Manufacturing apparatus and manufacturing apparatus control method

Abstract

To provide a manufacturing device for a resin molded article and a method for controlling the manufacturing device, which are capable of stably manufacturing a resin molded article with a good quality even with a short injection molding time.SOLUTION: There is provided a manufacturing device for a resin molded article, comprising: an injection molding unit 10 configured to perform injection of a resin into an injection mold to perform injection molding the resin molded article; a control unit 13 configured to control the injection by the injection molding unit 10; a calculation unit 14 configured to calculate a pressure reduction curve for reducing a pressure generated by the injection; and an input unit 15 in which a user inputs a condition of the pressure reduction curve, wherein the control unit 13 is configured to control the injection based on the pressure reduction curve.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an apparatus for manufacturing a resin molded product and a method for controlling the apparatus. [Background technology]

[0002] Conventionally, apparatuses for manufacturing resin molded products and methods for controlling such apparatuses have been known (see, for example, Patent Document 1). In recent years, new molding methods have been proposed for this type of apparatus for manufacturing resin molded products, which are capable of producing transparent, high-quality preforms and containers even when the injection molding time, particularly the cooling time, is significantly shortened. This has made it possible to dramatically shorten the molding cycle time in injection stretch blow molding apparatuses that are equipped with a preform temperature adjustment mechanism or post-cooling mechanism and that perform each of the injection molding, temperature adjustment, and blow molding steps at equal intervals. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-3973 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional resin molded product manufacturing apparatus, the shortening of the molding cycle time also shortens the processing time of each process, so if the quality of the injection-molded preform is low, there is a risk that downstream processes such as the blow molding process cannot be carried out properly. Therefore, it has become even more important to mold high-quality preforms in the injection molding process, which is the most upstream process.

[0005] The injection molding process consists of a filling process (injection process), a pressure holding process, and a cooling process. During the filling process, the screw or plunger movement speed is controlled based on the distance between the injection molding machine and each of the multiple cavities. During the pressure holding process, the injection pressure is controlled in multiple, stepped steps at predetermined intervals. However, pressure fluctuations accompanied by a sudden drop in pressure occur when switching between the filling process and the pressure holding process. These pressure fluctuations can lead to reduced preform quality and molding defects, and the impact of these pressure fluctuations is significant, especially in manufacturing equipment with short molding cycles. Similarly, the injection pressure during the pressure holding process is also controlled in a roughly stepped manner, resulting in undesirable pressure fluctuations. Therefore, an improved control method for the pressure holding process was needed to stably perform preform injection molding with short molding cycles.

[0006] An object of the present invention is to provide a manufacturing apparatus for resin molded products and a control method for the manufacturing apparatus that can stably manufacture high-quality resin molded products even in a short injection molding time. [Means for solving the problem]

[0007] The present invention is a manufacturing apparatus for resin molded products, comprising an injection molding unit that injects resin into an injection mold to injection mold the resin molded product, a control unit that controls the injection by the injection molding unit, a calculation unit that calculates a decompression curve for reducing the pressure generated by the injection, and an input unit that allows a user to input conditions for the decompression curve, and the control unit controls the injection based on the decompression curve.

[0008] In this case, the input unit may be configured to allow input of an order of the pressure reduction curve.The input unit may be configured to allow input of a time length of the pressure reduction curve.

[0009] The present invention also provides a method for controlling a manufacturing apparatus for a resin molded product, the method comprising: an injection molding unit that injects resin into an injection mold to injection mold the resin molded product; a control unit that controls the injection by the injection molding unit; a calculation unit that calculates a decompression curve for reducing the pressure generated by the injection; and an input unit through which a user inputs conditions for the decompression curve; the method comprising the steps of: calculating the decompression curve based on the conditions input to the input unit; and controlling the injection based on the calculated decompression curve.

[0010] In this case, the input unit may be configured to allow input of an order of the pressure reduction curve.The input unit may be configured to allow input of a time length of the pressure reduction curve. [Effects of the Invention]

[0011] The present invention can provide an apparatus and method for manufacturing resin containers that can produce high-quality containers even using a hot parison blow molding method with a shortened molding cycle time. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of a blow molding device according to a first embodiment of the present invention; [Figure 2] A flow chart of the entire process is shown below. [Figure 3] FIG. 1 shows a block diagram of a blow molding device. [Figure 4] 3 shows a graph of the variation of injection pressure in an injection molding process. [Figure 5] 1 shows an input screen displayed in an input section. [Figure 6] 10 shows an input screen displayed on an input unit according to the second embodiment. [Figure 7] 10 shows a hydraulic pressure display screen displayed on an input unit according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. (First embodiment) FIG. 1 is a schematic diagram of a blow molding apparatus according to a first embodiment of the present invention, and FIG. 2 is a process diagram of the entire process. In FIG. 1, step 1 indicates a preform molding step, step 2 indicates a post-preform cooling step, steps 3 and 4 indicate preform temperature equilibration steps, step 5 indicates a reheating step, step 6 indicates a temperature equalization step, step 7 indicates a stretch blow molding step, and step 8 indicates a container removal step.

