Liquid filling method

Abstract

To provide a liquid filling method that can be carried out by a filling device having a small and simple structure.SOLUTION: There is provided a liquid filling method for filling a liquid L into a container 10 by using a filling device 1. The filling device 1 comprises: a cylindrical body 33; and a rod body 36. The liquid filling method comprise: a filling start step of starting the supply of the liquid L from a liquid flow path 33a into the container 10 in a state in which a lower end of the rod body 36 is in contact with or close to a bottom 13 of the container 10 while keeping a state in which a lower end opening 33b of the cylindrical body 33 is opened; a first filling step of supplying a predetermined amount of the liquid L from the liquid flow path 33a into the container 10, after the filling start step, in a state in which the lower end opening 33b of the cylindrical body 33 is opened; and a second filling step of supplying a predetermined amount of the liquid L from the liquid flow path 33a into the container 10 at a pressure higher than a pressure in the first filling step, after the first filling step, in a state in which a lower end of the cylindrical body 33 is disposed inside a mouth portion 11 of the container 10, and the lower end opening 33b of the cylindrical body 33 is opened.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a liquid filling method for filling a container with a liquid using a filling device.

Background Art

[0002] Containers made of synthetic resin such as bottles made of polypropylene (PP) or polyethylene terephthalate (PET) are used for applications that contain various liquids such as beverages, cosmetics, pharmaceuticals, detergents, and toiletries such as shampoo as the content liquid.

[0003] Such containers are generally manufactured by blow molding a preform formed of a synthetic resin material having the above-described thermoplasticity.

[0004] As blow molding for forming a preform into a container, liquid blow molding is known in which a pressurized liquid is used instead of pressurized air as a pressurizing medium supplied to the inside of the preform. Liquid blow molding is performed by a liquid filling method in which a pressurized liquid is supplied to the preform using a filling device.

[0005] Conventionally, as such a liquid filling method, a filling device having a blow nozzle having a liquid supply port, a seal body for opening and closing the blow nozzle, a cylinder body supported vertically movably by the seal body, and a rod body disposed vertically movably inside the cylinder body is used. A prefill step of supplying a liquid from a liquid flow path provided inside the cylinder body to the inside of the preform at a pressure that does not stretch the preform, and after the prefill step, a blow molding step of supplying a liquid to the inside of the preform from the supply port of the blow nozzle at a pressure higher than that in the prefill step to blow-mold the preform is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-119099 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the conventional liquid filling method described above had a problem: the filling device required to implement the liquid filling method had to be large and complex in configuration, including a blow nozzle for supplying pressurized liquid in the blow molding process, as well as a cylindrical or rod-shaped body for supplying liquid in the prefill process.

[0008] This invention has been made in view of these problems, and its objective is to provide a liquid filling method that can be implemented using a compact and simple filling device. [Means for solving the problem]

[0009] The present invention relates to a liquid filling method for filling a container with liquid using a filling device, wherein the filling device comprises a cylindrical body whose inner surface is a liquid channel, a rod portion disposed to move up and down inside the cylindrical body, and a rod body provided at the lower end of the rod portion and having a lid portion that opens and closes the lower end opening of the cylindrical body, and the method comprising: a filling start step in which the supply of liquid from the liquid channel to the inside of the container is started with the lower end opening of the cylindrical body open and the lower end of the rod body in contact with or close to the bottom of the container; a first filling step in which, after the filling start step, a predetermined amount of liquid is supplied from the liquid channel to the inside of the container with the lower end opening of the cylindrical body open; and a second filling step in which, after the first filling step, a predetermined amount of liquid is supplied from the liquid channel to the inside of the container at a higher pressure than in the first filling step, with the lower end of the cylindrical body positioned inside the mouth of the container and the lower end opening of the cylindrical body open.

[0010] In the liquid filling method of the present invention, in the above configuration, it is preferable that in the filling start step and the first filling step, the lower end opening of the cylindrical body is brought close to the bottom of the container, and liquid is supplied to the inside of the container from the liquid flow path through the gap between the lid and the lower end opening of the cylindrical body.

[0011] In the liquid filling method of the present invention, in the above configuration, it is preferable that in the filling start step and the first filling step, the lower end of the rod body is brought into contact with or close to the bottom of the container and the lower end of the cylindrical body is positioned inside the opening, and liquid is supplied into the container from the liquid flow path.

