Paper container bottom molding machine

Abstract

We provide a paper container bottom molding device that can also handle continuous conveying. [Solution] The bottom forming apparatus 2 is equipped with a gripper 7 that holds the body portion 1a of the unformed paper container 1 and holds the bottom component portion facing downward, and is equipped with a mandrel 6 above the gripper 7 and a pressing means 10 below it. The mandrel 7 includes an engaging portion 15a that engages with the upper end of the paper container 1 when the pressing portion 11a reaches the position where the folding line of the paper container 1 is formed, and a holding means 12 that holds the paper container 1 on the mandrel 6. With the gripper 7 holding the paper container 1, when the upper end of the paper container 1 engages with the engaging portion 15a of the mandrel 6, the holding means 12 holds the paper container 1 to the mandrel 6 and the gripper 7 releases the paper container 1. In this state, the lifting means 13 brings the mandrel 6 closer to the pressing means 10 to form the bottom surface.

Description

Technical Field

[0001] The present invention relates to a bottom molding apparatus for paper containers, and more particularly to a bottom molding apparatus for paper containers that molds the bottom of a paper container using a mandrel and a pressing means.

Background Art

[0002] At present, a so-called gable-top paper container is known as a paper container for containing liquids such as beverages. The unformed paper container shown in Figure 2 has a rectangular tubular shape, and sealing portion constituting parts and bottom surface constituting parts with pre-formed folding lines are formed on the upper and lower parts of the body portion respectively. As a bottom molding apparatus for molding the bottom of such a paper container, an apparatus including a rotating body that rotates in a vertical plane and a plurality of mandrels arranged at equal intervals on the rotating body is known (Patent Document 1). In the bottom molding apparatus of Patent Document 1, while rotating the rotating body intermittently, the paper container held by the mandrel is stopped at the positions of respective means such as a heater and a pressing means, and the bottom surface is molded sequentially.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In the above-mentioned Patent Document 1, the rotating body must be rotated intermittently to stop the mandrels intermittently at the positions of the respective means, and continuous conveyance cannot be performed, so there is a problem that a large amount of paper containers cannot be efficiently molded. In view of such problems, the present invention provides a bottom molding apparatus for paper containers that is also compatible with continuous conveyance.

Means for Solving the Problem

[0005] In other words, the paper container bottom forming apparatus according to claim 1 comprises a gripper that holds the body of an unformed paper container having a rectangular tube shape and holds the bottom component that constitutes the bottom of the paper container facing downwards, a mandrel provided above the gripper and inserted into the body of the paper container, a lifting means for raising and lowering the mandrel, and a pressing means provided below the gripper and clamping the bottom of the paper container between itself and a pressing portion provided at the tip of the mandrel, The mandrel comprises an engaging portion that engages with the upper end of the paper container, and a holding means for holding the paper container engaged with the engaging portion in the mandrel. The gripper holds the paper container, the lifting mechanism lowers the mandrel so that the mandrel is inserted into the body of the paper container, and when the upper end of the paper container engages with the engaging portion, the holding mechanism holds the paper container and the gripper releases the paper container, and the lifting mechanism lowers the mandrel to the forming position so that the bottom surface of the paper container is formed by the pressing portion and the pressing mechanism. [Effects of the Invention]

[0006] According to the above invention, when a mandrel is inserted from above while the gripper is holding an unformed paper container, the holding means holds the paper container on the mandrel, and the paper container and mandrel are raised and lowered together, allowing the bottom surface to be formed in contact with the pressing means provided below. In other words, since the mandrel and the pressing mechanism can be moved as a single unit, it becomes possible to continuously move them, for example, using a rotary table, while forming the bottom surface of the paper container. Furthermore, when inserting the mandrel into the paper container, if the upper end of the paper container comes into contact with the engaging portion provided on the mandrel, the pressing portion of the mandrel will be positioned at the location where the bottom surface of the paper container is formed. This allows for accurate formation of the bottom surface in relation to the pressing means. [Brief explanation of the drawing]