[0014] 1, in a blow molding apparatus (apparatus for manufacturing resin containers) 200 according to this embodiment, preforms 1 are sequentially conveyed on rails (conveying paths) 6 and pass through each process at an injection molding station 110, a post-cooling station 115, a temperature adjustment station (heating section) 120, a stretch blow station (blow molding section) 130, and a removal station. As a result, the blow molding apparatus 200 sequentially cools and adjusts the temperature of the conveyed preforms 1. In a broad sense, the post-cooling station 115 is included as part of the temperature adjustment station 120, and is a station that is particularly responsible for forced cooling of the preforms 1.

[0015] The injection molding station 110 includes an injection device 11. The injection device 11 includes a heating barrel 11a, a screw 11b arranged inside the heating barrel 11a so as to be stroke movable and rotatable, a first screw drive unit 11c1 that rotates the screw, a second screw drive unit 11c2 that strokes the screw 11b, a pressure holding device 11d (a pressure holding cylinder incorporating a plunger 11d1 so as to be stroke movable), and a pressure holding device drive unit 11e.

[0016] The blow molding apparatus 200 performs blow molding on the preforms 1 injection-molded at the injection molding station 110 in multiple batches, rather than performing temperature adjustment and blow molding all at once. That is, the injection molding station 110 injection-moldes, for example, 36 preforms 1 at a time. However, the preforms are transported by rail 6, for example, 12 at a time, to the temperature adjustment station 120, where they are temperature-adjusted, and then blow-molded at the stretch blow station 130, for example, 12 at a time. Because the preforms 1 injection-molded at the injection molding station 110 are cooled in steps 2 to 4, they are heated using infrared lamps in the temperature adjustment station 120 after the post-cooling step. The molding cycle time of the blow molding apparatus 200 can be considered to be approximately the same as the injection molding time of the preforms 1. Furthermore, the number of blow moldings per molding cycle is preferably three, but is not limited to this. In other words, any number of blow moldings may be performed as long as one batch of injection-molded preforms is blow-molded in multiple batches.

[0017] The preform 1 injection-molded in the blow molding apparatus 200 is released from the injection molding station 110 in a soft state (high enough to maintain its outer shape) that retains heat above the glass transition point of the synthetic resin material (e.g., PET resin). That is, the blow molding apparatus 200 removes the preform 1 from the injection molding cavity of the injection molding station 110 before the outer surface temperature of the preform 1 molded in the injection molding station 110 becomes higher than the inner surface temperature, and cools the preform 1 by 10°C to 50°C in the post-preform cooling step of step 2 and the preform temperature equilibration steps of steps 3 and 4. In this way, the preform 1, which has stored heat during injection molding, is molded into the final container 1a in the stretch blow station 130 while utilizing the stored heat.

[0018] 2, the blow molding apparatus 200 shortens the preform molding cycle (injection molding cycle) by shortening the injection molding process and by using a post-cooling function that uses a temperature-controlled pot mold in the temperature adjustment process. At this time, in the injection molding station 110 that molds the preform 1, the cooling time is set to 2 / 3 or less, 1 / 2 or less, or 1 / 3 or less of the injection time (filling time), and preferably approximately 0 (zero) seconds.

[0019] Each step will be described below. First, in the injection molding process, as shown in Figure 2, the blow molding apparatus 200 injects (fills) material into the molding space of an injection mold set to a temperature between 5°C and 20°C over a predetermined injection time, and then completes the injection molding of the preform 1 after a predetermined short cooling time close to zero (0) seconds. Next, the blow molding apparatus 200 takes a predetermined mechanical operation time to remove the preform 1 from the injection molding station 110 into a receiving pot mold (not shown) (demolding; step 1 in Figure 1, injection molding process in Figure 2). For example, the injection time (filling time) is set to 3.0 to 3.5 seconds, and the cooling time is set to 0.5 to 1.0 seconds.

[0020] The machine operation time in the injection molding station 110 (FIG. 1) is the time it takes to open and close the injection mold and transfer the preform 1 from the injection mold to the receiving mold. The machine operation time is set, for example, to 3.5 seconds or more and 4.0 seconds or less. As the preform 1 is removed and transported by the mechanical operation of the injection mold opening / closing mechanism (not shown) and the receiving mold, it is cooled by contact with the ambient air and the receiving mold, so this essentially serves as both the receiving and forced cooling of the preform 1 in the temperature control step (first temperature control step (receiving and cooling step) in FIG. 2). In this case, the injection molding time of this embodiment (the sum of the injection time, cooling time, and machine operation time) is set to be shorter than the injection molding time (conventional injection molding cycle) of conventional technology (e.g., WO2012-057016A).

