Method for determining viscosity state of resin, injection device, and injection molding machine

Abstract

To provide a method to check the viscosity state of the resin.SOLUTION: Before the start of the molding cycle, an inspection process is performed. That is, the resin is metered in the injection device (3). The injection nozzle (21) is separated from the mold (13) and the screw (18) is advanced by pressure control at the specified pressure to extrude the resin. The length of the screw (18) advanced in the specified time and the extrusion stroke are measured. Whether this extrusion stroke is within the proper stroke range is checked, to confirm the viscous state of the resin. The proper stroke range is determined in advance by conducting a preparation process when the molding conditions are changed. The preparation process is also carried out by weighing the resin and advancing the screw (18) for a specified time by pressure control at a specified pressure to obtain the extrusion stroke, and the proper stroke range is determined based on the obtained extrusion stroke.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for determining the viscous state of a resin in an injection molding machine that injects resin into a mold, an injection molding machine that determines the viscous state of a resin, and an injection molding machine. [Background technology]

[0002] For injection molding machines, molding conditions suitable for each molded product are set. The molding conditions include heating cylinder temperature, mold clamping force, injection pressure, injection speed, injection stroke, dwell pressure, dwell time, etc. These must be set to appropriate values ​​to obtain high-quality molded products.

[0003] Incidentally, the viscosity of resin affects its fluidity. Changes in fluidity can cause molding defects; for example, if the fluidity is high, it can cause overpacking, while if it is low, it can cause poor transferability and short shots. Since the viscosity of resin changes depending on the resin temperature, the desired fluidity should be obtained by appropriately setting and controlling the heating cylinder temperature. However, the viscosity of resin also changes depending on the drying state and other conditions. The state of resin provided by resin manufacturers may differ depending on the product lot, which affects the viscosity and fluidity of the resin.

[0004] To obtain an accurate viscosity of the resin, it is necessary to measure it with a viscosity sensor installed in the injection molding machine, or to obtain the pressure difference by installing a pressure sensor in the resin flow path inside the mold, etc. In other words, it is necessary to install a dedicated device or sensor to measure the viscosity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3732821

[0006] Patent Document 1 proposes a method for measuring the viscosity of a resin without installing any special viscosity or pressure sensor in the injection molding machine. In the method described in this document, injection is performed with the injection nozzle separated from the mold and the screw speed is kept constant. The viscosity of the resin is calculated from the actual injection pressure value measured at this time, the inner diameter of the resin flow path in the injection nozzle, the length of the resin flow path, etc. This is displayed on the monitor of the controller of the injection molding machine and notified to the operator. Summary of the Invention [Problem to be solved by the invention]

[0007] To accurately measure the viscosity of the resin, it is necessary to provide a viscosity sensor or a pressure sensor in the injection molding machine, which increases costs. The method described in Patent Document 1 does not require a special viscosity sensor or the like, and is therefore low cost. However, the viscosity calculated from the actually measured injection pressure value, the inner diameter of the resin flow path of the injection nozzle, the length of the resin flow path, etc., cannot necessarily be expected to be highly accurate. In addition, simply displaying the viscosity does not allow the operator to judge whether or not the injection molding can be performed appropriately.

[0008] Therefore, in this disclosure, we provide a method for checking the viscosity state of a resin that checks whether the viscosity state of a resin is within an appropriate range, in other words, whether the flow state of the resin is within an appropriate range, rather than the viscosity data of the resin itself, and provides such information to an operator, as well as an injection device and an injection molding machine that implement such a method.

[0009] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0010] The method for checking the viscosity state of a resin according to the present disclosure is configured as follows. First, the resin is measured in the injection device. With the injection nozzle separated from the mold, the screw is advanced by pressure control at a specified pressure. In other words, the resin is extruded. The length by which the screw has advanced in a specified time, i.e., the extrusion stroke, is measured. It is checked whether or not this extrusion stroke is within a proper stroke range. Effect of the Invention

[0011] According to the present disclosure, if the extrusion stroke is within the appropriate stroke range, it is determined that the viscosity state of the resin is within the appropriate range, and if it is outside the range, it is determined that there is a problem with the viscosity state of the resin. There is no need to provide a special viscosity sensor or a resin pressure sensor, and this can be implemented at low cost. [Brief description of the drawings]

