JP4850930B2 - Method of manufacturing a molded product using an injection molding machine - Google Patents

Description

The present invention relates to a method for manufacturing a molded product using an injection molding machine .

  In a production system in which an injection molding machine and a post-process are directly connected, it is necessary to match the number of moldings with the number of post-processes. Therefore, conventionally, in order to prevent excessive supply in the event of abnormalities in the post-process, the molded product is discarded, which is very uneconomical. Under such circumstances, the injection molding machine can be automatically stopped by an operator or an abnormal signal from a subsequent process. However, once the injection molding machine is stopped, the mold temperature decreases, and the resin in the cylinder Temperature changes. For this reason, when the injection molding machine is restarted, it takes a long time for the mold temperature and the resin temperature to stabilize, resulting in a reduction in work efficiency.

For this reason, an injection molding machine, a post-process directly connected to the injection molding machine as in Patent Document 1, and a stocker for storing molded products different from those are provided, and a signal transmitted when the post-process is abnormal is injected into the injection molding machine. And a method of extending a molding cycle at the same time as conveying a molded product to a stocker. According to this method, by providing the stocker, it is possible to perform molding without stopping the molding machine when the post-process is abnormal, and it is possible to suppress an increase in the stocker by extending the molding cycle.
In addition, as another method, as in Patent Document 2, a stocker for accumulating molded products is provided between the injection molding machine and the post-process, and the number of moldings, the number of post-processes, and the accumulation of stockers are provided between them. A method has been proposed in which the production system is controlled by detecting the number with a sensor and extending or contracting the molding cycle.

In any of these inventions, the expansion and contraction of the molding cycle is performed by timer control of the cooling time or the intermediate time before the mold closing operation. Here, with reference to FIG. The relationship between one cycle of operation during a normal molding cycle and one cycle of operation during expansion / contraction of the molding cycle will be described. FIG. 2 is a diagram showing the operation of the injection molding process in the molding cycle. The operation C in FIG. 2 shows the operation during normal molding.
In FIG. 2, 11 is a mold closing process, 12 is a low pressure mold clamping process, 13 is a high pressure mold clamping process, 14 is an injection process, 15 is a pressure holding process, and 16 cooling process. Reference numeral 17 denotes a weighing process, 18 denotes a mold opening process, 19 denotes an ejector process, 20 denotes a standby process, and 21 denotes an intermediate time extension process.

  In operation C, the resin in the cylinder is first injected into the mold 14 after the low pressure mold clamping 12 and the high pressure mold clamping 13 are started from the mold closing 11. Next, at the same time as entering the cooling step 16 after the pressure holding step 15, a metering operation 17 is performed in which the resin for the next injection is sent to the cylinder tip. After the cooling step 16, the mold is opened 18 and the ejector 19 is taken out to take out the molded product. The period from the standby 20 of the molding machine during the removal of the molded product to the mold closing 11 of the next molding cycle is one cycle of the operation C during normal molding.

On the other hand, the operation D shows the operation at the time of expansion / contraction of the molding cycle when the injection molding machine receives a signal from the sensor counting the number of stockers.
FIG. 2 shows an example in which the expansion / contraction of the molding cycle is adjusted by extending the intermediate time from the standby 20 of the molding machine during the removal of the molded product to the mold closing 11 of the next molding cycle. In the above conventional example, in addition to adjusting (extending) such an intermediate time, it is disclosed that the molding cycle is expanded / contracted by adjusting (extending) the cooling time.
Even during the molding cycle expansion and contraction, from the mold closing 11 to the standby 20 after the ejector 19 is the same as the operation C at the time of normal molding, the subsequent intermediate time 21 is controlled by a timer. The timer is set longer when the number of stockers is larger, and shorter when the number is smaller. The period from the elapse of the intermediate time 21 set in the timer to the closing of the mold is one cycle of the operation D at the time of expansion / contraction of the molding cycle. The conventional example also discloses that the molding cycle is expanded and contracted by adjusting (extending) the cooling time in addition to adjusting (extending) the intermediate time as described above.

