JP2002059456A - Nozzle structure for injection molding and injection molding machine provided with this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent run-off of a melt, failure of molding, etc., from being generated by stabilizing forming condition of cold plug in an injection nozzle and to make amount of injection of a molding material constant and to improve quality of molding by stably forming the cold plug. SOLUTION: The first heater 35 and the second heater 34 are set around a nozzle apex part 32. In addition, a temperature sensor 36 for detecting temperature of a molding material 3 in the first region, a temperature sensor 37 for detecting temperature of the molding material 3 in the intermediate region and a temperature sensor 38 for detecting temperature of the molding material 3 in the second region are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle structure for injection molding and an injection molding machine provided with the same, and more particularly to a nozzle structure suitable for performing molten metal injection molding.

[0002]

2. Description of the Related Art In general, an injection molding machine has an open structure in which the tip opening of an injection nozzle is kept open. After the molding material is injected from the injection nozzle, the molding material is solidified in the vicinity of the tip opening of the injection nozzle. There is a configuration in which a so-called cold plug is formed, and thereafter, a molded product is taken out. In such an injection molding machine, usually, a heater is arranged around an injection nozzle,
At the time of injection, the temperature of the nozzle tip of the injection nozzle is raised, while after the injection is completed, the temperature of the nozzle tip is lowered to form the cold plug, and the molding material from the tip opening of the injection nozzle is formed. To prevent leakage. Such an injection nozzle is generally used as a hot runner nozzle for eliminating a runner portion adhering to a molded product. However, it can be configured as a nozzle used in a cold runner structure in which a runner is formed in a mold.

FIG. 8 shows a structure near an injection nozzle in the injection molding machine. The injection nozzle 10 is a nozzle cylinder 11
A nozzle tip 12 provided on the tip end side of the nozzle cylinder 11, a nozzle base 13 having an outer diameter larger than that of the nozzle cylinder 11, and connected to an injection cylinder (not shown);
It has a distal heater 14 disposed on the outer periphery of the nozzle cylinder 11 and the nozzle distal portion 12, and a proximal heater 15 disposed on the outer periphery of the nozzle base 13. The nozzle tip 12 is introduced into the mold 20, and its tip opening faces the cavity 20 a of the mold 20. The mold 20 has a fixed mold 21 and a movable mold 22, and the outer peripheral surface near the tip of the nozzle tip 12 is in contact with the fixed mold 21.

In FIG. 8 (a), when an injection screw (not shown) is driven in an injection cylinder (not shown) in the axial direction, a molding material 3 such as a low melting point metal in the injection cylinder flows through the nozzle flow path 10a in a molten state. After that, it is pushed out from the tip opening of the nozzle tip 12 into the cavity 20a. At this time, the distal-side heater 14 and the proximal-side heater 15 heat the nozzle cylinder 11, the nozzle distal end portion 12, and the nozzle base portion 13 of the injection nozzle 10, and the molding material 3 inside the cavity 20a is kept in a molten state. To lead to.

The temperature of the injected molding material 3 in the cavity 20a drops and solidifies gradually. At this time, by lowering the control temperature of the front heater 14,
The molding material 3 near the tip opening of the nozzle tip 12 is also solidified. Thereafter, as shown in FIG.
2 to open the molded article 4 away from the nozzle tip 12,
Take out. When the molded product 4 separates from the nozzle tip 12 in this way, a cold plug including the solid portion 5 and the semi-solid portion 6 where the molding material 3 is solidified is left in the nozzle tip 12.

FIG. 7 is an enlarged sectional view of the nozzle tip 12 of the injection nozzle 10. The nozzle tip 12 has a tapered portion 12b formed to decrease in diameter from the nozzle flow path 10a toward the tip opening 12a, and a tapered portion 12b formed on the tip opening 12a side of the tapered portion 12b. An opening taper portion 12d formed so as to increase in diameter toward the distal end opening 12a opposite to the tapered portion 12b is provided, and the inner diameter is formed to be the smallest between the tapered portion 12b and the opening tapered portion 12d. An aperture portion 12e is formed. Here, the tapered portion 12b is formed such that the inclination angle with respect to the axis of the nozzle flow path 10a is about 45 to 50 degrees.

[0007] The solidified region of the molding material 3 shown in FIG. 8 (a), after injecting the molding material 3, gradually extends toward the inside of the nozzle from the front end opening 12a, and eventually exceeds the narrowed portion 12e to form the tapered portion 12b. Is formed up to the inside. When the molded product is separated from the nozzle tip 12 as shown in FIG. 8B, the solidified region usually has a narrowed portion 12e.
Is designed so that the solidified region on the far side of the nozzle than the narrowed portion 12e remains in the nozzle as a cold plug.