[0012] [Figure 1] 1 is a front view showing an injection molding machine according to an embodiment of the present invention; [Diagram 2] 1 is a front cross-sectional view showing an injection device according to an embodiment of the present invention. [Figure 3A] 1 is a front cross-sectional view of an injection device according to the present embodiment, which performs a method for checking the viscosity state of a resin according to the present embodiment. [Figure 3B] 1 is a front cross-sectional view of an injection device according to the present embodiment, which performs a method for checking the viscosity state of a resin according to the present embodiment. [Figure 3C] 1 is a front cross-sectional view of an injection device according to the present embodiment, which performs a method for checking the viscosity state of a resin according to the present embodiment. [Figure 3D] 1 is a front cross-sectional view of an injection device according to the present embodiment, which performs a method for checking the viscosity state of a resin according to the present embodiment. [Figure 4] 4 is a flowchart showing a preparation process of the method for checking the viscosity state of a resin according to the present embodiment. [Diagram 5] 4 is a flowchart showing an inspection process of the method for checking the viscosity state of a resin according to the present embodiment. [Figure 6] 4 is a graph showing the changes in screw speed, screw pressure, and screw position when carrying out the method for checking the viscosity state of a resin according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Specific embodiments will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. In order to clarify the description, the following description and drawings are appropriately simplified. In each drawing, the same elements are given the same reference numerals, and duplicated descriptions are omitted as necessary. In addition, hatching is omitted in some parts to avoid cluttering the drawings.

[0014] The present embodiment will be described. <Injection molding machine> The injection molding machine 1 according to the present embodiment is configured in the same manner as a general injection molding machine. That is, as shown in FIG. 1, it is roughly configured with a mold clamping device 2 and an injection device 3 provided on a bed B, and is controlled by a controller 4. The mold clamping device 2 can be configured as a direct pressure type, but in this embodiment, it is configured as a toggle type. That is, the mold clamping device 2 is configured with a fixed platen 7, a movable platen 8, a mold clamping housing 9, tie bars 10, 10, ... connecting the mold clamping housing 9 and the fixed platen 7, and a toggle mechanism 11, and molds 13, 14 are provided on the fixed platen 7 and the movable platen 8. When the toggle mechanism 11 is driven, the molds 13, 14 are clamped.

[0015] <Injection device> The injection device 3 according to this embodiment is configured similarly to a general injection molding machine 3, and is shown generally in Fig. 1 and in cross section in Fig. 2. The injection device 3 is composed of a heating cylinder 17 and a screw 18 inserted in the heating cylinder 17. A hopper 20 is provided upstream of the heating cylinder 17, and an injection nozzle 21 is provided at the tip of the heating cylinder 17. The injection device 3 is equipped with a nozzle touch device 23, and is adapted to drive the injection device 3 toward the mold clamping device 2 to bring the injection nozzle 21 into contact with the mold 13, or to drive the injection device 3 in the opposite direction to move the injection nozzle 21 away from the mold 13.

[0016] <Controller> The injection molding machine 1 according to this embodiment is configured in the same manner as a general injection molding machine in terms of devices, members, etc., but is characterized by the processing performed by the controller 4. Specifically, when starting a molding cycle from a stopped state, the injection molding machine 1 according to this embodiment checks whether the viscosity state of the resin is within an appropriate range prior to starting the molding cycle. A program for performing processing for implementing this checking method is stored in the controller 4.

[0017] Next, this program will be explained in detail. In the following explanation, Figures 1 and 2 will be referred to as appropriate.

[0018] This program is composed of subprograms of a preparation means 30, an inspection means 40, a judgment means 50, and a viscosity calculation means 60. The preparation means 30 is a subprogram for a preparation process that is performed when molding conditions are changed. The inspection means 40 is a subprogram for an inspection process that is performed when a molding cycle is started from a stopped state. The judgment means 50 is a subprogram for performing a judgment process that judges whether or not the viscosity state of the resin is appropriate based on the result of the inspection process. The viscosity calculation means 60 is a subprogram for a viscosity calculation process that performs a process of calculating the viscosity as a reference and displaying it on the monitor of the controller 4. The preparation means 30 and the inspection means 40 are configured to perform a plurality of processes, and are composed of a plurality of means for performing these processes.

