Resin container manufacturing apparatus and manufacturing method

Abstract

A resin container manufacturing apparatus is configured to stretch a preform (10) disposed in a stretch blow molding die (144) by a stretch rod (145), and stretch the preform (10) by introducing a blow into the preform (10), thereby forming a resin container. The resin container manufacturing apparatus includes a detection device (182) for detecting an actual position of the stretch rod (145) inserted into the preform (10), and a supply control device (183) for controlling a supply state of the blow based on a detection result of the detection device (182).

Description

[0001] This application is a divisional application of the original application with application number 202080033679.8. Technical Field

[0002] This invention relates to an apparatus and method for manufacturing resin containers (hollow containers) filled with beverages, etc. More specifically, this invention relates to a resin container manufacturing apparatus and method, wherein a preform to be injection molded is formed into a resin container by stretch blow molding. Background Technology

[0003] For example, as equipment for manufacturing resin containers (hollow containers) made of resin materials such as polyethylene terephthalate (PET), a biaxial stretch blow molding apparatus is known in the related art in which a preform is stretched and blow molded to form a resin container.

[0004] Typically, biaxial stretch blow molding equipment is known to stretch a preform formed by injection molding by stretching a stretching rod while the preform is placed in a blow molding die, and to stretch the preform by using high-pressure blowing to form a resin container (see, for example, Patent Document 1).

[0005] When precast components are stretched by tension rods and air in this manner, the operation of the tension rods and the supply of air are typically controlled independently. For example, the start of the air supply is controlled based on a waiting time from the start time of air blowing, and is controlled independently of the operation of the tension rods.

[0006] Reference List

[0007] Patent documents

[0008] Patent document 1: JP-A-2003-231170. Summary of the Invention

[0009] Technical issues

[0010] Here, a resin container manufacturing apparatus is provided, including an injection molding section for injection molding preforms and a stretch blow molding section for stretch blow molding preforms. Preforms conveyed from the injection molding section are formed into resin containers (hollow containers) by the stretch blow molding section.

[0011] In such resin container manufacturing equipment, the resin container is formed by simultaneously injection molding a preform in the injection molding section and stretch blow molding the preform in the stretch blow molding section. Therefore, the stretch blow molding time needs to be set according to the injection molding time of the preform.

[0012] In recent years, the injection molding time (including cooling time) of preforms has been significantly reduced, thus there is a desire to shorten the molding cycle time (to achieve high cycle times). To shorten the molding cycle time, the stretch blow molding time needs to be shortened in accordance with the reduction in injection molding time.

[0013] However, when the tension rod and the air supply are controlled independently, it is difficult to cope with the shortening of the molding cycle time. That is, in the control based on the waiting time from the start of self-blowing (in the timer control type), as described above, it is difficult to cope with the shortened molding cycle time of blow molding.

[0014] In timer-controlled systems, the start time of the tension rod's descent and the start time of air introduction are set in 10-millisecond increments, for example, starting from the blow molding start time. Due to mechanical construction, a small error exists between the set start time and the actual start time related to the tension rod's descent or air introduction in timer-controlled systems. This error can affect blow molding. For example, the quality of the container (physical properties, appearance, etc.) may decrease, molding defects such as cracking may occur more frequently, and the formability and productivity of the container during blow molding may be unstable. When the blow molding time is short, the impact of this error on blow molding can be significant.

[0015] Furthermore, when the blow molding time is shortened, it is difficult to properly balance the start time of the drop of the tension bar and the start time of the air introduction, which are independent parameters.

[0016] When the molding cycle time (stretch blow molding time) is shortened, the quality of the resin container may deteriorate. In addition, molding defects such as cracking may occur frequently during blow molding, and molding stability may decrease.

[0017] This disclosure is made in view of this situation, and the purpose of this disclosure is to provide a resin container manufacturing apparatus and a resin container manufacturing method that can properly stretch blow-molded preforms in a relatively short time and can stably manufacture resin containers with good quality.

[0018] Problem Solution

[0019] According to one aspect for achieving the above-mentioned objectives, a resin container manufacturing apparatus is provided, the apparatus being configured to stretch a preform disposed in a stretch blow molding die by a stretching rod, and to form a resin container by introducing blown air into the preform, the resin container manufacturing apparatus comprising:

[0020] A detection device is used to detect the actual position of the tension rod inserted into the precast component; and

[0021] A supply control device is used to control the air supply status based on the detection results of the detection device.

[0022] Here, preferably, the drive source of the tension rod is a servo motor, and the detection device detects the actual position of the tension rod based on the rotational position of the servo motor.

[0023] According to another aspect for achieving the above-mentioned objective, a method for manufacturing a resin container is provided, wherein a preform disposed in a stretch blow molding die is stretched by a stretch rod and the preform is stretched to form a resin container by introducing air into the preform, the method comprising: detecting the actual position of the stretch rod inserted into the preform; and controlling the air supply state based on the actual position of the stretch rod.