[0012] In the liquid filling method of the present invention, in the above configuration, it is preferable that in the filling start step, the lower end opening of the cylindrical body is brought close to the bottom of the container, and liquid is supplied to the inside of the container from the liquid channel through the gap between the lid and the lower end opening of the cylindrical body, and in the first filling step, liquid is supplied to the inside of the container from the liquid channel through the gap between the lid and the lower end opening of the cylindrical body, while maintaining the gap and raising the cylindrical body and the rod body in accordance with the rise in the liquid level inside the container, thereby supplying liquid to the inside of the container from the liquid channel.

[0013] In the liquid filling method of the present invention, in the above configuration, the container is preferably a preform made of synthetic resin, the filling apparatus is a liquid blow molding apparatus, the first filling step is a prefill step in which liquid is supplied to the inside of the preform without stretching the preform, and the second filling step is a blow molding step in which the preform is blow molded.

[0014] In the liquid filling method of the present invention, in the above configuration, it is preferable that the container is extended axially by the rod body in the second filling step. [Effects of the Invention]

[0015] According to the present invention, a liquid filling method can be provided that can be implemented using a compact and simple filling device. [Brief explanation of the drawing]

[0016] [Figure 1] This is a cross-sectional view showing an example of a liquid filling apparatus used in a liquid filling method, which is one embodiment of the present invention. [Figure 2] Figure 1 is a cross-sectional view of the liquid filling apparatus shown in the state during the filling start process and the first filling process. [Figure 3] This is a cross-sectional view of the liquid filling apparatus shown in Figure 1, during the second filling process. [Figure 4] This is a cross-sectional view of the liquid filling apparatus shown in Figure 1, after the second filling process has been completed. [Figure 5] This is a cross-sectional view of the liquid filling apparatus shown in Figure 1, in a state where a modified version of the filling start process is being performed. [Figure 6] Figure 1 is a cross-sectional view of the liquid filling apparatus shown in Figure 1, in a state where the filling start process has been initiated according to another modified example. [Figure 7] This is a cross-sectional view of the liquid filling apparatus shown in Figure 1, during the first filling process according to another modified example. [Modes for carrying out the invention]

[0017] The following describes a liquid filling method according to one embodiment of the present invention with reference to the drawings.

[0018] One embodiment of the liquid filling method of the present invention is a liquid filling method for filling a container with liquid using a filling device. The filling device includes a cylindrical body with an inner liquid flow path, a rod portion disposed vertically movably inside the cylindrical body, and a rod body having a lid portion provided at the lower end of the rod portion for opening and closing the lower end opening of the cylindrical body. The filling start step of starting the supply of liquid from the liquid flow path into the container is performed with the lower end opening of the cylindrical body open and the lower end of the rod body in contact with or close to the bottom of the container. After the filling start step, in a state where the lower end opening of the cylindrical body is open, a first filling step of supplying a predetermined amount of liquid from the liquid flow path into the container is performed. After the first filling step, a second filling step of supplying a predetermined amount of liquid from the liquid flow path into the container at a pressure higher than that in the first filling step is performed with the lower end of the cylindrical body disposed inside the mouth of the container and the lower end opening of the cylindrical body open. The liquid filling method is characterized by having these steps.

[0019] The liquid filling method according to one embodiment of the present invention can be implemented using a filling device 1 having a configuration as shown in FIG. 1, for example.

[0020] In this embodiment, the container is a preform 10 made of synthetic resin. The filling device 1 shown in FIG. 1 is configured as a liquid blow molding device that blow-molds a container filled with liquid into a predetermined shape by supplying or filling pressurized liquid into a synthetic resin preform 10 as a container.

[0021] As the liquid-filled container formed by liquid blow molding with the filling device 1, for example, a relatively small bottle such as one with an internal volume of 300 ml or less is preferable, but it is not limited thereto.

[0022] The preform 10 is made of a synthetic resin having thermoplasticity such as polypropylene (PP) or polyethylene terephthalate (PET), and has a cylindrical mouth portion 11 that becomes the open end, a cylindrical body portion 12 connected to the mouth portion 11, and a hemispherical bottom portion 13 that closes the lower end of the body portion 12, and has a bottomed cylindrical shape (substantially test tube shape).

