JP2001079653A - Injection molding machine and nozzle temperature controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine excellent in safety and production efficiency, without leaking any molten metal from the tip part of a nozzle by controlling nozzle temp. so as to appropriately control the formation of cold plug. SOLUTION: A heating means 2 is disposed on the outer peripheral surface of the nozzle 1 disposed at the end part side of an injection unit, and temperature-sensing element 3, 10 are disposed at the front end part side and the rear end part side of the nozzle 1 interposing the heat means 2, respectively. In a process from the injection process to the retreating process of the injection unit after nozzle-touching to the die 5 by advancing the injection unit, the temp. is detected with a measuring temp. body 16 at the rear end part side of the nozzle 1, and in a process except above process, the temp. is detected with a measuring temp. body 3 at the front end part side of the nozzle 1 to control the temp. of the nozzle 1 by means of the heat-control of the heating means 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine for controlling the temperature of a nozzle so as to form a cold plug in which a molten material is solidified on the tip side of the nozzle, and a nozzle temperature control device therefor. The present invention relates to an injection molding machine suitable for injection molding of a metal material such as an aluminum alloy and a zinc alloy, and a nozzle temperature control device thereof.

[0002]

2. Description of the Related Art As a conventional metal injection molding machine, for example,
Some are as shown in FIG. In this metal injection molding machine, similar to an injection molding machine for injection molding a resin material, plasticization, measurement, and injection of a molding material are performed by a screw cylinder 7 provided with a screw inside the cylinder. A nozzle 1 is provided, and a metal material is injected into the molds 5 and 13. A nozzle heater 2 and a cylinder heater 9 as heating means are provided on the outer circumference of the nozzle 1 and the screw cylinder 7, respectively, and the nozzle 1 and the screw cylinder 7 are heated. The metal material heated by the nozzle heater 2 and the cylinder heater 9 becomes molten or semi-molten metal (hereinafter, referred to as molten metal) 8 in the storage portion at the tip of the screw cylinder 7 and in the nozzle 1, and the mold cavities 11, 12 It is injected inside. At this time, a cold plug 4 is formed in the nozzle 1.

[0003] As shown in FIG.
The molten metal injected into the mold cavities 11, 12 is deprived of heat by the molds 5, 13 and cooled, whereby a solidified or semi-solidified layer 18 is formed in the nozzle 1 and taken out together with the molded product. This is formed by separating the sprue to be formed and the cold plug 4 remaining in the nozzle 1. With the cold plug 4, the mold 5 after the injection unit is retracted,
During the process of removing the molded product from the mold 13 and spraying the release agent, the screw cylinder 7 and the molten metal 8 in the nozzle 1 are held so as not to leak from the tip of the nozzle 1, thereby preventing the molten metal 8 from being oxidized and burned. At the time of injection, a large injection power is applied to the molten metal 8, the cold plug 4 is discharged into the molds 5 and 13, and is accommodated in the cold plug catcher 6 provided in the mold 13. Subsequent to the discharge of the cold plug 4, the molten metal 8 in the nozzle 1 and the screw cylinder 7 is injected into the mold cavities 11, 12 to perform molding.

The temperature of the nozzle 1 is controlled by a temperature controller so that the cold plug 4 is properly formed in the nozzle 1. Specifically, the tip of a temperature measuring element 3 such as a thermocouple is embedded near the nozzle heater 2, and a temperature controller based on the measurement result of the temperature measuring element 3 controls the nozzle heater 2.
Is controlled so that the temperature of the nozzle 1 is controlled. In addition,
As the nozzle heater 2, a resistance heater, an induction heater, or the like is used.

[0005] The cold plug 4 in the nozzle 1 is
Since the temperature measuring element 3 is located near the tip, the nozzle heater 2
Rather than near the tip of the nozzle 1. Thereby, the actual temperature of the cold plug 4 can be measured, so that the generation and melting of the cold plug 4 can be easily controlled.

[0006]

As described above, in the conventional apparatus, the temperature measuring element 3 is installed on the tip side of the nozzle 1 with respect to the nozzle heater 2, and measures the temperature of the nozzle 1 to control the nozzle temperature. Therefore, there are the following problems.