[0024] Beneficial effects of the invention

[0025] According to this disclosure, even under conditions of very short stretch blow molding time (high cycle conditions), resin containers (hollow containers) with good quality can be stably manufactured by appropriately stretching preforms. Attached Figure Description

[0026] Figure 1 This is a top view showing the overall construction of a stretch blow molding apparatus according to an embodiment of the present disclosure.

[0027] Figure 2 It is a diagram showing the structure of the stretch blow molding part according to the present disclosure, and a cross-sectional view showing the stretch blow molding die.

[0028] Figure 3 This is a diagram illustrating the process of molding a hollow container by stretching a blow molding section according to an embodiment of the present disclosure.

[0029] Figure 4 This is a block diagram illustrating the construction of a stretch blow molding portion according to an embodiment of the present disclosure.

[0030] Figure 5 This is a diagram showing an example of a display provided in the control unit according to the first embodiment.

[0031] Figure 6 This is a schematic diagram showing the position of the tension rod at each time point.

[0032] Figure 7 This is a diagram illustrating the process of molding a hollow container by stretching a blow molding section according to an embodiment of the present disclosure.

[0033] Figure 8 This is a diagram showing an example of a display provided in the control unit according to the second embodiment. Detailed Implementation

[0034] (First Embodiment)

[0035] In the following text, reference will be made to Figures 1 to 5 The first embodiment of this disclosure is described in detail.

[0036] like Figure 1 As shown, the injection stretch blow molding apparatus 100, which is a resin container manufacturing apparatus according to this embodiment, includes: an injection section 110 for injection molding a bottomed cylindrical preform 10; a cooling section 120 for cooling the preform 10 formed by the injection section 110; a heating section (heating device) 130 for heating the preform 10; and a stretch blow molding process for forming a hollow container 20 by stretch blow molding the preform 10 heated by the heating section 130 (see...). Figure 3 ) stretch blow molding part 140.

[0037] The injection molding section 110 and the stretch blow molding section 140 are connected in series, and the injection stretch blow molding equipment 100 is a so-called Class 1.5 system equipment, in which the number of simultaneous injection molding and the number of simultaneous blow molding are different.

[0038] The injection stretch blow molding equipment 100 includes a conveying section 150, which includes a circular conveyor line (conveyor path) 151 circulating from a cooling section 120 to a heating section 130 and a stretch blow molding section 140. The conveying section 150 conveys a preform 10 from the cooling section 120 to the heating section 130 along the conveyor line 151, and conveys the preform 10 heated by the heating section 130 toward the stretch blow molding section 140. Furthermore, the conveying section 150 includes a clamping mechanism conveying section 155 that clamps the preform 10 conveyed along the conveyor line 151 and conveys the preform 10 into the stretch blow molding section 140.

[0039] The clamping mechanism conveying unit 155 conveys the preform 10 to the stretch blow molding unit 140, clamps and conveys the intermediate molded part in the stretch blow molding unit 140 as described later, clamps the hollow container 20 as the final molded part, and conveys the hollow container 20 from the stretch blow molding unit 140 to the take-out position.

[0040] The injection stretch blow molding apparatus 100 according to this disclosure is characterized by the construction of the stretch blow molding section (stretch blow molding apparatus) 140. Other constructions such as the injection molding section 110, the cooling section 120, and the heating section 130 are known, and these components will be briefly described herein.

[0041] The injection molding unit 110 includes a mold closing mechanism (mold closing device) 111, which closes a core mold (not shown) disposed on the upper side and a cavity mold (not shown) disposed on the lower side. In the injection molding unit 110, a plurality of preforms 10 are injection molded by filling the injection space defined by the core mold and the cavity mold with resin material (raw material) using an injection device.

[0042] The injection molding section 110 can mold N preforms 10 (N is an integer greater than or equal to 2) at a time. Specifically, the injection molding section 110 can simultaneously mold up to 24 preforms 10 (3 rows × 8 pieces). In this embodiment, the injection molding section 110 is configured to mold 12 preforms 10 (3 rows × 4 pieces) at a time.

[0043] The cooling section 120 forcibly cools the preform 10. The preform 10, which is injection molded by the injection section 110, is conveyed from the injection section 110 to the cooling section 120 by a conveying device (not shown) and is forcibly cooled by the cooling section 120. The preform 10, cooled to a predetermined temperature by the cooling section 120, is fed to the conveyor line 151 provided in the conveyor section 150 and is continuously conveyed along the conveyor line 151.

[0044] The preform 10 is molded by the injection molding section 110 in an upright position with its neck facing upward, and is conveyed from the injection molding section 110 to the cooling section 120 in this state. The cooling section 120 includes a reversing mechanism (not shown) that reverses the preform 10, which is conveyed in an upright position, to an inverted position with its neck facing downward. When the preform 10 is cooled in the cooling section 120, the preform 10 is reversed to an inverted position by the reversing mechanism and held in an inverted position on the conveying fixture 152.