[0021] After the receiving and cooling step, the blow molding apparatus 200 (FIG. 1) moves away from the injection molding station 110 while the preform 1 is still in the receiving pot mold, and transfers the preform 1 to the temperature adjustment station 120 by a transport member (not shown). This machine operation time is used to perform a temperature equalization process for the preform 1. At this time, the outer layer (skin layer) of the preform 1 rises in temperature by 80°C or more compared to the temperature immediately after release from the injection molding station 110 due to heat transfer from the inner layer (core layer).

[0022] After the first temperature adjustment step is completed, the blow molding apparatus 200 performs a forced cooling step (post-cooling step) on the preform 1 that has been carried into the temperature adjustment station 120, more precisely, the temperature-adjusted cavity mold 22 (cooling pot mold) of the post-cooling station 115 (step 2 in FIG. 1, second temperature adjustment step (forced cooling step) in FIG. 2). The preform 1 comes into contact with the temperature-adjusted cavity mold 22, whose temperature has been set to a temperature below the glass transition temperature of the material (for example, below 60°C), on its outer surface side, and is forcedly cooled.

[0023] When the second temperature adjustment step is completed, the blow molding apparatus 200 (FIG. 1) transfers the preform 1 to a conveying member (not shown) waiting on the rail 6 by mechanical operations such as inverting and lowering the temperature-controlled cavity mold 22 (step 3 in FIG. 1). Next, the preform 1 is transferred along the rail 6 together with the conveying member by mechanical operations such as an electric motor or sprocket to the temperature adjustment station 120 (step 4 in FIG. 1). During this mechanical operation time (for example, 3.5 seconds to 4.0 seconds), the blow molding apparatus 200 naturally cools and soaks the preform 1 in the temperature adjustment station 120 from immediately after the end of the post-cooling step until immediately before the start of the reheating step (third temperature adjustment step (natural cooling step) in FIG. 2).

[0024] After the preform 1 has been cooled and soaked in the third temperature control step, the blow molding apparatus 200 performs heating and soaking of the preform 1 in the reheating step (reheating station 120a) of the temperature control station 120, in the order of reheating, soaking, and reheating (step 5 in Figure 1, fourth temperature control step (reheating step) in Figure 2).

[0025] After the preform 1 has been reheated, temperature-soaked, and reheated in this order, the blow molding apparatus 200 transports the preform 1 in the air along rails 6 to soak it, and then loads the preform 1 into the blow molding station 130 (step 6 in FIG. 1, fifth temperature adjustment step (temperature-soaking step) in FIG. 2). Just before blow molding, heat transfer is caused between the inner and outer layers of the preform 1 (between the skin layer and the core layer) or in the thickness direction of the body portion 2b, reducing the temperature difference between the inner and outer layers and stabilizing the temperature distribution of the preform 1, thereby optimizing the temperature conditions of the preform 1 just before blow molding. The time for this step is set, for example, between approximately 1.0 and 2.0 seconds.

[0026] When the preform 1 is carried into the blow molding station 130, the blow molding device 200 blow-moldes the preform 1 in the blowing step to form a container 1a (step 7 in FIG. 1, blow molding step in FIG. 2).

[0027] Once the preforms 1 are blow-molded to form the container 1a, the blow molding apparatus 200 mechanically carries them out and removes the container 1a (step 8 in FIG. 1, removal step in FIG. 2). In this embodiment, M preforms 1 (e.g., 36 preforms) are injected at one time in the injection step, and then N preforms (12 preforms) smaller than M are subjected to the temperature adjustment step, natural cooling step, reheating step, and blowing step. The temperature adjustment step, natural cooling step, and reheating step are carried out continuously as the preforms 1 are transported along the rail 6, but the blowing step is divided into three batches in which 12 preforms are blow-molded at a time.

[0028] Through the above steps, the time required for the entire process, which shortens the cycle, using the blow molding apparatus 200, is shorter than the time required for the entire process using conventional equipment.