JP 2001-129863 A Japanese Examined Patent Publication No. 7-121547

  However, the method of Patent Document 1 has a problem in terms of production efficiency because a separate process must be provided for post-processing of the molded product conveyed to the stocker. On the other hand, in the method of Patent Document 2, although the problem of providing a separate process for post-processing of the molded product conveyed to the stocker can be solved, in these conventional examples, the molding cycle is reduced. As a method of expanding and contracting, there is the following problem in that the cooling time or the intermediate time is adjusted as described above.

That is, in normal molding, the mold temperature becomes high when the resin is injected, and gradually decreases after cooling and mold opening / closing steps. In addition, the resin generates shear heat due to the rotation of the screw during measurement, and the resin temperature becomes higher than the cylinder temperature. From the completion of measurement to the start of injection of the next molding cycle, the resin temperature decreases with time due to heat radiation from the cylinder to the outside air.
Therefore, if the molding cycle is constant, it can be considered that the mold temperature and the resin temperature at the time of injection are substantially constant. However, when the molding cycle is not constant, the time from injection to the next injection and the time from completion of measurement to the start of injection differ, resulting in a difference in mold temperature and resin temperature at the time of injection.

In particular, in the case where the expansion and contraction of the molding cycle is performed by adjusting the cooling time or the intermediate time as in the conventional example, the influence on the quality of the molded product becomes extremely large.
That is, when adjusting the cooling time, the temperature at which the molded product is taken out is changed, resulting in a dimensional difference due to post-shrinkage, and when adjusting the intermediate time, as described above, from the completion of the measurement, the next molding cycle is completed. Due to the difference in the time until the start of injection, there will be a significant difference between the mold temperature and the resin temperature at the time of injection.
These change the filling property of the resin, affect the resin pressure in the mold, and cause a dimensional difference in the molded product. Therefore, the expansion / contraction of the molding cycle by adjusting the cooling time and the intermediate time has a very limited range of good products.

In view of the above problems, the present invention can perform injection molding without causing as much temperature difference as possible between the resin temperature and the mold temperature at the time of injection in the resin injection process when performing injection molding by expanding and contracting the molding cycle. An object of the present invention is to provide a method for manufacturing a molded product using an injection molding machine that can suppress deterioration in quality of the molded product .

The present invention provides a method for producing a molded product using an injection molding machine configured as follows.
That is, the method for manufacturing a molded article using the injection molding machine of the present invention includes a low pressure clamping process, a high pressure clamping process, an injection process for injecting a resin weighed in a weighing process, and a cooling for cooling the injected resin. molded article which is molded in the molding cycle comprising the steps, after storing the stocker, and supplies the higher rear Engineering, a method for producing a molded article using an injection molding machine,
The molding cycle has a step of expanding and contracting the time of the molding cycle,
The step of expanding and contracting the time of the molding cycle includes:
Determining a delay time according to the amount of the molded product accumulated in the stocker;
Delaying the start time of the metering step of the resin and the high pressure mold clamping process start time after the low pressure mold clamping process or the injection process start time after the high pressure mold clamping process; and
It is characterized by containing .
Moreover, the manufacturing method of the molded article using the injection molding machine of the present invention is characterized in that the start time of the weighing process is delayed by setting the delay time in a timer at the start of the cooling process .

According to the present invention, when performing injection molding by expanding and contracting a molding cycle, injection molding can be performed without causing as much as possible the temperature difference between the resin temperature and the mold temperature during injection in the resin injection process. It is possible to realize a method of manufacturing a molded product using an injection molding machine that can suppress deterioration in product quality.

The operation | movement figure of the injection molding process at the time of expansion-contraction of the molding cycle in Example 1 of this invention. The operation | movement figure of the injection molding process at the time of expansion-contraction of the molding cycle in a prior art example. The figure which shows the structure of the production system in Example 2 of this invention. Explanatory drawing of the accumulation | storage number of a stocker, the signal, and operation | movement of an injection molding machine in Example 2 of this invention. The flowchart of operation | movement of the injection molding machine explaining Example 2 of this invention.

Shaped state for carrying out the present invention will be illustrated by the following examples.