[0045] As described above, since the injection molding section 110 forms 12 preforms 10 in this embodiment, the conveying jig 152 is continuously conveyed, and the preforms 10 are held separately by every other conveying jig 152.

[0046] The conveyor line 151 continuously and sequentially transports multiple conveyor clamps 152 by the driving force of sprockets 153, etc. The conveyor clamps 152 are arranged in multiple rows below the cooling section 120, and the conveyor clamps 152 holding the preform 10 are sequentially transported to the conveyor line 151. Then, the preform 10 held by the conveyor clamps 152 is transported along the conveyor line 151 and is transported to the heating section (heating device) 130.

[0047] In the heating section 130, the preform 10 held by the conveying clamp 152 is heated to a suitable stretching temperature while moving along the conveyor line 151. The conveying section 150 is configured such that the conveying clamp 152 moves along the conveyor line 151 while rotating. That is, the preform 10 is heated while rotating in the heating section 130. As a result, each preform 10 is heated to a substantially uniform temperature over its entire circumference in the heating section 130.

[0048] After the preform 10 is heated by the heating unit 130, the preform 10 is further conveyed along the conveyor line 151 and then conveyed to the stretch blow molding unit 140. Specifically, the preform 10 is conveyed along the conveyor line 151 to the reversing unit 156, which includes a reversing mechanism (not shown). The preform 10, which is continuously conveyed along the conveyor line 151, is reversed a predetermined number of times and brought into an upright state by the reversing unit 156. Then, the preform 10 in the upright state is clamped by the clamping mechanism conveying unit 155 and conveyed to the stretch blow molding unit 140.

[0049] Then, a predetermined number of preforms 10, held by the clamping mechanism conveying section 155 in the reversing section 156, are conveyed into the blown cavity mold 141. The clamping mechanism conveying section 155 adjusts the spacing between the preforms 10 appropriately while allowing the preforms 10 to slide.

[0050] The construction of the clamping mechanism conveying section 155 is not particularly limited as long as the clamping mechanism conveying section 155 can clamp the neck of the preform 10 and move the preform 10 to the stretch blow molding section 140 in this clamping state.

[0051] like Figure 2 As shown, the stretch blow molding section 140 includes a plurality of stretch blow molding dies 144, each stretch blow molding die including a blow cavity die 141, a bottom die 142, and a blow core die (blow nozzle die) 143 formed by a pair of split dies. A plurality of (e.g., two) cavities 141a are formed in the blow cavity die 141 for molding the preform 10 into a hollow container 20. The stretch blow molding section 140 includes a stretching rod 145 inserted into the preform 10 and stretching the preform 10 in the axial direction.

[0052] Multiple blow molding dies 141 disposed in the stretch blow molding section 140 are arranged adjacent to each other, and the multiple blow molding dies 141 are configured to move and close integrally. Figure 1 As shown, in this embodiment, two blow molding cavity molds (one of the split molds) 141 are fixed on a blow molding mold fixing plate 146, and a mold closing device (mold closing mechanism) 147 is connected to the blow molding mold fixing plate 146. That is, when the mold closing device 147 moves the blow molding mold fixing plate 146, the two blow molding cavity molds 141 are simultaneously closed or opened.

[0053] In such a stretch blow molding section 140, a hollow container 20 as a final product is formed by stretch blow molding each preform 10 provided in the cavity 141a of the blow molding mold 141.

[0054] Specifically, such as Figure 3As shown, the tension rod 145 is moved (lowered) and the bottom of the preform 10 is compressed by the tension rod, and air (primary air) is introduced into the preform 10, thereby stretching the preform 10 in the longitudinal and transverse directions. That is, the preform 10 expands to a predetermined size.

[0055] More specifically, such as Figure 3 As shown in (a), firstly, the tension rod 145 is moved (lowered) to a preset first position P1, and the preform 10 is stretched by the tension rod 145 in the longitudinal direction. Next, when the tension rod 145 reaches the preset first position P1, low-pressure air (primary air) is introduced into the preform 10, and the preform 10 is stretched in both the longitudinal and transverse directions. Figure 3 (b)). That is, the first position P1 is the reference position, and primary air is introduced into the preform 10 based on this reference position. During the introduction of primary air, the tension rod 145 is continuously moved (lowered). The primary air is set to a pressure of, for example, 0.3 MPa to 1.5 MPa.

[0056] After that, as Figure 3 As shown in (c), when the tension rod 145 is moved (lowered) to the preset second position P2 (below the first position P1), the pressure of the blowing air introduced into the preform 10 changes. That is, the blowing air introduced into the preform 10 is switched from primary air to secondary air with a higher pressure than primary air. That is, the second position P2 is the reference position, and secondary air is introduced into the preform 10 based on this reference position. By switching from primary air to secondary air, the preform 10 is further stretched in the longitudinal and transverse directions. At the same time, the tension rod 145 moves downward from the second position P2 to further stretch the preform 10 in the longitudinal direction, and the tension rod 145 stops at the third position P3, which is the preset final lowering position (stretching completion position). As a result, a hollow container 20 is formed as the final molded product. Figure 3 (d)). The secondary air is set to a pressure of, for example, 2.0 MPa to 3.5 MPa.