[0007] [Figure 1] Configuration diagram of a paper container bottom molding machine. [Figure 2] Perspective view of an unformed paper container [Figure 3] Cross-sectional view of section III-III in Figure 1 [Figure 4] Cross-section of a mandrel [Figure 5] Cross-section of a gripper [Figure 6] Gripper's plan [Figure 7] Cross-sectional view of the temporary molding means [Figure 8] Plan view of the triangular pressing mechanism [Figure 9] Cross-sectional view illustrating the heating means and pressing means. [Figure 10] Diagram illustrating the operation at the receiving location. [Figure 11] Diagram illustrating the operation in the mandrel set interval. [Figure 12] Diagram illustrating the operation in the heating section. [Figure 13] Diagram illustrating the operation in the temporary molding section. [Figure 14] Diagram illustrating the operation in the molding section. [Modes for carrying out the invention]

[0008] The following describes the illustrated embodiment. Figure 1 shows a bottom molding device 2 for molding the bottom surface of a paper container 1. This bottom molding device 2 constitutes part of a filling system for filling the paper container 1 with liquid. The filling system is controlled by a control means (not shown). The paper container 1 formed in this embodiment is called a gable top and comprises a rectangular cylindrical body 1a with a square cross-section, a gable roof-shaped sealing portion formed on the upper part of the body 1a, and a flat bottom surface formed on the lower part of the body 1a, with a resin stopper attached to the sealing portion. The bottom molding device 2 is supplied with the unformed paper container 1 shown in Figure 2, which has not yet had its sealing portion and bottom molded. The container is supplied in a rectangular tubular shape with only the body portion 1a molded. The unformed paper container 1 is obtained by bonding both ends of a substantially rectangular paper blank and forming the same into a cylindrical shape with a square cross-section. A sealing portion constituting part 1b that forms a sealing portion is provided above a body part 1a, and a bottom surface constituting part 1c that forms a bottom surface is provided below the body part 1a. The bottom surface constituting part 1c is composed of a pair of folding surfaces 1cb each having a triangular part 1ca formed by folding lines, a first bottom surface 1cc formed with a folding line provided adjacent to the folding surfaces 1cb, and a second bottom surface 1cd not formed with a folding line. Here, the folding line formed at the boundary between the body part 1a and the bottom surface constituting part 1c is referred to as a folding line O. When forming the bottom surface of the paper container 1, pressing the triangular part 1ca inward causes the folding surfaces 1cb to bend along the folding line O, and accordingly the first bottom surface 1cc and the second bottom surface 1cd bend along the folding line O. Then, the tip end of the first bottom surface 1cc and the tip end of the second bottom surface 1cd approach each other, and the tip end of the second bottom surface 1cd overlaps the tip end of the first bottom surface 1cc, whereby the bottom surface constituting part 1c below the folding line O is folded, and the bottom surface is formed. A coating containing an adhesive is formed on the surface of the paper container 1, and when the bottom surface constituting part 1c is folded and clamped in a heated state, the bottom surface constituting part 1c is bonded to form the bottom surface. The bottom surface forming apparatus 2 of the present embodiment is configured to form the bottom surface of the paper container 1 and attach a spout to the sealing portion constituting part 1b. In the filling system, the paper container 1 with an unformed sealing portion is filled with a liquid, and then the sealing portion is formed.

[0009] The bottom surface forming apparatus 2 includes a plurality of rotating wheels W, an intermediate wheel W1 to which an unformed paper container 1 is supplied, and a supply wheel W2 that transfers the paper container 1 from the intermediate wheel W1 to the bottom surface forming wheel W3 are provided upstream of the bottom surface forming wheel W3 that forms the bottom surface of the paper container 1. Further, on the downstream side of the bottom surface forming wheel W3, there are provided a discharge wheel W4 through which the paper container 1 with the formed bottom surface is discharged, and a spout mounting wheel W5 for mounting the spout onto the paper container 1. Grippers for holding the paper container 1 are respectively provided on the outer peripheries of the plurality of rotating wheels W, and the paper container 1 is transferred at a transfer position A where the supply wheel W2 and the bottom surface forming wheel W3 approach each other, for example. The configuration of the gripper will be described later, but by holding the opposing flat surfaces that constitute the body portion 1a of the paper container 1, the paper container 1 is conveyed while maintaining the shape of the body portion 1a. Note that the description of the spout mounting wheel W5 for mounting the spout onto the paper container 1 will be omitted.

