JP2005014224A - Injection pressure control method of injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection pressure control method of an injection molding machine capable of reducing the fluctuation of the outer diameter dimension of a molded product to enhance productivity. <P>SOLUTION: The correlation (proximate linear function α) between the outer diameter dimension of the molded product molded by the injection molding machine and injection pressure at the time of an injection process for molding the molded product having the outer diameter dimension is preliminarily calculated. After the elapse of predetermined operation (steps 1 and 2), the outer diameter dimension of the molded product next molded by the injection molding machine is measured (step 3). The magnitude of injection pressure to be increased and decreased in order to set the outer diameter dimension of the molded product molded on and after to the reference outer diameter dimension of the molded product is calculated on the basis of the correlation (proximate linear function α) (steps 4 and 5). The injection pressure increased and decreased in magnitude is set as the set value of the injection pressure in the injection process on and after (step 6). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling the injection pressure of an injection molding machine.
[0002]
[Prior art]
FIG. 5 is a schematic configuration diagram showing an injection device of a conventional injection molding machine.
[0003]
As shown in FIG. 5, the injection device of the conventional injection molding machine is provided with a heater (not shown) for heating the resin conveyed inside, a cylinder 6 having a nozzle formed at the tip, and a cylinder 6 A hopper 10 that stores the resin to be supplied, a screw 7 that is rotatably inserted into the cylinder 6 and that transports the resin supplied into the cylinder 6, and the screw 7 is moved in the axial direction thereof, so that the inside of the cylinder 6 A ball screw 5 for injecting the molten resin into a mold (not shown), an injection servo motor 3 for driving the ball screw 5, a timing belt 4 for transmitting the driving force of the injection servo motor 3 to the ball screw 5, and at the time of injection And a load cell 9 for measuring the pressure of the molten resin. At the tip of the screw 7, a backflow prevention ring 8 that prevents the resin from flowing back into the cylinder 6 when the resin is injected from a nozzle (not shown) of the cylinder 6 is attached.
[0004]
Further, the injection apparatus includes a process controller 1 that controls the injection servo motor 3 and a servo amplifier 2 that is interposed between the process controller 1 and the injection servo motor 3.
[0005]
In this injection apparatus, the injection servo motor 3 rotates the ball screw 5 via the timing belt 4 to move the screw 7 in the axial direction, and injects resin from the nozzle of the cylinder 6 into a mold (not shown). It is configured as follows.
[0006]
A signal relating to the pressure of the molten resin at the time of injection measured by the load cell 9 is output to the process controller 1. The process controller 1 generates a control signal for moving the screw 7 in the axial direction based on the set pressure signal, and inputs this control signal to the injection servo motor 3 via the servo amplifier 2. As described above, the process controller 1 is in charge of the closed loop control of the injection apparatus that outputs the set pressure signal and the pressure feedback signal from the load cell 9 and receives the control signal to the injection servo motor 3.
[0007]
The process controller 1 can control the injection servo motor 3 so as to inject the molten resin at several stages of injection pressure, and the user can set an arbitrary injection pressure from among the several stages of injection pressure. It is configured.
[0008]
[Problems to be solved by the invention]
In such an injection molding machine, in order to stably mold the shape and dimensions of the molded product, it is necessary to control so as to maintain the set injection pressure. Inadequate control of the injection pressure in the injection process causes defects such as burrs and short shots in the molded product. Since the injection pressure that can eliminate these defective phenomena varies depending on the phenomenon, such a defective phenomenon cannot be fundamentally eliminated unless the injection pressure is controlled in accordance with the cavity shape in the mold.
[0009]
For example, when molding a molded product that needs to be molded with high accuracy, such as a plastic ferrule for optical connectors, the amount of resin filled into the mold cavity due to factors such as room temperature and mold temperature changes However, a slight variation occurs. Such variation greatly hinders molding of a molded product with a desired accuracy when molding a highly accurate molded product. Conventionally, a molding engineer finds molding conditions such as injection pressure that can suppress such variations based on his own experience, and changes the setting of molding conditions each time variations occur, so that the resin filling amount The variation of was suppressed. However, such a method requires a lot of labor to satisfy the quality of the molded product.