When the die 5 is touched with a nozzle before injection, the tip of the nozzle 1 and the die 5 make a line contact with each other in a hemispherical shape having different curvatures. Since the heat of the nozzle 1 having a high temperature of several hundred degrees is maintained without being taken away by the mold 5, the temperature drop at the tip of the nozzle 1 does not cause much problem. However, as shown in FIG. Then, the heat of the nozzle 1 is rapidly taken by the mold 5 through the solidified metal 17. As a result, the tip of the nozzle 1 is rapidly cooled, and the temperature measured by the temperature measuring element 3 also decreases rapidly. The temperature controller keeps heating and outputting the nozzle heater 2 to maintain the temperature of the nozzle 1, The nozzle 1 is excessively heated. As a result, the temperature gradient from the tip of the nozzle 1 to the nozzle heater 2 becomes large, and the temperature of the nozzle heater 2 in the cooling process becomes higher by several tens of degrees than the temperature of the process other than the cooling time. There's a problem.

Particularly, in the case of a metal material, the thermal conductivity of an aluminum alloy is as large as 100 W / mK, that of a magnesium alloy is as large as 60 to 70 W / mK, and the thermal conductivity is 0.2 W / mK.
Since the thermal conductivity is several hundred times higher than that of a resin material of about / mK, there is a problem that the temperature at the tip of the nozzle 1 is significantly reduced.

During cooling, if the temperature of the nozzle heater 2 rises abnormally, the nozzle 1 may be retracted or the runner of the molded product may be separated from the molten metal 8 in the nozzle 1 by opening the mold 5. The molten metal 8 in the nozzle 1 may leak from the tip of the nozzle 1 in some cases. That is, when the cold plug 4 in the nozzle 1 and the runner portion of the molded product are cut off, there is no escape of heat to the mold 5 immediately thereafter, but the heat supply of the nozzle 1 by the nozzle heater 2 is not stopped immediately. Then, the cold plug 4 once formed is melted, and the molten metal 8 in the nozzle 1 leaks to the outside.

If the temperature gradient at the tip of the nozzle 1 is gentle, as shown in FIG.
7, a semi-solidified phase 18 which becomes a cold plug 4 having a certain length, and a continuous phase with a molten metal 8 exist.
When the molded product is separated from the molten metal 8 in the nozzle 1 by retreating or opening the mold, even if all the solidified metal 17 in the nozzle 1 adheres to the molded product side, the semi-solidified material becomes the cold plug 4. The leakage of the melt 8 can be prevented by the presence of the phase 18.

However, when the temperature gradient inside the nozzle 1 is large, the length of the semi-solidified phase 18 that becomes the cold plug 4 is formed to be very short. When all the solidified metal 17 in the nozzle 1 adheres to the molded product side when the molten metal 8 in the nozzle 1 is cut off, the semi-solidified phase 18 that becomes the cold plug 4
Since there is almost no leak, it is impossible to prevent the molten metal 8 from leaking.

As described above, since the temperature of the nozzle 1 is controlled by installing the temperature measuring element 3 on the tip side of the nozzle 1 with respect to the nozzle heater 2, the influence of the rapid temperature drop of the tip of the nozzle 1 during cooling can be reduced. The nozzle 1 is abnormally heated due to excessive heating of the nozzle heater 2 because the temperature measuring element 3 on the side is directly received, and there is a possibility that the molten metal 8 leaks from the nozzle 1 during molding or damages the apparatus. Nozzle 1
In the retreating process, the solidified metal leaked from the nozzle 1 and solidified is sandwiched between the nozzle 1 and the mold 5 to form a gap, and there is a risk that the molten metal 8 is ejected from the gap at the time of injection and that the apparatus may be damaged. is there. In addition, since the operation of fully automatic forming is interrupted to remove the leaked solidified metal, there is a problem that productivity is reduced. Conversely, as shown in FIG. 9, the temperature measuring element 16
Even if the cold plug 4 is installed, the actual temperature of the cold plug 4 cannot be measured accurately, so that the formation and melting of the cold plug 4 cannot be properly controlled, and furthermore, the control is not possible due to the influence of the heat flow of the cylinder heater 9 and the like. There is a problem that it becomes stable.

The present invention solves the above-mentioned problem, and controls the temperature of the nozzle 1 so as to appropriately control the formation of the cold plug 4 so that the molten metal 8 does not leak from the tip of the nozzle 1 and is safe and safe. An object of the present invention is to provide an injection molding machine with high production efficiency and a nozzle temperature control device for the injection molding machine.

