JP7673603B2 - Injection Molding Method - Google Patents

Description

The present invention relates to an injection molding method in which the screw rotation speed and back pressure are adjusted in the metering process to store a predetermined amount of metered resin in an injection cylinder, and the injection speed of the screw is adjusted in the injection process to inject and fill the metered resin into a mold cavity.

In injection molding, a material supply device is used to supply resin material into a temperature-controlled injection cylinder. The supplied resin material is plasticized and turned into molten resin by shear heat generated by the rotational movement of a screw with a spiral flight, and by the heat of a heater or the like installed in the injection cylinder, and is then rotated and transported to the tip of the screw, where it is stored as metered resin in the injection cylinder. As the metered resin is stored, the screw retreats, and at a specified retreat position, the screw's rotation stops and the screw position is maintained (this is called the metering process). Resistance is applied to the retreating movement of the screw to adjust the melting and mixing properties of the stored molding material (this is called back pressure control).

Next, the screw is moved forward to carry out the injection process, in which the measured resin is injected and filled into the mold cavity, the pressure-holding process to compensate for the shrinkage caused by cooling and solidifying the molten measured resin, and the cooling process to cool and solidify the molten measured resin within the mold cavity.The mold is then opened and the product is removed from the mold cavity as an injection-molded product. This series of molding operations is repeated until the required number of molded products is obtained.

Here, the quality of injection molded products depends on the stability of the resin temperature, which indicates the degree of melting and mixing of the metered resin stored in the metering process, which is the starting point of the molding operation. For example, fluctuations in resin temperature cause fluctuations in the flow state of the metered resin in the mold cavity, resulting in molding defects caused by fluctuations in resin temperature, such as product shorts, resin burrs, fluctuations in product weight, appearance defects such as welds and flow marks, the presence of voids and unmelted resin, product deformation and product dimensional errors, poor surface firmness and poor transfer. Fluctuations in the metered resin are difficult to correct in the injection process or pressure holding process that follow the metering process. For this reason, many proposals have been made for a long time regarding the stabilization of metered resin.

For example, as shown in Patent Document 1, temperature sensors are attached in the range from the injection cylinder to the mold, the temperature distribution of the metered resin is measured during the injection process, and the temperature is assigned to the heater arrangement of the injection cylinder to correct the heater temperature setting. Furthermore, in addition to this temperature correction, the screw rotation speed and back pressure value are also corrected. This is said to make it possible to achieve a uniform temperature of the metered resin.

JP 2000-176983 A

Here, as shown in Patent Document 1, even if the temperature of the metered resin in the injection cylinder can be adjusted uniformly, the metered resin will receive shear heat when it flows through the mold cavity in the subsequent injection process, and the resin temperature will change significantly. This shear heat is related to the shear rate and material viscosity. The shear rate is related to the flow rate of the metered resin and the flow path area through which the metered resin passes, and the degree of shear heat increases with an increase in flow rate, and the shear heat increases as the flow path becomes narrower. For example, when passing through a narrow gate part of the flow path, the amount of shear heat increases and the resin temperature rises. In addition, the material viscosity is related to the resin temperature, and as the resin temperature decreases, the material viscosity increases and the amount of shear heat increases. Since the quality of injection molding is greatly affected by the temperature state of the metered resin injected and filled into the mold cavity, Patent Document 1 does not promise the stabilization of the quality of injection molded products.

Therefore, the present invention aims to provide an injection molding method that can adjust the temperature of the metered resin injected and filled into the mold cavity to an appropriate state.

The injection molding method of the present invention comprises the steps of:
1. An injection molding method comprising: a metering step of adjusting a screw rotation speed and a back pressure to store a predetermined amount of metered resin in an injection cylinder; and an injection step of adjusting an injection speed of the screw to inject and fill the metered resin into a mold cavity,
a temperature measuring means for measuring a filling temperature of the metered resin injected and filled into the mold cavity during the injection process;
The filling temperature waveform of the metered resin is obtained from the measurement data of the temperature measuring means, and a temperature correction process is performed if the filling temperature waveform is outside a tolerance temperature range set for a reference temperature waveform.