[0010]
In general injection molding, the screw in the heated cylinder is advanced and the molten resin collected in front of the screw is injected from the nozzle of the cylinder into the mold, and bubbles and sink marks are generated in the molded product. In order to suppress this, a molded product is formed through a pressure-holding step in which a pressure-hold pressure is applied to the cavity for a while. Therefore, these injection / holding steps are most important in determining the quality of a molded product.
[0011]
Therefore, if the injection pressure setting condition when injecting the resin into the mold is wrong, when molding a molded product that requires molding with high accuracy, such as the plastic ferrule for optical connectors described above, Due to the required quality of the molded product, the outer diameter dimension, the eccentricity of the inner diameter, the inner diameter dimension, and the like are defective. When the molded product is a plastic ferrule for optical connectors, if the above defects occur during molding, the optical fiber cannot be held and connected with high accuracy, and the optical characteristics required for the product can be obtained. It will disappear.
[0012]
From the actual situation as described above, considerable experience is required to adjust the molding conditions for molding a high-precision molded product, and it is virtually impossible to stably mold a high-precision molded product. It was said.
[0013]
Here, the relationship between the injection pressure in the injection process and the defective phenomenon occurring in the molded product will be described in more detail. In the conventional injection pressure control (pressure filling control) method, the injection pressure set by the operator (molding engineer) is maintained. Since the injection pressure was controlled in such a manner, depending on the setting conditions, variations in the amount of resin filled into the mold cavity occurred. Specifically, if the set injection pressure is high, burrs are generated near the gate of the molded product. Conversely, if the set injection pressure is low, a short shot (insufficient filling) occurs. In addition, such a defective phenomenon is caused by a slight change in temperature of a mold or a cylinder, particularly when a molded product that needs to be molded with high accuracy is formed, resulting in a defect in the outer diameter of the molded product. It was the cause.
[0014]
This will be explained in detail using actual examples. When molding a molded product that needs to be molded with high accuracy, such as a plastic ferrule for optical connectors, the dimensional tolerance of each part is within ± 1 μm for the purpose of the product. It is necessary to fit in. For example, in the case of the SC type optical connector, the outer diameter is required to be within φ2.5 mm ± 1 μm, and the roundness between the outer diameter and the inner diameter is required to be 1 μm or less. However, since generally used molds are limited in rigidity and processing accuracy, it has been said that such a molded product requiring high accuracy cannot be stably molded.
[0015]
Here, the relationship between the injection holding time and the injection pressure / injection speed when the injection process is performed by an injection molding method using position switching control by general injection speed adjustment will be described with reference to FIG. To do.
[0016]
For example, when an injection process is performed by an injection molding method using position switching control by general injection speed adjustment, the outer diameter of the molded product depends on the shape of the molded product and the structure of the mold. From the experimental results, it was found that an injection pressure of 250 MPa or more is required to fall within the allowable error (see arrow A in FIG. 6). This value is about 246 MPa (2500 kgf / cm2) which is the allowable maximum injection pressure value of a general-purpose injection molding machine. ² In order to perform molding stably with a general-purpose injection molding machine, it is necessary to take measures against pressure resistance of each part of the injection molding machine. Taking a screw as an example of the countermeasure against pressure resistance, it is indispensable to take measures against the wear of the flight part including the deformation of the screw body due to the injection pressure. In this experiment, burrs were generated in the gate part and the runner part of the molded product depending on the injection pressure setting conditions, so that the good product could not be stably molded.
[0017]
In the actual molding process, the outer diameter of the molded article is measured with another outer diameter measuring device, and the optimum molding conditions are set by repeatedly changing the molding conditions based on the results. Therefore, it took a considerable time to find the optimum molding conditions and to stably mold the molded product. Further, even when optimum molding conditions are set, molding defects have occurred due to subsequent environmental changes (for example, room temperature, mold, or cylinder temperature changes).
