JP7553124B2 - Bag making, filling and packaging machine - Google Patents

Description

The present invention relates to a form-fill-seal machine that can adjust the tension applied to strip-shaped packaging material.

A form-fill-seal machine is known that includes at least a take-up roll around which a strip of film is wound and a feeder that feeds the strip of film from the take-up roll, and that forms the strip of film fed by the feeder into a bag and fills it with a product.

In a form-fill-seal machine with the above configuration, when the feed speed of the strip film by the feed device increases, the strip film is pulled, and when the feed speed decreases, the strip film slackens. Therefore, there are form-fill-seal machines that are equipped with a tension mechanism that applies a predetermined tension to the strip film (see, for example, Patent Documents 1 and 2).

JP 2016-175672 A JP 2006-027765 A

In Patent Document 1, tension is applied to the strip film using an air cylinder, which makes it difficult to fine-tune the tension. In Patent Document 2, the tension applied to the strip film is maintained constant by reducing the tension during the acceleration period when the payout speed increases, and increasing the tension during the deceleration period when the payout speed decreases. However, depending on the film properties and operating conditions, reducing the tension during the acceleration period may prevent the strip film from being properly paid out.

The present invention was made to solve the above problems, and its purpose is to provide a form-fill-seal machine that can appropriately adjust the tension applied to the strip of packaging material by the tension mechanism depending on the properties of the strip of packaging material and the operating conditions.

In order to solve the above-mentioned problems, the present invention provides a bag making, filling and packaging machine that fills products into bags formed from strip packaging material, comprising a winding roll on which the strip packaging material is wound, a feeding device that feeds the strip packaging material from the winding roll, a tensioning mechanism that is disposed on the feed path of the strip packaging material from the winding roll to the feeding device and applies tension to the strip packaging material fed from the winding roll by a tension servo motor, a cylinder former that overlaps both widthwise ends of the strip packaging material fed by the feeding device to form it into a tube, and a first sealing device that seals both ends of the strip packaging material overlapped by the cylinder former. The device is equipped with a second sealing device that seals the portions of the strip packaging material formed into a cylindrical shape by the first sealing device that correspond to the top and bottom of the bag containing the product, and a control device that controls the operation of the feeding device and the tension mechanism, and is characterized in that the control device is configured to be able to switch between a first control that increases the tension applied to the strip packaging material by the tension mechanism from a reference value during an acceleration period in which the feeding speed of the strip packaging material by the feeding device is accelerating, and a second control that decreases the tension applied to the strip packaging material by the tension mechanism from the reference value during the acceleration period.

According to the present invention, the tension applied to the strip of packaging material by the tensioning mechanism can be appropriately adjusted depending on the properties of the strip of packaging material and the operating conditions.

FIG. 2 is an overall perspective view of a vertical bag making, filling and packaging machine. FIG. 2 is a side view of a vertical form-fill-seal packaging machine. FIG. 4 is a schematic diagram of a tension mechanism. FIG. FIG. 2 is a hardware configuration diagram of a vertical bag form fill and pack packaging machine. 13 is a display example of a tension setting screen. 5A to 5C are diagrams showing an example of the relationship between the feed speed of the strip film by the film feed device and the tension applied to the strip film by the tension mechanism. 13 is a diagram showing another example of the relationship between the feed speed of the strip film by the film feed device and the tension applied to the strip film by the tension mechanism.

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 is realized, and the scope of the present invention is not limited to the scope of the embodiment. Therefore, the present invention can be implemented with various modifications to the embodiment. For example, the present invention can be applied not only to the vertical form-fill-seal packaging machine 1, but also to a horizontal form-fill-seal packaging machine.

Figure 1 is an overall perspective view of the vertical form, fill and seal machine 1. Figure 2 is a side view of the vertical form, fill and seal machine 1. The vertical form, fill and seal machine 1 is a device that forms a strip-shaped film Fw (strip-shaped packaging material) into bags Bp and fills the formed bags Bp with products. The vertical form, fill and seal 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.

