Bag-making / filling / packaging

Abstract

To provide a bag-making, filling and packaging machine which prevents the occurrence of defective sealing when starting the molding of a bag from a stopped state.SOLUTION: The form-fill-seal packaging machine performs a reverse feeding process for causing the feeding device to feed the strip packaging material in a reverse direction from a state where the feeding device and the first sealing device are stopped, a forward feeding process for causing the feeding device to feed the strip packaging material in a forward direction after the reverse feeding process is completed, and a leveling process for leveling a tension applied to the strip packaging material by the tension mechanism in parallel with the reverse feeding process and the forward feeding process.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a form-fill-seal packaging machine that is capable of adjusting the tension applied to a strip-shaped packaging material. [Background technology]

[0002] BACKGROUND ART Vertical form-fill-seal packaging machines have been known that include a vertical sealing device that seals both overlapping ends of a strip of film, and a horizontal sealing device that seals the portions of the strip of film formed into a cylindrical shape by the vertical sealing device that correspond to the top and bottom of a bag containing a product.

[0003] Furthermore, among such vertical form-fill-seal packaging machines, there are some that employ an ultrasonic sealing device in the vertical sealing device, which applies ultrasonic sealing to a strip of film by ultrasonic vibration (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-218171 Summary of the Invention [Problem to be solved by the invention]

[0005] Since ultrasonic sealing devices require a certain amount of time from when power supply to the ultrasonic horn starts until ultrasonic sealing is possible, if power supply to the ultrasonic horn starts at the same time as the transport of the strip film begins, there is a possibility that some areas of the strip film will not be sealed (so-called poor sealing).

[0006] The present invention has been made in consideration of the above circumstances, and its object is to provide a form-fill-seal packaging machine that prevents poor sealing when starting to form bags from a stopped state. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a form-fill-seal packaging machine for filling products into bags formed from strip packaging material, the machine comprising: a take-up roll around which strip packaging material is wound; a feeder for feeding the strip packaging material from the take-up roll; a tensioning mechanism disposed on a feed path of the strip packaging material from the take-up roll to the feeder for applying tension to the strip packaging material fed from the take-up roll; a tube former for overlapping both widthwise ends of the strip packaging material fed by the feeder to form a cylindrical shape; a first sealing device for sealing both widthwise ends of the strip packaging material overlapped by the tube former; a second sealing device for sealing portions of the strip packaging material formed into a cylindrical shape by the first sealing device that correspond to the top and bottom of a bag containing a product; and a control device for controlling the operations of the feeder, the tensioning mechanism, the first sealing device, and the second sealing device, The strip packaging material can be fed in a forward direction from the roll via the tension mechanism, the tube maker, and the first sealing device to the second sealing device, and in a reverse direction from the second sealing device via the first sealing device, the tube maker, and the tension mechanism to the take-up roll, and the control device executes a reverse feed process in which the feeding device feeds the strip packaging material in the reverse direction from a state in which the feeding device and the first sealing device are stopped, a forward feed process in which the feeding device feeds the strip packaging material in the forward direction after the reverse feed process is completed, and a leveling process in parallel with the reverse feed process and the forward feed process in which the tension mechanism levels the tension applied to the strip packaging material, and a preparation process in which the first sealing device prepares to seal the strip packaging material is started after the reverse feed process starts and completed before the forward feed speed in the forward feed process reaches a predetermined value. [Effects of the Invention]

[0008] According to the present invention, it is possible to obtain a form-fill-seal packaging machine that prevents the occurrence of poor sealing when starting to form bags from a stopped state. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is an overall perspective view of a vertical bag form-fill-seal packaging machine. [Figure 2] FIG. 1 is a side view of a vertical form-fill-seal packaging machine. [Figure 3] FIG. 2 is a schematic diagram of a tension mechanism. [Figure 4] FIG. [Figure 5] FIG. 1 is a hardware configuration diagram of a vertical form-fill-seal packaging machine. [Figure 6] 10 is a timing chart of a startup process. DETAILED DESCRIPTION OF THE INVENTION

[0010] A vertical form-fill-seal packaging machine 1 according to an embodiment will be described below with reference to the drawings. Note that the embodiment of the present invention described below is an example of how the present invention can be realized, and the scope of the present invention is not limited to the scope of the described embodiment. Therefore, the present invention can be implemented by incorporating various modifications to the embodiment. For example, the present invention is applicable not only to a vertical form-fill-seal packaging machine 1, but also to a horizontal form-fill-seal packaging machine.