[0018]
The present invention has been made to solve the above-described problems of the prior art, and can reduce variations in the outer diameter of a molded product, and can stably mold a particularly high-precision molded product. It is an object of the present invention to provide an injection pressure control method for an injection molding machine that can improve productivity.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, an injection pressure control method for an injection molding machine according to the present invention includes an outer diameter size of a molded product molded by the injection molding machine and an injection process in which a molded product having the outer diameter size is molded. A step of obtaining a correlation with the injection pressure, and measuring the outer diameter of the molded product molded next by the injection molding machine, and based on the correlation, the outer diameter of the molded product to be molded later Determining the magnitude of the injection pressure to be increased / decreased in order to make the standard outer diameter dimension of the molded product, and the injection pressure with the magnitude increased / decreased as a setting value of the injection pressure in the subsequent injection process And a setting step.
[0020]
According to the present invention, based on the measurement result obtained by measuring the outer diameter dimension of the molded article actually molded, the outer diameter dimension of the molded article to be molded thereafter is set to the reference outer diameter dimension value. An optimum injection pressure is obtained, and the set value of the injection pressure is automatically corrected. Therefore, it is possible to eliminate the need for an operator (molding engineer) to find and set optimum molding conditions based on his / her own experience. In addition, even when environmental changes occur (for example, room temperature or mold temperature changes), the injection pressure set value is automatically corrected in order to mold a molded product having a reference outer diameter, so molding defects Can be prevented from occurring. Therefore, it is possible to reduce the quality variation of the molded product (particularly, the variation in the outer diameter) and improve the productivity of the molded product.
[0021]
Further, the correlation may be obtained at least with respect to a tolerance range with respect to a reference outer diameter dimension of the molded product.
[0022]
Further, the correlation is an approximate first order obtained by a least square method from a plurality of data regarding the relationship between the outer diameter dimension of the molded article and the injection pressure at the time of the injection process for molding the molded article having the outer diameter dimension. It is good also as a structure represented by a function.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a schematic configuration diagram showing an injection device of an injection molding machine to which an embodiment of the present invention is applied.
[0025]
As shown in FIG. 1, the injection device of the injection molding machine according to the present embodiment includes a cylinder 6 including a heater (not shown) that heats the resin conveyed inside, a nozzle formed at the tip, and the cylinder A hopper 10 for storing the resin to be supplied in 6, a screw 7 that is rotatably inserted into the cylinder 6 and conveys the resin supplied in the cylinder 6, and the screw 7 is moved in the axial direction thereof, A ball screw 5 for injecting molten resin in the cylinder 6 into a mold (not shown), an injection servo motor 3 for driving the ball screw 5, a timing belt 4 for transmitting the driving force of the injection servo motor 3 to the ball screw 5; And a load cell 9 for measuring the pressure of the molten resin at the time of injection. At the tip of the screw 7, a backflow prevention ring 8 is attached to prevent the resin from flowing back into the cylinder 6 when the resin is injected from the nozzle of the cylinder 6.
[0026]
The injection apparatus further includes a control unit 15 including a process controller 1 that controls the injection servo motor 3 and a servo amplifier 2 interposed between the process controller 1 and the injection servo motor 3. In addition to the process controller 1, the control unit 15 includes a pressure calculation unit 12 connected to the process controller 1. Connected to the pressure calculation unit 12 is an outer diameter measuring device 11 that measures the outer diameter of a molded product molded by the injection molding machine.
[0027]
Also in the injection molding machine according to the present embodiment, a signal related to the pressure of the molten resin at the time of injection measured by the load cell 9 is output to the process controller 1. The process controller 1 generates a control signal for moving the screw 7 in the axial direction based on the pressure signal, and inputs the set control signal to the injection servo motor 3 via the servo amplifier 2. As described above, the process controller 1 is in charge of the closed loop control of the injection apparatus that outputs the set pressure signal and the pressure feedback signal from the load cell 9 and receives the control signal to the injection servo motor 3.
