JPH056090Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) This invention relates to an injection molding machine equipped with a function to automatically perform purging operations when changing the color or material of resin material, and in particular to a technology for shortening the time required for purging and reducing the amount of resin required for purging in an injection molding machine equipped with such an automatic purging function.

(Prior Art) In an injection molding machine, when changing the color or changing the resin material, it is necessary to remove the old resin material remaining in the cylinder or the injection nozzle provided at the tip of the cylinder. Therefore, in an injection molding machine,
When changing the color or material of these resin materials, a so-called purging operation is performed in which filling and injection operations are repeated multiple times using the new resin material to be replaced. The remaining old resin material is replaced with new resin material.

By the way, the filling and injection operations of the resin material during the above-mentioned purging operation have conventionally been performed manually by the operator, which has the problem of being troublesome and requiring skill. There were also problems in which the operator was unable to perform other tasks during the purging operation. Therefore, in recent years, in order to eliminate these problems, an injection molding machine with an automatic purging function has been proposed, which is equipped with a purging control means that automatically performs a predetermined purging operation based on a predetermined purging start signal. has been done.

According to an injection molding machine having such an automatic purging function, the purging operation can be automatically performed simply by the operator operating a command switch for starting purging to generate a purging start signal. Therefore, it is not necessary for the operator to become skilled in the purging operation, and the operator can be relieved from the troublesome work during the purging operation. This also makes it possible for employees to engage in other tasks.

(Problem) However, the conventional injection molding machines having the automatic purging function described above merely allow the operator to perform the purging operation automatically, which was previously performed manually. The filling and injection conditions of the resin material at the time, especially the heating conditions for the cylinder and injection nozzle, are as follows:
As with the manual operation by the operator, the heating conditions during normal molding operation of the injection molding machine remained the same. For this reason, with conventional injection molding machines that have such an automatic purging function, although it is expected that the purging operation will become more efficient due to automation, it cannot be expected that the efficiency of the purging operation will be improved due to other factors. From the aspect of
It was hard to say that it was necessarily completely satisfying.

(Solution Means) Against this background, the present invention has been developed because it is difficult to remove the old resin material inside the injection nozzle, especially the old resin material in the part that is in contact with the inner wall of the injection nozzle, and the purging operation is difficult. This was done by focusing on the fact that efficiency improvement is mainly hindered by the residual of old resin material in the part that is in contact with the inner wall of the injection nozzle, and the gist is as described above. , comprising a purging control means for automatically performing a predetermined purging operation based on a predetermined purging start signal, and by generating the purging start signal, the cylinder and the tip end of the cylinder are heated by the predetermined heating means. In an injection molding machine equipped with an automatic purging function, the purging control means automatically performs the purging operation under heating with an injection nozzle provided in the injection nozzle. It includes at least a plurality of heaters for heating, and the plurality of heaters are connected in series between power supplies during normal molding operation, and connected in parallel between power supplies during purging operation according to the purging start signal. a nozzle temperature raising means for raising the temperature of the injection nozzle to a predetermined purge temperature higher than the heating temperature during normal molding operation based on the purging start signal; and purge temperature detection means for directly or indirectly detecting that the temperature of the injection nozzle has reached the purge temperature during the temperature raising operation and outputting a purge temperature detection signal, and outputting the purge temperature detection signal from the purge temperature detection means. The purging operation by the purging control means is started based on the purge temperature detection signal.

(Function/Effect) According to the injection molding machine equipped with the automatic purging function according to the present invention, the temperature of the resin material in the injection nozzle is raised higher than before, in other words, the viscosity of the resin material in the injection nozzle is increased. Since the purging operation by the purging control means can be started in a state where the In comparison, it can be removed quickly.

Therefore, it is of course comparable to an injection molding machine that performs the purging operation manually, but also to a conventional injection molding machine that has an automatic purging function that simply performs the purging operation automatically based on a purging start signal. In comparison, it is possible to significantly shorten the time required for the purging operation, greatly improving the efficiency of the purging operation, and it is also possible to significantly reduce the amount of resin required for purging. be.

In particular, in the present invention, multiple heaters for heating the injection nozzle are connected in series during normal molding operation and in parallel during purging operation using a predetermined switch mechanism. Therefore, during the purging operation, the injection nozzle can be effectively heated by the plurality of heaters, and the time required to raise the temperature of the injection nozzle and, in turn, the purging operation time can be advantageously shortened.

(Examples) Hereinafter, in order to clarify the present invention more specifically, some examples thereof will be described in detail based on the drawings.

First, FIG. 1 schematically shows an example of an injection molding machine equipped with an automatic purging function according to the present invention. Reference numeral 10 denotes a heating cylinder, and a plurality of band heaters 14 are disposed on the outer peripheral surface of the heating cylinder, and the band heaters 14 are electrically heated and controlled by a cylinder heater heating circuit (not shown).
Further, in the figure, reference numeral 16 denotes an injection nozzle attached to the tip of the heating cylinder 10, and a band heater of the heating cylinder 10 is provided on the outer peripheral surface of the injection nozzle, which is energized and heated by a nozzle heater heating circuit 18. An appropriate number (in this case, two) of band heaters 20, which together with 14 constitute a heating means, are arranged.