[0014]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is characterized in that the tip of the nozzle (1) disposed on the tip side of the injection unit is melted. In a nozzle temperature control device of an injection molding machine for controlling the temperature of a nozzle (1) so as to form a cold plug (4) in which metal is solidified, the injection unit is advanced and after a nozzle touches a mold (5). The temperature control is different from the steps from the injection step to the injection unit retreating step and the other steps.

In this configuration, the temperature control is performed differently from the steps from the injection step after the nozzle is touched to the mold (5) by moving the injection unit forward and the injection unit retreating step, and the other steps. During the cooling time after the injection, heat is removed to the mold (5) through the solidified material, whereby the tip of the nozzle (1) is rapidly cooled. By performing the control, it is possible to prevent the tip of the nozzle (1) from being abnormally heated more than necessary.

According to a second aspect of the present invention, in the nozzle temperature control apparatus for an injection molding machine according to the first aspect, the injection unit is moved backward from an injection step after the injection unit is advanced and the nozzle is touched to the mold (5). The temperature control different from the steps up to the step and the other steps is performed by heating means (2) on the outer peripheral surface of the nozzle (1) arranged on the tip side of the injection unit.
The temperature measuring elements (3, 16) are respectively disposed on the front end side and the rear end side of the nozzle (1) with the heating means (2) interposed therebetween, and the injection unit is advanced to move the mold (5). In the steps from the injection step after the nozzle touching to the injection unit to the retreating step of the injection unit, the temperature is detected by the temperature measuring element (16) on the rear end side of the nozzle (1), and in other steps, the temperature of the nozzle (1) is detected. The temperature is detected by the temperature measuring element (3) on the tip side, and the temperature of the nozzle (1) is controlled by heating control of the heating means (2).

In this configuration, the temperature measuring elements (3, 1) are provided on the front end side and the rear end side of the nozzle (1) with the heating means (2) interposed therebetween.
6) are arranged, and the steps from the injection step after the injection unit is advanced and the nozzle (5) is touched by the nozzle to the injection unit retreating step are performed at the rear end side of the nozzle (1). In (16), the temperature is measured, and the heating means (2) is controlled to be heated to control the temperature of the nozzle (1). Therefore, during the cooling process, the temperature of the nozzle (1) is relatively stable. Since the temperature is measured by the temperature measuring element (16) on the end side and the temperature of the nozzle (1) is controlled, injection is performed as in the case of detecting the temperature by the temperature measuring element (3) on the tip side of the nozzle (1). During the subsequent cooling time, the tip of the nozzle (1) is rapidly cooled, and the tip of the nozzle (1) is not abnormally heated more than necessary.

That is, when the cooling process is controlled by the temperature measuring element (16) on the rear end side of the nozzle (1) instead of the temperature measuring element (3) on the front end side of the nozzle (1), the nozzle (1) ) Even if the tip cools rapidly, there is a heating means (2) between the mold (5) and the temperature measuring element (1) on the rear end side of the nozzle (1).
The temperature of 6) is stable without hardly decreasing. Even if the cooling time is long, if the temperature measurement element (3) is controlled by the temperature measurement element (3) on the tip side of the nozzle (1), the temperature measurement element (3) is a low-temperature mold (5) and a high-temperature heating means (2). The temperature at the tip of the nozzle (1) becomes unstable due to the heat flow and the nozzle (1) abnormally heats up, whereas the temperature measuring element (16) at the rear end of the nozzle (1) When controlled, the temperature is maintained by heating the heating means (2), and the nozzle (1)
Since the heating is carried out by being sandwiched between the heating means (2) and the heating means (9) of the screw ring (7), the heat flow is relatively small and the nozzle (1) is not abnormally heated. Therefore, even when the mold (5) is opened and the molded product is cut off from the nozzle (1), there is no possibility that the molten metal (8) leaks from the tip of the nozzle (1).

In the other steps, the temperature is detected by the temperature measuring element (3) on the tip side of the nozzle (1), and the temperature of the nozzle (1) is controlled by heating the heating means (2). ,
Since the actual temperature of the cold plug (4) can be measured, the formation and melting of the cold plug (4) can be easily controlled.