In the injection molding method of the present invention,
The temperature measuring means is preferably a plurality of temperature sensors incorporated in the injection molding die along the flow direction of the metered resin injected and filled from the gate of the die cavity.

In addition, in the injection molding method of the present invention,
It is preferable that the temperature measuring means is a thermo camera which opens the mold cavity a predetermined time after the completion of injection and filling of the metered resin and takes a thermal image of the metered resin.

Furthermore, in the injection molding method of the present invention,
It is preferable that the temperature correction process sets a position where the filling temperature waveform is outside the allowable temperature range as a correction position, converts the correction position to the screw position during the injection process, sets the screw position after conversion as a correction screw position, and corrects the screw rotation speed in the metering process based on the correction screw position.

In addition, in the injection molding method of the present invention,
It is preferable that the temperature correction process sets a position where the filling temperature waveform is outside the allowable temperature range as a correction position, converts the correction position to the screw position during the injection process, sets the screw position after conversion as a correction screw position, and corrects the back pressure in the metering process based on the correction screw position.

The present invention provides an injection molding method that can adjust the metered resin injected and filled into the mold cavity to an appropriate temperature state.

1 is a conceptual diagram of an injection molding machine according to an embodiment of the present invention. FIG. 2 is a conceptual diagram of a temperature measuring means according to an embodiment of the present invention. 2A to 2C are diagrams illustrating a molding operation using the injection molding apparatus shown in FIG. 1 . A diagram showing the flow state of metered resin in a mold cavity. 1A to 1C are diagrams illustrating an injection molding method according to an embodiment of the present invention.

Below, preferred embodiments for carrying out the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solutions of the inventions according to the claims. Furthermore, in the present embodiments, the scales and dimensions of each component may be exaggerated, and some components may be omitted.

[Injection molding machine]
First, an injection molding machine according to an embodiment of the present invention will be described with reference to Fig. 1. In the following description, the injection molding machine according to the embodiment of the present invention is based on a horizontal injection molding machine, but is not limited to this. The injection molding machine 100 shown in Fig. 1 includes an injection unit 10, an injection mold 20, an injection drive unit 30, and an injection control unit 40.

The injection device 10 comprises a cylindrical injection cylinder 11 and a screw 14 disposed within the injection cylinder 11. The injection control unit 40 operates the injection drive unit 30 to adjust the rotational movement and forward and backward movement of the screw 14. Here, with regard to the movement of the screw 14, the direction closer to the injection mold 10 is defined as forward F, the movement toward forward F is defined as forward movement, the direction away from the injection mold 10 is defined as backward B, and the movement toward backward B is defined as backward movement. In addition, the injection device 10 is operated to connect and disconnect the injection device 10 and the injection mold 20 by a drive unit (not shown) or the like, and is in a connected state when injection molding is performed.

The injection cylinder 11 has multiple heaters 12 arranged at predetermined intervals on its outer circumferential surface, and the temperature of the heaters 12 is controlled by a temperature adjustment device (not shown) to adjust the injection cylinder 11 to a predetermined temperature. In addition, a material hopper 13 is provided behind the injection cylinder 11, and resin material is supplied from the material hopper 13 into the injection cylinder 11 by a material supply device (not shown) or the like.

The screw 14 has a spiral flight 15 that spirals from the rear B to the front F. The spiral direction and angle of the flight 15 are set so that the resin material supplied from the material hopper 13 can be rotated and transported to the front F relative to the rotational direction of the screw 14. As shown in FIG. 1, the flight 15 is arranged in a single line at a fixed interval and angle, but is not limited to this. For example, the interval and angle may be variable, or multiple lines may be arranged. Alternatively, the flights 15 may be arranged in multiple lines only in a portion of the screw 14.