[0008]

However, in the above-described injection nozzle, the temperature of the entire nozzle tip 12 is controlled by the tip-side heater 14, so that the temperature drop of the nozzle tip 12 in the mold 20 is reduced. This only occurs as a result of heat radiation through the molding material or the fixed mold 21, and the temperature drop inside the nozzle tip 12 varies, so that the formation of the cold plug becomes unstable and the temperature inside the nozzle tip 12 decreases. If it is too high, outflow of molten metal due to poor formation of the cold plug is likely to occur, and the nozzle tip 1
If the temperature in 2 is too low, a load is applied to the narrowed portion 12e when the molded product is taken out, and there is a problem that the inner surface of the tip of the nozzle is easily worn or deformed.

Conventionally, a temperature sensor such as a thermocouple is disposed at the opening tapered portion 12d of the nozzle tip 12, and the time until the temperature sensor reaches the solid phase temperature is measured in advance. In some cases, the removal of the molded product is started, but the part where this temperature sensor is arranged is a part where the inside is completely solidified at the start of removal of the molded product. The solidification state of the portion where the cold plug is formed inside the 12e or the tapered portion 12b cannot be detected with good reproducibility, and it is difficult to stabilize the cold plug formation state. In particular, unlike the above, in an injection molding machine having a so-called cold runner type mold structure, a temperature sensor for controlling a heater is installed on the outer surface of an injection nozzle. It is impossible to accurately detect the temperature of the formed part.

[0010] Further, due to the instability of the cold plug formation state, the cold plug formation site or formation depth in the nozzle flow path also varies,
As a result, there is also a problem that the injection amount of the molding material varies and the molding quality deteriorates.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to prevent the outflow of molten metal and the occurrence of molding defects by stabilizing the state of forming a cold plug in an injection nozzle. . Another object of the present invention is to stably form a cold plug to stabilize the injection amount of a molding material and improve molding quality.

[0012]

According to a first aspect of the present invention, there is provided an injection molding nozzle structure for injecting a molding material into a molding die from a nozzle flow path. , Set near the tip opening of the nozzle,
A first region in which the solid-phase molding material is present at the start of removal of the molded article, and a liquid-phase molding at the start of removal of the molded product, which is set on a side that is located further back in the nozzle flow path than the first region. A second region in which a material is present, and an intermediate region, which is set between the first region and the second region and in which the molding material in a solid-liquid coexisting phase exists at the start of removal of a molded product, A temperature control means is provided for forming a temperature profile in which the temperature gradually decreases at least from the second region to the first region via the intermediate region.

According to the present invention, a temperature profile having a temperature gradient of the first area, the intermediate area, and the second area can be actively formed by the temperature control means. Can be stabilized and the reproducibility can be improved, so that the cold plug can be formed stably. In particular, it is possible to increase the temperature gradient at the nozzle tip by actively forming a temperature profile by the temperature control means. If the temperature gradient is increased, the reproducibility of the cold plug formation position and depth can be improved. Can be further improved.

An injection molding nozzle structure according to a second aspect of the present invention is an injection molding nozzle structure for injecting a molding material from a nozzle flow path into a molding die. A first region in which the solid-phase molding material is present at the start of removal of the article, and a liquid-phase molding material at the start of removal of the molded product, the first region being set on a side that goes back in the nozzle flow path from the first region. A second region where
An intermediate region in which the molding material in the solid-liquid coexistence phase exists at the time of starting the removal of the molded article, which is set between the region and the second region, and at least the temperature of the molding material in the intermediate region is detected. It is characterized in that it is configured to be possible.

According to the present invention, the intermediate region (for example, FIG. 7)
A portion corresponding to the constricted portion or the tapered portion, or
It is configured to detect the temperature of the part near the part with the smallest inner diameter at the nozzle tip), so that the solidification state of the molding material at the part to be a cold plug can be more accurately than before. Since it is possible to grasp the cold plug formation state, it is possible to stabilize the cold plug formation state by setting the removal timing of the molded product according to the temperature of the intermediate region.

In the present invention, there is provided a heating means for heating the molding material in the nozzle flow path, wherein the heating means at the time of starting the removal of the molded product has a higher heating value than the heat generated in the second region. It is preferable that the heat generation amount for the first region is configured to be small. In this case, the amount of heat generated by the heating unit in the first region is reduced, so that the first region can be reliably solidified while the molding material in the second region is maintained in the liquid phase.