[0057] After the blown air inside the hollow container 20 is expelled, at the moment when the subsequent preform 10 is conveyed, the hollow container 20 formed by the stretch blow molding section 140 (stretch blow molding die 144) is conveyed to the removal position Pa outside the stretch blow molding section 140 via the clamping mechanism conveying section 155. Then, at the removal position Pa (see... Figure 1 Remove the hollow container 20 from the equipment.

[0058] In the stretch blow molding section 140, the N preforms 10 formed at one time by the injection molding section 110 are divisible by n (n is an integer of 2 or greater), thus forming M (N / n, M is a natural number) hollow containers 20 at one time. In this embodiment, the 12 preforms 10 formed at one time by the injection molding section 110 are divisible by 3, thus four preforms 10 are stretch blow molded at one time to form hollow containers 20.

[0059] As described above, in the injection stretch blow molding equipment 100, when one injection molding is performed by the injection molding section 110, three stretch blow moldings are performed by the stretch blow molding section 140, so that the time for performing one stretch blow molding is very short. Therefore, in stretch blow molding, it is necessary to control the movement of the stretch rod 145 and the air supply with high precision.

[0060] Therefore, in the injection stretch blow molding machine 100, the actual position of the stretch rod 145 is detected, and the start and stop of the introduction of air (primary air and secondary air) into the preform 10 are controlled based on the detected actual position of the stretch rod 145. That is, regarding the control of the introduction of air into the preform 10, although a timer control type in which the air blowing start time is set as the starting point is used in related technologies, a position control type based on the actual position of the stretch rod 145 is used in this embodiment.

[0061] Here, as Figure 4 As shown in the block diagram, the stretch blow molding section 140 includes: a supply section 160 for supplying blown air to the blow molding die 143 (preform 10); a drive section 170 for driving the stretching rod 145; and a control section 180 for controlling the supply section 160 and the drive section 170.

[0062] Although not shown in the accompanying drawings, the supply unit 160 includes an air source and an air tank, and further includes a supply system for supplying blown air from the air tank to the blown core mold 143 and an exhaust system for discharging blown air from the blown core mold 143. The drive unit 170 includes an electric drive source for moving (lifting or lowering) the tension rod 145. In this embodiment, the drive unit 170 includes a servo motor (electric motor) as the drive source.

[0063] The control unit 180 controls the operation of various devices installed in the injection stretch blow molding equipment 100. For example, the control unit 180 controls the supply unit 160 and the drive unit 170. The control unit 180 includes, for example, input / output devices, storage devices (ROM, RAM, etc.), a central processing unit (CPU), timers and counters, etc.

[0064] Specifically, the control unit 180 includes a drive control device 181, a detection device 182, and a supply control device 183. The drive control device 181 controls the movement (lifting and lowering) of the tension rod 145 via a servo motor of the drive unit 170. The drive control device 181 appropriately controls, for example, the start and stop of the movement of the tension rod 145 and the movement speed of the tension rod 145, based on setting conditions set by the operator.

[0065] The detection device 182 detects the actual position of the tension rod 145 based on the rotational position (encoder output value) of the servo motor 171 installed in the drive unit 170. There are no particular limitations on the method by which the detection device 182 detects the actual position of the tension rod.

[0066] The supply control device 183 controls the air supply state based on the detection results of the detection device 182. Specifically, the supply control device 183 controls the supply section 160 based on the actual position of the tension rod 145 detected by the detection device 182, so as to appropriately control the start and stop of the air supply to the blown core mold 143, that is, the start and stop of the introduction of air (primary air and secondary air) into the preform 10. Therefore, the supply control device 183 can switch the air to be introduced into the preform 10 from primary air to secondary air based on the detection results of the detection device 182. In this embodiment, when the detection device 182 detects that the actual position of the tension rod 145 is in the second position P2, the supply control device 183 controls the supply section 160 to switch the air to be introduced into the preform 10 from primary air to secondary air.

[0067] In this manner, in the current embodiment, when the tension rod 145 reaches two predetermined lowering positions (first position P1 and second position P2), blowing air (primary air and secondary air) is appropriately introduced into the preform 10. As a result, blowing air can be introduced according to the length and elongation state of the preform 10, and high-cycle container molding can be accommodated. That is, hollow containers 20 that are difficult to mold under high-cycle conditions in related technologies can be manufactured. For example, with a blow molding time of 0.6 seconds, a large number of thin-walled containers weighing less than 10g can be manufactured simultaneously.