The injection screw 2 is rotatably and axially movable relative to the heating cylinder 10.
2 has been inserted, and as is well known,
As the injection screw 22 is rotated while the heating cylinder 10 and injection nozzle 16 are heated by the band heaters 14 and 20, the resin material supplied from the hopper 24 into the heating cylinder 10 is heated and fluidized. The resin material filled in the front of the injection screw 22 is filled with the injection screw 22 by moving the injection screw 22 forward after the resin filling operation. Material is adapted to be injected through the injection nozzle 16.

In addition, in FIG. 1, 26 is a thermocouple for measuring the temperature of the injection nozzle 16. Although such a thermocouple is also provided in the heating cylinder 10, it is omitted here.

Incidentally, although not shown in the drawings, the injection molding machine of this embodiment, like a conventional injection molding machine equipped with an automatic purging function, performs a resin material filling operation based on the rotational operation of the injection screw 22, and a resin material filling operation based on the rotational operation of the injection screw 22. A purging controller is provided as a purging control means that repeats the injection operation of the resin material based on the forward movement of 22 a predetermined number of times according to a predetermined program. and,
When changing the color of the resin material or changing the material, when a purging start switch 28 (described later) is operated and a purging start signal is generated, the purging controller is activated based on the purging start signal, similar to a conventional injection molding machine. The purging operation is automatically performed. However, in the injection molding machine of this embodiment, unlike conventional injection molding machines, the purging controller is not immediately activated based on the purging start signal, and the injection nozzle 16 is heated to a temperature higher than the normal molding operating temperature. After the temperature is raised to a predetermined purge temperature, the operation of the purge controller and eventually the purging operation are started.

That is, FIG. 2 shows the nozzle heater heating circuit 18 in detail, and as shown therein, the nozzle heater heating circuit 18
Based on the temperature detected by the thermocouple 26,
The normal molding temperature control device 30 controls the heating of the injection nozzle 16 to the normal molding operating temperature by controlling the current heating of the band heaters 20 and 20. A purging temperature control device 32 is provided for heating the injection nozzle 16 to the purging temperature by controlling the heaters 20 and 20 to heat the injection nozzle 16 to the purging temperature. Then, the break contact 28a of the purging start switch 28 with respect to the temperature control device 30 for normal molding is
Also, the make contacts 28b of the purging start switch 28 are connected in series to the purging temperature controller 32, and by switching the purging start switch 28, the normal molding temperature controller 30 and the purging temperature controller are connected in series. The device 32 is adapted to be alternatively activated. In addition, the purging initiation switch 28 provides break contacts 28a and make contacts 28c, as well as break contacts 28c and make contacts 28d, 28.
break contact 28c by switching the purging start switch 28.
Based on the opening and closing operations of the make contacts 28d and 28e, the two band heaters 20 and 20 are connected in series between the power supplies during normal molding operation, and in parallel between the power supplies during purging operation. It's summery. As a result, under heating control by the purging temperature control device 32, a voltage twice as high as the voltage applied under heating control by the normal molding temperature control device 30 is applied to each band heater 20,
20.

Here, the temperature control device 30 for normal molding is configured to control the energization of the electromagnetic contactor 34 by controlling the opening and closing of the make contact 30a during its operation, thereby controlling the energization of the band heaters 20, 20. The make contacts 34a and 34b of the electromagnetic contactor 34 connected in series are controlled to open and close to control the energization of the band heaters 20 and 20, which in turn controls the heating of the injection nozzle 16 to the normal molding operating temperature. There is. In addition, during operation, the purging temperature control device 32 controls the opening and closing of the make contact 32a to control the energization of the electromagnetic contactor 34, similar to the normal molding temperature control device 30. Accordingly, the band heaters 20, 20 are energized to control the heating of the injection nozzle 16 to the purge temperature.

In this embodiment, in contrast to the purging temperature control device 32, the purging temperature control device 3
A make contact 33 is provided which is closed based on the fact that the temperature of the injection nozzle 16 detected by the thermocouple 26 reaches the purge temperature after the start of the operation in step 2. Based on this, the purging controller is activated.

That is, in this embodiment, during normal molding operation when the break contacts 28a, 28c of the purging start switch 28 are closed, the band heaters 20, 20 connected in series are energized by the normal molding temperature control device 30. Based on the control, the injection nozzle 16 is heated to the normal molding operating temperature, and the purging start switch 28 is operated to open the make contacts 28b,
When 28d and 28e are closed, the injection nozzle 16 is heated to a purge temperature higher than the normal molding operation temperature based on the energization control of the band heaters 20 and 20 connected in parallel by the purging temperature controller 32. Furthermore, when the temperature of the injection nozzle 16 is raised from the normal molding operation temperature to the purge temperature based on the operation of the purging temperature controller 32, the make contact of the purging temperature controller 32 33 is closed to start the operation of the purging controller and thus the purging operation.