[0023] The outer circumferential surface of the mouth portion 11 is integrally provided with male threads 14 for attaching a cap to the mouth portion 11 of a liquid-filled container after molding by screw connection. Alternatively, instead of male threads 14, an annular engaging projection may be provided on the outer circumferential surface of the mouth portion 11 for attaching the cap by undercut engagement. Furthermore, a neck ring 15 is integrally provided between the mouth portion 11 and the body portion 12.

[0024] The preform 10 is not limited to the shape described above; as long as it has a cylindrical opening 11, its shape can be changed in various ways.

[0025] The filling device 1 is positioned above the blow molding mold 20. The mold 20 has a cavity 21 shaped to correspond to the final shape of a liquid-filled container, such as a bottle. The cavity 21 opens upward on the upper surface of the mold 20. The preform 10 is mounted in the mold 20 with its body 12 and bottom 13 positioned inside the cavity 21 of the mold 20, and its neck ring 15 supported on the upper surface of the mold 20, so that its mouth 11 protrudes upward from the mold 20.

[0026] The mold 20 can be opened to the left and right, and after the preform 10 is molded into a liquid-filled container, the liquid-filled container can be removed from the mold 20 by opening the mold 20 to the left and right.

[0027] The filling device 1 has a main body block 30 positioned above the mold 20. The main body block 30 integrally has a cylindrical engaging portion 31 at its lower end. The engaging portion 31 has an outer diameter smaller than the inner diameter of the opening 11 and can be fitted liquid-tightly inside the opening 11. In addition, a support hole 32 is provided inside the main body block 30, which opens downward at the engaging portion 31 and extends in the vertical direction.

[0028] The filling device 1 has a cylindrical body 33 positioned in the support hole 32. The cylindrical body 33 has an outer diameter that allows it to be inserted into the preform 10. The inside of the cylindrical body 33 is a liquid flow path 33a, and the lower end of the cylindrical body 33 is the lower end opening 33b of the liquid flow path 33a. Furthermore, while supported in the support hole 32, the cylindrical body 33 is movable vertically relative to the main body block 30 between an upper end position where the lower end opening 33b is positioned inside the engagement portion 31, and a lower end position where the lower end opening 33b moves so as to protrude downward from the engagement portion 31 and is close to the bottom 13 of the preform 10 mounted on the mold 20.

[0029] A liquid supply source 35 is connected to the liquid channel 33a via piping 34. The liquid supply source 35 can supply pressurized liquid L to the liquid channel 33a via piping 34. The liquid supply source 35 can also change the pressure of the liquid L supplied to the liquid channel 33a.

[0030] The filling device 1 has a rod body 36. The rod body 36 comprises a rod portion 36a that is vertically movable inside the cylindrical body 33, and a lid portion 36b provided at the lower end of the rod portion 36a that opens and closes the lower end opening 33b of the cylindrical body 33. The outer diameter of the rod portion 36a is smaller than the inner diameter of the cylindrical body 33, and the space between the outer circumferential surface of the rod portion 36a and the inner circumferential surface of the cylindrical body 33 forms a liquid flow path 33a.

[0031] When the cylindrical body 33 is in the upper end position, the lid portion 36b, which abuts against the lower end opening 33b and closes the lower end opening 33b, is positioned inside the engaging portion 31. When the rod portion 36a moves downward relative to the cylindrical body 33 from this state, the lid portion 36b moves away from the lower end opening 33b of the cylindrical body 33, and the lower end opening 33b of the cylindrical body 33 is opened. The rod portion 36 can also move downward, either alone or together with the cylindrical body 33, to a position where it abuts against or is close to the bottom 13 of the preform 10 mounted on the mold 20.

[0032] The filling device 1 can also be configured such that a suction device 40 is connected to the main body block 30. The suction device 40 is connected via piping 42 to a recess 41 provided on the inner circumferential surface of the support hole 32 of the main body block 30. By supplying negative pressure to the support hole 32 via piping 42 and the recess 41, the suction device 40 can discharge liquid adhering to the surface of the cylindrical body 33 located inside the support hole 32 to the outside. Furthermore, the recess 41, piping 42, and suction device 40 can also be used as a path for discharging air from inside the preform 10 to the outside in the first filling process described later.