In the present invention, it is preferable that a first heating means for heating at least one of the first area and the intermediate area, and a second heating means for heating the second area are provided. At least one of the first region and the intermediate region is the first region
Since the second region is heated by the heating unit and the second region is heated by the second heating unit, the second region is controlled by separately controlling the first heating unit and the second heating unit.
The first region can be reliably solidified while the molding material in the region is maintained in the liquid phase.

Here, the first heating means may be configured to heat both the first area and the intermediate area, and the second heating means may be configured to also heat the intermediate area. Is also good.

An injection molding nozzle structure according to a third aspect of the present invention is an injection molding nozzle structure for injecting a molding material from a nozzle flow path into a molding die, wherein the injection molding nozzle structure is set near a tip end opening of the nozzle. A first region in which the solid-phase molding material is present at the start of removal of the article, and a liquid-phase molding material at the start of removal of the molded product, the first region being set on a side that goes back in the nozzle flow path from the first region. A second region where
An intermediate region in which the molding material in a solid-liquid coexistence phase is present at the time of starting the removal of the molded article, which is set between the region and the second region, and at least one of the first region and the intermediate region It has a first heating unit for heating and a second heating unit for heating the second region.

In the present invention, the first heating means is configured to heat both the first region and the intermediate region. It is characterized in that the heat generation for the region is reduced.

[0021] In the present invention, it is preferable that a temperature sensor for detecting at least one of the temperature of the end of the second region on the side of the intermediate region and the temperature of the first region is provided. With this or these temperature sensors and the above-mentioned temperature sensor that detects the temperature of the intermediate region, the setting, confirmation, and control of the temperature profile at the nozzle tip can be easily performed. Here, a temperature sensor for detecting the temperature of the first area, a temperature sensor for detecting the temperature of the intermediate area, and a temperature sensor for detecting the temperature of the end of the second area on the intermediate area side are provided. It is desirable.

Next, an injection molding machine of the present invention is provided with the above-described injection molding nozzle.

In the present invention, it is preferable that the molding material is started to be taken out when the molding material in the intermediate region reaches a predetermined temperature.

In the present invention, the predetermined temperature is preferably a temperature of a solid-liquid coexisting phase of the molding material. Here, the predetermined temperature is such that the solid phase ratio of the solid-liquid coexisting phase is about 50 to 9
It is desirable that the temperature range be 0%. In particular, AZ9
In the case of a 1D magnesium alloy, about 520 to 575
Degree is desirable.

In each of the above-mentioned means, it is preferable that a throttle portion (notch) having a minimum opening area facing the nozzle flow path is provided in the nozzle tip portion. Further, it is desirable to provide a tapered portion on the nozzle base end side of the throttle portion. In these cases, the intermediate region is a throttle section, or
This is a region inside the narrowed portion and the tapered portion.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an injection molding nozzle structure and an injection molding machine using the same according to the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is an enlarged sectional view showing a structure of a nozzle tip portion in an injection molding nozzle structure of a first embodiment according to the present invention. The overall configuration of the injection nozzle 30 in the injection molding machine of the present embodiment is the same as that shown in FIG. 8 except for the vicinity of the nozzle tip 32 shown in FIG. 1, and a description thereof will be omitted. This embodiment is used for a so-called hot runner type mold structure similar to the conventional example.

In the present embodiment, a tip opening 32a is provided at the nozzle tip 32 of the injection nozzle 30, and a tip outer surface 32c is provided on the outer surface of the opening edge of the tip opening 32a. Is in contact with the fixed mold 21. Inside the distal end opening 32a, there is provided a stepped hole 32d having a two-stage structure that gradually increases in diameter toward the distal end opening 32a, and the inner diameter is the smallest at the inner side (nozzle base end side) of the stepped hole 32d. The formed throttle portion 32e is formed. Further, a tapered portion 32b whose diameter increases toward the nozzle base end side is formed on the nozzle base end side of the throttle portion 32e. The nozzle flow path 30a further on the nozzle base end side of the tapered portion 32b has a substantially constant inner diameter.