[0029] Figure 3 shows a block diagram of a blow molding machine, and Figure 4 shows a graph of the injection pressure fluctuations during the injection molding process, where the horizontal axis represents time and the vertical axis represents pressure. As shown in Figure 3, the blow molding apparatus 100 includes an injection molding section 10 (injection molding station 110), a control section 13, a calculation section 14, and an input section 15. The injection molding section 10 further includes a hydraulic injection device 11, an injection mold opening / closing device 16, and an injection mold 12. The injection mold opening / closing device 16 is responsible for the mold opening / closing and mold clamping operations of the injection mold 12 (injection core mold and injection cavity mold) for forming the molding space (cavity) for the preform 1. The mold opening / closing direction of the injection mold opening / closing device 16 is preferably set vertically to the machine base (up and down direction, perpendicular to the paper surface in Figure 1). The injection device 11 further includes a heating barrel 11a, a screw 11b arranged inside the heating barrel 11a so as to be stroke movable and rotatable, a first screw drive unit 11c1 that rotates the screw, a second screw drive unit 11c2 that strokes the screw 11b, a pressure dwelling device 11d (a pressure dwelling cylinder incorporating a plunger 11d1 so as to be stroke movable), and a pressure dwelling device drive unit 11e. Note that the pressure dwelling step S2 (described below) may be performed by the stroke movement of the screw 11a instead of using the pressure dwelling device, in which case the second screw drive unit 11c2 also serves as the pressure dwelling device drive unit 11e.

[0030] As described above, the injection molding section 10 is configured to injection mold the preform 1, which is a resin molded product, by injecting molten resin using the injection device 11 into the injection mold 12, which is closed by the injection mold opening and closing device. The injection device 11 forces the supplied solid resin against the inner surface of the heating barrel 11a by rotating the screw 11b, causing it to flow and become molten resin. Next, the injection device 11 moves the screw 11b backward a predetermined distance to measure the injection volume of molten resin, and then moves the screw 11b forward a predetermined distance to inject the molten resin into the injection mold 12.

[0031] The control unit 13 is a CPU that controls the injection of resin by the injection molding unit 10 (see FIG. 1, more specifically, the injection device 11) in an injection process (filling process) S1 and a pressure holding process S2, which will be described later. In the pressure holding process S2, the control unit 13 acquires, from the calculation unit 14, pressure holding curve data based on the pressure holding curve (decompression curve) calculated by the calculation unit 14, and controls the injection of resin in the injection molding unit 10 based on the acquired pressure holding curve data.

[0032] The calculation unit 14 is an arithmetic unit that calculates a holding pressure curve for controlling (reducing pressure, etc.) the pressure (pressure of the molten resin in the injection mold 12) applied to the screw 11b generated by injection by the injection molding unit 10 in the holding pressure step S2. The calculation unit 14 outputs the calculated holding pressure curve to the control unit 13 as holding pressure curve data.

[0033] The input unit 15 is an interface through which the user inputs the conditions for the holding pressure curve, and the information input by the user is output to the calculation unit 14. In this embodiment, a touch panel is used. The input unit 15 is configured to allow input of the order of the holding pressure curve. For example, if the user inputs that the order of the holding pressure curve is quadratic, the calculation unit 14 calculates the holding pressure curve using a quadratic curve. The input unit 15 is also configured to allow input of the time length of the holding pressure curve. Based on the time length input by the user, the calculation unit 14 determines the length of time for the control unit 13 to execute control based on the calculated holding pressure curve. Note that the order of the holding pressure curve does not have to be an integer and may be a decimal number such as 1.5. The control unit 13, calculation unit 14, and input unit 15 are mounted on a controller device 100A and connected to the blow molding apparatus 100.

[0034] As shown in FIG. 4, the injection molding process performed by the injection molding unit 10 consists of a filling step (injection step) S1, a pressure holding step S2, and a cooling step S3. During the filling step S1, which corresponds to time t0 to t3, the control unit 13 controls the movement speed of the injection device 11 (more specifically, the screw or plunger) according to the distance between the injection device 11 and each of the multiple cavity molds to fill (inject) the molten resin into the injection cavity mold 12. Meanwhile, during the pressure holding step S2, which corresponds to time t3 to t5, the control unit 13 controls the injection pressure of the injection molding unit 10 according to two pressure holding curves C1 and C2 calculated based on the conditions entered by the user into the input unit 15. Furthermore, during the cooling step S3, which corresponds to time t5 to t6, the control unit 13 controls the injection molding unit 10 so that the injection pressure becomes 0 (zero). That is, the injection molding unit 10 applies pressure to the resin only during the injection step S4, which is a combination of the filling step S1 and the pressure holding step S2.

[0035] 4, the control unit 13 increases the injection pressure stepwise at predetermined time intervals (for example, at equal intervals) during the filling step S1. Furthermore, during the pressure holding step S2, the control unit 13 reduces the injection pressure in a curved manner based on the pressure holding curves C1 and C2 calculated by the calculation unit 14. Here, the pressure holding curve C1 corresponding to the period from time t3 to t4 is set so that the amount of pressure reduction is greater than the pressure holding curve C1 corresponding to the period from time t4 to t5.