[0010] Figure 3 is a cross-sectional view of the bottom surface forming wheel W3, showing a cross-sectional view taken along section line III-III in Figure 1. The bottom surface forming wheel W3 includes a fixed shaft 3 fixed to the ground, and a rotating body 4 rotatably provided relative to the fixed shaft 3. The rotating body 4 is rotatably provided on the fixed shaft 3 via a bearing or the like, and a gear 4a provided at the lower end meshes with a worm gear 5 driven by a motor. With this configuration, when the motor rotates, the worm gear 5 and the gear 4a rotate in conjunction with each other to rotate the rotating body 4, and the gear 4a of the rotating body 4 meshes with gears of other rotating wheels W (not shown), thereby linking the rotation of the plurality of rotating wheels W.

[0011] The rotating body 4 of the bottom surface forming wheel W3 is provided with a mandrel 6 inserted into the body portion 1a of the paper container 1, a gripper 7 for holding the paper container 1, a pre-forming means 8 for pre-forming the bottom surface of the paper container 1, a heating means 9 for heating the bottom surface constituting portion 1c of the paper container 1, and a pressing means 10 for clamping the bottom surface of the paper container 1 between the pressing means 10 and the mandrel 6, and these components are provided at equal intervals on the outer peripheral edge of the bottom surface forming wheel W3. In this embodiment, the unformed paper container 1 is supplied with the bottom component 1c facing downwards, and the first bottom surface 1cc facing outwards from the rotating body 4.

[0012] The mandrel 6 is held by two upper tables 4b provided on the upper part of the rotating body 4 and includes a rod 11 that is inserted into the body 1a of the paper container 1, a holding means 12 that holds the paper container 1 on the rod 11, and a lifting means 13 that raises and lowers the rod 11. The rod 11 has a cylindrical shape, and a substantially square, plate-shaped pressing portion 11a is provided at its lower end. When forming the bottom surface of the paper container 1, the lower surface of the pressing portion 11a is positioned to clamp the bottom surface between itself and the pressing means 10. A cooling water passage is formed inside the rod 11 (not shown), and when the bottom surface is clamped between the rod and the pressing means 10, it cools the adhesive of the paper container 1 that has been heated by the heating means 9. Furthermore, a pressure absorbing means 14 is connected to the upper end of the rod 11, and is composed of a piston 14a connected to the rod 11 and a cylinder 14b that houses the piston 14a, with the cylinder 14b containing the required gas or liquid. With this configuration, when the bottom surface is clamped between the pressing portion 11a of the rod 11 and the pressing means 10, pressure from the pressing means 10 acts on the rod 11, and this pressure is absorbed by the piston 14a and cylinder 14b.

[0013] The holding means 12 includes a stopper member 15 fixed to the rod 11, a guide member 16 provided on the lower surface of the stopper member 15 and inserted into the inside of the paper container 1, and a clamp 17 provided on the lower surface of the stopper member 15 and holding the paper container 1. The stopper member 15 is positioned such that when the rod 11 is inserted into the body 1a of the paper container 1 and the lower surface of the pressing portion 11a descends to the position of the folding line O, the upper end of the paper container 1 comes into contact with the lower surface of the stopper member 15. Here, the lower surface of the stopper member 15 is referred to as the engaging portion 15a. In other words, the distance from the lower surface of the stopper member 15 to the lower surface of the pressing portion 11a is set to be approximately the same as the distance from the upper end of the paper container 1 to the folding line O. When the rod 11 is inserted into the unformed paper container 1 and the upper end of the paper container 1 comes into contact with the engaging portion 15a, the lower surface of the pressing portion 11a is positioned at the location of the folding line O.

[0014] The guide member 16 is provided on the rod 11, and its upper cross-section is formed to be substantially the same shape as the body portion 1a of the paper container 1, while its lower portion has a tapered shape that narrows downwards. With this configuration, when the rod 11 is inserted into the paper container 1, the paper container 1 is guided by the guide member 16, and then the upper end of the paper container 1 comes into contact with the engagement portion 15a. In this configuration, the outer surface of the guide member 16 is in close contact with the inner surface of the sealing component 1b of the paper container 1, making it possible to clamp the paper container 1 between the guide member 16 and the clamp 17.