[0019] <Preparation process> When starting a molding cycle from a stopped state, the injection molding machine 1 according to this embodiment checks whether the viscosity state of the resin is within an appropriate range through an inspection process described later. The appropriate range is checked based on a predetermined standard, i.e., an appropriate stroke range. The meaning of the term "appropriate stroke range" will be made clear in the following explanation, so it will not be explained here. The appropriate stroke range may be determined by an operator based on experience, but in the injection molding machine 1 according to this embodiment, it is determined in a preparation process.

[0020] The appropriate stroke range varies depending on the metering conditions. Here, the metering conditions are, for example, the type of resin used, the resin temperature, the inner diameter of the resin flow path in the injection nozzle, the length of the resin flow path in the injection nozzle, the holding pressure, and the switching pressure. Therefore, when the molding conditions are changed in the injection molding machine 1, the controller 4 is operated to execute the preparation means 30 to obtain the appropriate stroke range.

[0021] <Preparation process, weighing step> When the preparation means 30 is executed in the controller 4, the preparation process starts. As shown in Fig. 4, the preparation process first performs a measurement step S11. The measurement step S11 is performed by the measurement means 31 of the preparation means 30. The measurement step S11 measures the resin in the injection device 3. In the injection molding machine 1 according to this embodiment, the measurement step S11 is performed in a state where the injection nozzle 21 is separated from the mold 13. This state is shown in Fig. 3A.

[0022] In the metering step S11, when a resin having a relatively high viscosity is used, back pressure may be applied to the screw 18. When a resin having a relatively low viscosity is used, the metering may be performed while retracting the screw 18. Since the measurement step S11 is performed with the injection nozzle 21 separated from the mold 13, air may enter from the tip of the injection nozzle 21, as shown by reference symbol 25 in Fig. 3B. When measurement is completed, the measurement step S11 is also completed.

[0023] <Preparation process, measurement step> Next, the controller 4 performs a measuring step S12 shown in FIG. 4 by the measuring means 32. The measuring step S12 is performed with the injection nozzle 21 separated from the mold 13. This measuring step S12 consists of two stages. First, in the first stage, the screw 18 is advanced under constant speed control to extrude the resin from the injection nozzle 21. FIG. 6 shows the change in the speed of the screw 18, that is, the screw speed 71. Immediately after the start of the constant speed control, the speed increases rapidly from 0 as shown by reference numeral 71a, and after reaching a predetermined speed, it becomes constant as shown by reference numeral 71b. At this time, the position of the screw 18, that is, the screw position 72, advances slowly as shown by reference numeral 72a immediately after the start, but advances at a constant rate as shown by reference numeral 72b immediately thereafter. The pressure of the screw 18, that is, the screw pressure 73, increases as shown by reference numeral 73a.

[0024] When the screw 18 is advanced by speed control, the resin is eventually extruded from the tip of the injection nozzle 21. The air that had entered the tip of the injection nozzle 21 is extruded together with the resin. Then, the screw pressure 73 eventually reaches the switching pressure set in the controller 4. This operation reduces the variation in the state of the resin, particularly the density. This state is shown in Figure 3C. The position of the screw 18 at this timing is indicated by the reference numeral 26.

[0025] When the screw pressure 73 reaches the switching pressure, the controller 4 performs the next step of processing. That is, the drive of the screw 18 is switched to pressure control at a specified pressure. As shown in Fig. 6, after the screw pressure 73 is switched to pressure control at a specified pressure, the pressure becomes constant as shown by reference numeral 73b. The changes in the screw speed 71 and the screw position 72 when the screw 18 is extruded under pressure control are shown by reference numerals 71c and 72c, respectively.

[0026] The forward movement of the screw 18 is started under pressure control at a specified pressure, and then the forward movement of the screw 18 is stopped after a specified time. This state is shown in Fig. 3D. The controller 4 calculates the distance that the screw 18 has advanced in the specified time, that is, the difference between the screw positions of the reference numerals 26 and 27. This is stored as the extrusion stroke.

[0027] The extrusion stroke is closely related to the viscosity of the resin. If the viscosity is high, the extrusion stroke is short, and if the viscosity is low, the extrusion stroke is long. This extrusion stroke is affected by air that has entered the tip of the screw 18. In this embodiment, the drive of the screw 18 is started by speed control in the measurement step S12. Even if air has entered the tip of the injection nozzle 21 as shown in FIG. 3B when the injection nozzle 21 is separated from the mold 13 and measured in the measurement step S11, causing variation in the density of the resin, this process can reduce the variation in the density of the resin.

