of the molten resin in the injection nozzle can be measured. Accordingly, the temperature of the molten resin in the injection nozzle can be controlled to an appropriate temperature by operating the output of the band heater.

  It is also important to grasp the characteristics, changes, etc. of the injected molten resin. Patent Document 2 discloses a method for estimating the temperature distribution of the resin after being injected into the mold cavity. Methods for evaluating resin characteristics specific to an injection molding machine have been proposed. Patent document 2 is a patent document filed by the present applicant. In this document, the mold temperature is measured by a temperature sensor provided in the mold, and the inside of the cavity is measured based on the mold temperature. Describes a method for estimating the temperature distribution at each position in the thickness direction of the injected resin and the temperature change with the passage of time during cooling by a predetermined calculation. This makes it possible to analyze the behavior of the injection material that shrinks in the cavity as it cools and solidifies, for example. On the other hand, in Patent Document 3, it is necessary to realize the resin characteristics unique to each injection molding machine, for example, the relationship between the temperature of the molten resin and the injection pressure required to inject the molten resin, the injection speed and the injection speed. A method for evaluating / estimating the relationship with the injection pressure is described. In general, since the viscosity of the molten resin depends on the temperature of the molten resin, this method can appropriately evaluate and estimate the influence of the temperature of the molten resin on the injection pressure and the injection speed. In Patent Document 3, the temperature of the molten resin is a temperature in all zones of the heating cylinder, that is, an average temperature, and does not consider a temperature that changes partially and temporally with injection.

  According to an injection molding machine in which a temperature sensor is provided in the heating cylinder or an injection molding machine in which a temperature sensor is provided in the injection nozzle, it is possible to measure the temperature of the molten resin in the heating cylinder or in the injection nozzle. it can. Therefore, the temperature of these molten resins can be controlled by adjusting the output of the band heater. Further, as in the method described in Patent Document 2, it is possible to estimate the temperature distribution of the resin injected into the cavity and the temperature change with time. And like the method of patent document 3, the injection pressure and the injection speed which depend on the temperature of molten resin can be evaluated and estimated appropriately. However, in the conventional injection molding machine and the methods described in Patent Documents 2 and 3, no special consideration is given to the temperature rise of the molten resin accompanying the injection. When the molten resin is injected from the injection nozzle, heat is generated by friction and shearing action in the pipe, so that the molten resin on the outlet side of the injection nozzle, in other words, the molten resin immediately after injection is the molten resin in the heating cylinder or the injection nozzle. It becomes hotter than. In particular, in the case of an injection nozzle having a narrow flow path, such as an injection nozzle having a shut-off valve, the degree of the temperature rise of the molten resin accompanying injection is significant. Even the temperature sensor described in Patent Document 1 can only measure the temperature of the resin in the injection nozzle, and is substantially the same as the temperature of the resin in the heating cylinder. That is, it is not the temperature of the resin immediately after injection. The viscosity of the molten resin changes with temperature, and the temperature also affects the strength of the molded product. Moreover, since it becomes a cause of a burning and a silver streak when it becomes high temperature, management of the temperature of the resin after a raise is important. In particular, when it is desired to inject at a temperature in the vicinity of the allowable upper limit, consideration regarding this point is extremely important. However, this temperature rise is not considered in any of the methods described in any literature. If a temperature sensor is provided in the mold or at the tip of the injection nozzle, it seems possible to measure the temperature of the molten resin immediately after injection, but this can be simply measured and controlled to the desired temperature. Not a way. Furthermore, it is difficult to perform high pressure molding considering the pressure resistance performance of the temperature sensor. Therefore, even if a sensor is provided at such a position, the problem cannot be solved.

  An object of the present invention is to provide a method for controlling the temperature of a molten resin that solves the above-described problems. Specifically, the temperature of the molten resin injected from an injection nozzle is a predetermined temperature. It aims at providing the temperature control method of the molten resin which controls so that it may become target temperature. Further, the molten resin generates heat not only immediately after being injected from the injection nozzle, but also at the runner, gate, etc. in the mold due to friction and shear energy, and the temperature rises. Therefore, depending on molding conditions, it is necessary to consider the temperature of the molten resin in the mold. Accordingly, another object of the present invention is to provide a molten resin temperature control method for controlling the temperature of the molten resin immediately after being injected into the mold cavity to a predetermined target temperature.