According to a third aspect of the present invention, in the nozzle temperature control device for an injection molding machine according to the first aspect, the injection unit is retracted from the injection step after the injection unit is advanced and the nozzle is touched to the mold (5). The temperature control different from the steps up to the step and the other steps is performed by heating means (2) on the outer peripheral surface of the nozzle (1) arranged on the tip side of the injection unit.
To set two different temperatures for the heating means (2), from the injection step after the injection unit is advanced and the nozzle (5) is touched by the nozzle, to the injection unit retreating step. In the step, the heating means (2) is controlled so as to be at a lower temperature than the one temperature, and in the other steps, the heating means (2) is controlled to be heated at one temperature. It is characterized by the following.

In such a configuration, the steps from the injection step after the injection unit is advanced and the nozzle (5) is touched by the nozzle to the injection unit retreating step are performed with the other temperature set lower than one temperature. Heating means (2)
Is controlled so that the control temperature during the cooling time is lower than the control temperature before injection, and the heating means (2) is always in the state where heat is taken from the nozzle (1) to the mold (5). By making the temperature stable without heating output, the tip of the nozzle (1) is rapidly cooled during the cooling time after injection, and the tip of the nozzle (1) is abnormally heated more than necessary. Can be prevented.

According to a fourth aspect of the present invention, in the nozzle temperature control apparatus for an injection molding machine according to the first aspect, the injection unit is advanced from the injection step after the nozzle touches the mold (5) and the injection unit is retracted. The temperature control different from the steps up to the step and the other steps is performed by heating means (2) on the outer peripheral surface of the nozzle (1) arranged on the tip side of the injection unit.
And the injection unit is moved forward to mold (5)
The heating output to the heating means (2) is stopped from the injection step after the nozzle touch to the injection unit retreating step, and the heating means (2) is heated and controlled at a preset temperature in the other steps. It is characterized by having done.

In this configuration, the heating output to the heating means (2) is stopped from the injection step after the injection unit is advanced and the nozzle (5) is touched by the nozzle to the injection unit retreating step. During the cooling time after injection,
The tip of the nozzle (1) is rapidly cooled, and the nozzle (1)
It is possible to prevent the tip from being abnormally heated more than necessary.

However, in this case, if the cooling time is long, the temperature will be excessively lowered, so that it may take a long time to recover the temperature. Therefore, it is effective when the cooling time is short.

According to a fifth aspect of the present invention, there is provided a screw cylinder (7) having a screw inside a cylinder (7) for plasticizing, measuring, and injecting a molding material, and a screw cylinder (7) provided at a tip end thereof. A nozzle (1) for injecting the molten material into the mold (5, 13), a heating means (2) provided around the nozzle (1) for heating the nozzle (1), and a screw for the screw cylinder (7) The nozzle (1) is formed so as to form an injection piston cylinder that applies injection pressure, back pressure, and injection speed to the screw, and a cold plug (4) in which the molten material solidifies on the tip side inside the nozzle (1). A nozzle temperature control device for an injection molding machine according to any one of claims 1 to 4 for controlling temperature.

According to a sixth aspect of the present invention, in the injection molding machine of the fifth aspect, the injection molding machine is a metal injection molding machine using a molding material as a metal material such as a light alloy.

In this configuration, since a metal material such as a light alloy is used, it has a heat conductivity several hundred times that of a resin material. This is particularly effective because the heat at the tip of the nozzle (1) is easily taken away by the mold (5) through the mold (5).

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a state in which a nozzle of an injection molding machine according to an embodiment of the present invention is touched to a mold, and FIG. 2 is a schematic configuration diagram of an injection molding machine in FIG. FIG. 3 is a schematic configuration diagram showing a state in which the injection unit is retracted, a mold is opened, and a molded product is separated from a nozzle in the injection molding machine of FIG. 1, and FIG. 4 is another embodiment of the present invention. FIG. 5 is a schematic configuration diagram illustrating a state in which a nozzle of an injection molding machine having a plurality of nozzle heaters is touched to a mold. FIG. 5 illustrates an injection molding process when a nozzle set temperature during cooling is separately provided. It is a figure explaining the example of temperature setting. The same components as those in the conventional example are denoted by the same reference numerals,
The description is omitted.