The screw 14 is cylindrical in shape, with the diameter gradually increasing from the rear B to the front F. In other words, the volume of the gap between the screw 14 and the injection cylinder 11 is set to gradually decrease from the rear B to the front F, for example, as a transport zone, a compression zone, and a melting zone. As a result, the resin material supplied from the material hopper 13 is transported forward by the rotational action of the screw 14 and the flight 15, and the reduction in volume causes a compression action and shear heat to act on the resin material, and the resin material is melted in stages (called plasticization) due to the synergistic effect of the heat provided by the heater 12, and molten resin is generated toward the front F of the screw 14, and the molten resin is stored in the storage area 17 on the front F side of the screw 14 through a flow path in the backflow prevention device 16 arranged at the tip of the screw 14 (called metered resin). As the metered resin increases, the screw 14 retreats to the rear B side, stops rotating at a predetermined retreat position, and holds the stopped position (called the metering process). The backward movement of the screw 14 is restricted (called metering back pressure) to adjust the melting and mixing properties of the molding material (called back pressure control). In the injection process, the screw 14 is advanced to inject and fill the metered resin into the injection molding die 20. In this injection process, the flow path in the backflow prevention device 16 is closed.

In the injection mold 20, the fixed mold 21 and the movable mold 22 are supported by a clamping device (not shown), and the movable mold 22 can move forward and backward relative to the fixed mold 21 by the clamping device. Here, with regard to the operation of the movable mold 22, the operation of approaching the fixed mold 21 is defined as the mold closing operation, and the operation of moving away from the fixed mold 21 is defined as the mold opening operation. In addition, the position where the fixed mold 21 and the movable mold 22 abut during the mold closing operation is defined as the mold touch point, the operation further in the mold closing operation direction from the mold touch point is defined as the mold clamping operation, the completion position of the mold clamping operation is defined as the mold clamping limit, and the operation from the mold clamping limit to the mold touch point is defined as the pressure reduction operation. Within the range from the mold touch point to the mold clamping limit, the mold cavity 23 is formed. In addition, the fixed mold 21 is equipped with a resin flow path 24 through which the resin material flows, a valve gate 25 that opens and closes the resin flow path 24, and a gate 26 that connects the resin flow path 24 to the mold cavity 23. The resin flow path 24 is adjusted to a predetermined temperature in the same manner as the injection cylinder 11.

Here, as the resin material used in injection molding, for example, in the case of automobile interior parts, it is common to add colorants such as black, red, and blue to thermoplastic resins such as polypropylene (PP) resin and polyethylene (PE) resin to adjust the color tone of the parts. In addition, various additives such as plasticizers that give flexibility to thermoplastic resins, nucleating agents and clarifying agents that control the crystallinity of crystalline resins, flame retardants that suppress combustion, antistatic agents that suppress static electricity, lubricants that improve fluidity and releasability, weathering agents and ultraviolet degradation inhibitors that suppress deterioration due to ultraviolet rays, and reinforcing agents such as glass fibers and carbon fibers are appropriately selected. In addition, thermoplastic resins such as general-purpose resins such as polypropylene (PP) resin and polyethylene (PE) resin, engineering resins such as polyamide (PA) resin and polycarbonate (PC) resin, and super engineering resins such as polyphenylene sulfide (PPS) resin and polyether ether ketone (PEEK) resin are appropriately selected. Thermoplastic resins and additives are collectively called resin materials. Instead of a thermoplastic resin, a thermosetting resin such as phenol (PF) resin or melamine (MF) resin may be used.

[Temperature measurement means]
Next, a temperature measuring means for measuring the filling temperature of the metered resin injected and filled into the mold cavity in the injection step according to an embodiment of the present invention will be described with reference to FIG.

First, as shown in FIG. 2(a), as a temperature measurement means 50, multiple temperature sensors 51 are arranged on the movable mold 22 along the flow direction of the metered resin to be injected and filled from the gate 26 of the mold cavity 23. The temperature data measured by the multiple temperature sensors 51 is edited by the temperature receiving unit 52 into the filling temperature of the metered resin during the injection process, and the edited data is transmitted to the injection control unit 40. Note that in FIG. 2(a), the temperature sensors 51 are arranged along the mold cavity 23 below the gate 26, but this is not limited thereto, and for example, the temperature sensors 51 may be arranged over the entire range of the mold cavity 23. The temperature sensors 51 may also be arranged on the fixed mold 21, or may be arranged at a certain distance from the mold cavity 23.