[0068] The control unit 180 includes a relatively large display (display device) 190 that displays setting information for setting control conditions of various devices to be controlled on a screen, and a display control device 184 that controls the display status of the screen of the display 190.

[0069] like Figure 5As shown, the display 190 is provided with a main display unit 191 and a sub-display unit 192. The main display unit 191 can set and display various types of information (control conditions, setting values, etc.) as needed, while the sub-display unit 192 continuously displays specific information. In this embodiment, the central area of ​​the display 190 is used as the main display unit 191, and the header 193 located above the main display unit 191 and the footer 194 located below the main display unit 191 are used as the sub-display unit 192.

[0070] The display 190 is implemented, for example, by a touch panel, and serves as an input unit through which the operator inputs various control conditions (operation conditions of various devices and control conditions of various worktables).

[0071] The display control device 184 causes the main display unit 191 of the display 190 to display information for setting control conditions as needed. For example, in stretch blow molding, the display control device 184 displays a screen on which the actual position of the stretch rod 145 and the supply status of the blown air, including primary and secondary air, can be set in relation to each other.

[0072] When the operator controls the supply unit 160 via position-controlled air supply control, the operator inputs various control conditions (set values) into the display 190, which serves as a touch panel. For example, in the main display 191, the operator inputs the blow molding time (“Blow time”), the air decompression time (“Decomp. time”), etc., and inputs the values ​​for the first position (P1), the second position (P2), and the third position (P3) as the actual positions of the stretching rod 145 to the first blow molding start position (“Pri.”), the second blow molding start position (“Sec.”), and the stretching completion position (not shown), respectively. By performing such input operations, the operator can set the time for the supply unit 160 to supply primary air to be introduced into the preform 10 during the first blow molding (Pri.), and set the time for the supply unit 160 to supply secondary air to be introduced into the preform 10 during the second blow molding (Sec.). The air supply time can be set for each cavity 141a. The main display unit 191 can display the time (actual measurement value) taken for the tension rod 145 to reach each of the first position P1, the second position P2, and the third position P3.

[0073] As described above, in the injection stretch blow molding equipment 100 according to this embodiment, the operator can appropriately set the conditions for position control type blow supply control on a screen.

[0074] Furthermore, the injection stretch blow molding equipment 100 can switch between position-controlled air supply control and timer-controlled air supply control. Therefore, the operator can select the control system for stretch blow molding based on the hollow container 20 to be molded, thus improving the equipment's versatility.

[0075] exist Figure 5 In the example shown, in the air introduction time selection bar (“Air Introduction Time Selection”) on the screen of display 190, the air introduction control can be switched by selecting either the first air introduction control device (timer control: “Air Introduction Timer”) or the second air introduction control device (position control: “Extension Position”). The first air introduction control device defines the start time of air introduction, including primary air and secondary air, based on a timer (elapsed time), while the second air introduction control device defines the start time of air introduction, including primary air and secondary air, based on the actual position (lower position) of the extension rod.

[0076] As described above, in the resin container (hollow container) manufacturing equipment and resin container (hollow container) manufacturing method according to the present disclosure, preforms can be appropriately stretched to stably manufacture resin containers (hollow containers) with good quality, even under conditions of very short stretch blow molding time (high cycle conditions).

[0077] In the resin container (hollow container) manufacturing method according to this disclosure, the supply control device 183 switches the air to be introduced into the preform 10 from primary air to secondary air based on the detected actual position of the tension rod 145. Therefore, the movement of the tension rod 145 and the start time of the introduction of primary and secondary air can be appropriately balanced. As a result, the preform can be appropriately stretched to manufacture a resin container (hollow container) with good quality.

[0078] In the resin container (hollow container) manufacturing method according to this disclosure, a first position P1 and a second position P2 are provided, wherein the first position P1 is a reference position for starting the introduction of primary air, and the second position P2 is a reference position for starting the introduction of secondary air with a higher pressure than the primary air. When the actual position of the tension rod 145 reaches the first position P1, the supply control device 183 starts introducing primary air, and when the actual position of the tension rod 145 reaches the second position P2, which is below the first position P1, the supply control device 183 starts introducing secondary air. Specifically, when the detection device 182 detects that the actual position of the tension rod 145 is at the second position P2, the supply control device 183 switches the air to be introduced into the preform 10 from primary air to secondary air. Therefore, in the resin container (hollow container) manufacturing method according to this disclosure, the air can be switched with high precision based on the actual position of the tension rod 145. That is, in a manner corresponding to the vertical axis stretching (stretching in the longitudinal direction) of the preform 10 via the stretching rod 145, the horizontal axis stretching (stretching in the transverse direction) of the preform 10 can be performed using primary and secondary air, and the vertical and horizontal axis stretching can be performed in a more balanced manner. In the resin container (hollow container) manufacturing method according to this disclosure, secondary air is introduced when the actual position of the stretching rod 145 is detected to be at a second position P2 located below the first position P1. That is, since the secondary air is introduced at the appropriate time by position control based on the actual position of the stretching rod 145, misalignment and poor thickness distribution of the container can be prevented. In order to improve the quality such as the rigidity of the container, it is necessary to improve the orientation crystallinity of the resin material used to form the container. In order to improve the orientation crystallinity, it is effective to increase the stretching speed of the resin material (high-speed movement (descent) of the stretching rod, introduction of air in a short time, and stretching of the preform in a short time). However, when the stretching speed of the resin material increases, it is difficult to properly match the movement of the stretching rod and the introduction time of the air in the timer control type. On the other hand, in the resin container (hollow container) manufacturing equipment and resin container manufacturing method according to the present disclosure, even when the stretching speed of the resin material increases, the movement of the stretching rod 145 and the introduction time of the blowing can be easily and appropriately matched with each other, and even when the molding cycle time is shortened, containers with higher quality than those of the prior art can be manufactured.