[0036] Next, the input image displayed on the liquid crystal screen of the input unit 15 will be described. FIG. 5 shows the input screen displayed on the input unit. The LCD screen 20 of the input unit 15 is broadly composed of an injection condition area 21 where the user inputs conditions related to injection in the injection molding unit 10, and a pressure retention curve creation area 22 where the user inputs conditions for the pressure retention curve.

[0037] The injection condition area 21 has a filling condition setting display area (injection condition setting display area) 23 for setting and displaying input values ​​(setting values) for the conditions for causing the injection molding machine to execute the filling process S1, and a pressure holding condition setting display area 24 for setting and displaying input values ​​(setting values) for the conditions for causing the injection molding machine to execute the pressure holding process S2.

[0038] The filling condition setting display area 23 and the pressure maintaining condition setting display area 24 each display, in the upper section, the set pressure 25 of the screw 11b and the plunger 11d1 corresponding to the pressure of the hydraulic oil of the hydraulic pump of the second screw drive unit 11c2 and the pressure maintaining device drive unit 11e, and in the lower section, the set speed 26 of the screw 11b and the plunger 11d1 corresponding to the flow rate of the hydraulic oil of the hydraulic pump of the second screw drive unit 11c2 and the pressure maintaining device drive unit 11e. Note that in FIG. 5, the first to third sections display the pressures 25 and speeds 26 set corresponding to the filling process S1, and the fourth and fifth sections display the pressures 25 and speeds 26 set corresponding to the pressure maintaining process S2. That is, from right to left, the first row displays the filling process S1 set to operate the injection molding machine at a pressure of 12.0 MPa and at 40.0% of the rated speed (when the hydraulic oil discharge volume from the hydraulic pump is at its maximum) (as a percentage of the hydraulic oil flow rate at the rated speed); the second row displays the filling process S1 set to operate the injection molding machine at a pressure of 12.0 MPa and at 99.0% of the rated speed; the third row displays the filling process S1 set to operate the injection molding machine at a pressure of 12.0 MPa and at 99.0% of the rated speed; the fourth row displays the holding process S2 set to operate the injection molding machine at a pressure of 2.5 MPa and at 25.0% of the rated speed; and the fifth row displays the holding process S2 set to operate the injection molding machine at a pressure of 2.0 MPa and at 25.0% of the rated speed. The hydraulic pump of the second screw driving unit 11c2 is provided for the purpose of moving the screw inside the hollow injection cylinder (heating cylinder), and the hydraulic pump of the first screw driving unit 11c1 is provided separately for the purpose of rotating the screw to melt and measure the resin between the screw and the injection cylinder.

[0039] On the other hand, the pressure retention curve creation area 22 is a display screen for setting, for example, pressure retention curves C1 and C2 (see FIG. 4), and has three levels of pressure retention conditions 27, 28, and 29 for the pressure retention curves used in the pressure retention step S2. Note that actual numerical values ​​and the like are input by the user using a keyboard or the like.

[0040] Each of the holding pressure conditions 27, 28, and 29 has an order setting display area 30 of each holding pressure curve displayed in the upper section, and a holding pressure time setting display area 31 to which each stage of the holding pressure curve is applied displayed in the lower section. In Fig. 5, the first holding pressure condition 27 has "3" input as the order 30a and "0.50 S (seconds)" input as the holding pressure time 31a, the second holding pressure condition 28 has "3" input as the order 30a and "1.50 S (seconds)" input as the holding pressure time 31a, and the third holding pressure condition 29 has "0 (zero)" input as the order 30a and "0 (zero) S (seconds)" input as the holding pressure time 31a. That is, conditions are input only for the first pressure holding condition 27 corresponding to the pressure holding curve C1 (see Figure 4) and the second pressure holding condition 28 corresponding to the pressure holding curve C2 (see Figure 4), and the pressure holding curve corresponding to the third pressure holding condition 29 has not been calculated.

[0041] As described above, the conditions related to the holding pressure curve input by the user via the holding pressure curve creation area 22 are output as input data to the calculation unit 14. Upon receiving the input data, the calculation unit 14 calculates a holding pressure curve and outputs it to the control unit 13 as holding pressure curve data.

[0042] The blow molding apparatus 100 according to this embodiment includes an injection molding unit 10 that injects resin into an injection cavity mold 12 to injection-mold a preform 1; a control unit 13 that controls the injection by the injection molding unit 10; a calculation unit 14 that calculates dwelling pressure curves C1 and C2 for reducing and controlling the pressure generated by the injection in the dwelling step S2; and an input unit 15 through which the user inputs the conditions for the dwelling pressure curves C1 and C2. The control unit 13 controls the injection based on the dwelling pressure curve. This reduces the injection pressure in a curved manner based on the dwelling pressure curve, preventing sudden pressure fluctuations. This allows for the stable production of high-quality resin molded products even in short injection molding times.