[0028] Incidentally, when the screw 18 is advanced, it is first controlled at a constant speed, then switched from speed control to pressure control at a specified pressure, and then pressure controlled at a constant pressure. These can be easily implemented by various settings available in a typical injection molding machine. Advancing the screw 18 by speed control can be achieved by the so-called "injection" setting, switching from speed control to pressure control by the "holding pressure switch" setting, and advancing the screw 18 by pressure control by the "holding pressure" setting.

[0029] <Preparation process: Determining the appropriate stroke range> When the measurement step S12 is completed, the controller 4 checks the number of times the weighing step S11 and the measurement step S12 have been performed in step S13 shown in Fig. 4. If this number reaches the specified preparation number, the process proceeds to step S14 shown in Fig. 4. If not, the process returns to step S11. Note that, since the weighing step S11 and the measurement step S12 have been performed only once initially, the process returns to step S11.

[0030] When the weighing step S11 and the measuring step S12 are performed a prescribed number of times, the extrusion strokes for the prescribed number of times are obtained. Based on these extrusion strokes, the appropriate stroke range is determined in step S14. In this embodiment, the minimum value of the appropriate stroke range is determined from the minimum extrusion stroke among the extrusion strokes for the prescribed number of times, and the maximum value of the appropriate stroke range is determined from the maximum extrusion stroke among the extrusion strokes for the prescribed number of times. However, it is also possible to obtain an average value m and a variance σ from the extrusion strokes for the prescribed number of times, and to determine the appropriate stroke range based on these. In other words, the appropriate stroke range can be m ±2σ, m ±3σ, or the like. Once the appropriate stroke range is determined, the preparation process is completed.

[0031] <Inspection process> The injection molding machine 1 according to the present embodiment performs an inspection process when starting a molding cycle from a stopped state or when a molding defect occurs, to check whether the viscosity state of the resin is within an appropriate range. The inspection process is started when the controller 4 executes the inspection means 40.

[0032] <Inspection process, weighing step> In the inspection process, first, a measuring step S21 is performed as shown in Fig. 5. The measuring step S21 is performed by the measuring means 41 of the inspection means 40. The measuring step S21 in the inspection process performs the same process as the measuring step S11 in the preparation process. That is, the resin is measured in the injection device 3. In the injection molding machine 1 according to this embodiment, the measuring step S21 is performed in a state where the injection nozzle 21 is separated from the mold 13.

[0033] <Inspection process, measurement step> After the measurement step S21 is completed, the controller 4 performs the measurement step S22 shown in FIG. 5 using the measurement means 42. The measurement step S22 of the inspection step is also performed in the same manner as the measurement step S12 of the preparation step. That is, the measurement step S22 is performed with the injection nozzle 21 separated from the mold 13, and is a two-stage process. First, the screw 18 is advanced by speed control. When the pressure of the screw 18 reaches the switching pressure, the controller 4 performs the next stage of processing. That is, the drive of the screw 18 is switched to pressure control at a specified pressure. After a specified time, the advancement of the screw 18 is stopped to obtain an extrusion stroke.

[0034] <Inspection process comparison step> After the measurement step S22 is completed, the controller 4 performs a comparison step S23 shown in Fig. 5 using the comparison means 43. In the comparison step S23, the extrusion stroke obtained in the measurement step S22 is compared with the appropriate stroke range obtained in the preparation step. That is, it is checked whether the extrusion stroke is within the appropriate stroke range.

[0035] When the comparison step S23 is completed, the controller 4 checks the number of times that the weighing step S21, the measurement step S22, and the comparison step S23 have been performed in step S24 shown in Fig. 5. If this number of times reaches the specified number of inspections, the process proceeds to the determination step S25 shown in Fig. 5. If not, the process returns to step S21.

[0036] <Judgment process> After the weighing step S21, the measuring step S22 and the comparison step S23 are performed for a specified number of times in the inspection process, the controller 4 performs the judgment step S25 by the judgment means 50. The judgment step S25 is a step of judging whether the viscosity state of the resin is appropriate or not from the results of the judgment step S23 for the specified number of times. If the number of times that the extrusion stroke enters the appropriate stroke range in the judgment step S23 is equal to or greater than the standard number of times, the viscosity state of the resin is judged to be appropriate, and if it is less than the standard number of times, the viscosity state is judged to be inappropriate. For example, assume that the specified number of times of inspection is 5 times and the standard number of times is 3 times. In this case, if the number of times that the extrusion stroke enters the appropriate stroke range among the results of the judgment step S23 performed 5 times is 3 times or more, it is judged to be appropriate, and if it is 2 times or less, it is judged to be inappropriate.