[Example 1]
In Example 1, the above-described configuration of the present invention is applied to an injection molding method, which will be described with reference to the drawings.
FIG. 1 is a diagram showing an operation of an injection molding process when a molding cycle is expanded and contracted in the present embodiment.
In the operation A of FIG. 1, a configuration example in the case of adjusting the time for starting high-pressure mold clamping or the time for starting weighing will be described.
In addition, in operation B of FIG. 1, a configuration example in the case of adjusting the time for starting injection will be described. In the injection molding step shown in FIG. 1, the same reference numerals are given to the same components as those in the conventional example, and the description of the duplicate components is omitted.
In FIG. 1, 22 is a high-pressure mold clamping delay process, 23 is a metering delay process, and 24 is an injection delay process.
In the present embodiment, in the operation A of FIG. 1, the high pressure mold clamping delay time 22 from the completion of the low pressure mold clamping process 12 to the start of the high pressure mold clamping 13 is configured to timer-control the high pressure mold clamping delay time. Yes. Here, the timer is set longer when the number of stockers is larger, and shorter when the number is smaller. After the high pressure mold clamping delay time set in the timer has elapsed, the high pressure mold clamping 13 is started.
Further, in this embodiment, after the high pressure mold clamping process 13, the pressure holding process is performed in the pressure holding process 15 through the injection process 14. At the same time as entering the cooling step 16 after the pressure holding step 15, the metering delay time 23 until the start of metering is configured to perform timer control of the metering delay time.

In this embodiment, the mold opening 18 is performed after the cooling 16 and the standby 20 after the ejector 19 to the mold closing 11 of the next molding cycle is one cycle at the time of expansion / contraction of the molding cycle.
In this embodiment, the time for expanding and contracting the molding cycle is adjusted before the start of high-pressure clamping after the mold closing process with little change in the mold temperature. Compared to what is performed in the intermediate time extension step after the mold opening step, it is possible to remarkably suppress a decrease in mold temperature.
Further, in this embodiment, the measurement start time can be delayed by the timer control in the measurement delay process by the same time as the time delayed by the timer control in the high pressure mold clamping delay process 22, so By the heat radiation from the cylinder to the outside air before the start of the injection of the molding cycle, it is possible to remarkably suppress the decrease in the resin temperature as compared with the case where the resin temperature is decreased with time.

  In this embodiment, as shown in the operation B of FIG. 1, the time adjustment for expanding and contracting the molding cycle may be performed in the injection delay step or the measurement delay step in the same manner as the operation A. As in the case of the operation A, it is possible to remarkably suppress a decrease in mold temperature or resin temperature.

From the above, according to the present embodiment, when performing injection molding by expanding and contracting the molding cycle, injection molding is performed without causing as much as possible the temperature difference between the resin temperature and the mold temperature at the time of injection in the resin injection process. It becomes possible.
In the above description of the present embodiment, the process for adjusting the time for expanding and contracting the molding cycle is individually described. However, the expansion and contraction of the molding cycle in the present embodiment is the high-pressure mold clamping start time of the high-pressure mold clamping process. And / or adjustment of the injection start time of the injection process, and a time corresponding to the adjustment time of the high pressure mold clamping start time of the high pressure mold clamping process and / or the injection start time of the injection process, It can also be carried out by adjusting the measurement start time of the measurement process.

[Example 2]
In Example 2, the injection molding method of Example 1 described above is applied to a production system, and these will be described with reference to the drawings.
FIG. 3 shows the configuration of the production system in this embodiment.
In FIG. 3, 30 is an injection molding machine, 31 is a post process, 32 is a conveying means, 33 is a stocker, and 34 is a sensor.
The injection molding machine 30 is an apparatus for obtaining a plastic molded product from pellet resin by a known process, and there may be one or a plurality of units.
Moreover, the post-process 31 performs the assembly process of the molded product shape | molded with the injection molding machine 30 and other components, or the molded products shape | molded by the some injection molding machine 30, for example.
The conveying means 32 has a role of cooling the molded product from the injection molding machine 30 to the post-process 31 at the same time as taking out the molded product molded by the injection molding machine 30 from the mold and transferring it to the post-process 31. From the injection molding machine 30 to the post process 31, it operates at a constant speed so as to have a predetermined cooling time.
The stocker 33 temporarily accumulates the molded products molded by the injection molding machine 30 and transported by the transport means 32, and for example, the stocker 33 is stacked from the bottom as shown in the figure. Are passed to the post-process 31 in the order of arrival.
The sensor 34 is installed in the stocker 33, detects the number of molded articles accumulated in the stocker 33 in three stages of arbitrary accumulation numbers N1, N2, and N3, and transmits a signal 42 corresponding to the stage to the injection molding machine 30. Can do.