[0033] Alternatively, a seal ring 43 can be provided on the inner circumferential surface of the support hole 32, which contacts the outer circumferential surface of the cylindrical body 33 over its entire circumference to create a liquid-tight seal between the support hole 32 and the cylindrical body 33. In this case, the recess 41 is located below the seal ring 43, and the suction device 40 discharges the liquid adhering to the surface of the cylindrical body 33 below the seal ring 43 to the outside.

[0034] The filling device 1 may be configured without a suction device 40 or a seal ring 43.

[0035] Next, the procedure for filling the preform 10 with liquid L using the liquid filling method according to this embodiment and blow molding it into a liquid-filled container will be described.

[0036] First, as shown in Figure 1, the preform 10 is mounted on the mold 20 with the cylindrical body 33 in the upper position and the lower end opening 33b of the cylindrical body 33 closed by the lid portion 36b. Then, as shown in Figure 2, the main body block 30 is moved downward relative to the mold 20 to engage the engaging portion 31 with the opening portion 11.

[0037] Next, the filling process is initiated from this state.

[0038] As shown in Figure 2, in the filling start process, the rod body 36 is moved downward by a predetermined distance relative to the cylindrical body 33 to open the lower end opening 33b of the cylindrical body 33, and the rod body 36 is moved downward so that its lower end (lid portion 36b) is in contact with or close to the bottom 13 of the preform 10. The cylindrical body 33 is also moved downward so that the lower end opening 33b is close to the bottom 13 of the preform 10. At this time, a gap is created between the lid portion 36b and the lower end opening 33b of the cylindrical body 33. Then, in this state, liquid L is supplied from the liquid supply source 35 to the liquid channel 33a, thereby starting the supply of liquid L from the liquid channel 33a to the inside of the preform 10 through the gap between the lid portion 36b and the lower end opening 33b of the cylindrical body 33.

[0039] When the supply of liquid L to the inside of the preform 10 is started in the filling initiation process, the first filling process is then performed. In this embodiment, the first filling process is a prefill process for filling the inside of the preform 10 with liquid L prior to blow molding.

[0040] As shown in Figure 2, in the first filling step, with the lower end opening 33b of the cylindrical body 33 open, a predetermined amount of liquid L is supplied into the preform 10 from the liquid channel 33a. In this embodiment, since the lower end opening 33b of the cylindrical body 33 is brought close to the bottom 13 of the preform 10 in the filling start step, in the first filling step as well, the liquid L is supplied into the preform 10 from the liquid channel 33a through the gap between the lid 36b and the lower end opening 33b of the cylindrical body 33.

[0041] In the first filling process, the amount of liquid L supplied from the liquid channel 33a into the interior of the preform 10 is sufficient to fill the entire interior of the preform 10 with liquid L. Furthermore, the pressure of the liquid L supplied into the preform 10 during the first filling process is such that it does not cause the preform 10 to stretch.

[0042] Thus, in this embodiment, during the filling start step and the first filling step, the lower end (lid portion 36b) of the rod body 36 is brought into contact with or close to the bottom 13 of the preform 10, and the lower end opening 33b of the cylindrical body 33 is brought close to the bottom 13 of the preform 10. Liquid L is supplied from the liquid channel 33a into the interior of the preform 10 through the gap between the lid portion 36b and the lower end opening 33b of the cylindrical body 33. As a result, the liquid L discharged from the lower end opening 33b hits the bottom 13 that is close to the lower end opening 33b. This prevents the liquid L discharged from the lower end opening 33b from hitting the bottom 13 with force, allowing the liquid L to be filled into the interior of the preform 10 without foaming (without entraining air).

[0043] The first filling step is completed when a predetermined amount of liquid L is filled into the preform 10 and the preform 10 is filled with liquid L. By performing this first filling step, the air inside the preform 10 can be replaced with liquid L. In the first filling step, as liquid L is supplied into the preform 10, the air inside the preform 10 can be discharged to the outside through the gap between the engaging portion 31 and the cylindrical body 33, through the recess 41, the piping 42 and the suction device 40, but it may also be discharged through other routes.

[0044] Once the first filling process is completed, the second filling process is performed. In this embodiment, the second filling process is a blow molding process in which the preform 10 is blow molded.