[0043] In addition, the blow molding apparatus 100 allows the user to input conditions for calculating the holding pressure curve using the input unit 15, so that the injection pressure can be reduced based on the optimal holding pressure curve according to the material, shape, and size of the preform 1.

[0044] (Second embodiment) Fig. 6 shows an input screen displayed on the input unit according to the second embodiment, and Fig. 7 shows a hydraulic display screen displayed on the input unit according to the second embodiment. Note that in the second embodiment, only parts different from the first embodiment will be described, and the same reference numerals are used for components that are substantially the same as those in the first embodiment.

[0045] 6, the input screen according to this embodiment also has a filling condition setting display area (injection condition setting display area) 23 that displays input values ​​(set values) for the conditions for executing the filling process S1, a holding pressure condition setting display area 24 that displays input values ​​(set values) for the conditions for executing the holding pressure process S2 in the injection molding machine, and condition switching position setting display areas 32, 33, and 34 that set the screw position when switching between each condition. In this figure, an inverted triangular pointer 35 indicates the screw position.

[0046] The first condition switching position setting display area 32 displays the switching position between the injection conditions for the first stage and the injection conditions for the second stage of the filling process S1, which were input using the input unit 15 (see FIG. 3). That is, when the screw reaches the position input in the first condition switching position setting display area 32, the conditions input for the first stage in the filling condition setting display area 23 are switched to the conditions input for the second stage. In this embodiment, the filling process S1 is started from a position where the screw of the injection molding unit 10 is 200.00 mm away from the tip of the injection cylinder (injection tube, heating tube) (not shown). Therefore, from the position 200.00 mm from the tip, the screw operates at a pressure of 13.8 MPa and 80.0% of the rated speed, which are the first stage conditions displayed in the filling condition setting display area 23. Here, since 180.00 mm is displayed in the first condition switching position display area 32, when the screw reaches a position 180.00 mm from the tip, the operating conditions will switch so that the screw operates at a pressure of 12.5 MPa and a speed of 60.0% of the rated speed, which are the second stage conditions displayed in the filling condition setting display area 23.

[0047] The second condition switching position setting display area 33 displays the switching position between the second-stage injection conditions and the third-stage injection conditions input using the input unit 15. That is, when the screw reaches the position displayed in the second condition switching position setting display area 33, the conditions displayed in the second stage in the filling condition setting display area 23 are switched to the conditions displayed in the third stage. In this embodiment, when the screw of the injection molding unit 10 reaches 170.00 mm from the tip, the operating conditions are switched so that the screw operates at a pressure of 10.0 MPa and at 65.0% of the rated speed, which are the third stage conditions displayed in the filling condition display area 23.

[0048] The third condition switching position setting display area 34 displays the switching position between the third-stage injection conditions input using the input unit 15 and the fourth-stage injection conditions, which are the dwelling process S2. That is, when the screw reaches the position displayed in the third condition switching position setting display area 34, the conditions displayed in the third stage in the filling condition setting display area 23 are switched to the conditions displayed in the fourth stage, which is the dwelling condition setting display area 24. In this embodiment, when the screw of the injection molding unit 10 reaches 160.00 mm from the tip, the operating conditions of the dwelling device or screw are switched to operate at a pressure of 3.0 MPa and 10.0% of the rated speed, which are the fourth stage conditions displayed in the dwelling condition setting display area 24.

[0049] In this embodiment, a hydraulic display screen switching button 36 is defined at the bottom of the LCD screen 20, and when the user presses the hydraulic display screen switching button 36 by operating the input unit 15, the display on the LCD screen 20 switches to the hydraulic display screen 40.

[0050] As shown in FIG. 7, the hydraulic pressure display screen 40 includes a hydraulic pressure waveform graph area 41 and a screw position graph area 42.

[0051] The horizontal axis of the hydraulic waveform graph area 41 shows time in milliseconds, and the vertical axis shows pressure in MPa. The graph displayed in this hydraulic waveform graph area 41 shows a hydraulic waveform based on the actual measured value of the pressure applied to the screw, and gradually depicts the history of the molten resin pressure when injection molding preform 1 (see Figure 1) in accordance with the movement of the screw.

[0052] A moving pointer 43 is provided below the hydraulic waveform graph area 41, and a coordinate bar (coordinate cursor) 43a that moves in response to the moving pointer 43 is displayed within the hydraulic waveform graph area 41. In this diagram, the moving pointer 43 is located at the leftmost position, so the coordinate bar 43a is displayed overlapping the vertical axis of the graph. When the user moves the moving pointer 43 left or right by operating the input unit 15, the coordinate bar 43a also moves left or right together with the moving pointer 43.

