Injection molding method

Abstract

To provide an injection molding method capable of adjusting a metered resin injected and filled into a mold cavity to an appropriate temperature condition.SOLUTION: In an injection molding method for storing a predetermined amount of metered resin in an injection cylinder 11 by adjusting screw speed and back pressure in a metering process, and injecting and filling the metered resin into a mold cavity 23 by adjusting injection speed of a screw 14 in an injection process, temperature measuring means 50 for measuring a filling temperature of the metered resin injected and filled into the mold cavity 23 during the injection process is provided. A filling temperature waveform Z of the metered resin is obtained from measured data of the temperature measuring means 50, and when the filling temperature waveform Z is out of a range of allowable temperatures H and L set for a reference temperature waveform K, temperature correction processing is performed.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an injection molding method in which a predetermined amount of metered resin is stored in an injection cylinder by adjusting the screw rotation speed and back pressure in a metering process, and the metered resin is injected and filled into a mold cavity by adjusting the injection speed of the screw in an injection process.

[0002] 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 heat from 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).

[0003] Next, the screw is advanced to perform an injection process in which the metered resin is injected and filled into the mold cavity, a pressure-holding process to compensate for the cooling and solidification shrinkage of the molten metered resin, and a cooling process to cool and solidify the molten metered resin in the mold cavity, after which the mold is opened and the product is taken out of the mold cavity as an injection molded product. This series of molding operations is repeated until the required number of molded products is obtained.

[0004] Here, the quality of an injection molded product depends on the stability of the resin temperature, which indicates the degree of melting and kneading of the measured resin stored in the measuring process, which is the starting point of the molding operation. For example, when the resin temperature fluctuates, the flow state of the measured resin in the mold cavity fluctuates, resulting in molding defects due to the fluctuation of the 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. It is difficult to correct the fluctuation of the measured resin in the injection process or the pressure holding process following the measuring process. For this reason, many proposals have been made for the stability of the measured resin for a long time.

[0005] 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 measured temperature distribution is assigned to the heater arrangement of the injection cylinder, and the heater temperature setting is corrected. Furthermore, in addition to this temperature correction, the screw rotation speed and back pressure value are corrected. This is said to make it possible to achieve a uniform temperature of the metered resin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2000-176983 A Summary of the Invention [Problem to be solved by the invention]

[0007] 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 in 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 the 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 the material viscosity increases with a decrease in the resin temperature, and the amount of shear heat also 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 the injection molded product.

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an injection molding method capable of adjusting the temperature of a metered amount of resin injected and filled into a mold cavity to an appropriate state. [Means for solving the problem]

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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. Effect of the Invention

[0014] According to the present invention, it is possible to provide an injection molding method capable of adjusting the temperature of a metered amount of resin injected and filled into a mold cavity to an appropriate state. [Brief description of the drawings]

[0015] [Figure 1] 1 is a conceptual diagram of an injection molding machine according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a conceptual diagram of a temperature measuring means according to an embodiment of the present invention. [Diagram 3] 2A to 2C are diagrams illustrating a molding operation using the injection molding apparatus shown in FIG. [Figure 4] A diagram showing the flow state of metered resin in a mold cavity. [Diagram 5] 1A to 1C are diagrams illustrating an injection molding method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Preferred embodiments for carrying out the present invention will be described below 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 means of solving the problems 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.

[0017] [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.

[0018] The injection device 10 includes 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 the forward F is defined as forward movement, the direction away from the injection mold 10 is defined as backward B, and the movement toward the backward B is defined as backward movement. Also, the injection device 10 is operated to connect and separate 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.

[0019] The injection cylinder 11 has a plurality of 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. 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.

[0020] 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 with respect to the rotation direction of the screw 14. Note that, as shown in FIG. 1, the flight 15 is arranged in a single line at a constant interval and a constant 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.

[0021] The screw 14 is cylindrical in shape with a diameter that gradually increases 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 resin material is compressed and heated by shear due to the reduction in volume, and melted in stages (called plasticization) by 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 a 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 toward the injection molding die 20. In this injection process, the flow path in the backflow prevention device 16 is closed.