[0011] Figure 1 is an overall perspective view of a vertical form fill seal packaging machine 1. Figure 2 is a side view of the vertical form fill seal packaging machine 1. The vertical form fill seal packaging machine 1 is a device that forms a strip film Fw (strip packaging material) into bags Bp and fills the formed bags Bp with products. The vertical form fill seal packaging machine 1 mainly comprises a film supply device 10, a film feed device 20 (feed device), a product filling tube 30, a vertical sealing device 40 (first sealing device), a horizontal sealing device 50 (second sealing device), and a control device 70.

[0012] The strip film Fw is a strip-shaped packaging material that is used to make bags for packaging products. The strip film Fw is a film-like member that can be welded by applying heat, and examples include polyethylene (PE), polyethylene terephthalate (PET), biaxially oriented polypropylene (OPP), aluminum-backed paper, and aluminum-metalized paper. The product refers to granular foods such as candy, bean snacks, and snacks. However, specific examples of the product are not limited to these and include any item that is packaged in a bag Bp and shipped.

[0013] Film supply device 10 is a device that supplies strip-shaped film Fw wound around take-up roll 11 to film transport device 20. Film supply device 10 mainly includes take-up roll 11, multiple fixed guide rolls 12a-12h, a cylinder former 14, and a tension mechanism 60.

[0014] The take-up roll 11 rotates in the direction in which the strip film Fw is unwound by being driven by the film feeding device 20. The fixed guide rolls 12a-12h are arranged on the feed path of the strip film Fw from the take-up roll 11 through the cylinder former 14 to the film feeding device 20, and guide the strip film Fw as it is fed along the feed path. The tension mechanism 60 is arranged on the feed path of the strip film Fw, and applies appropriate tension to the strip film Fw as it is fed along the feed path.

[0015] The cylinder former 14 overlaps both widthwise ends of the strip film Fw to form the strip film Fw into a cylindrical shape. The cylinder former 14 then sends the cylindrically formed strip film Fw downward toward the product filling tube 30. The strip film Fw formed into a cylindrical shape by the cylinder former 14 moves downward along the outer peripheral surface of the product filling tube 30.

[0016] A date printing device 15 and a date inspection device 16 are disposed opposite the feed path of the strip film Fw from the winding roll 11 to the tube former 14. The date printing device 15 prints dates (e.g., manufacturing date, expiry date, best-before date, etc.) at predetermined positions on the strip film Fw supplied by the film supply device 10. The date inspection device 16 inspects whether the date has been properly printed by the date printing device 15.

[0017] Figure 3 is a schematic diagram of the tension mechanism 60. The tension mechanism 60 increases or decreases the tension applied to the strip film Fw. However, the specific configuration of the tension mechanism 60 is not limited to the example shown in Figure 3. As shown in Figure 3, the tension mechanism 60 mainly includes a pair of left and right levers 61L, 61R, multiple movable guide rolls 62, 63, a swing shaft 64, and a tension servo motor 65.

[0018] A pair of left and right levers 61L, 61R are pivotally supported on the frame of the vertical form-fill-seal-seal machine 1 at positions spaced apart in the width direction of the strip film Fw. Movable guide rolls 62, 63 and a pivot shaft 64 are attached to the levers 61L, 61R at positions spaced apart in the extension direction of the levers 61L, 61R. The pivot shaft 64 rotates when a driving force from a tension servo motor 65 is transmitted to it, thereby pivoting the levers 61L, 61R. As an example, as shown in FIG. 3(A), the pivot shaft 64 may be directly connected to the output shaft of the tension servo motor 65. As another example, as shown in FIG. 3(B), the pivot shaft 64 may be connected to the output shaft of the tension servo motor 65 via a drive pulley 66, a driven pulley 67, and a belt 68.

[0019] As shown in Figures 1 and 2, the strip film Fw unwound from the take-up roll 11 is passed over, in this order, fixed guide rolls 12a and 12b, movable guide roll 62, fixed guide roll 12c, movable guide roll 63, and fixed guide rolls 12d to 12h. The levers 61L and 61R are biased by the passed-over strip film Fw in a direction that decreases the distance between the movable guide roll 63 and the fixed guide roll 12d (i.e., decreases the tension applied to the strip film Fw). The tension mechanism 60 increases or decreases the distance between the movable guide roll 63 and the fixed guide roll 12d by controlling the rotational torque of the tension servo motor 65 to swing the levers 61L and 61R. This increases or decreases the tension applied to the strip film Fw.