[0028]
Further, the process controller 1 can control the injection servo motor 3 so as to inject the molten resin at several stages of injection pressure, and the user can set an arbitrary injection pressure from among the several stages of injection pressure. It is configured to be able to.
[0029]
FIG. 2 is a diagram showing a schematic configuration of the outer diameter measuring apparatus shown in FIG. With reference to FIG. 2, each structure and operation | movement of the outer diameter measuring apparatus 11 are demonstrated.
[0030]
The molded product molded by the injection molding machine is taken out from the molding die of the injection molding machine by a take-out robot (not shown) and is carried to the entrance camera 101 of the outer diameter measuring device 11. In the entrance camera 101, the presence or absence of pin breakage of the molded product is inspected by image inspection. After the inspection, the molded product is placed on the receiving stage 102 by a take-out robot (not shown).
[0031]
The molded product placed on the receiving stage 102 is conveyed to the mold 104 by the delivery arm 103. The molded product is gate-cut with this mold 104. The molded product that has been gate-cut by the mold 104 is conveyed to the separator 106 by the suction arm 105. The molded product conveyed to the separator 106 is conveyed onto the conveyor 108 by the transfer device 107 after the pitch of the molded products is changed by the separator 106.
[0032]
The molded product conveyed on the conveyor 108 is conveyed from the right side to the left side by the conveyor 108. The molded product is lifted from the conveyor 108 by the pull-in device 109 in the middle of its conveyance, then moved to the left outer diameter inspection unit 111 and then moved to the right outer diameter inspection unit 110. The molded product is inspected on the left outer diameter by the left outer diameter inspection unit 111 and inspected on the right outer diameter by the right outer diameter inspection unit 110. In this embodiment, each outer diameter inspection part 110,111 consists of a laser micrometer, and the outer diameter dimension of a molded product is optically measured by the laser micrometer. The outer diameter inspection units 110 and 111 are connected to the pressure calculation unit 12 of the control unit 15 of the injection molding machine, and the measurement results of the outer diameter inspection units 110 and 111 are the outer diameter inspection units 110 and 111, respectively. To the pressure calculation unit 12.
[0033]
The molded product whose outer diameter is measured by each of the outer diameter inspection units 110 and 111 is returned onto the conveyor 108 by the pull-in device 109 and is conveyed by the conveyor 108 to the end of the conveyor 108 (the left end in the figure). The
[0034]
The molded product conveyed to the end of the conveyor 108 is applied to the eccentricity inspection devices 113 and 114 by the sorting robot 112, where the eccentricity is inspected. The molded product is sorted for each level of dimensional accuracy by the sorting robot 112, and is conveyed to each classification box 115 divided according to the accuracy level.
[0035]
In addition, the molded product recognized as a defective product in each of the above steps is discharged into the discharge holes 116 and 117 and the discharge box 118 at each stage where it is recognized as a defective product.
[0036]
The control unit 15 in the injection molding machine of the present embodiment uses pressure filling control by adjusting the injection pressure instead of performing the injection process by the injection molding method using the position switching control by the general injection speed adjustment described above. An injection process is performed by an injection molding method. The “injection pressure control” itself is provided as a standard function by a general-purpose injection molding machine. The injection pressure control method in this example is between the outer diameter obtained by measuring the actually molded product with the outer diameter measuring device 11 and the injection pressure when the molded product is injection molded. Focusing on the correlation, the injection pressure is controlled on the basis of the correlation, and a molded product having a desired size is to be molded.
[0037]
As described above, when the injection process is performed by an injection molding method using a general position switching control, the outer diameter dimension of the molded product is within an allowable error, depending on the shape of the molded product and the structure of the mold. It has become clear from experimental results that an injection pressure of 250 MPa or more is required for storage. Since this injection pressure exceeds the maximum allowable injection pressure value of 246 MPa of a general-purpose injection molding machine, the general-purpose injection molding machine performs general position switching control on a molded product stored within a desired tolerance. It cannot be molded by the injection molding method used.