  In order to achieve the above object, the present invention is provided with a heating cylinder in which a heater is provided on the outer peripheral portion and an injection nozzle is provided on the tip portion, and the heating cylinder can be driven in the rotational direction and the axial direction. A method for controlling the resin temperature in the heating cylinder or the injection nozzle to be a predetermined pre-injection target temperature in an injection device comprising a screw or a plunger provided to be axially drivable To do.

  First, an injection nozzle outlet side target temperature, which is a temperature target value of the resin immediately after injection at the injection nozzle, is determined. Next, an increase in the resin temperature that generates heat due to the loss of the injection pressure during injection is estimated. The pre-injection target temperature of the resin in the heating cylinder or the injection nozzle is determined so that the pre-injection target temperature plus the estimated increase becomes the injection nozzle outlet side target temperature. Further, the loss of the injection pressure that contributes to the heat generation of the resin is equivalent to the injection pressure when the injection nozzle is injected in a state of being separated from the sprue of the mold. In another invention, a target temperature in the cavity that is a temperature target value of the resin immediately after being injected into the cavity in the mold is determined. Next, an increase in the resin temperature that generates heat due to the loss of the injection pressure during injection is estimated. The pre-injection target temperature of the resin in the heating cylinder or the injection nozzle is determined so as to be the target temperature in the cavity obtained by adding the estimated increase to the pre-injection target temperature.

Thus, in order to achieve the above object, the invention according to claim 1 is a heating cylinder in which a heater is provided in the outer peripheral portion and an injection nozzle is provided in the tip portion, and a rotation direction and an axial direction are provided in the heating cylinder. The resin temperature in the heating cylinder or in the injection nozzle is a predetermined pre-injection target temperature in an injection device comprising a screw provided in a driveable manner or a plunger provided in an axial direction. When controlling in such a manner, the injection nozzle outlet side target temperature, which is the temperature target value of the resin immediately after injection in the injection nozzle, is determined, and the increase in the resin temperature that generates heat with the loss of injection pressure during injection is estimated, the pre-injection target temperature, so as to determine as plus rise which is the estimated injection-Delivery target temperature is the injection nozzle outlet target temperature, the The pressure loss corresponding to the loss of the output pressure is considered to be equivalent to the injection pressure measured when the injection nozzle is injected away from the mold sprue, thereby estimating the estimated rise temperature. It is comprised as a temperature control method of resin characterized by this.
According to a second aspect of the present invention, there is provided a heating cylinder in which a heater is provided on the outer peripheral portion and an injection nozzle is provided on the tip portion, and a screw provided in the heating cylinder so as to be driven in the rotational direction and the axial direction. Or an injection device comprising an axially drivable plunger, wherein the injection nozzle is controlled when the resin temperature in the heating cylinder or the injection nozzle is controlled to a predetermined pre-injection target temperature. The target temperature on the injection nozzle outlet side, which is the target temperature value of the resin immediately after injection, is estimated, the amount of increase in the resin temperature that generates heat due to the loss of injection pressure at the time of injection is estimated, and the target temperature before injection is It is determined that the pre-target temperature plus the estimated increase becomes the injection nozzle outlet side target temperature, and the increase in the resin temperature is determined by the injection device. Dynamic driving energy, constructed as a temperature control method of a resin, wherein the energy of the predetermined ratio is estimated as being contributed.
According to a third aspect of the present invention, there is provided a heating cylinder in which a heater is provided on an outer peripheral portion and an injection nozzle is provided on a distal end portion, and a screw provided in the heating cylinder so as to be driven in a rotational direction and an axial direction. Or a plunger provided so as to be drivable in the axial direction, when the resin temperature in the heating cylinder or the injection nozzle is controlled to be a predetermined pre-injection target temperature. The target temperature in the cavity, which is the temperature target value of the resin immediately after being injected into the cavity, is estimated, the amount of increase in the resin temperature that generates heat with the loss of injection pressure during injection is estimated, and the target temperature before injection is as plus the injection rise which is the estimated Delivery target temperature is determined to be the cavity within the target temperature, the loss of the injection pressure to the screw during the injection Of the actual injection pressure applied to the resin I, configured as a temperature control method of the resin and estimates the rise of the resin temperature as a predetermined ratio is changed to heat energy.