[0045] In the second filling step, as shown in Figures 3 and 4, the cylindrical body 33 is positioned at its upper end, that is, its lower end (lower end opening 33b) is located inside the mouth portion 11, which is the part of the preform 10 that is not stretched by blow molding. With the lower end opening 33b of the cylindrical body 33 open, a predetermined amount of liquid L is supplied from the liquid channel 33a into the interior of the preform 10 at a higher pressure than in the first filling step. Note that in the second filling step, the cylindrical body 33 is not limited to the upper end position; it may be positioned at any other position as long as it is located inside the mouth portion 11 that is not stretched by blow molding.

[0046] In the second filling step, the amount of liquid L supplied from the liquid channel 33a into the interior of the preform 10 is sufficient to blow-molde the body 12 and bottom 13 of the preform 10 into a shape that conforms to the cavity 21 of the mold 20. Furthermore, the pressure of the liquid L supplied into the interior of the preform 10 in the second filling step is higher than that of the first filling step, and is sufficient to blow-molde the body 12 and bottom 13 of the preform 10 into a shape that conforms to the cavity 21 of the mold 20.

[0047] As shown in Figure 3, in the second filling step, the rod 36 may be used to stretch the preform 10 axially (up and down). That is, the rod 36 may function as a stretching rod. In this case, the rod 36 is moved downward, and the lid 36b presses down on the bottom 13, thereby stretching the body 12 and bottom 13 of the preform 10 axially. This allows the preform 10 to be biaxially stretched blow-molded in the second filling step, making it possible to mold the preform 10 into a liquid-filled container with greater precision. It is preferable that the axial (up and down) stretching of the preform 10 by the rod 36 is performed with only the cylindrical body 33 raised relative to the rod 36, so that the lower end opening 33b of the cylindrical body 33 is positioned inside the unstretched portion (mouth 11) that is not stretched by blow molding.

[0048] As shown in Figure 4, when a predetermined amount of liquid L pressurized to a higher pressure than in the first filling step is supplied to the inside of the preform 10 in the second filling step, the body 12 and bottom 13 of the preform 10 are stretched radially and axially by the pressure of the liquid L, and are blow-molded into a shape that conforms to the inner surface of the cavity 21 of the mold 20.

[0049] In this embodiment, the liquid filling method is configured such that the lower end of the cylindrical body 33 is positioned inside the opening 11 of the preform 10, which is not stretched during blow molding. As a result, the pressure from the liquid L supplied into the preform 10 from the lower end opening 33b of the cylindrical body 33 acts mainly on the opening 11 and is suppressed from acting directly on the inner surface of the body 12, which is the part of the preform 10 that is stretched during blow molding. This prevents the body 12 from becoming locally thinned and causing the preform 10 to rupture or deform due to the pressure of the liquid L supplied into the preform 10 from the lower end opening 33b of the cylindrical body 33 acting directly on the body 12.

[0050] Furthermore, when the preform 10 is blow-molded in the second filling step, the air inside the preform 10 has already been replaced with a non-bubbling liquid L in the first filling step. Therefore, when the liquid L is supplied to the inside of the preform 10 in the second filling step, it is possible to suppress the entrainment of air by the liquid L. As a result, in the second filling step, the preform 10 can be blow-molded with liquid L to a predetermined shape that conforms to the inner surface of the cavity 21 with high precision.

[0051] Once the second filling process is complete, the preform 10 is formed into a liquid-filled container C with liquid L inside.

[0052] Once the second filling process is complete, the cylindrical body 33 moves to its upper end position and the rod body 36 moves upward, closing the lower end opening 33b of the cylindrical body 33 with the lid portion 36b.

[0053] After the second filling step, a suck-back step may be performed to draw a predetermined amount of liquid L back from inside the liquid-filled container C into the liquid channel 33a, thereby forming a predetermined amount of headspace inside the liquid-filled container C.

[0054] Alternatively, after the second filling process or after the suck-back process is completed, the main body block 30 may be moved upward to detach the engaging portion 31 from the opening 11, and then a cap-attaching process may be performed in which a cap is attached to the opening 11.