[0020] More specifically, by increasing the rotational torque of the tension servo motor 65, the levers 61L, 61R swing in a direction that increases the distance between the movable guide roll 63 and the fixed guide roll 12d against the biasing force of the strip film Fw (i.e., they operate in a direction that increases the tension applied to the strip film Fw).On the other hand, by decreasing the rotational torque of the tension servo motor 65, the levers 61L, 61R swing in a direction that decreases the distance between the movable guide roll 63 and the fixed guide roll 12d (i.e., they operate in a direction that decreases the tension applied to the strip film Fw).

[0021] The tension servo motor 65 is capable of rotating forward and reverse under the control of the control device 70. The forward and reverse rotations are opposite to each other. When the tension servo motor 65 rotates forward, the tension mechanism 60 swings the levers 61L and 61R in a direction that increases the tension against the biasing force of the strip film Fw. On the other hand, when the tension servo motor 65 rotates reversely, the tension mechanism 60 swings the levers 61L and 61R in a direction that decreases the tension. However, the drive source that operates the tension mechanism 60 is not limited to the tension servo motor 65, and may be another motor such as a stepping motor, or may be an air cylinder, etc.

[0022] FIG. 4 is a schematic diagram of the film feeding device 20. The film feeding device 20 passes the strip film Fw supplied from the film supply device 10 along a feeding path through the cylinder former 14, vertical sealing device 40, and horizontal sealing device 50, in that order. Hereinafter, the feeding direction of the strip film Fw along the feeding path from the film supply device 10 through the tension mechanism 60, cylinder former 14, and vertical sealing device 40 toward the horizontal sealing device 50 will be referred to as the "forward direction," and the direction from the horizontal sealing device 50 through the vertical sealing device 40, cylinder former 14, and tension mechanism 60 toward the film supply device 10 will be referred to as the "reverse direction." As shown in FIG. 4, the film feeding device 20 mainly comprises a pair of guide shafts 21A and 21B and a pair of feeding units 22L and 22R.

[0023] The pair of guide shafts 21A, 21B are disposed vertically and spaced apart, extending in the left-right direction. The pair of feed units 22L, 22R are disposed opposite each other, sandwiching the product filling tube 30. The pair of feed units 22L, 22R are supported by the pair of guide shafts 21A, 21B so that they can slide toward and away from each other. This allows the position of the pair of feed units 22L, 22R to be changed to match the diameter of the product filling tube 30.

[0024] Each of the pair of feed units 22L, 22R mainly includes base plates 23L, 23R, drive pulleys 24L, 24R, driven pulleys 25L, 25R, tension pulleys 26L, 26R, feed belts 27L, 27R, and feed servo motors 28L, 28R. The pair of feed units 22L, 22R have the same basic configuration except that they are reversed left and right, so the configuration of feed unit 22R will be described below.

[0025] The base plate 23R is slidably supported on a pair of guide shafts 21A, 21B. The drive pulley 24R, driven pulley 25R, and tension pulley 26R are rotatably supported on the base plate 23R at positions spaced apart from one another. More specifically, the drive pulley 24R and driven pulley 25R are positioned at positions spaced apart in the vertical direction (i.e., the feed direction of the strip film Fw). The tension pulley 26R is supported on the base plate 23R so as to be movable in the left-right direction.

[0026] The feed belt 27R is stretched over a drive pulley 24R, a driven pulley 25R, and a tension pulley 26R. By sliding the feed unit 22R along the pair of guide shafts 21A and 21B, the portion of the feed belt 27R between the drive pulley 24R and the driven pulley 25R comes into contact with the strip of film Fw covering the outer surface of the product filling tube 30. Furthermore, by moving the tension pulley 26R, tension is applied to the feed belt 27R.

[0027] The feed servo motor 28R is a servo motor that generates a driving force to rotate the drive pulley 24R. When the drive pulley 24R is rotated by the driving force of the feed servo motor 28R, the feed belt 27R revolves around the drive pulley 24R, the driven pulley 25R, and the tension pulley 26R. When the feed belt 27R revolves while in contact with the strip film Fw, the tubular formed strip film Fw is transported along the product filling tube 30.

[0028] The feed servo motors 28L, 28R are capable of rotating forward and reverse under the control of the control device 70. The forward and reverse rotations are opposite to each other. The film feed device 20 feeds the strip film Fw in the forward direction when the feed servo motors 28L, 28R rotate forward, and feeds the strip film Fw in the reverse direction when the feed servo motors 28L, 28R rotate reversely.