As shown in FIG. 1, a metal injection molding machine according to the present embodiment has a screw provided inside a cylinder, and a screw cylinder 7 is used to form a metal material as a molding material. Plasticization, metering, and injection are performed. The nozzle 1 is provided at the tip of the screw cylinder 7, and the molding material is injected by making the nozzle 1 touch the dies 5 and 13. A nozzle heater 2 and a cylinder heater 9 as heating means are provided on the outer circumference of the nozzle 1 and the screw cylinder 7, respectively.
Is heated. The molding material heated by the nozzle heater 2 and the cylinder heater 9 is held as molten or semi-molten metal (hereinafter, referred to as molten metal) 8 in the storage portion at the tip of the screw cylinder 7 and in the nozzle 1, and is held in the mold cavity 11. , 12. In addition, 14 is an ejector pin, and 15 is a fixed side mold plate.

The temperature of the nozzle 1 is controlled by controlling the heating of the nozzle heater 2 so that the cold plug 4 in which the molten metal 8 solidifies is formed on the tip side of the nozzle 1. The temperature control of the nozzle 1 is different from the steps from the injection step after the injection unit is advanced and the nozzle 5 touches the mold 5 to the injection unit retreating step, and the other steps. The temperature control of the nozzle 1 will be described with reference to the following first and second embodiments.

(First Embodiment) To control the temperature of the nozzle 1, temperature measuring elements 3, 16 are respectively disposed on the front end side and the rear end side of the nozzle 1 with the nozzle heater 2 interposed therebetween, as shown in FIG. Next, in the steps from the injection step after the injection unit is advanced and the nozzle 5 touches the mold 5 to the injection unit retreating step, the temperature is measured by the temperature measuring element 16 on the rear end side of the nozzle 1, and FIG. In other steps shown in FIG. 3, the temperature is measured by the temperature measuring element 3 on the tip side of the nozzle 1 and the temperature of the nozzle 1 is controlled by controlling the heating of the nozzle heater 2. The different temperature control is performed from the injection step after the injection unit is advanced and the nozzle 5 touches the mold 5 to the injection unit retreating step. However, the different temperature control is performed only during the cooling step. You may do it.

More specifically, one resistance heating band heater type nozzle heater 2 is installed on the outer peripheral surface of the nozzle 1 of the in-line screw type metal injection molding machine having a clamping force of 450 t.
The temperature measuring elements 3 and 16 were set on the front end side and the rear end side of the nozzle 1 with the nozzle heater 2 interposed therebetween, and injection molding was performed using a metal material of AM60 magnesium alloy.

The temperature measuring element for control is the temperature measuring element 16 at the rear end of the nozzle 1 during the cooling step, and is changed to the temperature measuring element 3 at the tip of the nozzle 1 in the other steps. The set value of the thermometer 3 at the tip of the nozzle 1 is set to 540 ° C, the set value of the thermometer 16 at the rear end of the nozzle 1 is set to 590 ° C, and the control method is to set the deviation between the temperature set value and the measured value. This was performed by PID control that outputs in proportion to the output.

As a result, before the start of injection, the value measured by the temperature measuring element 3 on the tip side of the nozzle 1 is stable at about 540 ° C.
The value measured by the temperature measuring element 16 on the rear end side of the nozzle 1 was stable at about 590 ° C., which is higher than that, because the temperature measuring element 16 was disposed between the nozzle heater 2 and the screw cylinder 7.

Next, after the molds 5 and 13 were closed, the injection unit advanced and the nozzle 1 touched the mold 5. At this time, the nozzle 1
The temperature of the temperature measuring element 3 on the tip end side of the nozzle 1 starts to drop due to the deprivation of heat, but there is almost no temperature drop due to the nozzle touch, and the temperature measured by the temperature measuring element 16 on the rear end side of the nozzle 1 is almost zero. There was no change.

After the injection, the temperature at the tip of the nozzle 1 began to decrease with a slight delay in response by the distance between the solidified portion in the nozzle 1 and the solidified metal 17. During the cooling process, the temperature measuring element for control is changed from the temperature measuring element 3 at the tip of the nozzle 1 to the temperature measuring element 16 at the rear end of the nozzle 1 and measured by the temperature measuring element 16 at the rear end of the nozzle 1. The temperature is controlled to be 590 ° C. set in advance depending on the temperature. Therefore, the temperature measuring element 3 on the tip side of the nozzle 1
Is lowered to about 480 ° C., but the temperature of the temperature measuring element 16 at the rear end side of the nozzle 1 is controlled to about 590 ° C., and the liquid phase of the AM60 magnesium alloy It did not become higher than the linear temperature of 615 ° C., and the cold plug 4 could be formed reliably.