[0079] (Second Embodiment)

[0080] Next, we will refer to Figures 6 to 8The second embodiment of this disclosure is described in detail. In the description of the second embodiment, the parts that are the same as those in the first embodiment will be omitted. The difference between the second embodiment and the first embodiment is that when a predetermined standby time has elapsed since the tension rod 145 has been moved (lowered) to the second position P2, a switch from primary air to secondary air is performed.

[0081] Figure 6 This is a diagram showing the position of the tension rod 145 at each time point. Figure 7 This diagram illustrates the process of molding a hollow container 20A using a stretch blow molding section 140A according to the second embodiment. In this specification, the time interval during which the stretch rod 145 descends from its initial position to its second position P2 (from time point t0 to time point t2) is called the stretching time; the time interval during which the stretch rod 145 stops at its second position P2 and primary air is introduced into the preform 10 (from time point t2 to time point t3) is called the first standby time; the time interval during which the stretch rod 145 stops at its second position P2 and secondary air is introduced into the preform 10 (from time point t3 to time point t4) is called the second standby time; and the time interval during which the stretch rod 145 rises from its second position P2 to its initial position (from time point t4 to time point t6) is called the retraction time. In the second embodiment... Figure 6 In the example shown by the solid line, the second position P2 and the third position P3 are set to the same position.

[0082] like Figure 6 As shown, from time point t0 to time point t1, the tension rod 145 descends to the first position P1. As a result, the preform 10 is stretched in the longitudinal direction. Simultaneously, from time point t0 to time point t1, since air is not introduced into the preform 10, the preform 10 is not stretched in the transverse direction. Figure 7 (a) in the middle.

[0083] From time point t1 to time point t2, the tension rod 145 descends from the first position P1 to the second position P2 and does not stop at the first position P1. That is, the tension rod 145 continues to descend during the stretching time, and the preform 10 continues to be stretched in the longitudinal direction. Simultaneously, at time point t1, the detection device 182 detects that the tension rod 145 has descended to the first position P1 and transmits the detection result to the supply control device 183. The supply control device 183 controls the supply unit 160 to introduce primary air into the preform 10 based on the detection result. As a result, at time point t1, primary air begins to be introduced into the preform 10. When primary air is introduced into the preform 10, the preform 10 is stretched in the transverse direction. Figure 7 (b) in the middle.

[0084] Next, the actual position of the tension rod 145 during the first standby time and the air blown into the preform 10 will be described. At time t2, the detection device 182 detects that the tension rod 145 has descended to the second position P2 and transmits the detection result to the drive control device 181. The drive control device 181 controls the tension rod 145 based on the detection result, so that the tension rod 145 stops at the second position P2 during a time period from the time point when the actual position of the tension rod 145 is detected to be at the second position P2 until the first standby time and the second standby time have elapsed (i.e., the time period from time t2 to time t4). Therefore, during the first standby time and the second standby time, the tension rod 145 stops at the second position P2. At time t2, the detection device 182 transmits the detection result to the supply control device 183. Upon receiving the detection result, the supply control device 183 controls the supply unit 160 to switch the air to be introduced into the preform 10 from primary air to secondary air when a predetermined first standby time (i.e., at time t3) has elapsed since the time point from which the actual position of the tension rod 145 was detected to be at the second position P2. That is, in this embodiment, the second position P2 is the position used as the starting point (reference) when the supply control device 183 begins counting the time points at which secondary air begins to be introduced into the preform 10. Because the supply control device 183 controls the supply unit 160 in this manner, primary air continues to be introduced into the preform 10 during the first standby time. Therefore, at time t2, the approximately central portion of the side surface of the preform 10 in the longitudinal direction becomes in a state where the degree of expansion in the transverse direction is greater than the degree of expansion of other portions in the transverse direction. Figure 7 (c) in the middle, and at time point t3, the preform 10 is in a state where a sufficient amount of primary air is introduced into the preform 10. Figure 7 (d)). Then, at time t3, secondary air with a pressure higher than that of the primary air is introduced.