[0029] The product filling cylinder 30 is a cylindrical member with open top and bottom ends. The product filling cylinder 30 is installed between the cylinder former 14 and the horizontal sealing device 50, extending vertically along the feed direction of the cylindrically formed strip film Fw. A hopper 31 is attached to the top opening of the product filling cylinder 30. The product filling cylinder 30 fills bags Bp formed by the vertical sealing device 40 and the horizontal sealing device 50 with product supplied through the hopper 31 from a combination weighing device (product supply device) (not shown) through the bottom opening.

[0030] The vertical sealing device 40 is positioned facing the product filling tube 30. More specifically, the vertical sealing device 40 is positioned downstream of the tube former 14 and upstream of the horizontal sealing device 50 in the feeding direction of the strip film Fw by the film feeding device 20. The vertical sealing device 40 seals both ends of the strip film Fw that has been overlapped by the tube former 14.

[0031] The vertical sealing device 40 according to this embodiment is an ultrasonic sealing device that applies ultrasonic sealing to a strip of film Fw by ultrasonic vibration. The vertical sealing device 40 applies pressure to and vibrates both overlapping ends of the strip of film Fw, thereby melting and welding (ultrasonic sealing) the overlapping ends. As shown in FIG. 1, the vertical sealing device 40 includes an ultrasonic horn 41 (resonator), an ultrasonic wave generating unit 42, and an anvil 43.

[0032] The ultrasonic horn 41 and the anvil 43 are disk-shaped metal members. The ultrasonic horn 41 and the anvil 43 are supported rotatably around a rotation axis in a direction (horizontal direction) perpendicular to the feed direction (up-down direction) of the strip film Fw, with their outer peripheral surfaces in contact with each other. The ultrasonic horn 41 and the anvil 43 rotate while applying pressure to both overlapping ends of the strip film Fw formed into a cylindrical shape by the cylinder former 14.

[0033] The ultrasonic generator 42 generates ultrasonic vibrations using power supplied from the control device 70. More specifically, the ultrasonic generator 42 converts high-frequency electrical energy into mechanical vibration energy using a converter formed of a piezoelectric element, and then amplifies the mechanical vibration energy using a booster to generate ultrasonic vibrations. These ultrasonic vibrations are transmitted to the anvil 43 through the ultrasonic horn 41. Then, the overlapping ends of the strip film Fw, which is pressed between the ultrasonic horn 41 and the anvil 43, are melt-welded by frictional heat generated by the ultrasonic vibrations.

[0034] In this embodiment, an example of a roller-type ultrasonic sealing device has been described, but the specific example of the vertical sealing device 40 is not limited to this, and a block-type ultrasonic sealing device may also be used. Furthermore, the vertical sealing device 40 is not limited to an ultrasonic sealing device. As another example, the vertical sealing device 40 may be a device that thermally seals the strip film Fw using a pair of seal blocks with built-in heaters, similar to the horizontal sealing device 50 described below.

[0035] The horizontal sealing device 50 is located downstream of the vertical sealing device 40 in the feed direction of the strip film Fw. The horizontal sealing device 50 forms the tubular strip film Fw into bags Bp by welding (sealing) the tubular strip film Fw at predetermined intervals. More specifically, the horizontal sealing device 50 seals the portions of the tubular strip film Fw formed by the vertical sealing device 40 that correspond to the bottom and top of the bags Bp. The horizontal sealing device 50 also cuts the boundary between two consecutive bags Bp.

[0036] The horizontal sealing device 50 includes a pair of sealing blocks 51 and 52. The pair of sealing blocks 51 and 52 are arranged opposite each other, sandwiching the strip film Fw formed into a cylindrical shape by the vertical sealing device 40. Each of the pair of sealing blocks 51 and 52 has a built-in heater. The pair of sealing blocks 51 and 52 come into contact with and separate from each other while sandwiching the strip film Fw. The pair of sealing blocks 51 and 52 then heat the strip film Fw while sandwiching it, thereby welding the strip film Fw.

[0037] Figure 5 is a hardware configuration diagram of the vertical form-fill-fill-seal machine 1. As shown in Figure 5, the control device 70 includes, for example, a CPU 71 (Central Processing Unit) that serves as a calculation means, and a memory 72 that serves as a storage means. The memory 72 is configured, for example, as a ROM (Read Only Memory) that stores various programs, a RAM (Random Access Memory) that serves as a work area for the CPU 71, an HDD (Hard Disc Drive), or a combination of these. The CPU 71 reads and executes the programs stored in the memory 72 to realize each of the processes described below.