[0038]
On the other hand, when the injection pressure control method is used instead of the above-described position switching control method as the injection holding pressure switching control method, the injection pressure required to keep the outer diameter dimension of the molded product within the allowable error. Can be lowered to 190 to 210 MPa. Therefore, if this injection pressure control method is used, even a general-purpose injection molding machine can mold a molded product contained within a desired tolerance. In this case, since the injection pressure is relatively low, it is possible to suppress the occurrence of burrs in the gate part and the runner part of the molded product.
[0039]
In addition, when molding is performed by an injection molding method using general position switching control, that is, when molding is performed by an injection molding method using closed loop control related to the screw position, environmental changes (particularly cylinder temperature changes) may occur. If this occurs, the amount of molten resin charged at the tip of the screw 7 and injected into the mold will vary, which is considered to cause an error in the outer diameter of the molded product. Yes.
[0040]
On the other hand, when molding is performed by an injection molding method using an injection pressure control method, that is, when molding is performed by an injection molding method using closed loop control related to injection pressure, a molten resin is used regardless of such a temperature change. Therefore, it is possible to stably mold a molded product having an outer diameter within an allowable range.
[0041]
Here, the process for obtaining the correlation between the outer diameter of the molded product and the injection pressure will be described with reference to FIG.
[0042]
For example, when the standard outer diameter of a molded product is φ2.5000 mm, several molded products having an outer diameter within a range of ± several μm with respect to the standard outer diameter are actually molded. Then, the outer diameter of these molded products is measured by the outer diameter measuring device 11. The pressure calculation unit 12 stores a plurality of data relating to the outer diameter dimensions of those molded products measured by the outer diameter measuring device 11 and the injection pressure when each molded product is molded.
And the pressure calculation part 12 calculates by the least square method based on those data, calculates | requires approximate linear function (alpha) (y = ax + b) showing the correlation between the outer diameter dimension of a molded article, and injection pressure, The approximate linear function α is stored. Thus, the correlation between the outer diameter of the molded product and the injection pressure is obtained in advance before starting mass production of the molded product, and stored in the pressure calculation unit 12.
[0043]
In the example shown in FIG. 3, the correlation with the injection pressure is an approximate linear function α in the range of −2 μm (φ2.4980 mm) to +1 μm (φ2.5010 mm) of the reference outer diameter dimension (φ2.5000 mm) of the molded product. It has been demanded. From this approximate linear function α, it can be seen that the injection pressure needs to be increased by 10 MPa in order to form a molded product having an outer diameter dimension larger by 1 μm (0.001 mm). The tolerance for the reference outer diameter of the molded product of this example is ± 0.001 mm (± 1 μm), and the above correlation (approximate linear function α) is thus at least the reference outer diameter of the molded product. It is preferable to obtain the allowable error range for.
[0044]
Next, an outline of the function and operation of the control unit 15 shown in FIG. 1 will be described with reference to FIGS.
[0045]
When manufacturing a molded product, first, molding of the molded product is started based on certain molding conditions, and after molding is repeated until the molded product is stably molded (for example, from the start of molding). After the 20-shot molding), the operator (molding technology) confirms that a molded product whose outer diameter is within an acceptable quality range (for example, φ2.5000 ± 0.001 mm) is molded. When the operator confirms, the operator operates the control unit 15 to link the pressure calculation unit 12 with the measurement result of the outer diameter measuring device 11 (outer diameter dimension interlocking on).
[0046]
Thereafter, the outer diameter of the molded product is measured by the outer diameter inspection units 110 and 111 of the outer diameter measuring device 11, and the measurement result is automatically input to the pressure calculation unit 12. The pressure calculation unit 12 compares the outer diameter dimension of the measurement result with the reference outer diameter dimension stored in advance in the pressure calculation unit 12. Then, from the comparison result, the pressure calculation unit 12 stores in advance in the pressure calculation unit 12 how much the injection pressure should be increased / decreased in order to make the outer diameter dimension of a molded product to be molded later the reference outer diameter dimension. Based on the approximated linear function α, the setting value of the injection pressure in the subsequent injection process is automatically changed to the calculated value.