Around the nozzle tip 32, a first heater 35 composed of a high-frequency coil or the like is arranged at the base end side of the nozzle of the first heater 35, similar to the tip heater 14 shown in FIG. Is provided with the second heater 34 provided in. The first heater 35 is configured so that the winding pitch of the coil gradually increases as it proceeds toward the tip opening 32a (that is, the nozzle tip side) in the nozzle tip 32. The first heater 35 is configured to heat the portion from the distal end opening 32a through the stepped hole 32d, the throttle portion 32e, and the tapered portion 32b to a portion further advanced to the nozzle base end side.

The nozzle tip 32 has the stepped hole 32d
A temperature sensor 36, such as a thermocouple, for detecting the temperature of the molding material 3 (the molding material 3 in the first region) existing inside the nozzle; A temperature sensor 37 such as a thermocouple for detecting the temperature of the molding material 3 (the molding material 3 in the intermediate region) in the portion 32e and the tapered portion 32b, and is disposed closer to the nozzle than the temperature sensor 37. And a temperature sensor 38 such as a thermocouple for detecting the temperature of the molding material 3 (the molding material 3 in the second region) closer to the nozzle base end than the tapered portion 32b. These temperature sensors 3
6, 37, and 38 are provided in the nozzle channel 30a from the outer surface of the nozzle.
Is housed in the innermost part of the hole formed toward the nozzle channel 30 and is configured to more accurately detect the temperature of the molding material 3 in the nozzle flow path 30a.

Also in the present embodiment, when the molding material 3 is injected into the mold 20 similarly to the above-described conventional injection nozzle, the set temperatures of the first heater 35 and the second heater 34 are increased to increase the nozzle temperature. After the temperature is increased, and after the injection of the molding material 3, the nozzle temperature is decreased by lowering the set temperature of the first heater 35 and the second heater 34 while maintaining the pressure of the molding material 3 (holding pressure). Then, a cold plug to be described later is formed. Here, the set temperature of the second heater may be fixed, and only the set temperature of the first heater may be increased or decreased.

In this case, in the present embodiment, the first heater 35 is provided at the nozzle distal end portion 32, and the second heater 34 is provided at the base end side of the nozzle with respect to the first heater 35. The first heater 35 and the second heater 34 can be operated in different modes. For example, the molding material 3 is transferred to the mold 2 by increasing the elevation ratio of the set temperature of the first heater 35 at the time of injection and holding pressure to be greater than the elevation ratio of the set temperature of the second heater 34.
After injection into the nozzle portion 0, the temperature of the nozzle distal end portion 32 can be lowered more rapidly than before while maintaining the molding material 3 on the nozzle proximal end side in the liquid phase. A cold plug can be quickly formed in the vicinity. Further, by making the amount of heating by the first heater 35 smaller than the amount of heating by the second heater 34, the temperature profile in which the temperature gradually decreases toward the nozzle tip side in the nozzle tip portion 32 is actively (intent). Since the temperature gradient at the nozzle tip 32 can be made larger than before, the cold plug formation state can be stabilized, and the end of the solidified region when the cold plug is formed can be formed. The position of the part can be further stabilized.

In particular, at the nozzle tip 32, the first heater 35 is configured so that the winding pitch of the heating coil gradually increases toward the tip opening 32a.
The amount of heat released from the first heater 35 to the nozzle tip 32 gradually decreases toward the tip opening 32a.
A large temperature gradient can be intentionally formed even in the region of the nozzle tip 32 heated by the heater 35.

In the present embodiment, the nozzle flow path in the nozzle tip 32 is defined as a first area on the nozzle tip side (an area where the solid phase molding material 3 exists when the molded article 4 separates from the nozzle tip 32). And a second region on the base end side of the nozzle (a region where the liquid-phase molding material 3 exists when the molded product 4 separates from the nozzle distal end portion 32), and an intermediate portion between the first region and the second region. It can be considered separately from a region (a region where the molding material 3 in the solid-liquid coexisting phase exists when the molded product 4 separates from the nozzle tip portion 32). When considered in this way, in the present embodiment, the temperature sensors 36, 37, and 38 are provided in each of the first area, the intermediate area, and the second area so that the temperature of each area can be detected. Has become.

In the present embodiment, when the injection of the molding material 3 into the mold 20 is completed, and the molding material in the mold 20 solidifies to form the molded product 4, the vicinity of the tip opening 32a is formed. The molding material is also solidified, and the solidified region gradually expands from the distal end opening 32a toward the nozzle base end. The expansion of the solidified region is caused by the heat radiation through the tip outer surface portion 32c in contact with the molding material already solidified in the mold 20 or the fixed mold 21, and the set temperature of the first heater 35 is reduced, or The first heater 35 and the second
This is facilitated by a decrease in the set temperatures of both heaters 34.