[0038] However, the specific configuration of the control device 70 is not limited to this, and may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0039] A feed amount sensor 73 is connected to the control device 70. The feed amount sensor 73 detects the amount of feed of the strip film Fw by the film feeding device 20 and outputs a feed amount signal indicating the detected feed amount to the control device 70. The feed amount sensor 73 may, for example, detect the amount of feed in the forward direction by the film feeding device 20 as a positive feed amount, and detect the amount of feed in the reverse direction by the film feeding device 20 as a negative feed amount. The feed amount sensor 73 may have a well-known configuration, and may, for example, be an optical sensor or a rotary encoder provided on the feed servo motors 28L, 28R.

[0040] The control device 70 controls the operations of the film supply device 10, the film feed device 20, the vertical sealing device 40, and the horizontal sealing device 50 based on the feed signal output from the feed amount sensor 73. More specifically, the control device 70 controls the rotation speed, rotation torque, or rotation amount of each servo motor by outputting a command current (pulse signal) through a servo amplifier. The control device 70 also supplies power to the ultrasonic horn 41 and the sealing blocks 51 and 52, causing the ultrasonic horn 41 to generate ultrasonic vibrations and heat the heaters in the sealing blocks 51 and 52.

[0041] [Bag making and filling process] The control device 70 repeatedly performs a bag making and filling process in which bags Bp are formed from the strip film Fw and filled with products by operating the film supply device 10, film feeding device 20, vertical sealing device 40, and horizontal sealing device 50 in conjunction with each other. This allows the vertical form-fill-seal packaging machine 1 to produce multiple bags Bp in sequence. The bag making and filling process will be briefly described below.

[0042] First, the control device 70 drives the film feed device 20 to feed the strip film Fw forward from the take-up roll 11. The control device 70 also drives the vertical sealing device 40 to ultrasonically seal the overlapping edges of the strip film Fw, thereby forming the strip film Fw into a cylindrical shape. The control device 70 then sandwiches and seals the portion of the cylindrically formed strip film Fw that corresponds to the top of the first bag and the portion that corresponds to the bottom of the second bag immediately behind the first bag, using the sealing blocks 51 and 52. The control device 70 then cuts the boundaries between adjacent bags Bp.

[0043] 6, during the bag-making and filling process, the control device 70 maintains the feed speed of the film feeding device 20 at V2 and the amplitude of the ultrasonic vibrations generated by the ultrasonic horn 41 at A1. Furthermore, during the bag-making and filling process, the control device 70 maintains the tension applied to the strip film Fw by the tension mechanism 60 at "bag-making tension." The following process will be explained using the amount of rotation of the tension servo motor 65 when the tension mechanism 60 applies bag-making tension to the strip film Fw as the reference (=0).

[0044] [Startup process] The vertical form-fill-seal packaging machine 1 stops the bag-making and filling process, for example, when a part (e.g., a cutter) or consumable (e.g., a strip of film Fw) is replaced, regular maintenance is performed, an error occurs (e.g., a sealing failure), or the machine is temporarily shut down (powered off). At this time, the film feeding device 20, the vertical sealing device 40, and the horizontal sealing device 50 are stopped. The stopped state of the film feeding device 20 refers to the stop of feeding of the strip of film Fw (more specifically, the stop of power supply to the feed servo motors 28L and 28R). The stopped state of the vertical sealing device 40 refers to the stop of ultrasonic vibration (more specifically, the stop of power supply to the ultrasonic horn 41). The stopped state of the horizontal sealing device 50 refers to the stop of heat generation by the heaters of the sealing blocks 51 and 52 (more specifically, the stop of power supply to the heaters).

[0045] If the bag making and filling process is started on the stopped vertical form fill packaging machine 1, the strip film Fw may be fed forward without being properly sealed, particularly by the vertical sealing device 40, resulting in the formation of poorly sealed bags Bp. Therefore, the vertical form fill packaging machine 1 according to this embodiment performs the startup process shown in Figure 6 before starting the bag making and filling process from a stopped state of the film feeding device 20, vertical sealing device 40, and horizontal sealing device 50.

[0046] Figure 6 is a timing chart of the startup process. The startup process is performed to prevent poor sealing when starting the bag-making and filling process from a stopped state. In other words, the startup process is a process that puts the vertical sealing device 40 into a state where it can properly seal the strip film Fw. As shown in Figure 6, the startup process includes a reverse feed process, a forward feed process, a leveling process, and a preparation process.