[0037] <Alarm output> If it is determined in the process of step S26 shown in Fig. 5 that the viscosity state of the resin is inappropriate, the controller 4 performs the alarm output S27 shown in Fig. 5. That is, an alarm is output from a speaker attached to the controller 4. Alternatively, a message that the viscosity state of the resin is inappropriate is displayed on an attached monitor. The operator can recognize that there is a problem with the viscosity state of the resin before starting the molding cycle, and can take appropriate measures.

[0038] <Resin viscosity calculation process> The injection molding machine 1 according to this embodiment can calculate the viscosity of the resin from the extrusion stroke obtained in the measurement step S22 and display it as a reference value on the monitor of the controller 4. The viscosity of the resin calculated from the extrusion stroke is not necessarily highly accurate, so it is not essential for the operation of the injection molding machine 1. Therefore, the calculation of the viscosity may be omitted. However, by providing the viscosity as a reference value to the operator, it can become one of the pieces of information for determining whether or not to start the molding cycle. In this embodiment, when the viscosity state of the resin is determined to be appropriate in the process of step S26, or when the alarm output S27 is completed, the resin viscosity calculation step S28 shown in FIG. 5 is performed.

[0039] In the resin viscosity calculation step S28, an average value is obtained from the extrusion strokes for the specified number of tests that have already been obtained. The resin viscosity η [Pa s] is calculated using the average extrusion stroke according to the following (Equation 2). The obtained viscosity η is displayed on a monitor attached to the controller 4 as a reference value. The process is then completed.

[0040]

number

[0041] In this embodiment, both the measurement step S11 (see FIG. 4) of the preparation process and the measurement step S21 (see FIG. 5) of the inspection process have been described as being performed with the injection nozzle 21 separated from the mold 13. However, the measurement steps S11 and S21 may be performed with the injection nozzle 21 touching the mold 13. If the measurement is performed with the injection nozzle 21 in contact, it is possible to prevent air from entering from the tip of the injection nozzle 21. When the measurement steps S12 (see FIG. 4) and S22 (see FIG. 5) are then performed with the injection nozzle 21 separated from the mold 13, there is no need to expel air from the injection nozzle 21, so there is no need to perform two-stage processing. In other words, the measurement steps S12 and S22 may be started with the screw 18 under pressure control at a specified pressure.

[0042] <Experiment> An experiment was conducted to confirm whether the viscous state of a resin can be appropriately determined by the method for checking the viscous state of a resin according to the present embodiment.

[0043] (1) Using the injection molding machine 1 according to the present embodiment, a preparation process was carried out under the following conditions. Resin used: Polycarbonate (PC) Heating cylinder (tip) temperature setting: 290℃ Conditions for weighing step S11 Conditions for implementation: The injection nozzle 21 was spaced apart from the mold 13. Metering complete: When the screw position is 85mm. Conditions for measurement step S12 Speed ​​control: Screw speed is 10mm / s Switching pressure for pressure control: 3MPa Specified pressure for pressure control: 10MPa, 30MPa Specified time: 1s Required preparation times: 10 times

[0044] When the specified pressure was set to 10 MPa and when it was set to 30 MPa, the weighing step S11 and the measurement step S12 were repeated the specified number of times to obtain the extrusion stroke, as shown in the following table.

[0045] [Table 1]

[0046] (2) The minimum and maximum values ​​of the extrusion stroke at the specified pressures of 10 MPa and 30 MPa were read from the table, and the appropriate stroke range was determined as follows: When the specified pressure is 10MPa: The appropriate stroke range is 11.42 to 12.26 When the specified pressure is 30MPa: The appropriate stroke range is 43.34 to 44.21

[0047] (3) Next, the temperature setting of the heating cylinder (tip) was changed to a value 5°C higher, and the inspection process was carried out. All other conditions were the same as those in the preparation process. Resin used: Polycarbonate (PC) Heating cylinder (tip) temperature setting: 295℃ (+5℃) Conditions for weighing step S21 Conditions for implementation: The injection nozzle 21 was spaced apart from the mold 13. Metering complete: When the screw position is 85mm. Conditions for measurement step S22 Speed ​​control: Screw speed is 10mm / s Switching pressure for pressure control: 3MPa Specified pressure for pressure control: 10MPa, 30MPa Specified time: 1s Specified number of inspections: 3 times when the specified pressure is 10MPa, 10 times when the specified pressure is 30MPa

[0048] When the specified pressure was set to 10 MPa and when it was set to 30 MPa, the weighing step S21 and the measurement step S22 were repeated the specified number of times to obtain the extrusion stroke, as shown in the following table.