As described above, the present invention includes a heating cylinder in which a heater is provided on the outer periphery and an injection nozzle is provided on the tip, and a screw provided in the heating cylinder so as to be able to be driven in the rotational direction and the axial direction. Alternatively, in an injection device comprising a plunger provided so as to be drivable in the axial direction, it is configured as a method for controlling the resin temperature in the heating cylinder or the injection nozzle so as to become a predetermined pre-injection target temperature. . Then, an injection nozzle outlet side target temperature that is a temperature target value of the resin immediately after injection in the injection nozzle is determined, and an increase in the resin temperature that generates heat due to a loss of injection pressure at the time of injection is estimated, and the target temperature before injection Is determined so that the target temperature before injection plus the estimated increase is the target temperature on the injection nozzle outlet side. Therefore, it is possible to control the temperature of the resin on the injection nozzle outlet side so as to be the target temperature on the injection nozzle outlet side. As a result, the resin injected into the mold can be injected at a desired temperature. And since it can prevent that the temperature of resin exceeds an allowable upper limit, generation | occurrence | production of molding defects, such as a burn and a silver streak, can be suppressed. The value is particularly high when the resin is injected at a temperature in the vicinity of the allowable upper limit. According to the present invention, the pressure loss corresponding to the loss of the injection pressure is regarded as equivalent to the injection pressure measured when the injection nozzle is injected away from the mold sprue, and the estimated rise temperature Is configured to estimate. That is, the pressure loss can be measured only by performing a test of injecting the injection nozzle away from the mold, and the temperature rising with the injection can be easily estimated. Since the rising temperature can be estimated by a simple method, it can be easily carried out even in a conventional injection molding machine. According to another aspect of the invention, the increase in the resin temperature is estimated to be caused by a predetermined percentage of the driving energy for driving the injection device, so that the servo for driving the injection device is used. By measuring the driving energy of the motor, that is, the energy consumption, the temperature rise can be easily estimated. According to another invention, when the resin temperature in the heating cylinder or the injection nozzle is controlled so as to become a predetermined pre-injection target temperature, it is the temperature target value of the resin immediately after being injected into the cavity in the mold. Establishing the target temperature in the cavity and estimating the increase in the resin temperature that generates heat due to the loss of injection pressure during injection, the target temperature before injection is the target temperature before injection plus the estimated increase Is configured to determine a target temperature in the cavity. Therefore, the temperature of the resin immediately after being injected into the cavity in the mold can be controlled to be a desired temperature. Therefore, molding defects such as burning, silver streak, and black streak can be reliably prevented.

It is side surface sectional drawing which shows a part of injection molding machine which concerns on embodiment of this invention. It is a block diagram which shows the temperature control method of resin which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below. An injection molding machine 1 according to the present embodiment includes an injection device 2, a mold clamping device 6 including a fixed plate 4, a movable plate 5, and a mold opening / closing mechanism, and a part thereof is shown in FIG. . A fixed mold 8 is attached to the fixed platen 4, and a sprue 8 a of the fixed mold 8 is exposed on the back surface by a cutout 4 a formed on the fixed platen 4. The injection nozzle 17 of the injection device 2 touches the sprue 8a. A movable mold 9 is attached to the movable platen 5. When the fixed mold 8 and the movable mold 9 are clamped, a cavity 10 is configured. Resin is injected into the cavity 10 from the gate 11.

  The injection device 2 is also configured in the same manner as a conventionally known injection device, and includes a heating cylinder 13 having a predetermined diameter, a screw 14 provided in the heating cylinder 13 so as to be driven in the rotational direction and the axial direction, and the like. It is configured. An injection nozzle 17 is provided at the tip of the heating cylinder 13 via an adapter block 15, and a plurality of band heaters 19, 19,... Are provided on the outer peripheral surfaces of the heating cylinder 13, adapter block 15, and injection nozzle 17. It is rolled up. The heating cylinder 13 is provided with a heating cylinder temperature sensor 20 embedded to a depth near the cylinder bore 13a. Similarly, the injection nozzle 17 has an injection nozzle temperature sensor 21 embedded to a depth near the resin flow path 17a. Is provided. These temperature sensors 20, 21 are connected to the controller 23 of the injection molding machine by signal lines S1, S2, and the temperature of the molten resin in the heating cylinder 13 and the injection nozzle 17, that is, the temperature of the molten resin before injection, is determined. It is sent to the controller 23. The band heaters 19, 19,... Are operated by power supplied from a predetermined power supply device, and a signal line is connected to the power supply device so that it can be controlled from the controller 23. Are connected to the controller 23 directly by signal lines S3, S3,. Although not shown in FIG. 1, a hopper for supplying a resin material is provided near the rear end of the heating cylinder 13, and the screw is driven in the rotational direction and the axial direction at the rear end of the screw 14. A drive mechanism is provided. Further, the injection device is also provided with a mechanism for moving the entire injection device forward or backward. The injection device 17 is moved forward to cause the injection nozzle 17 to touch the sprue 8a of the fixed mold 8 or to be moved backward to cause the injection nozzle 17 to move backward. And the stationary mold 8 can be separated from each other.