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 of such materials include polyethylene (PE), polyethylene terephthalate (PET), biaxially oriented polypropylene (OPP), aluminum-backed paper, and aluminum-vapor-deposited paper. Products refer to granular foods such as candy, bean snacks, and snacks. However, examples of products are not limited to these, and include any item that is packaged in a bag Bp and shipped.

The film supply device 10 is a device that supplies the strip-shaped film Fw wound around the winding roll 11 to the film advancement device 20. The film supply device 10 mainly comprises the winding roll 11, a number of fixed guide rolls 12a to 12h, a cylinder former 14, and a tension mechanism 60.

The take-up roll 11 rotates in the direction to unwind the strip film Fw when driven by the film feed device 20. The fixed guide rolls 12a to 12h are arranged on the feed path of the strip film Fw from the take-up roll 11 through the tube maker 14 to the film feed 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 an appropriate tension to the strip film Fw as it is fed along the feed path.

The tube former 14 overlaps both widthwise ends of the strip film Fw to form the strip film Fw into a cylindrical shape. The tube former 14 also sends the strip film Fw formed into a cylindrical shape downward toward the product filling tube 30. The strip film Fw formed into a cylindrical shape by the tube former 14 moves downward along the outer circumferential surface of the product filling tube 30.

A date printing device 15 and a date inspection device 16 are arranged facing the feed path of the strip film Fw from the winding roll 11 to the tube maker 14. The date printing device 15 prints dates (e.g., date of manufacture, 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.

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.

The pair of left and right levers 61L, 61R are supported by the frame of the vertical bag making, filling and packaging machine 1 so as to be able to swing at positions spaced apart in the width direction of the strip film Fw. The movable guide rolls 62, 63 and the swing shaft 64 are attached to the levers 61L, 61R at positions spaced apart in the extension direction of the levers 61L, 61R. The swing shaft 64 swings the levers 61L, 61R by rotating the swing shaft 64 when the driving force of the tension servo motor 65 is transmitted thereto. As an example, as shown in FIG. 3(A), the swing 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 swing 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.

As shown in Figures 1 and 2, the strip film Fw unwound from the winding roll 11 is passed over the fixed guide rolls 12a and 12b, the movable guide roll 62, the fixed guide roll 12c, the movable guide roll 63, and the fixed guide rolls 12d to 12h in that order. The levers 61L and 61R are biased by the passed strip film Fw in a direction to reduce the distance between the movable guide roll 63 and the fixed guide roll 12d (i.e., to reduce 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.

More specifically, by increasing the rotational torque of the tension servo motor 65, the levers 61L and 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. This 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 and 61R swing in a direction that decreases the distance between the movable guide roll 63 and the fixed guide roll 12d. This decreases the tension applied to the strip film Fw.

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

The pair of guide shafts 21A, 21B are arranged to extend in the left-right direction at positions spaced apart in the up-down direction. The pair of feed units 22L, 22R are arranged opposite each other with the product filling tube 30 in between. 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 pair of feed units 22L, 22R to change their positions to match the diameter of the product filling tube 30.

Each of the pair of feed units 22L, 22R mainly comprises a base plate 23L, 23R, a drive pulley 24L, 24R, a driven pulley 25L, 25R, a tension pulley 26L, 26R, a feed belt 27L, 27R, and a feed servo motor 28L, 28R. The pair of feed units 22L, 22R have the same basic configuration except that they are inverted left and right, so the configuration of the feed unit 22R will be described below.

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

The feed belt 27R is stretched across the drive pulley 24R, driven pulley 25R, and tension pulley 26R. By sliding the feed unit 22R along the pair of guide shafts 21A, 21B, the portion of the feed belt 27R between the drive pulley 24R and driven pulley 25R comes into contact with the strip-shaped film Fw that covers the outer surface of the product filling tube 30. By moving the tension pulley 26R, tension is applied to the feed belt 27R.