[0049] [Table 2]

[0050] Whether the specified pressure was 10 MPa or 30 MPa, the extrusion strokes for the specified number of tests all exceeded the appropriate stroke range. It was confirmed that the resin temperature had risen by +5°C, and the resin's fluidity had increased. In other words, it was confirmed that the resin's viscous state can be appropriately determined by the method for checking the resin's viscous state according to this embodiment.

[0051] (4) Next, the inspection process was carried out using the wet resin, with all other conditions being the same as those in the preparation process. Resin used: Polycarbonate (PC) Used in wet condition Heating cylinder (tip) temperature setting: 290℃ Conditions for weighing step S21 Conditions for implementation: The injection nozzle 21 was spaced apart from the mold 13. Metering complete: When the screw position is 85mm. Conditions for measurement step S22 Speed ​​control: Screw speed is 10mm / s Switching pressure for pressure control: 3MPa Specified pressure for pressure control: 10MPa, 30MPa Specified time: 1s Specified number of inspections: 3 times when the specified pressure is 10MPa, 5 times when the specified pressure is 30MPa

[0052] When the specified pressure was set to 10 MPa and when it was set to 30 MPa, the weighing step S21 and the measurement step S22 were repeated the specified number of times to obtain the extrusion stroke, as shown in the following table.

[0053] [Table 3]

[0054] Whether the specified pressure was 10 MPa or 30 MPa, the extrusion strokes for the specified number of tests were all larger than the appropriate stroke range. It was confirmed that the resin had high fluidity when the resin was wet. In other words, it was confirmed that the resin viscosity state confirmation method according to the present embodiment can appropriately determine the resin viscosity state.

[0055] Although the invention made by the present inventor has been specifically described above based on the embodiment, it goes without saying that the present invention is not limited to the embodiment already described, and various modifications are possible without departing from the gist of the invention. The above-described examples may be implemented in appropriate combination. [Explanation of symbols]

[0056] 1 Injection molding machine 2 Mold clamping device 3 Injection unit 4 Controller 13 Mold 14 Mold 17 Heating cylinder 18 Screw 21 Injection nozzle 23 Nozzle touch device 30 Preparation means 31 Measuring means 32 Measuring means 40 Inspection means 41 Measuring means 42 Measuring means 43 Comparison means 50 Judgment means 60 Viscosity calculation means

Claims

1. Equipped with an inspection process to check the viscosity state of the resin, The inspection process includes a weighing step, a measuring step, and a comparing step, The measuring step measures the resin in a state where an injection nozzle of an injection device is separated from a mold, The measuring step includes: starting to advance the screw by speed control in advance in a state where the injection nozzle is separated from the mold to extrude the resin; switching to pressure control at a specified pressure after the pressure of the screw reaches a switching pressure; and obtaining an extrusion stroke, which is the stroke of the screw advanced in a specified time during the pressure control; The method for checking the viscosity state of a resin, wherein the comparison step compares the extrusion stroke with a proper stroke range that is a range of proper extrusion strokes.

2. The viscosity state confirmation method further comprises a preparation step performed when molding conditions are changed, 2. The method for checking the viscosity state of a resin according to claim 1, wherein the preparation process comprises repeating the weighing step and the measurement step a specified number of times, which is a specified preparation number, and determining the appropriate stroke range based on the extrusion stroke for the specified preparation number of times.

3. A method for checking the viscosity state of a resin as described in claim 1 or 2, wherein the inspection process further includes a viscosity calculation process for calculating the viscosity of the resin based on the extrusion stroke obtained in the comparison step, the inner diameter of the heating cylinder, the inner diameter of the injection nozzle, and the resin flow path length of the injection nozzle.

4. The method for checking the viscosity state of a resin according to any one of claims 1 to 3, wherein the inspection process further comprises a determination process for determining whether the viscosity state of the resin is appropriate or not based on the comparison result in the comparison step.