[0047]
In the case of this example, when the outer diameter dimension of the initially obtained molded product is φ2.4990 mm and the injection pressure when the molded product is molded is 190 MPa, from the approximate linear function α in FIG. In order to set the outer diameter dimension of the molded product to φ2.5000 mm which is the reference outer diameter dimension value, the set value of the injection pressure is changed to 200 MPa.
[0048]
The injection pressure set value thus changed is input from the pressure calculation unit 12 to the process controller 1, and the injection pressure set value already set in the process controller 1 is automatically changed to a new set value. The Thereafter, the process controller 1 executes the injection process based on the set value of the injection pressure corrected as described above. The operation from the measurement of the outer diameter dimension of the molded article actually molded in this way to the change of the set value of the injection pressure is performed at any time in the subsequent injection molding process.
[0049]
Thus, according to the present embodiment, based on the measurement result obtained by measuring the outer diameter dimension of the actually molded product, the outer diameter dimension of the molded product to be molded thereafter is determined as the reference outer diameter dimension value. An optimum injection pressure is obtained to achieve this, and the set value of the injection pressure is automatically corrected. Therefore, it is possible to eliminate the need for an operator (molding engineer) to find and set optimum molding conditions based on his / her own experience. In addition, even when environmental changes occur (for example, room temperature or mold temperature changes), the injection pressure set value is automatically corrected in order to mold a molded product having a reference outer diameter, so molding defects Can be prevented from occurring. Therefore, it is possible to reduce the quality variation of the molded product (particularly, the variation in the outer diameter) and improve the productivity of the molded product.
[0050]
Next, an example of the injection pressure control method for the electric injection molding machine according to the embodiment of the present invention will be described with reference to the flowchart shown in FIG.
[0051]
First, an operator (molding engineer) starts molding a molded product based on certain molding conditions and repeats molding until the molded product is stably molded (for example, 20 shots from the start of molding). After that, it is confirmed that a molded product whose outer diameter is within an acceptable quality range (for example, φ2.5000 ± 0.001 mm) is formed (step 1). .
[0052]
When a molded product whose outer diameter dimension is within the allowable range for quality is to be molded, the operator operates the control unit 15 to turn on the “outer diameter dimension interlocking mode” of the pressure calculation unit 12. Then, the pressure calculation unit 12 is interlocked with the measurement result of the outer diameter measuring device 11 (step 2). The outer diameter of the molded product molded thereafter is measured by the outer diameter inspection units 110 and 111 of the outer diameter measuring device 11 (step 3), and the measurement result is automatically input to the pressure calculation unit 12.
[0053]
Then, the outer diameter of the measurement result is compared with the reference outer diameter (φ2.5000 mm) stored in advance in the pressure calculator 12 by the pressure calculator 12 (step 4). When the outer diameter dimension of the measurement result does not match the reference outer diameter dimension (N), the pressure calculation unit 12 sets the outer diameter dimension of the molded product to be molded thereafter as the reference outer diameter dimension from the comparison result. Therefore, how much the injection pressure should be increased or decreased is determined based on the approximate linear function α stored in advance in the pressure calculation unit 12 as described above (step 5). The pressure calculation unit 12 automatically changes the set value of the injection pressure in the subsequent injection process to the obtained value, and inputs the changed set value of the injection pressure to the process controller 1. As a result, the set value of the injection pressure already set in the process controller 1 is automatically changed to a new set value (step 6).
[0054]
For example, when the measured outer diameter of the molded product is φ2.495 mm and the set value of the injection pressure when the molded product is molded is 195 MPa, the approximate linear function stored in advance in the pressure calculation unit 12 From α (see FIG. 3), it is required to increase the injection pressure by 5 MPa in order to mold a molded product having an outer diameter dimension as large as φ0.0005 mm (0.5 μm). Therefore, in this case, the new injection pressure is set to 200 MPa obtained by adding 5 MPa to the original set value of 195 MPa.