[0047] First, the control device 70 executes the reverse feed process. The reverse feed process is a process for feeding the strip film Fw in the reverse direction by rotating the feed servo motors 28L and 28R in the reverse direction. More specifically, the control device 70 starts the reverse feed process at time t1 and ends it at time t4. The reverse feed process also includes an acceleration section from time t1 to t2, a constant speed section from time t2 to t3, and a deceleration section from time t3 to t4. The acceleration section is a section in which the feed speed of the strip film Fw in the reverse direction gradually increases (i.e., accelerates). The constant speed section is a section in which the feed speed of the strip film Fw in the reverse direction is constant. The deceleration section is a section in which the feed speed of the strip film Fw in the reverse direction gradually decreases (i.e., decelerates).

[0048] That is, the control device 70 gradually increases the feed speed of the strip film Fw in the reverse direction until it reaches -V1 (mm / sec) (acceleration section), maintains the feed speed of the strip film Fw in the reverse direction at -V1 until a predetermined time (t2 to t3) has elapsed (constant speed section), and gradually decreases the feed speed until the feed speed of the strip film Fw in the reverse direction reaches 0 (deceleration section). That is, the acceleration section is the section before the constant speed section and the deceleration section. The constant speed section is the section between the acceleration section and the deceleration section. The deceleration section is the section after the acceleration section and the constant speed section. However, the constant speed section can be omitted.

[0049] Next, the control device 70 executes the forward feeding process after the reverse feeding process is completed (after the reverse feeding speed reaches 0). The forward feeding process is a process in which the strip film Fw is fed in the forward direction by rotating the feed servo motors 28L and 28R in the forward direction. More specifically, the control device 70 starts the forward feeding process at time t4 (i.e., simultaneously with the end of the reverse feeding process) and continues the forward feeding process until the bag making and filling process is completed. The forward feeding process also includes an acceleration section from time t4 to t5 and a constant speed section from time t5 onwards. The control device 70 gradually increases the feed speed of the strip film Fw in the forward direction until it reaches V2 (mm / sec) (acceleration section), and then maintains the forward feed speed of the strip film Fw at V2 (constant speed section).

[0050] The control device 70 also executes a leveling process in parallel with the reverse feed process and the forward feed process. More specifically, the leveling process is a process for leveling the tension applied by the tension mechanism 60 to the strip film Fw (more specifically, maintaining it within a predetermined range including the tension during bag making) while the reverse feed process and the forward feed process are being executed. More specifically, the leveling process is a process for adjusting the operating amount of the tension mechanism 60 (the rotation amount R of the tension servo motor 65) so that the tension applied to the strip film Fw is leveled. In other words, the leveling process is a process for keeping the rotational torque of the tension servo motor 65 constant (maintaining it within a predetermined range including the reference value).

[0051] In the reverse feed process, the control device 70 rotates the tension servo motor 65 in the forward direction, gradually increasing the rotation amount R from a reference value (=0) to R1. More specifically, the control device 70 reduces the amount of forward rotation per unit time of the tension servo motor 65 in the constant speed section (t2 to t3) compared to the acceleration section (t1 to t2). The control device 70 also reduces the amount of forward rotation per unit time of the tension servo motor 65 in the deceleration section (t3 to t4) even more than in the constant speed section (t2 to t3). That is, of the straight line showing the change in the rotation amount R in FIG. 6, the slope of the constant speed section is smaller than the slope of the acceleration section, and the slope of the deceleration section is smaller than the slope of the constant speed section.

[0052] Furthermore, in the acceleration section (t4 to t5) of the forward processing, the control device 70 rotates the tension servo motor 65 in the reverse direction, thereby gradually decreasing the rotation amount R from R1 to the reference value (= 0). Furthermore, in the constant speed section (from t5) of the forward processing, the control device 70 maintains (i.e., stops) the rotation amount R of the tension servo motor 65 at the reference value (= 0).

[0053] As described above, during the leveling process, the controller 70 increases the amount of operation of the tension mechanism 60 in the direction that increases the tension applied to the strip film Fw (i.e., the amount of forward rotation of the tension servo motor 65) as the amount of reverse feed of the strip film Fw increases (t1 to t4). On the other hand, during the leveling process, the controller 70 increases the amount of operation of the tension mechanism 60 in the direction that decreases the tension applied to the strip film Fw (i.e., the amount of reverse rotation of the tension servo motor 65) as the amount of reverse feed of the strip film Fw decreases (t3 to t4) or the amount of forward feed of the strip film Fw increases (t4 to t5). The feed amount of the strip film Fw is determined by the feed amount signal output from the feed amount sensor 73.