5. 5. The method for checking the viscosity state of a resin as described in claim 4, wherein the judgment step determines whether the viscosity state of the resin is appropriate or not based on the number of inspection steps in which the extrusion stroke falls within the appropriate stroke range in the comparison step when the inspection step is performed a specified number of times.

6. 6. The method for checking a viscosity state of a resin according to claim 4, wherein in the determining step, an alarm is outputted if the viscosity of the resin is determined to be inappropriate.

7. A heating cylinder having an injection nozzle at its tip; a screw contained within the heating cylinder; A controller, The controller includes an inspection means for inspecting a viscosity state of the resin, The inspection means includes a measuring means for rotating the screw to melt the resin and measure the melted resin into the heating cylinder; a measuring means for moving the screw forward under pressure control at a specified pressure while the injection nozzle is separated from the mold to extrude a measured amount of resin, and obtaining an extrusion stroke, which is the stroke of the screw moving forward in a specified time; A comparison means for comparing the push stroke with a proper stroke range, The metering means is configured to perform the metering operation while the injection nozzle is spaced apart from the mold, The measurement means is configured to start advancing the screw by speed control in advance, and switch to pressure control after the pressure of the screw reaches a switching pressure.

8. The controller further comprises a preparation means for executing when a molding condition is changed, 8. The injection device according to claim 7, wherein the preparation means repeatedly performs the weighing means and the measuring means a specified number of times, which is a specified preparation number, and determines the appropriate stroke range based on the extrusion stroke for the specified preparation number of times.

9. An injection device as described in claim 7 or 8, wherein the inspection means further includes a viscosity calculation means for calculating the viscosity of the resin based on the extrusion stroke obtained by the comparison means, the inner diameter of the heating cylinder, the inner diameter of the injection nozzle, and the resin flow path length of the injection nozzle.

10. 10. The injection device according to claim 7, wherein the inspection means further comprises a determination means for determining whether or not the viscosity state of the resin is appropriate based on a comparison result by the comparison means.

11. 11. The injection device according to claim 10, wherein the determining means performs the inspection means a specified number of times, and determines whether the viscosity state of the resin is appropriate or not based on the number of inspections performed by the inspection means in which the extrusion stroke falls within the appropriate stroke range as determined by the comparing means.

12. 12. The injection device according to claim 10, wherein the determining means outputs an alarm when the viscosity of the resin is determined to be inappropriate.

13. The apparatus includes an injection device that measures and injects resin, and a mold clamping device that clamps the mold, The injection device includes a heating cylinder having an injection nozzle at its tip; a screw contained within the heating cylinder; A controller, The controller includes an inspection means for inspecting a viscosity state of the resin, The inspection means includes a measuring means for rotating the screw to melt the resin and measure the melted resin into the heating cylinder; a measuring means for moving the screw forward under pressure control at a specified pressure while the injection nozzle is separated from the mold to extrude a measured amount of resin, and obtaining an extrusion stroke, which is the stroke of the screw moving forward in a specified time; A comparison means for comparing the push stroke with a proper stroke range, The metering means is configured to perform the metering operation while the injection nozzle is spaced apart from the mold, The measurement means is configured to start the forward movement of the screw by speed control in advance, and switch to pressure control after the pressure of the screw reaches a switching pressure.

14. The controller further comprises a preparation means for executing when a molding condition is changed, 14. The injection molding machine according to claim 13, wherein the preparation means repeatedly performs the weighing means and the measuring means a specified number of times, which is a specified preparation number, and determines the appropriate stroke range based on the extrusion stroke for the specified preparation number of times.

15. An injection molding machine as described in claim 13 or 14, wherein the inspection means further includes a viscosity calculation means for calculating the viscosity of the resin based on the extrusion stroke obtained by the comparison means, the inner diameter of the heating cylinder, the inner diameter of the injection nozzle, and the resin flow path length of the injection nozzle.

16. 16. The injection molding machine according to claim 13, wherein the inspection means further comprises a determination means for determining whether or not the viscosity state of the resin is appropriate based on a comparison result by the comparison means.

17. 17. The injection molding machine according to claim 16, wherein the determining means performs the inspection means a specified number of times, and determines whether the viscosity state of the resin is appropriate or not based on the number of inspections performed by the inspection means in which the extrusion stroke falls within the appropriate stroke range as determined by the comparing means.

18. 18. The injection molding machine according to claim 16, wherein the determining means outputs an alarm when the viscosity of the resin is determined to be inappropriate.

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