The timing at which the molded product 4 separates from the nozzle tip 32 by opening the movable die 22 (ie, at the time of starting the removal of the molded product) is determined as shown in FIG. It is most preferable that the semi-solid region spreads and reaches the inside of the tapered portion 32b, and the semi-solid region formed of the solid-liquid coexisting phase is formed before that. In the state shown in the drawing, when the movable mold 22 is opened and the molded product 4 is separated from the nozzle tip 32, as shown by a dotted line in the drawing, a solid portion is provided inside the tapered portion 32b and the throttle portion 32e of the nozzle tip 32. A cold plug consisting of 5 and a semi-solid portion 6 is left.

In the injection molding machine using the injection nozzle 30 of the present embodiment, the time when the removal of the molded product 4 is started is determined by the temperature detected by the temperature sensor 37 in order to form the inside of the narrowed portion 32e and the tapered portion 32b. It is preferable that the time is when the material 3 is found to have dropped to the temperature of the solid-liquid coexisting phase. For example, when the temperature detected by the temperature sensor 37 is very close to the actual temperature of the molding material 3, the separation timing of the molded article 4 is determined by the temperature sensor 3.
It is desirable that the detection temperature of 7 be the time when the temperature of the solid-liquid coexisting phase of the molding material 3 is reached.

In practice, while the molding material 3 in the stepped hole 32d is solidified at the solid phase temperature, the molding material 3 in the nozzle flow path 30a closer to the nozzle base end than the tapered portion 32b becomes liquid phase. At the time when the temperature is maintained, the temperature is controlled so that the molding material 3 inside the narrowed portion 32e and the tapered portion 32b becomes the temperature of the solid-liquid coexisting phase. It is preferable to be configured so as to separate from.

The control system and the control method of the nozzle temperature in the injection molding machine will be described in detail in a third embodiment which will be described later.
The control system and control method of the third embodiment can be similarly applied.

[Second Embodiment] Next, the structure of an injection nozzle according to a second embodiment of the present invention will be described with reference to FIG. The injection nozzle 40 of this embodiment is different from the injection nozzle of the first embodiment, and is applied to a so-called cold runner type mold structure. Mold 50
Has a fixed mold 51 opposed to the tip opening 42a of the injection nozzle 40, and a movable mold (not shown) which forms a cavity in combination with the fixed mold 51. Inside the fixed mold 51, a tip opening 42a is provided. An introduction path (sprue portion) 51a for guiding the molding material 3 to an opposing cavity (not shown) is provided.

Inside the distal end opening 42a, there is provided a tapered distal end hole 42d whose base end side is slightly opened toward the distal end opening 42a. A throttle 42e having an inner diameter is formed. The first nozzle is further located on the nozzle base end side of the throttle section 42e.
A tapered portion 42b similar to that of the embodiment is formed.
Nozzle flow path 4 further on the nozzle base end side of tapered portion 42b
Oa has a structure having a substantially constant inner diameter.

In this embodiment, similarly to the first embodiment, a first heater 45 for heating the nozzle tip 42 and a first heater 45 disposed on the nozzle base end side of the first heater 45 are provided. And two heaters 44. The first heater 45 is the first heater 3 of the first embodiment.
Similarly to 5, the winding pitch of the high-frequency coil is gradually increased toward the nozzle tip side, and as a result, the amount of heat generated by the first heater 45 gradually decreases toward the nozzle tip side. Is configured.

The nozzle tip 42 has the tip hole 42d
And a temperature sensor 47 for detecting the temperature of the molding material 3 inside the narrowed portion 42e and the tapered portion 42b.
And a temperature sensor 48 for detecting the temperature of the molding material 3 in the nozzle flow path 40a closer to the nozzle base end than the tapered portion 42b. These temperature sensors are introduced and arranged in holes drilled from the outer surface of the nozzle as in the first embodiment.

In this embodiment, as in the first embodiment, the first heater 45 and the second heater 44 are provided.
Are independently provided, the temperature of the nozzle tip 42 can be rapidly lowered, so that a cold plug can be formed more rapidly than in the conventional case. Further, since the temperature gradient in the axial direction of the nozzle tip 42 can be intentionally formed, the formation state and formation position of the cold plug can be stabilized.

In this cold runner type injection nozzle, a stepped hole having the same structure as that of the first embodiment may be provided at the nozzle tip side of the throttle portion.