2(b), a thermo camera 54 that captures thermal images is used as the temperature measuring means 50. Specifically, after the measured resin is injected and filled into the mold cavity 23, the movable mold 22 is opened at any timing, and the molded product 53 in a state in which the measured resin has not completely cooled and solidified is photographed by the thermo camera 54. The thermal image data photographed by the thermo camera 54 is edited by the image receiving unit 55 as the filling temperature of the measured resin during the injection process, and the edited data is transmitted to the injection control unit 40. Note that the means shown in FIG. 2(b) is less accurate than the means shown in FIG. 2(a) because time has passed between the injection and filling of the measured resin and the temperature measurement, but it is suitable for grasping the filling temperature. Also, in FIG. 2(b), the temperature is measured using one thermo camera 54, but multiple thermo cameras 54 may be used. Also, the temperature was measured when the molded product 53 was attached to the fixed mold 21, but the temperature may be measured while the molded product 53 is being transported by a robot or the like, for example.

In addition to these means, for example, the filling temperature during the injection process may be calculated from CAE flow analysis data obtained using a CAE flow analysis method. In this case, the positional relationship between the filling temperature and the screw 14 can be easily displayed, and can be used in the temperature correction process described below. These temperature measurement means may be used alone or in combination as necessary. Note that if the temperature measurement means is provided on the injection device 10 side rather than the resin flow path 24, it is not preferable because the metered resin will be subjected to shear heat when passing through the resin flow path 24, gate 26, etc.

[Injection molding operation]
Next, the injection molding operation according to the embodiment of the present invention will be described with reference to Fig. 3. Fig. 3(a) shows a cross-sectional view of the injection cylinder 11 and the injection molding die 20 in the metering process, and Fig. 3(b) shows an injection control pattern in the injection process with the screw position S on the horizontal axis and the injection speed on the vertical axis.

First, as shown in FIG. 3(a), the injection control unit 40 operates the injection drive unit 30 to start the metering process based on a metering control pattern in which metering conditions such as the heating temperature of the injection cylinder 11, the rotation speed of the screw 14, back pressure, and the metering completion position KE are set. When the position of the screw 14 reaches the metering completion position KE, a predetermined amount of metered resin is stored in the storage area 17 and the metering process ends. During the metering process, the valve gate 25 is in a closed state. The metering completion position KE also becomes the injection start position SS of the subsequent injection process (KE=SS).

3(b), the injection control unit 40 operates the injection drive unit 30 to start the injection process based on the injection control pattern of the multi-stage injection speed set according to the characteristics of the resin material and the shape of the mold cavity 23, etc. The screw 11 moves forward from the injection start position SS toward the injection pressure holding switch position VP, and the metered resin is injected and filled into the mold cavity 23. After the screw position S reaches the injection pressure holding switch position VP, the process moves to a pressure holding process to compensate for the cooling solidification shrinkage amount of the metered resin, and then, after the cooling process, the injection mold 20 is opened and the molded product 53 is taken out of the mold cavity 23. During the injection process and the pressure holding process, the valve gate 25 is in an open state. Note that in FIG. 3(b), the injection control pattern of the injection speed is shown, but it is not limited to this, and for example, the injection control pattern of the injection pressure may be used. In this case, the injection speed changes in conjunction with the setting of the injection pressure.

Here, during the injection process, the metered resin is significantly affected by shear heating when it flows from the resin flow path 24 to the mold cavity 23. This shear heating is related to the shear rate and the material viscosity; the higher the shear rate and the higher the material viscosity, the greater the shear heating, and the metered resin generates heat and its temperature rises.