[0015] The clamp 17 is provided at a position opposite the guide member 16, and is provided so as to be reciprocable by an air cylinder 17a. When the clamp 17 is retracted and in the open state, a gap is formed between it and the guide member 16, and the sealing component 1b of the paper container 1 is positioned between the guide member 16 and the clamp 17. In the closed position with the clamp 17 advanced, the sealing component 1b of the paper container 1 is held between the clamp 17 and the guide member 16, and the paper container 1 is held by the mandrel 6. The air cylinder 17a is controlled by a control means, which recognizes the position of each mandrel 6 from the rotational position of the bottom-forming wheel W3, and operates the air cylinder 17a according to the rotational position of the mandrel to move the clamp 17 forward or backward.

[0016] As shown in Figure 3, the lifting mechanism 13 includes a lifting member 13a provided on the upper part of the pressure absorbing mechanism 14, a cam follower 13b provided on the lifting member 13a, and a cam 13c that moves the cam follower 13b up and down. The lifting member 13a is provided to penetrate the upper table 4b vertically and to be movable vertically, and the cam 13c is provided to surround the fixed shaft 3 and has a cam rail into which the cam follower 13b engages. As the cam follower 13b moves up and down along the cam 13c, the rod 11 connected to the lifting member 13a moves up and down, allowing it to approach the pressing means 10 and temporary forming means 8 located below from above.

[0017] As shown in Figure 5, the gripper 7 is held by an upper ring 4c connected to the rotating body 4 via a connecting member 21, and a lower ring 4d connected to the upper ring 4c via a connecting rod 22. Figure 5 shows the gripper 7 holding the paper container 1, and the height of the paper container 1 at this time is the receiving position for receiving the unformed paper container 1 from the intermediate wheel W1. At this time, the pre-forming means 8 and the pressing means 10 are located below the paper container 1 held by the gripper 7. The gripper 7 described above consists of a slide rail 23 provided on the upper surface of the lower ring 4d, a pair of gripping members 24 provided to be able to move toward and away from the slide rail 23, and an opening and closing mechanism 25 for opening and closing the gripping members 24. As shown in Figure 6, the slide rail 23 is provided in a direction perpendicular to the radial direction of the lower ring 4d, and the gripping member 24 is movable along the slide rail 23. The gripping members 24 are positioned opposite each other on either side of the paper container 1, and a contact member 24a biased by a spring is provided at the position where the paper container 1 is held. When the gripping members 24 are brought closer together, the contact member 24a contacts the body 1a of the paper container 1, and the paper container 1 is gripped by the biasing force of the spring.

[0018] The opening and closing mechanism 25 consists of a plate cam 25a that is movable up and down along the connecting rod 22, a cam follower 25b provided on the plate cam 25a, and a cam 25c that moves the cam follower 25b up and down. The plate cam 25a has a slit formed in an inverted V shape (not shown), and the cam follower 24b provided at the end of the gripping member 24 engages with this slit. With this configuration, when the plate cam 25a is moved up and down, the cam follower 24b of the gripping member 24 moves back and forth along the slit. However, since the direction of movement of the gripping member 24 is restricted by the slide rail 23, the two gripping members 24 move toward and away from each other along the slide rail 23. The cam 25c is provided so as to surround the rotating body 4, and is fixed to a retaining member 26 (shown by dashed lines in Figure 5) that extends to the outside of the rotating body 4, thereby preventing it from moving relative to the rotating body 4. When the rotating body 4 rotates, the cam follower 25b moves the plate cam 25a up and down along the cam 25c, causing the gripping member 24 to move toward and away from the gripper 7, thereby opening and closing the gripper 7.

[0019] As shown in Figure 7, the temporary forming means 8 is held on a ring-shaped middle table 4e fixed to the rotating body 4 via a connecting member (not shown), and includes a pair of temporary folding members 31 that press against the triangular portion 1ca of the folded surface 1cb of the paper container 1, an opening and closing mechanism 32 that opens and closes the temporary folding members 31, a pusher 33 that presses against the first bottom surface 1cc of the paper container 1, and a swinging mechanism 34 that swings the pusher 33. Figure 7 shows the state immediately before the temporary forming means 8 temporarily forms the bottom surface of the paper container 1. At this time, the unformed paper container 1 is held on the mandrel 6 by the holding means 12 and lowered by the lifting means 13 to the forming position where the bottom surface of the paper container 1 is formed.