  In the injection molding machine 1, when the molten resin in the heating cylinder 13 is pushed out by the screw 14 and injected from the injection nozzle 17, the molten resin flows through the resin flow path 17 a of the injection nozzle 17 and receives heat and friction to generate heat. . You can also say: Since the molten resin is throttled by the resin flow path 17a of the injection nozzle 17, a predetermined amount of the injection pressure given by the screw 14 is lost. The energy corresponding to the pressure loss changes to thermal energy, and the temperature of the molten resin rises. Therefore, the temperature of the molten resin immediately after being injected from the injection nozzle 17 or the resin on the injection nozzle outlet side is higher than that of the molten resin before injection in the heating cylinder 13. In the present embodiment, the temperature of the molten resin before injection in the heating cylinder 13 is controlled so that the resin on the injection nozzle outlet side has a desired temperature. Hereinafter, the control method will be described with reference to FIG.

First, the injection device 2 is moved backward to separate the injection nozzle 17 and the sprue 8a of the fixed mold 8 from each other. The injection nozzle outlet side target temperature Tt, which is the target temperature value, is set in the controller 23 for the resin on the injection nozzle outlet side. Further, the specific heat c and the density d, which are physical property values of the molten resin, are input to the controller 23, and other physical property values are also input as necessary (step S1). The injection speed v is determined as the injection condition, and this is also set in the controller 23 (step S2). A temporary target temperature T ₀ that is a temporary target temperature is set for the temperature of the molten resin before injection in the heating cylinder 13 (step S3). Tentative target temperature T ₀ is set to a temperature lower than the injection nozzle injected resin the target temperature Tt. For example, it is possible to set a value obtained by subtracting only a fixed number from the injection nozzle outlet target temperature Tt as a tentative target temperature T _0. Alternatively, when the temperature rise of the molten resin in the injection nozzle 17 can be empirically predicted, a value obtained by subtracting the predicted temperature rise from the injection nozzle outlet side target temperature Tt is set as the temporary target temperature T _0. Also good.

The band heaters 19, 19,... Are operated and the screw 14 is rotated to supply the resin material from the hopper. The supplied resin material is melted by the heat of the band heaters 19, 19,... And the shear energy generated by the rotation of the screw 14, and is measured at the tip of the screw 14. The time controller 23 includes a band heater 19, by adjusting the ... output temperature of the molten resin within the heating cylinder 13 is controlled to be the tentative target temperature T ₀ (step S4). An injection operation is executed according to a command from the controller 23. That is, the screw 14 is driven in the axial direction at the set injection speed v. Then, the molten resin is injected from the injection nozzle 17 into the atmosphere. Storing the injection stroke L and the injection pressure _{P 0} in this case the controller 23 (step S5).

As described above, the energy corresponding to the pressure loss at the time of injection changes to thermal energy and raises the temperature of the molten resin. That is, the pressure loss contributes to the temperature rise ΔT of the molten resin. Since the molten resin injected at the injection pressure P ₀ is injected into the atmospheric pressure from the injection nozzle 17, the pressure loss due to the injection can be regarded as equivalent to the injection pressure P ₀ . The energy given to the resin by the screw 14 is given by the following equation from the injection pressure P ₀ and the injection stroke L, where the sectional area S of the heating cylinder 13 is taken.
P ₀ × S × L (1 set)
On the other hand, since the mass of the injected resin is given by S × L × d from the cross-sectional area S of the heating cylinder 13, the injection stroke L, and the density d, the thermal energy is expressed by the following equation according to the temperature rise ΔT and the specific heat c. Given in.
S × L × d × ΔT × c (2 formulas)
When the temperature increase ΔT is calculated on the assumption that all the energy applied by the screw 14 has changed to thermal energy, the temperature increase ΔT is given by the following equation.
ΔT = P ₀ / (d × c) (3 formulas)
The estimated value T ′ of the resin immediately after being injected from the injection nozzle 17, that is, the temperature of the injection nozzle outlet side resin, is calculated by the following equation (step S6).
T ′ = T ₀ + ΔT (4 formulas)