[0085] Next, the actual position of the tension rod 145 and the air blown into the preform 10 during the time period from time point t3 to time point t6 (the second standby time and the reversal time) will be described. As mentioned above, the tension rod 145 stops at the second position P2 during the second standby time. That is, the second position P2 and the third position P3 are... Figure 6The positions shown by the solid lines are the same. At time point t4, the drive control device 181 controls the tension rod 145 to lift it from the second position P2 to the initial position. That is, at time point t4, the tension rod 145 begins to move upward relative to the bottom of the preform 10. At time point t6, the detection device 182 detects that the tension rod 145 has been lifted to the initial position and transmits the detection result to the drive control device 181. The drive control device 181 controls the tension rod 145 based on the detection result, so that the tension rod 145 stops at the initial position. Therefore, during the reversal time, the tension rod 145 continues to rise, and at time point t6, the tension rod 145 stops rising. On the other hand, from time point t3 to time point t5, secondary air is continuously introduced into the preform 10. As a result, at time point t5, the preform 10 becomes the hollow container 20A as the final molded product. Figure 7 (e)). At time t5, the supply control unit 183 controls the supply unit 160 to stop the supply of blowing air and discharge the blowing air. Therefore, from time t5 to time t6, blowing air is not supplied to the preform 10 and is discharged.

[0086] Figure 8 This is a diagram illustrating a display example of a display 190A according to the second embodiment. (See diagram for reference.) Figure 8 As shown, the display 190A according to the second embodiment is provided with a main display unit 191A capable of setting and displaying various types of information (control conditions, setting values, etc.) as needed, and a sub-display unit 192 having the same configuration as in the first embodiment. The main display unit 191A differs from the main display unit 191 according to the first embodiment in that the setting and display area related to the timer control performed by the supply control device 183 is set adjacent to the display area related to the secondary air blowing (Sec.). Figure 8 (The middle is the right neighbor), and a three-stage air introduction device (position and timer combination control "Stretch Position 2") is added, wherein the three-stage air introduction device limits the start time of air introduction, including primary air and secondary air, based on the lowering position of the stretching rod and the timer (the elapsed time). The time corresponding to the first standby time is entered (set) in the setting area related to the timer control. The display area related to the timer control displays the measured value of the first standby time. For example, when the operator performs a predetermined input operation on the timer control corresponding to the resin container to be manufactured, the supply control device 183 controls the supply unit 160 to switch the air to be introduced into the preform from primary air to secondary air when the time input by the operator has elapsed since the stretching rod 145 descends to the second position P2.

[0087] For example, when manufacturing relatively large resin containers (e.g., 1500ml containers), more primary air needs to be introduced into the preform 10 before the introduction of secondary air, compared to manufacturing small resin containers (e.g., 500ml containers). This is because large resin containers need to have a greater width in the transverse direction than small resin containers. Therefore, if secondary air is introduced into the preform 10 while primary air is not adequately introduced, a container of poor quality may be produced.

[0088] In the resin container (hollow container) manufacturing apparatus and method according to this disclosure, when a predetermined first standby time (the time period from time t2 to time t3) has elapsed since the detection device 182 detected that the actual position of the tension rod 145 was at the second position P2, the supply control device 183 controls the supply unit 160 to switch the blowing air to be introduced into the preform 10 from primary air to secondary air. Therefore, primary air continues to be introduced into the preform 10 until the predetermined first standby time has elapsed since the detection device 182 detected that the actual position of the tension rod 145 was at the second position P2, and then, secondary air begins to be introduced into the preform 10. Thus, primary air can be sufficiently introduced into the preform 10 before secondary air is introduced. In this way, compared with the injection stretch blow molding apparatus 100 according to the first embodiment, the injection stretch blow molding apparatus 100A according to the second embodiment can introduce more primary air into the preform 10 before introducing secondary air. Therefore, the injection stretch blow molding apparatus 100A can manufacture containers of good quality, especially when manufacturing relatively large resin containers. In the resin container (hollow container) manufacturing apparatus and method according to the invention, even with a short molding cycle time (high descent speed of the stretch rod 145), by combining position control based on the actual position of the stretch rod 145 and timer control, the vertical stretching of the stretch rod 145 on the preform 10 and the horizontal stretching of the preform 10 by the primary and secondary air can be performed in a balanced manner. Therefore, the injection stretch blow molding apparatus 100A can properly stretch the preform 10, and as a result, resin containers (hollow containers) of good quality can be manufactured.

[0089] In the resin container (hollow container) manufacturing apparatus and method according to this disclosure, secondary air is introduced into the preform 10 during a time period (from time point t3 to time point t5), including a second standby time (from time point t3 to time point t4). Therefore, after secondary air has been introduced into the preform 10 to a certain extent, the tension rod 145 begins to move (lift) towards its initial position. Thus, according to the injection stretch blow molding equipment 100A, it is possible to prevent the container from becoming an undesirable shape.