[0055] Furthermore, the main body block 30 may be moved upward to disengage the engaging portion 31 from the opening 11, and then the suction device 40 may be activated to discharge the liquid L adhering to the surface of the cylindrical body 33 to the outside.

[0056] As described above, the liquid filling method according to this embodiment includes a cylindrical body 33 whose interior is a liquid flow path 33a, a rod portion 36a arranged to move up and down inside the cylindrical body 33, and a rod body 36 provided at the lower end of the rod portion 36a and having a lid portion 36b that opens and closes the lower end opening 33b of the cylindrical body 33. However, it can be carried out using a small and simple filling device 1 that does not have a blow nozzle for blow molding. Therefore, according to the liquid filling method according to this embodiment, a liquid-filled container C can be manufactured easily and inexpensively by filling the preform 10 with liquid L using a small and simple filling device 1.

[0057] In particular, when manufacturing relatively small liquid-filled containers C, such as those with a capacity of 300 ml or less, in the second filling process, when supplying pressurized liquid L from the liquid channel 33a inside the cylindrical body 33, which has a smaller diameter than the mouth 11, into the preform 10, the pressure of the liquid L, i.e., the blow pressure, is eliminated, making it possible to easily and reliably manufacture liquid-filled containers C.

[0058] In the above embodiment, during the filling start step and the first filling step, the lower end opening 33b of the cylindrical body 33 is brought close to the bottom 13 of the preform 10, and liquid L is supplied from the liquid channel 33a into the interior of the preform 10 through the gap between the lid 36b and the lower end opening 33b of the cylindrical body 33. However, as shown in Figure 5, during the filling start step and the first filling step, the lower end (lid 36b) of the rod body 36 may be brought into contact with or close to the bottom 13 of the preform 10, and the lower end (lower end opening 33b) of the cylindrical body 33 may be positioned inside the mouth 11 of the preform 10, with liquid L being supplied from the liquid channel 33a into the interior of the preform 10.

[0059] In this case, during the filling start step and the first filling step, the liquid L discharged from the lower end opening 33b of the cylindrical body 33 flows along the rod portion 36a and is supplied to the bottom 13 of the preform 10 at low pressure. Therefore, even in this case, the liquid L discharged from the lower end opening 33b does not hit the bottom 13 with force, and the preform 10 can be filled with liquid L without foaming (without entraining air).

[0060] Furthermore, in the case shown in Figure 5, the second filling process can be carried out without moving the cylindrical body 33 and the rod body 36 after the completion of the first filling process, thus simplifying the liquid filling method.

[0061] In addition, even in the case shown in Figure 5, the rod body 36 may be moved downward to stretch the preform 10 in the axial direction before starting the filling process and the first filling process, but this stretching is not required.

[0062] As shown in Figure 6, in the filling start step, the lower end opening 33b of the cylindrical body 33 is brought close to the bottom 13 of the preform 10 and liquid L is supplied into the preform 10 from the liquid channel 33a through the gap between the lid 36b and the lower end opening 33b of the cylindrical body 33. Alternatively, as shown in Figure 7, in the first filling step, liquid L is supplied into the preform 10 from the liquid channel 33a through the gap between the lid 36b and the lower end opening 33b of the cylindrical body 33, and liquid L may be supplied into the preform 10 from the liquid channel 33a while raising the cylindrical body 33 and the rod body 36 while maintaining the gap between the lid 36b and the lower end opening 33b of the cylindrical body 33 as the liquid level S inside the preform 10 rises.

[0063] In this case, the liquid L discharged from the lower end opening 33b of the cylindrical body 33 during the filling start process does not hit the bottom 13 forcefully, as shown in Figure 2, and as a result, the liquid L can be filled into the preform 10 without foaming (without entraining air). Furthermore, in the first filling process, the liquid L discharged from the lower end opening 33b of the cylindrical body 33 is always discharged into the liquid L near the liquid surface S, which suppresses agitation of the liquid L inside the preform 10, and as a result, the liquid L can be filled into the preform 10 without foaming (without entraining air).

[0064] In the case shown in Figure 7, after the completion of the first filling process, the rod body 36 may be moved downward to stretch the preform 10 in the axial direction, but this stretching is not required.