FIG. 4 is an explanatory diagram of the accumulated number of stockers, signals, and operations of the injection molding machine in this embodiment.
In FIG. 4, reference numeral 41 denotes the number of stocks in the stocker 33, 42 denotes a signal corresponding to the number 41 stored by the sensor 34 that has detected the stock number 41, 43 denotes the signal 42, and the operation of the injection molding machine 30 that has received the signal 42. Show.
The sensor 34 detects an arbitrary accumulation number 41 of the stocker 33 in three stages N1, N2, and N3 (N1 <N2 <N3). When the accumulation number 41 of the stocker 33 is N1, the signal 42 indicates S1 and the accumulation number 41. When N is N2, the signal 42 transmits S2 to the injection molding machine 30, and when the accumulation number 41 is N3, the signal 42 transmits S3 to the injection molding machine 30.
When the injection molding machine 30 receives S1 of the signal 42, the injection molding machine 30 receives the delay time T1 from the completion of holding pressure to the start of measurement and / or the delay time T1 from completion of mold closing to the start of mold clamping, and receives S2 of the signal 42. In this case, the delay time from the completion of the pressure holding to the start of measurement and / or the delay time T2 from the completion of mold closing to the start of mold clamping, and when S3 of the signal 42 is received, the molding is stopped and waits.

FIG. 5 shows a molding operation flowchart of the injection molding machine 30. Here, the case where the molding cycle is expanded and contracted by adjusting the time for starting high-pressure mold clamping will be described, but the same applies to the case where the time for starting injection is adjusted.
The one-cycle molding process starts with the mold closing 51 first. After the mold is closed, the low-pressure mold clamping 52 is entered, where the operation is determined by the signal 42 corresponding to the number 41 stored in the stocker 33.
When S1 of the signal 42 is received, a timer with a delay time T1 from the low pressure mold clamping 52 to the high pressure mold clamping 53 is received. When S2 of the signal 42 is received, a delay time T2 from the low pressure mold clamping 52 to the high pressure mold clamping 53 is received. Set and count the timer.

When S3 of the signal 42 is received, the molding is stopped and the process waits 61. The high-pressure mold clamping 53 is performed 60 after the delay times T1 and T2 from the low-pressure mold clamping 52 to the high-pressure mold clamping 53, and the resin in the cylinder is injected 54. Thereafter, the process proceeds to the holding pressure 55 and enters the cooling 56 after completion of the holding pressure, and at the same time, a delay time from the completion of the holding pressure 55 to the start of measurement 63 is set by the signal 42 corresponding to the accumulated number 41 of the stocker 33.
When setting the delay time until the measurement start 63, when S1 of the signal 42 is received, the delay time T1 from 55 after the completion of pressure holding to the measurement start 63, and when receiving the signal S2, from 55 after the completion of pressure holding. A timer with a delay time T2 until the measurement start 63 is set. The metering is started 63 after the delay times T1 and T2 from the completion of the pressure holding 55 to the metering start 63 have elapsed.
In parallel with the set delay time, a standby 59 for cooling 56, mold opening 57, ejector 58, removal of a molded product, etc. is performed, and one cycle is completed.