When the injection unit retreats, the nozzle 1
When the temperature measuring element for control was automatically changed to the temperature measuring element 3 on the tip side, the temperature of the tip of the nozzle 1 gradually recovered from the cooled state, and eventually returned to the stable state before injection.

On the other hand, a case where the control is performed only by the temperature measuring element 3 on the tip side of the nozzle 1 as in the related art will be described.

Before the injection, the temperature is controlled by the temperature measuring element 3 on the tip side of the nozzle 1.
The portion of the thermometer 16 on the rear end side was stable at about 590 ° C.
Although the temperature of the tip of the nozzle 1 dropped due to the nozzle touch, the temperature was hardly lowered due to immediate injection, and the temperature measured by the thermometer 16 at the rear end of the nozzle 1 hardly changed.

In the subsequent injection step, when the molten metal 8 is injected into the mold cavities 11 and 12 in a short time of 0.1 second or less immediately after the injection, the molten metal 8 is immediately solidified, and subsequently the molten metal 8 at the tip of the nozzle 1 is also cooled. Begins to solidify. As a result, heat was transferred from the nozzle 1 to the dies 5 and 13 through the solidified metal 17, and the temperature of the temperature measuring element 3 at the tip of the nozzle 1 began to rapidly decrease.

The cooling time is about 15 seconds, during which time
Since the temperature of the temperature measuring element 3 at the tip of the nozzle 1 drops from 540 ° C. before injection to about 500 ° C., the nozzle heater 2 corrects the temperature drop and sets the PID so that the temperature becomes the set value.
The heating output was kept under control. Although the heating output to the nozzle heater 2 was larger than the heating output before injection, the mold 5,
Since the thermal conductivity to the nozzle 13 was large, the temperature could not be raised to the control temperature of 540 ° C., and the temperature of the nozzle 1 could be recovered only to 520 to 530 ° C.

At this time, the temperature measuring element 16 on the rear end side of the nozzle 1 is
Nozzle heaters 2 and 6 whose heating output was increased within the cooling time
The temperature was raised from 590 ° C. to about 620 ° C. because it was located between the cylinder heater 9 and the temperature maintained at 10 ° C.

After the cooling time is over, when the nozzle 1 separates from the mold 5, there is no escape of heat from the nozzle 1 to the molds 5 and 13, so that the temperature at the tip of the nozzle 1 has recovered to the control temperature. Until the temperature at the tip of the nozzle 1 stabilizes to the control temperature, the temperature of the temperature measuring element 16 at the rear end of the nozzle 1 is 600 ° C. or higher. The temperature gradually decreased to the temperature before injection after weakening. Thus, the temperature measuring element 1 on the rear end side of the nozzle 1
In the measurement of No. 6, during the cooling time and for a while after the cooling time ends, the temperature of the nozzle 1 other than the tip of the nozzle 1 is increased from the stable time before the injection, whereby the molten metal held in the nozzle 1 is heated. 8 is also heated to a high temperature.

As a result, the inside of the nozzle 1 may be heated to a temperature higher than 615 ° C., which is the liquidus temperature of the AM60 magnesium alloy, and the cold plug 4 that is supposed to be generated in the nozzle 1 during the cooling time may be generated. The nozzle 1 is separated from the mold 5 without producing the molten metal, and the molten metal 8 is
The length of the cold plug 4 made of the solidified phase or semi-solidified phase is shortened due to leakage or a large temperature gradient in the nozzle 1, and the molten metal 8 held in the nozzle 1 and the screw cylinder 7 is reduced. The cold plug 4 was discharged to the outside of the nozzle 1 due to the pressure, and the molten metal 8 sometimes leaked from the tip of the nozzle 1.