[0020] The temporary folding member 31 is a roughly triangular member positioned to sandwich the paper container 1, and is provided to move toward and away from along a slide rail 35 provided on the upper surface of the middle table 4e. The temporary folding member 31 is held with its vertex facing inward and is provided at the height of the triangular portion 1ca of the paper container 1 when it is in the molding position. The opening and closing mechanism 32 has a mechanism similar to the opening and closing mechanism 25 of the gripper 7, and consists of a rod 32a provided radially on the middle table 4e, a plate cam 32b provided so as to be able to reciprocate horizontally along the rod 32a, a cam follower 32c provided on the upper surface of the plate cam 32b, and a cam 32d that moves the cam follower 32c radially. As shown in Figure 8, the plate cam 32b is provided with a V-shaped slit 32e, and the cam follower 31a provided on the temporary folding member 31 engages with the slit 32e. The cam 32d is provided by the holding member 26 so as not to rotate relative to the rotating body 4, and is configured to move the plate cam 32b, on which the cam follower 32c is attached, in the radial direction. With this configuration, when the plate cam 32b moves along the cam 32d, the cam follower 31a of the temporary folding member 31 moves back and forth along the slit 32e, causing the temporary folding member 31 to move toward and away from each other along the slide rail 35, pressing the triangular portion 1ca of the bottom surface component 1c from both sides.

[0021] The pusher 33 described above is a plate-shaped member with a U-shaped cross-section that is pivotably mounted on the upper end of a stay 33a erected on a lower table 4f (see Figure 3), the base end of which is fixed to the rotating body 4. Furthermore, the pusher 33 is located outside the first bottom surface 1cc of the paper container 1 held by the gripper 7, and is positioned at the molding position that forms the bottom surface of the paper container 1. When the pusher 33 swings against the paper container 1 located at the above-mentioned molding position, the pusher 33 comes into contact with the first bottom surface 1cc of the bottom surface component 1c and presses the first bottom surface 1cc toward the second bottom surface 1cd.

[0022] The rocking mechanism 34 consists of an arc-shaped link member 34a that is pivotably mounted on the pusher 33, a movable member 34b to which the link member 34a is connected and which is movable horizontally, a cam follower 34c provided on the movable member 34b, and a cam 34d that moves the cam follower 34c in the horizontal direction. The movable member 34b is provided so as to be able to reciprocate radially along a rod 34e provided on the lower surface of the middle table 4e, and the cam follower 34c is provided on the lower surface of the movable member 34b. The cam 34d is provided by the holding member 26 so as not to rotate relative to the rotating body 4, and is configured to move the movable member 34b, on which the cam follower 34c is provided, in the radial direction. When the rotating body 4 rotates, the movable member 34b reciprocates along the cam 34d, causing the pusher 33 to swing via the link member 34a.

[0023] As shown in Figure 9, the heating means 9 is provided on the lower table 4f (see Figure 3) and includes a heater unit 9a and an air cylinder 9b for raising and lowering the heater unit 9a. The heater unit 9a is equipped with a heat source that radiates heat and a blower, and a rectangular cylindrical cover 9c capable of accommodating the bottom component 1c of the paper container 1 is provided on the upper part of the heater unit 9a. The air cylinder 9b is fixed to the lower table 4f and is configured to raise and lower the heater unit 9a between a raised position (dandent line) that heats the bottom component 1c of the paper container 1 and a lowered position that retracts so as not to interfere with the pressing means 10. When the container 1 is heated by the heating means 9, the paper container 1 is positioned in the molding position by the lifting means 13. From this position, the heater unit 9a rises to the raised position, causing the bottom component 1c of the container 1 to be housed in the cover 9c.