[0054] Furthermore, the control device 70 executes a preparation process in parallel with the reverse feed process, forward feed process, and leveling process. The preparation process is a process for preparing the vertical sealing device 40 to seal the strip film Fw. More specifically, the preparation process is a process for supplying power to the ultrasonic horn 41 to generate ultrasonic vibrations with an amplitude A1 (mm) that enables ultrasonic sealing. As shown in FIG. 6, the amplitude A of the ultrasonic vibrations generated by the ultrasonic horn 41 gradually increases with the start of power supply from the control device 70 (t1), and reaches A1 after a predetermined time (t1 to t5) has elapsed.

[0055] The control device 70 according to this embodiment starts the preparation process at time t1 simultaneously with the start of the reverse transport process and the leveling process. As another example, the control device 70 may start the preparation process after the start of the reverse transport process and the leveling process. In other words, the control device 70 may start the preparation process after the start (t1) of the reverse transport process and the leveling process.

[0056] Furthermore, the control device 70 according to this embodiment completes the preparatory process (i.e., causes the ultrasonic vibrations generated by the ultrasonic horn 41 to reach amplitude A1) before the constant speed period of the forward feed process starts (t5). As another example, the control device 70 may complete the preparatory process before the forward feed process starts (t4). That is, the control device 70 may complete the preparatory process before the forward feed speed of the strip film Fw reaches a predetermined value V2.

[0057] Furthermore, in the preparation process, the control device 70 may supply power to the heater of the horizontal sealing device 50 to heat it up to a predetermined temperature. However, since the time required for the heater to increase in temperature is short compared to the increase in the amplitude of the ultrasonic vibration, the present specification will mainly explain the preparation process of the vertical sealing device 40.

[0058] [Effects of the embodiment] According to the above embodiment, by starting the preparatory process after the reverse feed process has started, it is possible to reduce the power consumption of the vertical form-fill-seal packaging machine 1. Also, by completing the preparatory process before the forward feed speed reaches a predetermined value in the forward feed process, it is possible to prevent sealing defects in the form-fill-seal process. Furthermore, by performing the reverse feed process prior to the forward feed process, it is possible to double-seal a portion of the tubular strip film Fw with the vertical sealing device 40, further preventing sealing defects.

[0059] Here, when the strip film Fw is fed in the reverse direction during the reverse feed process, slack occurs in the strip film Fw along the feed path between the tension mechanism 60 and the film feed device 20. Therefore, the leveling process equalizes the tension applied to the strip film Fw by the tension mechanism 60 during the reverse feed process and the forward feed process. This prevents the strip film Fw from becoming too loose or too tight. Note that "leveling the tension" does not necessarily mean keeping the tension constant at all times, but may also mean keeping it within a predetermined range that includes the tension during bag making.

[0060] Furthermore, according to the above embodiment, the tension of the strip film Fw during the reverse feed process can be further equalized by increasing the amount of operation of the tension mechanism 60 in the direction in which the tension increases (i.e., the amount of forward rotation of the tension servo motor 65) in accordance with the amount of feed of the strip film Fw in the reverse direction.

[0061] Furthermore, according to the above embodiment, the tension of the strip film Fw can be further leveled out by adjusting the amount of forward rotation per unit time of the tension servo motor 65 in each of the acceleration section, constant speed section, and deceleration section of the reverse feed process.

[0062] In the above embodiment, an example has been described in which the rotation amount of the tension servo motor 65 is controlled based on the feed amount detected by the feed amount sensor 73, but the specific control method is not limited to the above example. As another example, the control device 70 may control the oscillation angle of the oscillation shaft 64 based on the feed amount detected by the feed amount sensor 73. As yet another example, the control device 70 may perform torque control so that the rotation torque of the tension servo motor 65 becomes constant (falls within a predetermined range including a reference value).

[0063] As an example, in the case of a strip film Fw whose elongation is negligibly small, rotation amount control or swing angle control can be performed using the feed amount sensor 73. As another example, in the case of a strip film Fw whose elongation is relatively large, torque control can be performed. However, the correspondence between the type of strip film Fw and the specific control method is not limited to the above example.