[0090] This disclosure is not limited to the above embodiments. For example, although a structure including four cavities has been described in the above embodiments, wherein the stretch blow molding part (stretch blow molding die) is arranged in a row, the number of cavities is not particularly limited, and can be eight, twelve, etc.

[0091] Although in the second embodiment the drive control device 181 controls the tension rod 145 to stop at the second position P2 during the first standby time and the second standby time, the present invention is not limited to such an example. For example, as Figure 6 As shown by the dashed line, the drive control device 181 can control the tension rod 145 to stop at the second position P2 during the first standby time, and can also control the tension rod 145 to further descend from the second position P2 to the third position P3 during the second standby time. In this case, at time point t4, the detection device 182 detects, for example, that the tension rod 145 has descended to the bottom of the hollow container 20A, and transmits the detection result to the drive control device 181. Then, the drive control device 181 controls the tension rod 145 based on the detection result to raise the tension rod 145 to the initial position.

[0092] This application is based on Japanese patent application filed on April 3, 2019 (Japanese Patent Application No. 2019-071569), the contents of which are incorporated herein by reference.

Claims

1. A resin container manufacturing apparatus configured to stretch a preform disposed in a stretch blow molding die by means of a stretching rod, and to stretch the preform by introducing air into the preform to form a resin container, the resin container manufacturing apparatus characterized in that it comprises: The control unit is configured to switch the air introduction operation by selecting any one of a plurality of introduction operations. The plurality of the aforementioned introduction operations include at least: The first operation includes introducing the blowing air based on a timer; and The second step involves introducing the airflow based on the actual position of the tension rod. The resin container manufacturing equipment has a display device for displaying information and for receiving input setting information used to set control conditions for various devices. The control unit is configured to select the air blowing operation based on the setting information input through the display device.

2. The resin container manufacturing equipment as described in claim 1, wherein, The control unit includes: A detection device is used to detect the actual position of the tension rod inserted into the preform; and A supply control device is used to control the air supply state based on the detection results of the detection device.

3. The resin container manufacturing equipment as described in claim 2, wherein, In the second operation, the supply control device is configured to: Based on the detection result of the detection device indicating that the tension rod has reached the first position, primary air, which is used as the blowing air, is introduced into the preform. as well as Based on the detection result of the detection device indicating that the tension rod has reached the second position, the blowing air introduced into the preform is switched from the primary air to secondary air with a higher pressure than the primary air.

4. The resin container manufacturing equipment as described in claim 2, wherein, The multiple introduction operations also include a third operation based on a combination of the timer and the actual position of the tension rod.

5. The resin container manufacturing equipment as described in claim 4, wherein, In the third operation, the supply control device is configured to: Based on the detection result of the detection device indicating that the tension rod has reached the first position, primary air, which is used as the blowing air, is introduced into the preform. as well as In response to the elapsed first standby time from the time point at which the detection device detects that the tension rod has reached the second position, the blowing air introduced into the preform is switched from the primary air to secondary air with a higher pressure than the primary air.

6. The resin container manufacturing equipment according to any one of claims 2 to 5, wherein, The drive source for the tension rod is a servo motor; and The detection device detects the actual position of the tension rod based on the rotational position of the servo motor.

7. A method for manufacturing a resin container, wherein a preform disposed in a stretch blow molding die is stretched by a stretching rod, and the preform is stretched by introducing air into the preform to form a resin container, the method comprising: Switch between multiple air introduction operations by selecting any one of them; The plurality of the aforementioned introduction operations include at least: The first operation includes introducing the blowing air based on a timer; and The second step involves introducing the airflow based on the actual position of the tension rod. In the resin container manufacturing method, the air blowing operation is selected based on setting information input via a display device, wherein the display device is used to display and to receive input setting information for setting control conditions of various devices.

8. The method for manufacturing a resin container as described in claim 7, wherein, The second operation includes: In response to the tension rod reaching a first position, primary air, as the blowing air, is introduced into the preform; and In response to the tension rod reaching the second position, the blowing air introduced into the preform is switched from the primary air to secondary air with a higher pressure than the primary air.

9. The method for manufacturing a resin container as described in claim 7, wherein, The multiple introduction operations also include a third operation based on a combination of the timer and the actual position of the tension rod.

10. The method for manufacturing a resin container as described in claim 9, wherein, The third operation includes: In response to the tension rod reaching a first position, primary air, as the blowing air, is introduced into the preform; and In response to the elapsed first standby time from the point when the tension rod reaches the second position, the blowing air introduced into the preform is switched from the primary air to secondary air with a higher pressure than the primary air.

11. The method for manufacturing a resin container as described in claim 7, further comprising: The actual position of the tension rod is detected based on the rotational position of the servo motor that acts as the drive source for the tension rod.

Images