[0024] The pressing means 10 is provided on the lower table 4f (see Figure 3) and includes a swingable pressing plate 41 and a swinging mechanism 42 for swinging the pressing plate 41. The pressing plate 41 is pivotably mounted on a bracket 41a fixed to the lower table 4f, and is positioned in a molding position for forming the bottom surface of the paper container 1. The upper surface of the pressing plate 41 is machined to be flat, and the pressing plate 41 is designed to swing between a pressing position (dimensions) where it is positioned horizontally and a retracted position where its tip is positioned downward. Then, when the pressing plate 41 swings against the paper container 1 located in the molding position described above, the upper surface of the pressing plate 41 becomes horizontal, and the bottom surface of the paper container 1 is clamped between the pressing portion 11a of the mandrel 6 and the pressing plate 41.

[0025] The above-described swinging mechanism 42 comprises an arm member 42a swingably mounted on the bracket 41a, and a link member 42b swingably connected to the pressing plate 41 and the arm member 42a. As shown in Figure 3, it also comprises a lifting bar 42c connected to the link member 42b, a cam follower 42d fixed to the lifting bar 42c, and a cam 42e that moves the cam follower 42d up and down. The arm member 42a forms a parallel link with the pressing plate 41, and by moving the link member 42b up and down, the pressing plate 41 swings in conjunction with it. The lifting bar 42c is provided to penetrate the lower table 4f, and the cam follower 42d is provided on the side of the lifting bar 42c. The cam 42e is provided so as to surround the rotating body 4, and by moving the lifting bar 42c up and down via the cam follower 42d, the pressing plate 41 is swung via the link member 42b.

[0026] The operation of the bottom molding apparatus 2 will be explained below using Figures 10 to 14. In all Figures 10 to 14, the right side of the diagram represents the inside of the bottom molding wheel W3. As shown in Figure 1, the bottom forming wheel W3 performs various processes while transporting the paper container 1. Starting from the receiving position A of the paper container 1 from the supply wheel W2, the following sections are set: mandrel setting section B for inserting the mandrel 6, heating section C for heating the bottom component 1c, heating means removal section D for removing the heating means 9 from the paper container 1, temporary forming section E for temporary forming the bottom, forming section F for forming the bottom, and mandrel removal section G for retracting the mandrel 6 from the paper container 1. After that, the paper container 1 with the formed bottom is discharged to the discharge wheel W4 at the handover position H.

[0027] Figure 10 shows the bottom molding wheel W3 receiving the unformed paper container 1 from the supply wheel W2 at the receiving position A. At the receiving position A described above, the gripper 7 of the bottom forming wheel W3 receives the unformed paper container 1 held by the gripper of the supply wheel W2. At this time, as explained in Figure 6, the gripping members 24 of the gripper 7 move closer to each other and clamp the opposing planes that make up the body 1a of the paper container 1. Here, the paper container 1 supplied to the bottom molding wheel W3 is supplied with its bottom component 1c facing downwards, and with the first bottom surface 1cc of the bottom component 1c facing outwards from the bottom molding wheel W3. Furthermore, the paper container 1 held by the gripper 7 is positioned at the receiving position, at which time the mandrel 6 is retracted above the paper container 1 by the lifting means 13, and the temporary forming means 8, heating means 9, and pressing means 10 are positioned below the paper container 1.

[0028] Figure 11 shows the state in which the mandrel 6 is inserted into the body 1a of the paper container 1 in the mandrel set section B described above. When the rod 11 of the mandrel 6 is lowered by the lifting mechanism 13, the pressing portion 11a is inserted into the paper container 1, and the upper end of the paper container 1 engages with the engaging portion 15a formed on the lower surface of the stopper member 15. As a result, the lower surface of the pressing portion 11a of the mandrel 6 is positioned along the folding line O of the paper container 1. Then, the control means activates the clamp 17 of the holding means 12, which clamps the paper container 1 between the guide member 16 and the clamp 17, and the paper container 1 is held on the mandrel 6 by the holding means 12.

[0029] Next, in mandrel set section B, the heating means 9 is brought close to the bottom component 1c of the paper container 1, as shown in Figure 12. In Figure 11, when the paper container 1 is held on the mandrel 6 by the holding means 12, the gripper 7 releases the paper container 1, and in that state, the lifting means 13 moves the mandrel 6 further downward. As a result, the paper container 1 descends from the receiving position to the molding position, and since the gripper 7 is open at this time, damage due to displacement with the gripper 7 is prevented. Meanwhile, the heating means 9 uses the air cylinder 9b to raise the heater unit 9a to the raised position, thereby housing the bottom component 1c of the paper container 1 inside the cover 9c.