[0055]
Then, the outer diameter of the molded product formed thereafter is measured by the outer diameter inspection units 110 and 111 of the outer diameter measuring device 11 (step 3), and the outer diameter of the measurement result and the pressure calculation unit 12 are measured. The operation (step 4) for comparing the reference outer diameter dimension stored in advance is repeated.
[0056]
On the other hand, if the outer diameter dimension of the measurement result matches the reference outer diameter dimension (Y), the molding process is continued with the current set value of the injection pressure (step 7).
[0057]
【The invention's effect】
As described above, the injection pressure control method of the injection molding machine according to the present invention includes the outer diameter dimension of the molded product molded by the injection molding machine and the injection in the injection process in which the molded product having the outer diameter dimension is molded. The step of obtaining the correlation with the pressure and the outer diameter of the molded product formed next by the injection molding machine are measured. Based on the correlation, the outer diameter of the molded product to be molded thereafter is determined as the molded product. Because there are a step of obtaining the magnitude of the injection pressure to be increased / decreased to obtain the reference outer diameter size, and a step of setting the injection pressure whose size has been increased / decreased as a set value of the injection pressure in the subsequent injection steps The variation in the outer diameter of the molded product can be reduced, and a highly accurate molded product can be stably molded. As a result, productivity can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of an injection apparatus of an injection molding machine to which the present invention is applied.
FIG. 2 is a diagram showing a schematic configuration of the outer diameter measuring apparatus shown in FIG.
FIG. 3 is a graph showing an approximate linear function α representing the correlation between the outer diameter size of a molded product and the injection pressure.
FIG. 4 is a flowchart illustrating an example of an injection pressure control method for an electric injection molding machine according to an embodiment of the present invention.
FIG. 5 is a schematic configuration diagram showing an injection device of a conventional injection molding machine.
FIG. 6 is a graph showing a relationship between an injection holding time and an injection pressure / injection speed when an injection process is performed by an injection molding method using a general position switching control.
[Explanation of symbols]
1 Process controller
2 Servo amplifier
3 Injection servo motor
4 Timing belt
5 Ball screw
6 cylinders
7 Screw
8 Backflow prevention ring
9 Load cell
10 Hopper
11 Outside diameter measuring device
12 Pressure calculator
15 Control unit
101 Entrance camera
102 Receiving stage
103 Delivery arm
104 mold
105 Suction arm
106 Separator
107 Transfer equipment
108 conveyor
109 Pull-in device
110 Right outside diameter inspection part
111 Left outer diameter inspection part
112 Sorting robot
113, 114 Eccentricity inspection device
115 classification box
116,117 discharge hole
118 discharge box

Claims (3)

A method for controlling the injection pressure of an injection molding machine,
A step of obtaining a correlation between an outer diameter dimension of a molded article molded by the injection molding machine and an injection pressure at the time of an injection process for molding the molded article having the outer diameter dimension;
In order to measure the outer diameter of the molded product molded next by the injection molding machine, and to set the outer diameter of the molded product to be molded later to the reference outer diameter of the molded product based on the correlation. Determining the magnitude of the injection pressure to be increased or decreased;
An injection pressure control method for an injection molding machine, comprising: setting the injection pressure whose size has been increased or decreased as a set value of an injection pressure in a subsequent injection process. The injection pressure control method for an injection molding machine according to claim 1, wherein the correlation is obtained at least with respect to a tolerance range with respect to a reference outer diameter of the molded product. The correlation is an approximate linear function obtained by a least square method from a plurality of data relating to the relationship between the outer diameter dimension of the molded product and the injection pressure at the time of the injection process for molding the molded product having the outer diameter dimension ( The injection pressure control method for an injection molding machine according to claim 1 or 2, represented by α).

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