JP2981099B2 - Injection molding machine barrel temperature control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a barrel temperature of an injection molding machine, that is, a temperature of a molten resin to be injected.

[0002]

2. Description of the Related Art Generally, an injection molding machine is configured to control its barrel temperature to a predetermined temperature state in order to stabilize the quality of a molded product.

That is, in FIG. 3, an injection molding machine is
The barrel 10 includes a screw 12 that is rotatably disposed in the barrel 10 so as to advance and retreat, and is provided with barrel temperature detecting means (thermocouples and the like) 14a, 14b, 1
A plurality (three in the illustrated example) of barrel heating zones including band heaters 16a, 16b, and 16c having a 4c are provided. Therefore, the injection molding machine configured as described above is
Each of the heating zones 16a, 16b, and 16c is provided with each of the temperature detecting means 14a, 14b, and 14c,
8b, 18c, each switch 20a, 20b, 20c,
The heating power is set via the heating power supply 22.

[0004] More specifically, the resin material that falls from the hopper (not shown) into the barrel 10 is rotated by the heating zone 16 on the one hand and the screw 12 on the other hand during the plasticizing and measuring step. A predetermined amount is measured by the kneading, heat generation and metering action due to retraction, and this is formed into a molten resin at a predetermined temperature, and this molten resin is a plunger function of the screw 12 which is reversed and advanced in the molding process. Thus, the resin is injected from the nozzle 24 into a mold (not shown) and processed into a molded product.

[0005] Reference numerals P1 and P2 in the figure indicate the positions of the forward end (injection completed) and the retreat limit (completion completed) of the tip of the screw 12, respectively. That is, the screw 12 moves between the positions P1 and P2 to the right (illustrated by the solid line) during the plasticizing and weighing process, and moves to the left (in the direction indicated by the dotted arrow) during the injection process. I do.

[0006]

However, the above-described barrel temperature control method has the following basic difficulties.

[0007] In other words, the conclusion is first explained in FIG. 4. In the conventional barrel temperature control method, the molten resin measured and stored during the plasticizing and measuring step generally has a curve t (t1-t2). Has a temperature distribution as represented by Note that, in FIG.
1 (P2) and P2 (P1) indicate that during the plasticizing and measuring step S1, the screw is moved from P1 to P2 during the injection side process.
, While moving from P2 to P1 at the time of the injection step S2.

The temperature distribution t will now be described. First, in the plasticization measuring step in which the screw retreats while rotating inside the barrel, the resin raw material is heated by the heating action from the heating zone via the barrel temperature detecting means. As described above, the heating is controlled, and the heating is controlled by the heat generated by the retreating and kneading of the screw. However, in this heating control, when the screw retreats, the position of the screw related to the heating action changes accordingly.On the other hand, in the heating action, the kneading effective length of the screw is shortened. At the same time, the heating effect decreases. For this reason, the temperature distribution of the molten resin generally tends to decrease from the forward limit position P1 to the backward limit position P2 as shown by the curve t. It is clear that this tendency to decrease becomes more pronounced as the injection amount increases, that is, as the screw retreat length increases.

As described above, in the conventional barrel temperature control method, a substantial temperature difference actually occurs in the temperature distribution of the injection molten resin. As a result, the quality of the molded product varies considerably, and the variation has a problem that the quality of the molded product, that is, the injection amount of the molten resin increases, and the variation increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a barrel temperature control method for an injection molding machine capable of stabilizing the quality of a molded product by making the temperature distribution of an injection molten resin uniform.

[0011]

In order to achieve the above object, a method of controlling a barrel temperature of an injection molding machine according to the present invention comprises:
The injection-side process includes an injection molding machine including a plasticizing measurement step when the screw is retracted and an injection step when the screw is advanced, and the injection molding machine includes a plurality of barrel heating units each having a barrel temperature detecting unit on the outer peripheral surface of the barrel. A barrel temperature control method for an injection molding machine in which each of the heating zones is individually heated and controlled via the temperature detection means, wherein the injection molding machine is provided with sequence control means interlocked with a molding cycle. In addition to the heating control through the temperature detecting means, the heating control of each of the heating zones is performed through a specific time zone during the injection-side process through the sequence controlling means.

In this case, the specific time zone during the injection side process is as follows:
It can be set to start after a lapse of a predetermined time in the injection step and end when a predetermined time in the subsequent plasticizing and measuring step.

Further, the specific time zone during the injection-side process can be set separately for each heating zone, and the heating control by the sequence control means can be set to be performed separately for each heating zone. can do.

[0014]

According to the present invention, the barrel heating zone is additionally compensated for by a new heating action in a specific time zone in the injection side process via the sequence control means, separately from the conventional heating action via the temperature detection means. The heating is controlled. Therefore,
According to the present invention, the difficulty of the conventional heating operation (and the kneading heat generation effect), that is, the reduction of the molten resin temperature (temperature difference) caused by the reduction of the heating effect and the delay of the response time is compensated by the additional heating effect. Since it is replenished, the temperature distribution of the injection molten resin temperature is made uniform, and the quality of the molded product is stabilized.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a barrel temperature control method for an injection molding machine according to the present invention. 3 and 4 for convenience of explanation.
The same reference numerals are given to the same components as those in the conventional structure shown in FIG.

In FIG. 1, first, the basic configuration of the barrel temperature control method according to the present invention is the same as the above-described conventional configuration (FIG. 3). Therefore, to briefly explain again, the injection molding machine includes a screw 12 which is rotatably disposed in the barrel 10 so as to advance and retreat, and is provided on the outer peripheral surface of the barrel 10 with means for detecting the temperature of the barrel. 14
band heaters 16a, 16 having a, 14b, 14c
b, 16c, and each heating zone 16a, 16b, 16c is provided with a respective temperature detecting means 14a, 14b, 14c and a respective heating control unit 1.
8a, 18b, 18c and switches 20a, 20b, 2
0c and heating power via the heating power supply 22. It should be noted that in the figure, the reference symbol P
Reference numerals 1 and P2 indicate positions of the forward end and the backward end of the screw 12 tip, and reference numeral 24 indicates a molten resin injection nozzle.