[0030] In the heating section C described above, as shown in Figure 12, the bottom component 1c of the paper container 1 is heated by the heating means 9, melting the adhesive contained in the coating formed on the surface of the paper container 1. In the subsequent heating means detachment section D, the heating means 9 lowers the heater unit 9a and detaches it from the paper container 1. At this time, the paper container 1 is maintained in the molding position by the lifting means 13 of the mandrel 6.

[0031] Next, in the temporary molding section E, the bottom surface of the paper container 1 is temporarily molded as shown in Figure 13. The paper container 1 is held in the molding position by the mandrel 6, and the temporary folding member 31 of the temporary molding means 8 is located at the height of the triangular portion 1ca of the bottom surface component 1c. First, the opening / closing mechanism 32 brings the temporary folding member 31 closer and presses against the triangular portion 1ca of the bottom surface component 1c. As a result, the folding surface 1cb folds inward along the folding line O, and consequently, the first bottom surface 1cc and the second bottom surface 1cd also fold inward along the folding line O (not shown). As a result, the leading edges of the first base surface 1cc and the second base surface 1cd come closer together, and with the temporary folding member 31 pressing against the triangular portion 1ca, the pusher 33 swings as shown in Figure 12, pressing against the first base surface 1cc from the outside. As a result, the pressed first base surface 1cc bends along the folding line O, and the second base surface 1cd deforms to cover the first base surface 1cc, completing the preliminary molding of the base surface. At this time, the lower surface of the pressing portion 11a of the mandrel 6 is at the height of the folding line O, which is the height of the bottom surface of the paper container 1, so that the temporary folding member 31 and the pusher 33 can accurately perform temporary forming of the bottom surface.

[0032] Next, in molding section F, the bottom surface of the paper container 1 is molded as shown in Figure 14. When the temporary folding member 31 and pusher 33 of the temporary forming means 8 are retracted, the pressing plate 41 of the pressing means 10 swings and presses against the bottom surface of the paper container 1. At this time, the lower surface of the pressing portion 11a of the mandrel 6 is at the same height as the bottom surface of the paper container 1, and when the pressing plate 41 is positioned in the pressing position, the bottom surface is clamped between the pressing portion 11a and the pressing plate 41. Cooling water flows through the inside of the mandrel 6, cooling the adhesive on the heated bottom component 1c, which then bonds the bottom components 1c together, completing the molding of the bottom surface. Here, when the bottom surface is clamped between the mandrel 6 and the pressing means 10, pressure from the pressing plate 41 acts on the pressing portion 11a of the mandrel 6, but this pressure is absorbed by the pressure absorbing means 14. At this time, the mandrel 6 may rise slightly, but since the gripper 7 is open, scratches on the outer surface of the paper container 1 due to friction are prevented.

[0033] In the mandrel evacuation section G described above, mandrel 6 is evacuated from paper container 1. When the pressing plate 41 of the pressing means 10 is retracted, the lifting means 13 raises the mandrel 6 to position the paper container 1 in the receiving position, and then the gripper 7 holds the paper container 1. Next, when the holding means 12 for the mandrel 6 opens and the paper container 1 is opened, the lifting means 13 further raises the mandrel 6, retracting the rod 11 above the paper container 1. Then, when the gripper 7 moves to the transfer position H with the discharge wheel W4, the paper container 1 is transferred between it and the discharge wheel W4. After that, a stopper is attached to the paper container 1 by the stopper attachment wheel W5, and then liquid is filled into it.