[0053] Below the moving pointer 43, an Old button 45, a Last button 46, an Act button 47, and a Best button 48 are defined.

[0054] The Old button 45 is a button for displaying the most recent 50 hydraulic pressure waveforms in the hydraulic pressure waveform graph area 41 when pressed by operating the input unit 15 .

[0055] The Last button 46 is a button for displaying the hydraulic waveform of the last injection molding in the hydraulic waveform graph area 41 when pressed by operating the input unit 15 .

[0056] The Act button 47 is a button for displaying the hydraulic waveform of the injection molding currently being performed in the hydraulic waveform graph area 41 when pressed by operating the input unit 15 .

[0057] The Best button 48 is a button for displaying, when pressed by operating the input unit 15, a hydraulic waveform that the control unit 13 previously determined to be optimal in the hydraulic waveform graph area 41. Note that optimal here means that there are no sudden pressure changes, there is little pressure fluctuation, and there is no behavior that causes the pressure to plateau.

[0058] The screw position graph area 42 shows time in milliseconds on the horizontal axis and the screw position from the tip of the injection cylinder in mm on the vertical axis. The graph displayed in this screw position graph area 42 is based on the actual measured screw position and is gradually drawn in accordance with the movement of the screw when injection molding the preform 1.

[0059] A moving pointer 44 is provided below the screw position graph area 42, and a coordinate bar (coordinate cursor) 44a that moves in response to the moving pointer 44 is provided within the screw position graph area 42. In this diagram, the moving pointer 44 is located at the leftmost position, and therefore the coordinate bar 44a is displayed overlapping the vertical axis of the graph. When the user moves the moving pointer 44 left or right by operating the input unit 15, the coordinate bar 44a also moves left or right along with the moving pointer 44. The moving pointer 43 in the hydraulic waveform graph area 41 and the moving pointer 44 in the screw position graph area 42 are linked to each other, so that when either moving pointer 43, 44 is operated left or right, the other moving pointer 43, 44 also moves left or right in the same manner.

[0060] Since the screw position graph area 42 has the same horizontal axis as the hydraulic pressure waveform graph area 41, for example, when 20 milliseconds have elapsed since the start of injection molding, the screw position graph area 42 shows that the screw is located at a position of approximately 180 mm, and at this time, the hydraulic pressure waveform graph area 41 shows that the actual pressure is approximately 7.0 MPa.

[0061] Also, for example, when 30 milliseconds have elapsed since the start of injection molding, the screw is positioned at approximately 170 mm, and at this time, it can be seen from the hydraulic pressure waveform graph area 41 that the actual pressure is approximately 9.5 MPa.

[0062] Furthermore, 40 milliseconds after the start of injection molding, the screw is positioned at approximately 160 mm, and at this time, it can be seen from the hydraulic pressure waveform graph area 41 that the actual pressure is approximately 10.0 MPa.

[0063] In this embodiment, the hydraulic pressure waveform graph area 41 and the screw position graph area 42 are provided, with their time axes corresponding to each other. For example, if a user discovers that an abnormal pressure drop occurs 20 milliseconds after the start of injection molding, as shown in the hydraulic pressure waveform graph area 41, the user can easily determine by referring to the screw position graph area 42 that the abnormality occurs when the screw is positioned at approximately 180 mm. Here, since the first condition switching position display area 32 displays 180 mm as shown in FIG. 6 , the user can easily determine that the first condition switching position, i.e., the position where the screw switches between the first and second stages of the filling process S1, was inappropriate. Thus, the user can operate the operation unit 15 to input, for example, 178 mm into the first condition switching position display area 32 to increase the distance traveled under the conditions for the first stage of the filling process S1, thereby eliminating the abnormal pressure effect.

[0064] In this embodiment, condition switching position display areas 32, 33, and 34 can be set to input the position for switching the filling conditions, and a hydraulic waveform graph area 41 and a screw position graph area 42, which correspond to the time axis, can be displayed on the liquid crystal screen 20. Therefore, unnecessary pressure fluctuations such as pressure drops in the filling step S1 of the injection process can be easily suppressed, and the molding quality and molding stability of the preform 1 can be improved.

[0065] Furthermore, by setting the injection time, holding pressure, and holding pressure curve, there is no need to extend the injection time unnecessarily, which contributes to shortening the molding cycle.