[0022] 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 is movable 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 a mold closing operation, and the operation of moving away from the fixed mold 21 is defined as a mold opening operation. In addition, the position where the fixed mold 21 and the movable mold 22 come into contact with each other in the mold closing operation is defined as a mold touch point, the operation further in the mold closing operation direction from the mold touch point is defined as a mold clamping operation, the completion position of the mold clamping operation is defined as a mold clamping limit, and the operation from the mold clamping limit to the mold touch point is defined as a pressure reducing operation. A mold cavity 23 is formed within the range from the mold touch point to the mold clamping limit. In addition, the fixed mold 21 is provided 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.

[0023] 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. In addition, instead of thermoplastic resins, thermosetting resins such as phenol (PF) resin and melamine (MF) resin may be used.

[0024] [Temperature measurement method] 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.

[0025] First, as shown in FIG. 2(a), as the temperature measurement means 50, a plurality of temperature sensors 51 are arranged on the movable mold 22 along the flow direction of the metered resin injected and filled from the gate 26 of the mold cavity 23. The temperature data measured by the plurality of 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.

[0026] As shown in FIG. 2(b), a thermo camera 54 that captures a thermal image 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 from the injection and filling of the measured resin until the temperature is measured, but it is suitable for grasping the filling temperature. Also, in FIG. 2(b), the temperature is measured by one thermo camera 54, but multiple thermo cameras 54 may be used. Also, the temperature is measured when the molded product 53 is 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.

[0027] In addition to these means, for example, the filling temperature during the injection process may be calculated from CAE flow analysis data of 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 for the temperature correction process described later. 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 is subjected to shear heat when passing through the resin flow path 24, the gate 26, etc.

[0028] [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 mold 20 in the metering process, and Fig. 3(b) shows the injection control pattern in the injection process with the screw position S on the horizontal axis and the injection speed on the vertical axis.

[0029] 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 becomes the injection start position SS of the subsequent injection process (KE = SS).

[0030] As shown in FIG. 3(b), the injection control unit 40 starts the injection process by operating the injection drive unit 30 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. The screw 11 advances 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 of the metered resin, and then the injection mold 20 is opened after the cooling process to remove the molded product 53 from 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 is not limited thereto, and may be, for example, an injection control pattern of the injection pressure. In this case, the injection speed changes in conjunction with the setting of the injection pressure.

[0031] Here, in the injection process, the metered resin is significantly affected by shear heat when it flows within the range from the resin flow path 24 to the mold cavity 23. This shear heat is related to the shear rate and the material viscosity, and the higher the shear rate and the higher the material viscosity, the greater the shear heat is, causing the metered resin to generate heat and rise in temperature.

[0032] 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. The shear heat increases as the flow rate increases, and also increases as the flow path area decreases. For example, when the metered resin passes through the valve gate 25 or gate 26, which has the smallest flow path area, 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 Figure 3(b), the shear heat is the largest in area B with a high-speed injection setting, followed by area A with a medium-speed injection setting, and the shear heat is the smallest in area 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 the change in injection speed.

[0033] 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 obviously 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.

[0034] [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 injected 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).

[0035] First, as shown in FIG. 4(a), the measured resin in the storage area 17 passes through the resin flow path 24, the opened valve gate 25, and the gate 26 by the forward movement of the screw 14, and is injected and filled into the mold cavity 23. As the screw 14 advances, the mold cavity 23 is filled with the measured resin. Next, as shown in FIG. 4(b), when the screw 15 reaches the injection pressure holding switching position VP, the injection process is completed and the process is switched to the pressure holding process, and the screw 14 is pressed with a predetermined pressure to perform pressure holding and filling. At the time of completion of this injection process, the mold cavity 23 is filled with the measured 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 measured resin injected and filled into the mold cavity 23 is measured using the temperature measuring means shown in FIG. 2. Furthermore, the measured resin in the mold cavity 23 is filled from the gate 26 (injection filling position G) and flows toward the final injection filling position M.

[0036] 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 molding and the upper and lower limit allowable temperatures (H, L) are superimposed on this. The reference temperature waveform K and the allowable temperatures (H, L) are obtained, for example, from the 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.

[0037] If the filling temperature waveform Z is within the allowable temperature (H, L) range for obtaining a good molding, which is set for the reference temperature waveform, then stable production of good moldings is guaranteed, and the injection molding operation continues without correction. If the filling temperature waveform Z is outside the allowable temperature (H, L) range, then stable production of good moldings is difficult, and the temperature correction process shown below is performed.