The shear rate is related to the flow rate of the metered resin and the area of the flow path through which the metered resin passes. As the flow rate increases, the shear heat increases, and as the area of the flow path decreases, the shear heat increases. For example, when the metered resin passes through the valve gate 25 or gate 26, which has the smallest area of the flow path, the shear heat increases, and as a result, the temperature of the metered resin after passing through increases significantly. Furthermore, the shear heat also varies greatly depending on the injection speed of the injection control pattern. For example, as shown in FIG. 3(b), the shear heat is the largest in region B with a high-speed injection setting, followed by region A with a medium-speed injection setting, and the shear heat is the smallest in region C with a low-speed injection setting. As a result, even within the range of injection filling of one shot, the temperature of the metered resin varies greatly depending on the magnitude of the shear heat caused by changes in the injection speed.

In addition, the material viscosity is related to the resin temperature, and as the resin temperature decreases, the material viscosity increases and the shear heat also increases. For example, in area C, the time elapsed from the start of injection filling is longer than in areas A and B, and the metered resin is cooled and its temperature decreases while flowing in the mold cavity 20 by contacting the injection molding mold, which is clearly adjusted to a temperature lower than that of the metered resin. When this happens, the material viscosity increases and the shear heat increases, so the temperature of the metered resin increases. However, the shear heat is kept low by setting the injection speed low, and in the end, we come to the conclusion that it is correct to measure the temperature distribution of the metered resin injected and filled into the actual mold cavity 23. In other words, the quality control of injection molded products is correct to control the temperature of the metered resin injected and filled into the mold cavity 23 rather than the temperature control of the metered resin stored in the injection cylinder 11.

[Injection molding method]
Next, an injection molding method according to an embodiment of the present invention will be described with reference to Figures 4 and 5. Figure 4 shows the injection and filling state of the metered resin in the mold cavity 23 during the injection process. Also, Figure 5 shows the procedure for temperature correcting the metered resin based on the filling temperature during the injection process. Here, the description will start from the point where the metering process shown in Figure 3(a) is completed and the injection process is started based on the injection control pattern shown in Figure 3(b).

First, as shown in FIG. 4(a), the forward movement of the screw 14 causes the metered resin in the storage area 17 to pass through the resin flow path 24, the open valve gate 25, and the gate 26, and to be injected and filled into the mold cavity 23. As the screw 14 advances, the mold cavity 23 is filled with the metered resin. Next, as shown in FIG. 4(b), when the screw 15 reaches the injection pressure holding switch position VP, the injection process is completed and the process switches to the pressure holding process, in which the screw 14 is pressed with a predetermined pressure to perform pressure holding and filling. At the completion of this injection process, the mold cavity 23 is filled with the metered resin, and the original molded product 53 is obtained. During the injection process and the pressure holding process, the valve gate 25 is in an open state. During this injection process, the filling temperature of the metered resin injected and filled into the mold cavity 23 is measured using the temperature measuring means shown in FIG. 2. Additionally, the measured resin in the mold cavity 23 is filled through the gate 26 (injection filling position G) and flows toward the final injection filling position M.

Next, the injection control unit 40 obtains a filling temperature waveform Z (dashed line in the figure) from the measurement data of the filling temperature, as shown in FIG. 5(a), with the injection filling position of the molded product 53 on the horizontal axis and the filling temperature on the vertical axis. A reference temperature waveform K (solid line in the figure) that can obtain a good molded product and the upper and lower limit allowable temperatures (H, L) are overlaid on this. The reference temperature waveform K and the allowable temperatures (H, L) are obtained, for example, from past mass production results of injection molding and set in the injection control unit 40. Alternatively, they may be obtained from the calculation results of CAE flow analysis. Note that in FIG. 5(a), the allowable temperatures (H, L) are set to two points, the upper and lower limits, but this is not limited to this, and for example, the number of set points may be increased from the state of the filling temperature waveform Z. Alternatively, the number of set points may be selected according to the measurement control pattern of the measurement process.