It is checked whether or not the estimated value T ′ of the temperature of the injection nozzle outlet side resin obtained by the equation 4 is sufficiently close to the injection nozzle outlet side target temperature Tt. Specifically, it is determined by the following equation based on a predetermined threshold value Ts (step S7).
| T′−Tt | <Ts (5 formulas)
If the above equation is false, adjusting the tentative target temperature T _0. For example, when T ′ <Tt, the temporary target temperature T ₀ is increased by Tt−T ′. If T ′> Tt, the temporary target temperature T ₀ is decreased by T′−Tt (step S8). Based on the tentative target temperature T ₀ which is increased or decreased, the process is repeated from step S4. Equation 5 is the case of true determines the provisional target temperature T ₀ as a target temperature Tk of the resin in the heating cylinder 13 (step S9).

  The injection device 2 is moved forward and the injection nozzle 17 is touched to the sprue 8a of the fixed mold 8. Control is performed so that the resin in the heating cylinder 13 reaches the target temperature Tk. A molding cycle is performed as is conventionally known.

Strictly speaking, since the viscosity of the molten resin depends on the temperature, the injection pressure P ₀ changes as the temperature of the resin changes. In the above-described embodiment, up to satisfy Equation 5 by changing the temperature of the molten resin within the heating cylinder 13, and to adjust the tentative target temperature T ₀ by performing a repeated injection. Therefore, even when the viscosity of the molten resin changes, the injection pressure P ₀ can be detected accurately every time. That is, the temperature rise ΔT can be accurately estimated. However, it can be considered that the viscosity of the molten resin is constant within a predetermined temperature range. Alternatively, the change in viscosity can be ignored depending on the type of resin. In such a case, the injection pressure P ₀ needs to be measured only once. Then, the target temperature Tk of the resin in the heating cylinder 13 can be determined by the following equation.
Tk = Tt−P ₀ / (d × c) (6 formulas)

  The molten resin generates heat not only by the injection nozzle 17 but also when flowing through the sprue 8a, the gate 11 and the like due to friction and shearing action. Therefore, the resin immediately after being injected into the cavity 10 has a higher temperature than the resin in the heating cylinder 13. A person skilled in the art can easily understand so that it will not be described in detail. However, by applying the above-described method, a target temperature in the cavity, which is a temperature target value, is determined for the resin immediately after being injected into the cavity 10. The temperature of the resin in the heating cylinder 13 can be controlled so as to be realized. In this case, it is necessary to estimate the temperature rise of the resin that has reached the cavity, and this rise can also be estimated and calculated as a result of the loss of the injection pressure. Actually, it is difficult to accurately measure the loss of the injection pressure that contributed to the temperature rise. However, for example, a predetermined ratio α of the actual injection pressure applied by the screw 14 when the molten resin is injected into the cavity is a heat ratio. It can be assumed that the energy has changed. Then, the increase in temperature of the resin can be calculated. By doing so, it can be ensured that the temperature of the resin injected into the cavity falls within a desired range.

The embodiment of the present invention can be variously modified. Various modifications can be made to the control method. For example, when estimating the temperature rise ΔT of the molten resin, in this embodiment, the molten resin is injected into the atmosphere from the injection nozzle 17 and the measured injection pressure P ₀ is equivalent to the pressure loss due to injection. It is considered to be calculated. This can also be calculated from the drive energy of the screw 14 in the injection device 2. That is, it is calculated that a predetermined ratio of the driving energy for driving the screw 14 contributes to the temperature rise of the molten resin. The drive energy E of the screw 14 can be calculated from the torque N (N · m) of the servo motor that drives the screw 14 and the rotation angle θ (rad) by the following equation.
E = N x θ (7 formulas)
Alternatively, it can be calculated from the power consumption W (W) of the servo motor and the time t (s) by the following equation.
E = W × t (8 formulas)
A predetermined ratio of thus calculated is driving energy E, for example, the following energy E ₁ corresponding to the mechanical efficiency η is assumed to contribute to temperature increase of the molten resin.
E ₁ = E × η (9 formulas)
In this way, calculate the energy E _1, it is possible to easily calculate the temperature rise. By adopting such a method, there is an effect that it is not necessary to provide a sensor for measuring the injection pressure.