(Second Embodiment) The temperature control of the nozzle 1 is not limited to this, and two different temperature settings can be set for the nozzle heater 2 so that only the cooling process after injection is performed at one temperature. Alternatively, the heating of the nozzle heater 2 may be controlled so that the temperature of the nozzle heater 2 is set to the other lower temperature, and the nozzle heater 2 is controlled at one temperature in other steps. For example, as shown in FIG. 5, the other temperature in the cooling step may be set to 480 ° C., and the other temperature in the other steps may be set to 540 ° C. The other temperature is such that the control temperature during the cooling time is lower than the control temperature before injection, and the heating means 2 does not need to keep heating and outputting even when the heat escapes from the nozzle 1 to the mold 5. It is necessary to

More specifically, in the nozzle temperature control device, two control temperatures can be set, and as shown in FIG.
In the other steps, the set temperature of the nozzle 1 was set to 480 ° C., the temperature of the nozzle 1 was measured by the temperature measuring element 3 on the tip side of the nozzle 1, and the nozzle 1 was controlled by heating control of the nozzle heater 2. Temperature control.

Before injection, the temperature measuring element 3 on the tip side of the nozzle 1
Stable at 40 ° C, nozzle 1 during cooling time after injection
Tip temperature began to drop. However, the control temperature during the cooling time is 480 ° C., which is lower than the control temperature before injection of 540 ° C., so that the nozzle heater 2 is not constantly heated and output even when the heat escapes from the nozzle 1 to the dies 5 and 13. Since the temperature was too stable, the nozzle heater 2 was not excessively heated. At this time, the temperature measuring element 1 on the rear end side of the nozzle 1
The measured temperature of No. 6 was about 590 ° C., and there was almost no change from the temperature before injection measured at the same position.

From the injection step after the injection unit is advanced and the nozzle 5 touches the mold 5 until the injection unit is retracted (or during the cooling step), the heating output to the nozzle heater 2 is stopped, and the other steps are performed. Then, the heating of the nozzle heater 2 may be controlled at a preset temperature. However, in this case, if the cooling time is long, the temperature will be too low, and it will take a long time to recover the temperature. Therefore, it is effective when the cooling time is short.

(Third Embodiment) Further, in a third embodiment shown in FIG. 4, a plurality of nozzle heaters 19 and 20 are used for the nozzle 1, and the first temperature measuring element 2 is provided on the tip side of the nozzle 1.
1 is disposed, a second temperature measuring element 22 is disposed between the nozzle heaters 19 and 20, and a third temperature measuring element 23 is disposed at the rear end side of the nozzle 1. In the temperature control in this case, in the steps from the injection step after the injection unit is advanced and the nozzle 5 touches the mold 5 to the injection unit retreating step, the temperature is detected by the second temperature measuring element 22 and the other steps are performed. Then, the first end of the nozzle 1
The temperature of the nozzle 1 is controlled by controlling the temperature of the nozzle heater 2 by detecting the temperature with the temperature measuring element 21.

[0050]

According to the present invention, with such a configuration, the temperature from the step from the injection step after the injection unit is advanced and the nozzle 5 touches the mold 5 to the step of retracting the injection unit is different from the other steps. Since the control is performed, the tip of the nozzle (1) is rapidly cooled by transmitting heat to the mold (5) through the solidified metal during the cooling time after the injection. Is set as a separate temperature control, it is possible to prevent the tip of the nozzle (1) from being abnormally heated more than necessary. Therefore, as in the conventional case, the nozzle (1) is excessively heated during the cooling time, and the nozzle (1) is retracted when the unit is retracted or the mold is opened.
There is an effect that the molten metal (8) does not leak from the container, the safety is improved, and the productivity is improved without damaging the device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a state in which a mold is touched to a nozzle of an injection molding machine according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a state at the time of injection in the injection molding machine of FIG. 1;

FIG. 3 is a schematic configuration diagram of the injection molding machine in FIG. 1 in a state where an injection unit is retracted, a mold is opened, and a molded product is separated from a nozzle.

FIG. 4 shows another embodiment of the present invention, and is a schematic configuration diagram of a state where a nozzle of an injection molding machine having a plurality of nozzle heaters is touched to a mold.

FIG. 5 is a diagram illustrating an example of temperature setting in one cycle when a nozzle setting temperature during cooling is separately provided in the present invention.

FIG. 6 is a schematic configuration diagram illustrating a state where a nozzle of a conventional injection molding machine is touched by a mold.

7 is a schematic configuration diagram illustrating a state at the time of injection in the injection molding machine of FIG. 6;

8 is a schematic configuration diagram of the injection molding machine in FIG. 6 when an injection unit is retracted, a mold is opened, and a molded product is separated from a nozzle.