If the filling temperature waveform Z is within the allowable temperature range (H, L) set for obtaining a good molded product relative to the reference temperature waveform, it is assumed that stable production of good molded products is guaranteed, and the injection molding operation continues without making any corrections. If the filling temperature waveform Z is outside the allowable temperature range (H, L), it is assumed that stable production of good molded products is difficult, and the temperature correction process shown below is performed.

First, the injection filling position where the filling temperature waveform Z and the tolerances (H, L) intersect is set as the correction position (S1 to S3). Next, the correction position (S1 to S3) is converted to the position of the screw 14 during the injection process. This conversion may be performed, for example, using CAE flow analysis, but it is preferable to use the short shot filling method, which divides and reproduces the actual injection process. The short shot filling method is a means of stopping the screw 14 in the middle of the injection process, as shown in FIG. 4(a), in the range from the metering completion position KE shown in FIG. 3(a) to the injection pressure holding switching position VP shown in FIG. 4(b), to obtain a molded product 53 in a short shot state. By finely dividing the intermediate stopping position of the screw 14, the position of the screw 14 during the injection process and the flow state of the metered resin in the mold cavity 23 can be accurately grasped. For this reason, it is a means that is widely used at injection molding sites. Note that the position of the screw 14 during the injection process is also the position of the screw 14 during the metering process.

Next, as shown in FIG. 5(b), the converted correction positions (S1-S3) are overlaid on a graph showing the metering control pattern with the horizontal axis being the position of the screw 14 during the metering process as the correction screw positions (HS1-HS3), and the correction pattern for the temperature correction process is set. Here, the screw rotation speed and back pressure during the metering process are selected as adjustment items for the temperature correction process. This was selected from the viewpoint of immediate effect and reliability, with the aim of predicting the quality of the injection molded product in the injection process, immediately performing appropriate correction processing in the metering process, and achieving stable production of good products from the next shot. Note that the means of adjusting the temperature of the injection cylinder 11 by adjusting the heater 12 is not preferred because it takes time to adjust the temperature and immediate effect cannot be expected, and it is extremely difficult to finely adjust the temperature of the metered resin in a narrow range in the storage area 17.

First, the temperature correction process using the screw rotation speed will be described. In the range from the metering start position KS to the corrected screw position HS1, the filling temperature waveform Z is within the range of the allowable value (H, L), so the screw rotation speed N0 of the previously set metering control pattern is set. In the range from the corrected screw position HS1 to HS2, the filling resin temperature waveform Z exceeds the upper limit allowable value H, so in order to lower the temperature of the metered resin, the screw rotation speed N1 is lowered (N1 < N0). This reduces the shear heat generated by the rotation operation of the screw 14, and as a result, the metered resin at a low temperature is stored. In the range from the corrected screw position HS2 to HS3, the filling temperature waveform Z is within the range of the allowable value (H, L), so the screw rotation speed N0 of the previously set metering control pattern is set. In the range from the corrected screw position HS3 to the metering completion position KE, the filling resin temperature waveform Z is lower than the lower limit allowable value L, so in order to raise the temperature of the metered resin, the screw rotation speed N2 is raised (N2 > N0). This increases the shear heat generated by the rotation of the screw 14, resulting in the storage of high-temperature metered resin. By performing these temperature correction processes during the metering process, it is possible to optimize the temperature of the metered resin injected and filled into the mold cavity 23.

Next, the temperature correction process using back pressure will be described. In this case, as with the screw rotation speed, the back pressure BP0 of the pre-set metering control pattern is set without correction within the range of the allowable values (H, L) based on the allowable values (H, L) of the filling temperature waveform Z and the reference waveform K and the corrected screw position (HS1 to HS3). If it is higher than the allowable value H, the metering back pressure BP1 is lowered (BP1 < BP0) to reduce the shear heat generation and obtain a metered resin with a lower temperature. If it is lower than the allowable value L, the metering back pressure BP2 is increased (BP2 > BP0) to increase the shear heat generation and obtain a metered resin with a higher temperature. The temperature correction process using back pressure is also performed during the metering process, and the temperature of the metered resin injected and filled into the mold cavity 23 can be optimized.