[0064] Furthermore, according to the above embodiment, by increasing the amplitude A of the ultrasonic vibrations generated by the vertical sealing device 40 to a predetermined value A1 in the preparation process before the bag-making and filling process is performed, it is possible to prevent the occurrence of defective sealing. However, the present invention is also applicable to a vertical sealing device 40 equipped with a pair of seal blocks each having a built-in heater. In this case, the control device 70 simply supplies power to the heater to generate heat in the preparation process. [Explanation of symbols]

[0065] 1...Vertical form-fill-seal packaging machine, 10...Film supply device, 11...Winding roll, 12a to 12h...Fixed guide roll, 14...Cylinder former, 15...Date printing device, 16...Date inspection device, 20...Film feeding device, 21A, 21B...Guide shaft, 22L, 22R...Feed unit, 23L, 23R...Base plate, 24L, 24R, 66...Drive pulley, 25L, 25R, 67...Follower pulley, 26L, 26R...Tension pulley, 27L, 27R...Feed Belt, 28L, 28R...feed servo motor, 30...product filling tube, 31...hopper, 40...vertical sealing device, 41...ultrasonic horn, 42...ultrasonic generator, 43...anvil, 50...horizontal sealing device, 51, 52...seal block, 60...tension mechanism, 61L, 61R...levers, 62, 63...movable guide roll, 64...oscillating shaft, 65...tension servo motor, 68...belt, 70...control device, 71...CPU, 72...memory, 73...feed amount sensor

Claims

1. In a form-fill-seal machine that fills products into bags formed from a strip-shaped packaging material, a take-up roll on which the strip-shaped packaging material is wound; a feeding device that feeds out the strip packaging material from the winding roll; a tension mechanism disposed on a feeding path of the strip packaging material from the winding roll to the feeding device, the tension mechanism applying tension to the strip packaging material fed from the winding roll; a cylinder former that overlaps both widthwise ends of the strip-shaped packaging material fed by the feeding device to form it into a cylindrical shape; a first sealing device that seals both ends of the strip-shaped packaging material that has been overlapped by the tube former; a second sealing device for sealing the portions of the strip-shaped packaging material formed into a cylindrical shape by the first sealing device, the portions corresponding to the top and bottom of the bag containing the product; a control device that controls operations of the feeding device, the tension mechanism, the first sealing device, and the second sealing device, The feeding device is a forward direction from the take-up roll through the tension mechanism, the cylinder former, and the first sealing device toward the second sealing device; The strip packaging material can be fed in a reverse direction from the second sealing device through the first sealing device, the cylinder former, and the tension mechanism toward the take-up roll, The control device, from a state in which the feeding device and the first sealing device are stopped, a reverse feeding process for causing the feeding device to feed the strip packaging material in the reverse direction; a forward feeding process in which, after the reverse feeding process is completed, the feeding device feeds the strip packaging material in the forward direction; a leveling process for leveling the tension applied to the strip-shaped packaging material by the tension mechanism in parallel with the reverse feeding process and the forward feeding process; a preparation process for preparing the first sealing device to seal the strip-shaped packaging material is started after the reverse feed process has started, and is completed before the forward feed speed in the forward feed process reaches a predetermined value.

2. The bag form, fill and seal machine according to claim 1, a control device for controlling the tension mechanism in a direction that increases the tension applied to the strip packaging material as the amount of reverse feed of the strip packaging material increases during the leveling process;

3. The bag form, fill and seal machine according to claim 2, The tension mechanism includes: a lever that can swing in a direction to increase or decrease the tension applied to the strip-shaped packaging material and is biased by the strip-shaped packaging material in a direction to decrease the tension; a servo motor capable of rotating in a forward direction to swing the lever in a direction to increase tension against the biasing force of the strip-shaped packaging material, and rotating in a reverse direction to swing the lever in a direction to decrease tension, The form-fill-seal packaging machine is characterized in that the control device increases the amount of forward rotation of the servo motor as the amount of reverse feed of the strip-shaped packaging material increases during the leveling process.

4. The bag form, fill and pack machine according to claim 3, The reverse transport process includes: an acceleration section in which the speed of the packaging material in the reverse direction is increased; A constant speed section where the feeding speed of the strip packaging material is constant; a deceleration section in which the feeding speed of the packaging strip in the reverse direction is reduced, In the leveling process, the control device The amount of forward rotation of the servo motor per unit time in the constant speed section is made smaller than that in the acceleration section, a forward rotation amount per unit time of the servo motor in the deceleration section being further reduced than that in the constant speed section;

5. The bag form, fill and pack machine according to claim 3, The form-fill-seal packaging machine, wherein the control device controls the torque of the servo motor in the leveling process so that the rotational torque falls within a predetermined range including a reference value.

6. The bag form, fill and seal machine according to claim 1, the first sealing device applies ultrasonic sealing to the strip-shaped packaging material by ultrasonic vibration; The form-fill-seal packaging machine, wherein the control device causes the ultrasonic vibrations generated by the first sealing device to reach a predetermined amplitude during the preparation process.

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