In addition, in FIG. 2, 36, 36 are circuit breakers inserted in series with the band heaters 20, 20.

Therefore, according to such an injection molding machine, by switching the purging start switch 28 of the nozzle heater heating circuit 18, the injection nozzle 16 is started.
The temperature of the injection nozzle 16 can be automatically raised to a purge temperature higher than the normal molding operation temperature, and the temperature of the injection nozzle 16 is raised to the purge temperature.
This allows the purging controller to perform the purging operation, and the injection nozzle 1
6. Furthermore, the purging operation can be performed with the temperature of the resin material inside the injection nozzle 16 being higher than before, in other words, the viscosity of the resin material inside the injection nozzle 16 is lower than before. It can be done.

Therefore, during purging, the old resin material in the part that was in contact with the inner wall of the injection nozzle 16, which was particularly difficult to remove, can be removed much more quickly than in the past, and the purging operation can be performed manually. The time required for the purging operation is significantly reduced, not only compared to injection molding machines that perform the purging operation automatically, but also compared to conventional injection molding machines that have an automatic purging function that simply performs the purging operation automatically. As a result, the efficiency of the purging operation can be greatly improved, and the amount of resin required for purging can also be significantly reduced.

In addition, in such an injection molding machine, the time from the switching operation of the purging start switch 28 until the temperature of the injection nozzle 16 rises to the purge temperature, and furthermore, the time until the start of the purging operation is simply controlled by the band heaters 20, 20. The total time required for purging can be reduced more effectively than in an injection molding machine in which only two parts are connected in series. Moreover, in this example,
Since such an effect can be enjoyed without adding more band heaters 20, it can be advantageously applied in cases where it is difficult to add more band heaters 20 to the injection nozzle 16.

As is clear from the above description, in this embodiment, the purging temperature controller 32 constitutes the nozzle temperature raising means, and the thermocouple 26
and the make contact 33 of the purging temperature control device 32 constitute a purge temperature detection means.
In addition, in this embodiment, the purging start switch 2
The closing signals of the 8 make contacts 28b, 28d, and 28e constitute the purging start signal, and the closing signal of the make contact 33 of the purging temperature control device 32 constitutes the purge temperature detection signal.

Although typical embodiments of the present invention have been described in detail above, these are literal illustrations, and it goes without saying that the present invention should not be interpreted as being limited to such specific examples.

For example, in the embodiment described above, after the start of the purging operation based on the generation of the purge temperature detection signal, the temperature of the injection nozzle 16 is maintained at the purge temperature or a temperature slightly higher than the purge temperature (final target temperature). In this state, a purging operation is performed by a purging controller. However, during a purging operation by a purging controller, if the temperature is higher than that during normal molding operation, the temperature of the injection nozzle 16 is lowered than the purge temperature. It is also possible to maintain the temperature. Even in this way, the purpose of the present invention can be achieved to some extent.

In addition, various changes, modifications, improvements, etc. may be made to the present invention without departing from the spirit of the invention, although it is omitted to list specific examples such as the configuration of the nozzle temperature raising means and the purge temperature detection means. It goes without saying that it can be implemented in this manner.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of an injection molding machine according to the present invention, and Fig. 2 is a circuit diagram showing an example of a nozzle heater heating circuit in the injection molding machine of Fig. 1. 10 ... heating cylinder, 14, 20 ... band heater (heating means), 16 ... injection nozzle, 18
......Nozzle heater heating circuit, 26 ......Thermocouple, 2
8: Purging start switch; 30: Temperature control device for normal molding; 32: Temperature control device for purging (nozzle temperature raising means); 33: Make contact; 34:
...electromagnetic contactor.

Claims (1)

[Claims for Utility Model Registration] A purging control means for automatically performing a predetermined purging operation based on a predetermined purging start signal is provided, and by generating the purging start signal, the predetermined heating means
In an injection molding machine having an automatic purging function, the purging operation is automatically performed by the purging control means while the cylinder and the injection nozzle provided at the tip of the cylinder are heated. The means includes at least a plurality of heaters for heating the injection nozzle, and the plurality of heaters are connected in series between power supplies during a normal molding operation, and connected between power supplies during a purging operation according to the purging start signal. a nozzle temperature raising means for raising the temperature of the injection nozzle to a predetermined purge temperature higher than the heating temperature during normal molding operation based on the purging start signal; A purge temperature detection means is provided which directly or indirectly detects that the temperature of the injection nozzle reaches the purge temperature by the temperature raising operation by the nozzle temperature raising means and outputs a purge temperature detection signal. An injection molding machine having an automatic purging function, characterized in that the purging control means starts a purging operation based on a purge temperature detection signal output from the purge temperature detection means.