[0034] According to the bottom molding apparatus 2 of this embodiment, the bottom surface of the paper container 1 is molded while the rotating wheel W is continuously rotated, making it possible to efficiently mold the bottom surface while continuously conveying the paper container 1. In other words, by holding the unformed paper container 1 with the gripper 7 so that the bottom component 1c is facing downwards, and by providing the mandrel 6 above the paper container 1 and the pressing means 10 below it, it becomes possible to move them together as a single unit. In contrast, Patent Document 1 provides mandrels 6 radially to a rotating body 4, and forms the bottom surface by various processing means provided at each stopping position while intermittently moving the rotating body 4. As a result, it is not possible to continuously form the bottom surface, and high-speed processing is not possible. Furthermore, in this embodiment, the mandrel 6 is provided with an engaging portion 15a that the upper end of the paper container 1 abuts against, and the lower surface of the pressing portion 11a of the mandrel 6 is positioned at a location corresponding to the bottom surface of the unformed paper container 1. Therefore, when performing temporary forming or forming of the bottom surface with the temporary forming means 8 or the pressing means 10, the bottom surface component 1c can be accurately folded. Furthermore, since the holding means 12 holds the paper container 1 on the mandrel 6, the gripper 7 moves the paper container 1 up and down while the paper container 1 is open, thus preventing scratches on the outer surface of the paper container 1 due to displacement with the gripper 7.

[0035] In the above embodiment, the paper container 1 is transported along an arc-shaped transport path by a rotating wheel W while the bottom surface is formed; however, this does not prevent the rotating wheel W from rotating intermittently. Alternatively, the gripper 7 and mandrel 6 may be moved in a linear direction while the bottom surface is formed. Furthermore, as the holding means 12 provided on the mandrel 6, a configuration different from the above embodiment is also conceivable, such as forming a negative pressure hole on the surface of the guide member 16 to generate negative pressure, thereby adsorbing and holding the upper end of the paper container 1 by negative pressure. Furthermore, if the paper container 1 is supplied to the bottom molding wheel W3 with its bottom surface already partially formed, the pre-forming means 8 can be omitted. In the above-described temporary molding means 8, the pusher 33 is configured to press the first bottom surface 1cc of the bottom surface component 1c, but it may also press the second bottom surface 1cd, in which case the material should be supplied so that the second bottom surface 1cd faces outward from the rotating body 4. [Explanation of symbols]

[0036] 1 Paper container 1a Body 1c Bottom component 1ca Triangular part 1cb Folded surface 1cc First base surface 1cd 2nd bottom surface 2 Bottom surface forming device 6 Mandrel 7 Grippa 8 Pre-forming means 9 Heating means 10 Pressing means 11 Rod 11a Pressing part 12 Holding means 13 Lifting mechanism 15 Stopper member 15a Engaging part 31 Temporarily folded member 33 Pusher W3 Bottom Molded Wheel

Claims

1. A paper container bottom forming apparatus comprising: a gripper that holds the body of an unformed paper container having a rectangular tube shape and holds the bottom component that forms the bottom surface of the paper container facing downward; a mandrel provided above the gripper and inserted into the body of the paper container; a lifting means for raising and lowering the mandrel; and a pressing means provided below the gripper and clamping the bottom surface of the paper container between itself and a pressing portion provided at the tip of the mandrel, The mandrel comprises an engaging portion that engages with the upper end of the paper container, and a holding means for holding the paper container engaged with the engaging portion in the mandrel. A paper container bottom forming apparatus characterized in that, with the gripper holding the paper container, the lifting means lowers the mandrel so that the mandrel is inserted into the body of the paper container, and when the upper end of the paper container engages with the engaging portion, the holding means holds the paper container and the gripper releases the paper container, and the lifting means lowers the mandrel to the forming position so that the bottom surface of the paper container is formed by the pressing portion and the pressing means.

2. The paper container is equipped with a temporary forming means for folding the bottom component to temporarily form the bottom surface, The above-mentioned temporary molding means is provided below the gripper, The paper container bottom molding apparatus according to claim 1, characterized in that when the holding means holds the paper container and the gripper releases the paper container, the lifting means lowers the mandrel to the molding position, the temporary molding means temporarily molds the bottom surface of the paper container, and then the pressing means molds the bottom surface.

3. The bottom surface of the above-mentioned paper container is composed of a pair of folded surfaces having triangular sections formed by fold lines, a first bottom surface with fold lines formed adjacent to the folded surfaces, and a second bottom surface without fold lines. The above-described temporary forming means comprises a pair of temporary folding members that press the triangular portion inward of the paper container, and a pusher that presses the first bottom surface or the second bottom surface. The paper container bottom forming apparatus according to claim 2, characterized in that when the temporary folding member presses the triangular portion and folds the folding surface, the pusher presses the first bottom surface or the second bottom surface to temporarily form the bottom surface.

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