[0038] First, the injection filling positions where the filling temperature waveform Z and the allowable values ​​(H, L) intersect are defined as the correction positions (S1 to S3). Next, the correction positions (S1 to S3) are converted to the positions 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 a short shot filling method in which the actual injection process is divided and reproduced. The short shot filling method is a means for obtaining a molded product 53 in a short shot state by 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). By finely dividing the intermediate stopping positions 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, this means is widely used in injection molding sites. The position of the screw 14 during the injection process is also the position of the screw 14 during the metering process.

[0039] Next, as shown in FIG. 5(b), the converted correction positions (S1-S3) are set as the correction screw positions (HS1-HS3) and are superimposed on a graph showing the metering control pattern with the horizontal axis being the position of the screw 14 during the metering process, and a correction pattern for the temperature correction process is set. Here, the screw rotation speed and back pressure during the metering process are set 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 obtaining 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 preferable 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 of the storage area 17.

[0040] First, the temperature correction process using the screw rotation speed will be described. In the range from the metering start position KS to the correction screw position HS1, since the filling temperature waveform Z is within the allowable value range (H, L), the screw rotation speed N0 of the preset metering control pattern is used. In the range from the correction screw position HS1 to HS2, since the filling resin temperature waveform Z exceeds the upper allowable value H, in order to lower the temperature of the metered resin, the screw rotation speed N1 is decreased (N1 < N0). As a result, the shear heat generation due to the rotation operation of the screw 14 is reduced, and as a result, the metered resin at a low temperature is stored. In the range from the correction screw position HS2 to HS3, since the filling temperature waveform Z is within the allowable value range (H, L), the screw rotation speed N0 of the preset metering control pattern is used. In the range from the correction screw position HS3 to the metering completion position KE, since the filling resin temperature waveform Z is lower than the lower allowable value L, in order to raise the temperature of the metered resin, the screw rotation speed N2 is increased (N2 > N0). As a result, the shear heat generation due to the rotation operation of the screw 14 is increased, and as a result, the metered resin at a high temperature is stored. 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.

[0041] Next, the temperature correction process using the back pressure will be described. Also in this case, similar to the screw rotation speed, based on the allowable value range (H, L) of the filling temperature waveform Z and the reference waveform K and the correction screw positions (HS1 to HS3), the back pressure BP0 of the preset metering control pattern is used without correction within the allowable value range (H, L). When it is higher than the allowable value H, in order to reduce the shear heat generation and obtain a metered resin at a low temperature, the metering back pressure BP1 is decreased (BP1 < BP0). When it is lower than the allowable value L, in order to increase the shear heat generation and obtain a metered resin at a high temperature, the metering back pressure BP2 is increased (BP2 > BP0). The temperature correction process using the back pressure is also performed during the metering process, and it is possible to optimize the temperature of the metered resin injected and filled into the mold cavity 23.

[0042] Here, the temperature correction process may be performed by combining the screw rotation speed and the back pressure. For example, if the rotation speed of the screw 14 is excessively increased in order to obtain a metered resin at a high temperature, resin material that is not completely melted (referred to as unmelted resin) may be mixed into 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 amount of 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, and the metering process may take longer, resulting in a significant decrease in productivity. 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.

[0043] [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.

[0044] Although the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the above-mentioned embodiments. Various modifications and improvements can be made to the above-mentioned embodiments. [Explanation of symbols]

[0045] 100 injection molding machine 10 Injection device 11 Injection cylinder 12 Heater 13 Material hopper 14 Screw 15 flights 16 Backflow prevention device 17 Storage Area F forward B Back 20 Injection mold 21 Fixed mold 22 Movable mold 23 Mold Cavity 24 Resin flow path 25 Valve Gate Gate 26 30 Injection drive unit 40 Injection control section 50 Temperature measurement means 51 Temperature Sensor 52 Temperature receiver 53 Molded products 54 Thermal Camera 55 Image receiving unit KE Weighing completion position KS Weighing start position SS injection start position VP Injection pressure changeover position A, B, C area G, M injection filling position Z filling temperature waveform K Reference temperature waveform H, L Allowable temperature S1~S3 correction position HS1~HS3 Compensation screw position N0~N2 screw rotation speed BP0~BP2 Back pressure

Claims

1. 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. 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.

3. 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. 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.

5. 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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