[0065] Furthermore, in the case shown in Figure 7, the second filling step may be performed without moving the rod body 36 downward after the completion of the first filling step. Alternatively, in the first filling step, the lower end of the rod body 36 may be kept close to or in contact with the bottom 13 of the preform 10, while only the cylindrical body 33 is raised to match the liquid level S (the gap between the lid portion 36b and the lower end opening 33b of the cylindrical body 33 gradually increases).

[0066] In the modified steps shown in Figures 5 to 7, as in the case shown in Figures 1 to 4, a liquid-filled container C can be easily and inexpensively manufactured by filling the preform 10 with liquid L using a small and simple filling device 1.

[0067] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention.

[0068] For example, in the above embodiment, the case in which the liquid filling method according to this embodiment is carried out using the filling device 1 with the configuration shown in Figure 1 was described, but the liquid filling method according to this embodiment can also be carried out using a filling device 1 with a different configuration.

[0069] Furthermore, in the above embodiment, the container was described as a preform 10 made of synthetic resin, the filling device 1 as a liquid blow molding device, the first filling step being a prefill step in which liquid L is supplied to the inside of the preform 10 without stretching the preform 10, and the second filling step being a blow molding step in which the preform 10 is blow molded. However, the liquid filling method according to this embodiment can also be used for purposes such as filling a predetermined amount of liquid as the contents into the inside of a container such as a blow molded container made of synthetic resin. [Explanation of Symbols]

[0070] 1 Filling device 10 Preforms (containers) 11 Mouth 12 Torso 13 Bottom 14 Male screw 15 Neck Rings 20 molds 21 Cavity 30 Main Block 31 Engaging part 32 Support hole 33 Cylinder 33a Liquid channel 33b Bottom opening 34 Piping 35 Liquid Source 36 Rod Body 36a Rod section 36b Lid 40 Suction device 41 Recess 42 Piping 43 Seal ring L liquid C. Container containing liquid S liquid level

Claims

1. A liquid filling method for filling a container with liquid using a filling device, The aforementioned filling device A cylindrical body whose interior serves as a liquid channel, The rod body comprises a rod portion that is vertically movable inside the cylindrical body, and a lid portion provided at the lower end of the rod portion for opening and closing the lower end opening of the cylindrical body. A filling start step in which the lower end opening of the cylindrical body is opened and the lower end of the rod body is in contact with or close to the bottom of the container, and liquid is supplied from the liquid channel into the inside of the container. After the filling start step, a first filling step is performed in which, with the lower end opening of the cylindrical body open, a predetermined amount of liquid is supplied from the liquid channel into the container. A liquid filling method characterized by comprising: a second filling step, after the first filling step, in which the lower end of the cylindrical body is positioned inside the mouth of the container and the opening at the lower end of the cylindrical body is opened, and a predetermined amount of liquid is supplied from the liquid channel to the inside of the container at a pressure higher than that of the first filling step.

2. The liquid filling method according to claim 1, wherein in the filling initiation step and the first filling step, the lower end opening of the cylindrical body is brought close to the bottom of the container, and liquid is supplied to the inside of the container from the liquid channel through the gap between the lid and the lower end opening of the cylindrical body.

3. The liquid filling method according to claim 1, wherein in the filling initiation step and the first filling step, the lower end of the rod body is brought into contact with or close to the bottom of the container and the lower end of the cylindrical body is positioned inside the opening, and liquid is supplied into the container from the liquid channel.

4. In the filling initiation step, the lower end opening of the cylindrical body is brought close to the bottom of the container, and liquid is supplied from the liquid channel into the inside of the container through the gap between the lid and the lower end opening of the cylindrical body. The liquid filling method according to claim 1, wherein in the first filling step, liquid is supplied into the container from the liquid channel through the gap between the lid and the lower end opening of the cylindrical body, and liquid is supplied into the container from the liquid channel while maintaining the gap and raising the cylindrical body and the rod body in accordance with the rise in the liquid level inside the container.

5. The aforementioned container is a preform made of synthetic resin, The filling apparatus is a liquid blow molding apparatus, The first filling step is a pre-fill step in which liquid is supplied to the inside of the preform without stretching the preform, The liquid filling method according to any one of claims 1 to 4, wherein the second filling step is a blow molding step of blow molding the preform.

6. The liquid filling method according to claim 5, wherein in the second filling step, the container is extended in the axial direction by the rod body.

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