[Third Embodiment] Next, an injection nozzle and an injection molding machine according to a third embodiment of the present invention will be described with reference to FIGS. Injection nozzle 6 of this embodiment
Numeral 0 can be used for the hot runner mold structure similar to the first embodiment.

The injection nozzle 60 has a distal end opening 62a, a narrowed portion 62e, a tapered portion 62b, and a distal end outer surface portion 62c similar to those in the first embodiment. Inside the tip opening 62a, there is a tapered tip hole 6 opened toward the tip opening 62a.
2d is formed. Further, in substantially the same manner as in the first embodiment, a temperature sensor 66 is disposed at a position corresponding to the distal end hole 62d, and a temperature sensor 67 is disposed at a position corresponding to the narrowed portion 62e and the tapered portion 62b. The temperature sensor 68 is arranged closer to the nozzle base end.

A first heater 65A is formed around the nozzle tip 62 of the present embodiment on the nozzle tip side.
An intermediate heater 65B is formed on the base end side of the nozzle. The first heater 65A is configured to heat the portion from the nozzle base end side of the distal end hole 62d to the portion where the narrowed portion 62e and the tapered portion 62b are formed, and the intermediate heater 65B is configured to heat the tapered portion. The configuration is such that the portion of the nozzle distal end portion 62 closer to the nozzle base end than the end portion of 62b is heated.

In the present embodiment, the injection nozzle 60 is provided with a first region (a region where the solid-phase molding material 3 exists at the time of starting the removal of the molded product) and a second region (the molding region) at the base end of the nozzle. A region where the liquid-phase molding material 3 exists at the time of starting the removal of the article; and an intermediate region between the first region and the second region (the molding material 3 of the solid-liquid coexisting phase at the time of starting the removal of the molded product).
In this embodiment, temperature sensors 66, 67, and 68 are provided in each of the first area, the intermediate area, and the second area to detect the temperature of each area. You can do it.

Further, as described above, the portion from the first region to the intermediate region is configured to be heated by the first heater 65A, and the portion included in the nozzle tip 62 of the second region is configured to be heated by the intermediate heater 65B. When the molded article 4 is separated from the nozzle tip 62, the set temperature of the first heater 65A is reduced, and the set temperature of the intermediate heater 65B is changed to the temperature of the first heater 65A. By setting the temperature higher than the set temperature, the temperature of the first region and the intermediate region can be rapidly and reliably lowered while maintaining the molding material 3 in the second region in the liquid phase. In addition to stabilizing the forming position, the forming speed of the cold plug can be increased, the molding cycle can be shortened, and the productivity can be improved. It made.

In this embodiment, the first region and the intermediate region are mainly heated by the first heater 65A. However, the first region and the intermediate region are each heated by separate heating means. You may comprise so that it may be possible. In this case, finer temperature control becomes possible.

In the present embodiment, the temperature of the portion of the injection nozzle 60 near the nozzle base end, that is, the portion of the second region other than the nozzle tip 62, is controlled closer to the nozzle base end than the nozzle end 62. And a temperature sensor 69 for performing feedback control of the second heater 64 is provided.

FIG. 4 shows the injection nozzle 6 of this embodiment.
FIG. 2 shows a block diagram of a configuration of a nozzle temperature control system in an injection molding machine provided with 0. The temperature sensors 66, 67, 68,
Reference numeral 69 denotes each of the temperature measurement circuits 660, 670, 68
0,690, and these temperature measuring circuits are configured to output respective temperature data. The temperature data output from the temperature measurement circuits 660, 680, 690 are stored in the heater controllers 661, 681, 6
91 are respectively input. Heater controller 66
1, 681, 691, based on the above-mentioned temperature data and the temperature command (temperature setting value) sent from the nozzle temperature controller 610, in a manner that the temperature data approaches the temperature setting value. , Intermediate heater 65
B, and power is supplied to the second heater 64, respectively.

The nozzle temperature controller 610 is configured to exchange data with a control device of a molding machine via an input / output circuit 612. In general, an injection molding machine is provided with a molding cycle in which steps of mold clamping, injection, holding pressure, mold opening, and removal of a molded product are sequentially performed. The nozzle temperature controller 610 determines the operation timing of each step in the molding cycle of the molding machine,
The first heater 65A, the intermediate heater 65B, and the second heater 64 operate to maintain the correspondence with the control state of the nozzle temperature.