FIG. 9 is a schematic configuration diagram illustrating a state in which a temperature measuring element is provided only on the rear end side of a nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Nozzle heater (heating means) 3,16 Temperature measuring element 4 Cold plug 6 Cold plug catcher 7 Screw cylinder 8 Molten 9 Cylinder heater (heating means) 10 Temperature measuring element, 11,12 Mold cavity 5,13 Mold, 17 solidified metal 18 semi-solidified phase, 21 first temperature measuring element 22 second temperature measuring element 23 third temperature measuring element

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Hieda 1-6-1, Funakoshiminami, Aki-ku, Hiroshima-shi, Hiroshima F-term in Japan Steel Works, Ltd.

Claims (6)

[Claims] 1. An injection molding machine for controlling the temperature of a nozzle (1) disposed at the distal end of an injection unit so as to form a cold plug (4) in which a molten material is solidified at the distal end of the nozzle (1). In the nozzle temperature control apparatus, the injection unit is advanced to perform a temperature control different from the steps from the injection step after the nozzle touches the mold (5) to the injection unit withdrawal step, and the other steps. A nozzle temperature control device for an injection molding machine, characterized in that: 2. The nozzle temperature control device for an injection molding machine according to claim 1, wherein: a step from an injection step after the injection unit is advanced and a nozzle touches a mold (5) to a step of retracting the injection unit; The temperature control different from the other steps is as follows. A heating means (2) is provided on the outer peripheral surface of a nozzle (1) provided on the tip side of the injection unit, and the nozzle is provided with the heating means (2) interposed therebetween. (1) The temperature measuring elements (3, 16) are arranged on the front end side and the rear end side, respectively. From the injection step after the injection unit is advanced and the nozzle (5) is touched by the nozzle, to the injection unit retreating step. In the step, the temperature is detected by the temperature measuring element (16) on the rear end side of the nozzle (1). In the other steps, the temperature is detected by the temperature measuring element (3) on the front end side of the nozzle (1), The temperature of the nozzle (1) is controlled by the heating control of the means (2) Nozzle temperature controller of the injection molding machine, characterized in that the. 3. The nozzle temperature control device for an injection molding machine according to claim 1, wherein: a step from an injection step after the injection unit is advanced and the nozzle is touched to the mold (5) to a step of retracting the injection unit; The temperature control different from the other steps is as follows. A heating means (2) is provided on the outer peripheral surface of a nozzle (1) provided on the tip side of the injection unit, and the heating means (2) is controlled. Two different temperature settings are possible. In the steps from the injection step after the injection unit is advanced and the nozzle (5) is touched by the nozzle to the injection unit retreating step, the other is set lower than one temperature. The heating means (2) is controlled so as to be at a temperature, and in other steps, the heating means (2) is controlled to be heated at one temperature. . 4. A nozzle temperature control device for an injection molding machine according to claim 1, wherein: a step from an injection step after advancing the injection unit and touching the mold with a nozzle to a step of retracting the injection unit; The temperature control different from the other steps is as follows. A heating means (2) is arranged on the outer peripheral surface of a nozzle (1) arranged on the tip side of the injection unit, and the injection unit is advanced to mold. The heating output to the heating means (2) is stopped from the injection step after the nozzle touch in (5) to the injection unit retreating step, and in other steps, the heating means (2) is heated and controlled at a preset temperature. A nozzle temperature control device for an injection molding machine, characterized in that: 5. A screw cylinder having a screw inside the cylinder for plasticizing, measuring and injecting a molding material.
Provided at the tip of the screw cylinder (7), and the mold (5, 1
3) a nozzle (1) for injecting a molding material, a heating means (2) provided on the outer periphery of the nozzle (1) for heating the nozzle (1), and a screw of a screw cylinder (7) to advance the screw. An injection piston cylinder for giving an injection pressure, a back pressure and an injection speed to the nozzle, and a temperature control for the nozzle (1) so as to form a cold plug (4) in which a molten material is solidified at a tip side in the nozzle (1). An injection molding machine comprising the nozzle temperature control device for an injection molding machine according to any one of claims 1 to 4. 6. The injection molding machine according to claim 5, wherein the injection molding machine is a metal injection molding machine using a molding material as a metal material such as a light alloy.