[0066] Although the present invention has been described above based on the embodiment, the present invention is not limited to this. For example, in the above embodiment, the condition switching position display area 32, 33, 34 is divided into three stages, and the pressure maintaining condition display area 24 is divided into two stages, but the present invention is not limited to this. [Explanation of symbols]

[0067] 1...Preform (plastic molded product) 1a…Container 6...Rail 10...Injection molding section 12...Injection cavity mold (injection mold) 13...Control unit 14...Calculation section 15...Input section 20...LCD screen 21…Injection condition area 22...Packing curve creation area 23…Filling condition setting display area 24…Package condition setting display area 25...Pressure setting display area 26…Speed ​​setting display area 27...First holding pressure condition 28...Second holding pressure condition 29...Third holding pressure condition 30…Order setting display area 31…Dwell time setting display area 32...First condition switching position setting display area 33...Second condition switching position table setting display area 34...Third condition switching position setting display area 35...Pointer 36...Hydraulic pressure display screen switching button 40...Hydraulic pressure display screen 41...Hydraulic pressure waveform graph area 42...Screw position graph area 43...Moving pointer 44...Moving pointer 45...Old button 46...Last button 47...Act button 48...Best button 100...Blow molding device (manufacturing device for resin molded products) C1...Pressure holding curve (decompression curve) C2...Pressure holding curve (decompression curve) S1…Filling process S2…Pressure holding process S3…Cooling process S4…Injection process

Claims

1. an injection molding section having an injection device with a screw movably and rotatably disposed therein, the injection molding section injecting a resin into an injection mold using the injection device to injection mold a resin molded product; a control unit that controls the injection by the injection molding unit; an input unit that displays an input screen for inputting molding conditions of the injection molding unit; a calculation unit that calculates a pressure holding curve for controlling the pressure generated by the injection to be reduced in a pressure holding step, The input screen includes: an injection condition area for inputting conditions for causing the injection molding unit to execute a filling process; and a holding pressure curve creation area for inputting conditions for causing the injection molding unit to execute the holding pressure process, the pressure retention curve creation region is configured to allow input of conditions related to a first pressure retention curve and a second pressure retention curve to be sequentially used in the pressure retention process, The control unit controls the injection based on the first holding pressure curve and the second holding pressure curve so that the amount of pressure reduction on the first holding pressure curve corresponding to a first time interval is greater than the amount of pressure reduction on the second holding pressure curve corresponding to a second time interval that is after the first time interval.

2. 2. The manufacturing apparatus according to claim 1, wherein the dwelling pressure curve creation area has a dwelling pressure time setting display area provided so that a time length for which each of the dwelling pressure curves is applied can be input.

3. 2. The manufacturing apparatus according to claim 1, wherein the pressure-holding curve creation area has an order setting display area that is provided so that the order of each of the pressure-holding curves can be input.

4. 2. The manufacturing apparatus according to claim 1, wherein the holding pressure curve is calculated based on the time length and the order of the holding pressure curve inputted into the holding pressure curve creation area.

5. 2. The manufacturing apparatus according to claim 1, wherein the injection molding section further comprises a pressure holding device incorporating a movably mounted plunger for injecting resin into the injection mold.

6. an injection molding section having an injection device with a screw movably and rotatably disposed therein, the injection molding section injecting a resin into an injection mold using the injection device to injection mold a resin molded product; a control unit that controls the injection by the injection molding unit; an input unit that displays an input screen for inputting molding conditions of the injection molding unit; a calculation unit for calculating a holding pressure curve for reducing and controlling the pressure generated by the injection in a holding pressure process, The input screen includes: an injection condition area for inputting conditions for causing the injection molding unit to execute a filling process; and a holding pressure curve creation area for inputting conditions for causing the injection molding unit to execute the holding pressure process, In the method for controlling a manufacturing apparatus, the holding pressure curve creation area is configured to allow input of conditions related to a first holding pressure curve and a second holding pressure curve to be used sequentially in the holding pressure step, calculating the first and second retention pressure curves based on the conditions input in the retention pressure curve creation region; and controlling the injection pressure of the injection molding section based on the calculated first and second holding pressure curves so that the first holding pressure curve corresponding to a first time interval has a larger amount of pressure reduction than the second holding pressure curve corresponding to a second time interval that is after the first time interval.

7. 7. The manufacturing apparatus control method according to claim 6, wherein the dwelling pressure curve creation area has a dwelling pressure time setting display area that is provided so that the time length for which each of the dwelling pressure curves is applied can be input.

8. 7. The manufacturing apparatus control method according to claim 6, wherein the holding pressure curve creation area has an order setting display area provided so that each order of the holding pressure curve can be input.

9. 7. The manufacturing apparatus control method according to claim 6, wherein the holding pressure curve is calculated based on the time length and the order of the holding pressure curve inputted into the holding pressure curve creation region.

10. 7. The method for controlling a manufacturing apparatus according to claim 6, wherein the injection molding section further comprises a pressure maintaining device incorporating a movably mounted plunger for injecting resin into the injection mold.

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