For example, in the injection nozzle 60, before the molding material 3 is injected into the mold 20, the set temperatures of the first heater 65A and the intermediate heater 65B are increased, so that the nozzle tip 62 Increase the temperature of the cold plug formed inside. Molding material 3
After the is injected, by lowering the set temperature of the first heater 65A and the intermediate heater 65B, the temperature drop in the nozzle tip 62 is promoted, and when the molded product separates from the nozzle tip, The control is such that the cold plug is left.

In the present embodiment, the nozzle tip 62
The three temperature data detected by the three temperature sensors 66, 67, and 68 and output from the temperature measurement circuits 660, 670, and 680 are compared with each other by the comparator 611. The output voltage of the comparator 611 is When the predetermined value is reached, a signal is sent to the control device of the molding machine via the input / output circuit 612, the molding machine performs the mold opening operation, and the molded product separates from the nozzle tip 62 and is removed from the mold. Is configured.

Here, the output voltage of the comparator 611 is output from the temperature measurement circuit 670 in the temperature range between the temperature data output from the temperature measurement circuit 660 and the temperature data output from the temperature measurement circuit 680. A signal indicating the relative position of the temperature data to be output. At this time,
Since the temperature data output from the temperature measurement circuits 660 and 680 are controlled by the heater controllers 661 and 681, the output voltage of the comparator 611 substantially corresponds to the temperature range between the temperature setting values of the heater controllers 661 and 681. 2 shows the relative position of the temperature detected by the temperature sensor 67 in FIG.

The predetermined value of the output voltage of the comparator 611 for determining the start of the removal of the molded product is as follows.
For example, it is a value indicating that the temperature of the molding material in the intermediate region has reached a predetermined temperature in the temperature region of the solid-liquid coexisting phase.

FIG. 5 shows the temperature profile of the molding material 3 in each part of the injection nozzle at the start of the removal of the molded product. In the present embodiment, by controlling the first heater 65A and the intermediate heater 65B separately from the second heater 64, the temperature gradient naturally formed by heat radiation to the mold 20 at the nozzle tip 62 is reduced. Instead, it is possible to intentionally form a temperature gradient that falls toward the nozzle tip side. As shown in FIG. 5, at the time of starting the removal of the molded product, the temperature sensor 66 detects the solid phase temperature (temperature lower than the solidus) T66, and the temperature sensor 67 detects the temperature of the solid-liquid coexisting phase (solidus The temperature sensor 68 detects a liquidus temperature (a temperature higher than the liquidus line) T68. Further, the temperature sensor 69 detects the temperature T68 detected by the temperature sensor 68.
It is configured to detect a higher liquidus temperature T69.

Specifically, in the case of the Al-Mg based magnesium alloy AZ91D, as shown by the dashed line in the phase diagram (equilibrium diagram) of FIG.
The liquid phase is at about 600 ° C. or higher, and the solid-liquid coexisting phase is at about 500 to 600 ° C. Here, a region surrounded by the liquidus line L and the solidus line S indicates a solid-liquid coexisting phase. In the case of the present embodiment, the molded article is taken out when the molding material in the intermediate region becomes a solid-liquid coexisting phase.

In particular, the solid phase ratio in the intermediate region (the ratio of the solid phase portion in the solid-liquid coexisting phase) at the start of removal of the molded product is set to about 5%.
It is preferable to set it in the range of 0 to 90%. If the solid phase ratio is lower than this range, the possibility that the molten metal will flow out due to poor formation of the cold plug increases.If the solid phase ratio is higher than this range, the molding cycle becomes longer and the inside of the nozzle becomes longer. The load applied to the constricted portion increases, which causes abnormal wear inside the nozzle tip and shortens the life of the nozzle.

With the above magnesium alloy AZ91D,
A molded product having a product weight of about 50 g was molded by the above-mentioned injection molding machine. At this time, the temperature controllers 661, 681, 6
91 (or the nozzle temperature controller 6
10 to the respective temperature controllers 661, 681, 691) were set as shown in Table 1 below. Table 1 also shows the detected temperature T67 (the temperature in the intermediate region) detected by the temperature sensor 67.

[0063]

[Table 1]

As a result of operating the injection molding machine at the temperature settings shown in Table 1 above, it is possible to greatly reduce the outflow of molten metal, defective molding, and defective quality of molded products in a shorter molding cycle than before. Was.

It should be noted that the injection molding nozzle structure and the injection molding machine of the present invention are not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention. It is.

[0066]

As described above, according to the present invention,
The cold plug can be stably formed in the injection nozzle, and it is possible to reduce the outflow of molten metal, poor molding, poor quality of molded products, and the like.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a structure of a nozzle tip portion in a first embodiment of an injection molding nozzle structure according to the present invention.