However, according to the present invention, in the above configuration, the injection molding machine further includes sequence control means 26 which is linked to a molding cycle, and the heating zones 16a, 16b, 16c are provided with temperature detecting means 14a, 14c.
In addition to the heating control via the b and 14c, also at a specific time zone during the injection side process via the sequence control means 26, similarly via each of the switches 20a, 20b and 20c and the heating power supply 22 , And is configured to perform heating control in an additional compensation manner.

That is, in FIG. 2, the temperature distribution of the molten resin is, for example, as described above in the conventional heating operation (and the kneading heat generation operation) in which the barrel heating zone is controlled to be heated through the temperature detecting means. As shown in the figure, it is set to a downward-sloping tendency as generally shown in FIG. However, in this case, the heating zone further starts after a lapse of a predetermined time T1 in the injection step, that is, after a predetermined time T1 in the injection step S2 via the sequence control means 26,
The heating is forcibly controlled during a time period T3, which ends when a predetermined time T2 of the subsequent plasticizing and measuring step S1 has elapsed.

Therefore, the temperature distribution of the molten resin becomes a flat curve t 'by additionally compensating for the disadvantage of the conventional curve t, that is, the insufficient heating Δt. Note that the heating control after the specific time zone T3 naturally continues to the heating operation via the conventional temperature detecting means again. Also, in the heating control via the sequence control means 26, preferably, the specific time zone is set separately for each heating zone, and the heating control is performed separately for each heating zone. This is for appropriately controlling, for example, the amount of plasticizing heat and the amount of kneading / heating of the resin material at the relevant positions of the screw in accordance with the type of molding resin and the performance of the screw.

As described above, in the present invention, the barrel heating zone is separated from the heating effect via the conventional temperature detecting means, and further by the heating action in a specific time zone during the injection side process via the sequence control means. The heating is controlled in an additional compensation manner. Therefore, according to the present invention, the difficulty in the conventional temperature control method-that is, the decrease in the molten resin temperature (temperature difference) due to the reduction in the heating effect and the delay in the response time is compensated for, and therefore the injection molten resin temperature is reduced. The temperature distribution is made uniform and the quality of the molded product is stabilized.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and many modifications and changes can be made without departing from the spirit of the present invention.

[0022]

As described above, the barrel temperature control method for an injection molding machine according to the present invention provides an injection molding machine in which the injection-side step includes a plasticizing measurement step when the screw is retracted and an injection step when the screw is advanced. The injection molding machine is provided with a plurality of barrel heating zones each having a barrel temperature detecting means on the outer peripheral surface of the barrel, whereby each of the heating zones is heated and controlled via the temperature detecting means. In the barrel temperature control method of the machine, the injection molding machine is provided with sequence control means interlocked with a molding cycle, whereby each heating zone is separated from the heating control via the temperature detection means, and further through the sequence control means. Thus, the heating control is performed during a specific time period during the injection side process, so that the temperature control method using the conventional temperature detecting means can be performed. The decrease in temperature of the molten resin (temperature difference) that has occurred due to the above can be additionally compensated for by the heating effect of the newly provided sequence control means, whereby the temperature distribution of the temperature of the injected molten resin can be made extremely uniform. You.
Therefore, the quality of the injection molded product can be reliably stabilized.

[Brief description of the drawings]

FIG. 1 is a block control system diagram showing one embodiment of a barrel temperature control method for an injection molding machine according to the present invention.

FIG. 2 is an explanatory diagram showing a temperature distribution of a molten resin by the barrel temperature control method in FIG.

FIG. 3 is a block control system diagram for implementing a conventional barrel temperature control method for an injection molding machine.

4 is an explanatory diagram showing a temperature distribution of a molten resin by the barrel temperature control method in FIG.

[Explanation of symbols]

 Reference Signs List 10 barrel 12 screw 14a, 14b, 14c temperature detecting means (thermocouple) 16a, 16b, 16c band heater (heating zone) 18a, 18b, 18c heating control unit 20a, 20b, 20c switch 22 heating power supply 24 nozzle 26 sequence control means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-45912 (JP, A) JP-A-62-249723 (JP, A) JP-A-4-148912 (JP, A) 15120 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 45/72-45/78

Claims (4)

(57) [Claims] 1. An injection molding machine comprising: an injection molding machine comprising a plasticization measuring step at the time of screw retreat and an injection step at the time of screw advancement, wherein said injection molding machine has a barrel temperature detecting means on its outer peripheral surface. A plurality of barrel heating zones having a plurality of barrel heating zones, wherein each of the heating zones is controlled to be heated via the temperature detecting means. A sequence control means interlocked with a molding cycle of the injection molding machine. In addition to the heating control via the temperature detecting means, the heating control of each of the heating zones is carried out at a specific time during the injection side process via the sequence control means. A method of controlling the barrel temperature of a molding machine. 2. The injection molding according to claim 1, wherein the specific time period in the injection side process is set so as to start after a lapse of a predetermined time in the injection process and to end when a predetermined time in the subsequent plasticizing and measuring process. Machine barrel temperature control method. 3. The specific time zone during the injection-side process is set separately for each heating zone.
A barrel temperature control method for an injection molding machine as described in the above. 4. The heating control by the sequence control means,
4. The method of controlling a barrel temperature of an injection molding machine according to claim 1, wherein the setting is performed separately for each heating zone.