Here, the screw rotation speed and back pressure may be combined to perform temperature correction processing. For example, if the rotation speed of the screw 14 is excessively increased in order to obtain a high-temperature metered resin, resin material that is not completely melted (called unmelted resin) may mix with the metered resin, resulting in molding defects such as foreign matter contamination. In this case, the rotation speed of the screw 14 is reduced to suppress the generation of unmelted resin, and the insufficient shear heat is compensated for by increasing the back pressure. Also, if an excessively high back pressure is set in an attempt to obtain high shear heat, the storage speed of the metered resin may slow down, the metering process may take longer, and productivity may decrease significantly. In this case, the back pressure is slightly reduced and the rotation speed of the screw 14 is increased to compensate for the shear heat and shorten the metering process time.

[effect]
In this way, by correcting the measurement control pattern of the measurement process based on the filling temperature of the measured resin during the injection process, the measured resin injected and filled into the mold cavity can be adjusted to an appropriate state. As a result, stable production of high-quality injection molded products can be ensured. In addition, correction processing can be performed in the measurement process following the injection process, and the next shot of injection molding can be performed in the corrected state. This makes it possible to avoid continuous production of defective products and provide injection molding with high production efficiency.

The above describes a preferred embodiment of the present invention, but the technical scope of the present invention is not limited to the scope described in the above embodiment. Various modifications and improvements can be made to the above embodiment.

100 Injection molding machine 10 Injection unit 11 Injection cylinder 12 Heater 13 Material hopper 14 Screw 15 Flight 16 Backflow prevention device 17 Storage area F Front B Rear 20 Injection molding mold 21 Fixed mold 22 Movable mold 23 Mold cavity 24 Resin flow path 25 Valve gate 26 Gate 30 Injection drive unit 40 Injection control unit 50 Temperature measurement means 51 Temperature sensor 52 Temperature receiving unit 53 Molded product 54 Thermo camera 55 Image receiving unit KE Measurement completion position KS Measurement start position SS Injection start position VP Injection pressure holding switching position A, B, C Areas G, M Injection filling position Z Filling temperature waveform K Reference temperature waveform H, L Allowable temperature S1 to S3 Correction position HS1 to HS3 Correction screw position N0 to N2 Screw rotation speed BP0 to BP2 Back pressure

Claims (5)

1. An injection molding method comprising: a metering step of adjusting a screw rotation speed and a back pressure to store a predetermined amount of metered resin in an injection cylinder; and an injection step of adjusting an injection speed of the screw to inject and fill the metered resin into a mold cavity,
a temperature measuring means for measuring a filling temperature of the metered resin injected and filled into the mold cavity during the injection step , the filling temperature corresponding to a filling position in the mold cavity ;
an injection molding method comprising the steps of: obtaining a filling temperature waveform, which is the filling temperature of the metered resin corresponding to the filling position in the mold cavity, from the measurement data of the temperature measuring means; and performing temperature correction processing if the filling temperature waveform is outside an allowable temperature range set for a reference temperature waveform.
2. The injection molding method according to claim 1, wherein the temperature measuring means is a plurality of temperature sensors incorporated in the injection molding die along a flow direction of the metered resin injected and filled from a gate of the die cavity.
2. The injection molding method according to claim 1, wherein the temperature measuring means is a thermo camera which opens the mold cavity and takes a thermal image of the metered resin after a predetermined time has elapsed since the completion of injection and filling of the metered resin.
4. The injection molding method according to claim 1, wherein the temperature correction process defines a position where the filling temperature waveform is outside the allowable temperature range as a correction position, converts the correction position into a position of the screw during the injection process, defines the position of the screw after the conversion as a correction screw position, and corrects the rotation speed of the screw in the metering process based on the correction screw position.
4. The injection molding method according to claim 1, wherein the temperature correction process defines a position where the filling temperature waveform is outside the allowable temperature range as a correction position, converts the correction position into a position of the screw during the injection process, defines the position of the screw after the conversion as a correction screw position, and corrects the back pressure in the metering process based on the correction screw position.

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