FIG. 2 is an enlarged sectional view showing a structure of a nozzle tip portion in a second embodiment of an injection molding nozzle structure according to the present invention.

FIG. 3 is an enlarged sectional view showing a structure of a nozzle tip portion in a third embodiment of an injection molding nozzle structure according to the present invention.

FIG. 4 is a configuration block diagram of a nozzle temperature control system according to a third embodiment.

FIG. 5 is a graph showing a temperature profile when the injection nozzle of the third embodiment starts removing a molded product.

FIG. 6 is an equilibrium diagram of a magnesium alloy.

FIG. 7 is an enlarged sectional view showing a shape of a nozzle tip of a conventional injection nozzle.

FIG. 8 is a cross-sectional view showing a state at the time of injection (a) and at the time of removal of a molded product (b) in a conventional injection molding machine.

[Explanation of symbols]

30, 40, 60 Injection nozzle 30a, 40a, 60a Nozzle flow path 32, 42, 62 Nozzle tip 32a, 42a, 62a Tip opening 34, 44, 64 Second heater 35, 45, 65A First heater 65B Middle Heaters 36, 37, 38, 46, 47, 48, 66, 67, 6
8,69 Temperature sensor 20,50 Mold 21 Fixed type 22 Movable type 51 Fixed type

Claims (10)

[Claims] 1. An injection molding nozzle structure for injecting a molding material into a molding die from a nozzle flow path, wherein the solid phase is set near a tip end opening of the nozzle and a solid phase is formed at the start of removal of a molded product. A first region where a molding material is present;
A second region in which the liquid-phase molding material is present at the start of removal of a molded product, the second region being set on a side further back in the nozzle flow path than the first region, and the first region and the second region. An intermediate region in which the molding material in the solid-liquid coexistence phase is present at the time of starting the removal of the molded product, the temperature gradually increasing at least from the second region to the first region through the intermediate region. Characterized by comprising a temperature control means for forming a temperature profile in which the temperature decreases. 2. A nozzle structure for injection molding for injecting a molding material into a molding die from a nozzle flow path, wherein the solid phase is set near a tip end opening of the nozzle, and the solid phase is formed at the start of removal of a molded product. A first region where a molding material is present;
A second region in which the liquid-phase molding material is present at the start of removal of a molded product, the second region being set on a side further back in the nozzle flow path than the first region, and the first region and the second region. An intermediate region in which the solid-liquid coexisting phase of the molding material is present at the time of starting the removal of the molded product, wherein at least the temperature of the molding material in the intermediate region is configured to be detectable. Characteristic nozzle structure for injection molding. 3. The method according to claim 1, further comprising a heating unit for heating the molding material in the nozzle flow path, wherein the heating unit is configured to start the second molding when the molding product is taken out. A nozzle structure for injection molding, wherein a heat value for the first region is smaller than a heat value for the region. 4. The method according to claim 1, wherein at least one of the first region and the intermediate region is heated.
A nozzle structure for injection molding, comprising: a heating unit; and a second heating unit that heats the second region. 5. An injection molding nozzle structure for injecting a molding material into a molding die from a nozzle flow path, wherein the solid phase is set near the tip end opening of the nozzle, and the solid phase is formed at the start of removal of the molded product. A first region where a molding material is present;
A second region in which the liquid-phase molding material is present at the start of removal of a molded product, the second region being set on a side further back in the nozzle flow path than the first region, and the first region and the second region. A first heating means for heating at least one of the first region and the intermediate region, the intermediate region having a solid-liquid coexisting phase when the molding material is started to be taken out and having the intermediate region set therebetween. And a second heating means for heating the second region. 6. The apparatus according to claim 5, wherein the first heating means is configured to heat both the first area and the intermediate area, and the first heating means is configured to heat the intermediate area at the time of starting removal of a molded product. A nozzle structure for injection molding, characterized in that the heat generation amount for the first region is reduced. 7. The temperature sensor according to claim 1, wherein at least one of a temperature of an end of the second region on the intermediate region side and a temperature of the first region is detected. A nozzle structure for injection molding, comprising: 8. An injection molding machine comprising the injection molding nozzle according to claim 1. 9. The injection molding machine according to claim 8, wherein the molding material is started to be taken out when the molding material in the intermediate region reaches a predetermined temperature. 10. The injection molding machine according to claim 9, wherein the predetermined temperature is a temperature of a solid-liquid coexisting phase of the molding material.