Other variations of the control method are possible. For example, in the above description, the temperature of the resin in the heating cylinder 13 is controlled, but the temperature of the resin in the injection nozzle 17 may be controlled. Further, the injection pressure P ₀ measured when the injection nozzle 17 is injected away from the fixed mold 8 is explained as if it is a constant value, but strictly speaking, the injection pressure P ₀ varies depending on the screw position. To do. That is, the injection pressure P ₀ is a function of the screw position. Then, the injection pressure P ₀ may be given by integration in the formula 1, the formula 3, and the like. Further, loss of pressure in the description, i.e. energy by the injection pressure P ₀ are all described as changes into thermal energy, some of the energy has changed in the kinetic energy of the molten resin. Therefore, when estimating the increase in the temperature of the resin at the outlet of the injection nozzle 17, the calculation may be performed by taking into account the kinetic energy of the injected resin.

  Variations on the device are possible. In the present embodiment, the injection is performed by the injection device 2 in which the screw 14 is provided in the heating cylinder 13. However, the present invention can also be implemented in a so-called plunger type injection device in which a plunger is provided instead of the screw 14.

DESCRIPTION OF SYMBOLS 1 Injection molding machine 2 Injection apparatus 4 Fixed board 5 Movable board 6 Clamping apparatus 8 Fixed side metal mold 9 Movable side metal mold 10 Cavity 13 Heating cylinder 14 Screw 17 Injection nozzle 19 Band heater 20, 21 Temperature sensor 23 Controller

Claims (3)

A heating cylinder having a heater at the outer periphery and an injection nozzle at the tip, and a screw that can be driven in the rotational direction and the axial direction in the heating cylinder, or an axial drive. In the injection device comprising the plunger, the resin temperature in the heating cylinder or the injection nozzle is controlled so as to become a predetermined pre-injection target temperature,
The injection nozzle outlet side target temperature, which is the temperature target value of the resin immediately after injection in the injection nozzle, is determined,
Estimate the rise in resin temperature that generates heat with the loss of injection pressure during injection,
The pre-injection target temperature is determined so that the pre-injection target temperature plus the estimated increase is the injection nozzle outlet side target temperature ,
The pressure loss corresponding to the injection pressure loss is considered to be equivalent to the injection pressure measured when the injection nozzle is injected away from the mold sprue, thereby estimating the estimated rise temperature. A method for controlling the temperature of a resin. A heating cylinder having a heater at the outer periphery and an injection nozzle at the tip, and a screw that can be driven in the rotational direction and the axial direction in the heating cylinder, or an axial drive. In the injection device comprising the plunger, the resin temperature in the heating cylinder or the injection nozzle is controlled so as to become a predetermined pre-injection target temperature,
The injection nozzle outlet side target temperature, which is the temperature target value of the resin immediately after injection in the injection nozzle, is determined,
Estimate the rise in resin temperature that generates heat with the loss of injection pressure during injection,
The pre-injection target temperature is determined so that the pre-injection target temperature plus the estimated increase is the injection nozzle outlet side target temperature ,
The resin temperature control method is characterized in that the increase in the resin temperature is estimated as a contribution of a predetermined ratio of drive energy for driving the injection device. A heating cylinder having a heater at the outer periphery and an injection nozzle at the tip, and a screw that can be driven in the rotational direction and the axial direction in the heating cylinder, or an axial drive. In the injection device comprising the plunger, the resin temperature in the heating cylinder or the injection nozzle is controlled so as to become a predetermined pre-injection target temperature,
Determine the target temperature in the cavity, which is the target temperature of the resin immediately after being injected into the cavity in the mold,
Estimate the rise in resin temperature that generates heat with the loss of injection pressure during injection,
The pre-injection target temperature is determined so that the pre-injection target temperature plus the estimated increase is the target temperature in the cavity ,
The resin temperature control is characterized in that the increase in the resin temperature is estimated by assuming that a predetermined ratio of the actual injection pressure applied to the resin by the screw at the time of injection is changed to thermal energy. Method.

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