Next, the production system of the present embodiment will be described with reference to FIGS.
The molded product molded by the injection molding machine 30 is taken out from the mold, placed on the conveying means 32, and reaches the stocker 33 after cooling for a predetermined time. The post-process 31 receives the molded products in the order of arrival at the stocker 33 and performs post-processing.
When the accumulation number 41 of the stocker 33 is N1 or less, S1 is transmitted from the sensor 34 as the signal 42.
In the injection molding machine 30, after completion of the mold closing 51 and the low pressure mold clamping 52, a timer with a delay time T1 is set from the low pressure mold clamping 52 to the high pressure mold clamping 53 in accordance with S1 of the signal 42. After the lapse of the delay time T1, the high pressure mold clamping 53 is performed 60 and the injection 54 is performed.
Next, after holding the pressure 55, the cooling 56 is entered, and at the same time, a timer with a delay time T1 is set from the pressure holding completion 55 to the measurement start 63. After delay time T2 elapses 62, weighing 63 is started. At the same time, the cooling 56, the mold opening 57, the ejector 58, and the standby 59 during taking out the molded product are performed. Since the molding cycle at this time is a normal cycle and coincides with the tact of the post-process 31, the accumulated number 41 of the stocker 33 does not increase.

  When an abnormality occurs in the post-process 31 and the molded product cannot be processed, the molded product is accumulated in the stocker 33. When the accumulated number 41 eventually reaches N2, the sensor 34 transmits S2 of the signal 42. In the injection molding machine 30, after completion of the mold closing 51 and the low pressure mold clamping 52, a timer with a delay time T1 is set from the low pressure mold clamping 52 to the high pressure mold clamping 53 in accordance with S1 of the signal 42. After the lapse of the delay time T1, the high pressure mold clamping 53 is performed 60 and the injection 54 is performed. Then, after holding pressure 55, a timer of delay time T1 is set from holding pressure completion 55 to measurement start 63 at the same time as cooling starts. After delay time T2 elapses 62, weighing 63 is started. At the same time, the cooling 56, the mold opening 57, the ejector 58, and the standby 59 during taking out the molded product are performed. This operation prevents the mold temperature from falling by waiting in the mold closed state, and keeps the time from the completion of measurement 64 to the start of injection 51 to be equal to the normal cycle, thereby preventing the resin temperature from falling and extending and contracting the molding cycle. To do. When the post-process 31 returns, the tact of the post-process 31 becomes shorter than the extended cycle of the injection molding machine 30, so that the digestion amount of the post-process 31 exceeds the supply amount of the molded product and is accumulated in the stocker 33. Molded articles will gradually decrease. When the accumulation number 41 of the stocker 33 returns to N1 or less again, a signal S1 is transmitted from the sensor 34. The injection molding machine 30 delays from the low pressure mold clamping 52 to the high pressure mold clamping 53 to the delay time T1 from the low pressure mold clamping 52 to the measurement start 63 according to S1 of the signal 42 after the mold closing 51 and the low pressure mold clamping 52 are completed. Time T1 is set and the process returns to the normal cycle. On the other hand, when an abnormality occurs in the post-process 31 and the time until return becomes longer, the number of accumulated articles 41 accumulated in the stocker 33 continues to increase beyond N2, and the accumulation number 41 eventually reaches N3. Then, a signal S3 is transmitted from the sensor 34. The injection molding machine 30 stops and waits 61 after the mold closing 51 and the low-pressure clamping 52 in accordance with S3 of the signal 42 while the mold is closed.

11: Mold closing process 12: Low pressure mold clamping process 13: High pressure mold clamping process 14: Injection process 15: Pressure holding process 16: Cooling process 17: Metering process 18: Mold opening process 19: Ejector process 20: Standby process 22: High pressure Clamping delay process 23: Weighing delay process 24: Injection delay process

Claims (2)

After accumulating in a stocker a molded product molded in a molding cycle including a low-pressure mold clamping process, a high-pressure mold clamping process, an injection process for injecting the resin weighed in the weighing process, and a cooling process for cooling the injected resin , and it supplies the higher rear Engineering, a method for producing a molded article using an injection molding machine,
The molding cycle has a step of expanding and contracting the time of the molding cycle,
The step of expanding and contracting the time of the molding cycle includes:
Determining a delay time according to the amount of the molded product accumulated in the stocker;
Delaying the start time of the metering step of the resin and the high pressure mold clamping process start time after the low pressure mold clamping process or the injection process start time after the high pressure mold clamping process; and
Method for producing a molded article using an injection molding machine, characterized in that it contains. The method of manufacturing a molded article using an injection molding machine according to claim 1, wherein the start time of the weighing process is delayed by setting the delay time in a timer at the start of the cooling process.

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