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 rotates due to the driving force of the feed servo motor 28R, the feed belt 27R rotates around the drive pulley 24R, the driven pulley 25R, and the tension pulley 26R. When the feed belt 27R rotates while in contact with the strip film Fw, the strip film Fw formed into a cylindrical shape is transported downward along the product filling tube 30.

The product filling tube 30 is a cylindrical member with an open top and bottom. The product filling tube 30 is installed between the tube maker 14 and the horizontal sealing device 50, extending vertically along the feed direction of the strip-shaped film Fw formed into a cylindrical shape. A hopper 31 is attached to the top opening of the product filling tube 30. The product filling tube 30 fills the 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.

The vertical sealing device 40 is disposed in a position facing the product filling tube 30. More specifically, the vertical sealing device 40 is disposed 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 includes a pair of sealing blocks 41, 42 arranged to sandwich the overlapped ends of the strip film Fw. The pair of sealing blocks 41, 42 move toward and away from each other as the rotation of a servo motor is transmitted. Each of the pair of sealing blocks 41, 42 has a built-in heater. The pair of sealing blocks 41, 42 sandwich and heat the overlapped ends of the strip film Fw, thereby welding (sealing) both ends in the width direction. This causes the strip film Fw to be formed into a cylindrical shape.

The horizontal sealing device 50 is disposed downstream of the vertical sealing device 40 in the feed direction of the strip film Fw. The horizontal sealing device 50 forms the strip film Fw into bags Bp by welding (sealing) the cylindrically formed strip film Fw at predetermined intervals. More specifically, the horizontal sealing device 50 seals the portion of the strip film Fw formed into a cylindrical shape by the vertical sealing device 40 that corresponds to the bottom of the bag Bp and the portion that corresponds to the top of the bag Bp. The horizontal sealing device 50 also cuts the boundary between two consecutive bags Bp.

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

Figure 5 is a hardware configuration diagram of the vertical form fill and pack packaging machine 1. As shown in Figure 5, the control device 70 includes, for example, a CPU 71 (Central Processing Unit) which is a calculation means, and a memory 72 which is a storage means. The memory 72 is, for example, a ROM (Read Only Memory) which stores various programs, a RAM (Random Access Memory) which serves as a working area for the CPU 71, a 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 process described below.

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).

The control device 70 is connected to a feed amount sensor 73 and an operation panel 74. The feed amount sensor 73 detects the length of the strip film Fw fed in the feed direction by the film feed device 20, and outputs the detected length to the control device 70. The operation panel 74 includes a display that shows information (screen) to the operator, and an operation device (e.g., a touch panel, push button, etc.) that accepts operations by the operator.

Figure 6 shows an example of the tension setting screen. The tension setting screen is used to set the amount of tension that the tension mechanism 60 applies to the strip film Fw during each period of the sending process (acceleration period A-C, constant speed period D, deceleration period E-G) described below.

The tension setting screen includes, for example, a text box 81 for receiving input of a torque reference value α, a radio button 82 for selecting tension control during acceleration periods A-C (a collective term for the first control and second control described below), text boxes 83 and 84 for receiving input of the amount of tension increase β or decrease γ during acceleration periods A-C, a radio button 85 for selecting tension control during deceleration periods E-G, and text boxes 86 and 87 for receiving input of the amount of tension increase β or decrease γ during deceleration periods E-G.

The magnitude of tension (=reference value α) to be applied to the strip film Fw during the constant speed period D is input in text box 81. The option [Increase tension] of radio buttons 82 and 85 indicates that a first control is executed to increase the tension above the reference value α. The option [Decrease tension] of radio buttons 82 and 85 indicates that a second control is executed to decrease the tension below the reference value α. The option [No tension increase/decrease] of radio buttons 82 and 85 indicates that neither the first control nor the second control is executed. The amount of tension increase β in the first control is input in text boxes 83 and 86. The amount of tension decrease γ in the second control is input in text boxes 84 and 87.

The operator sets (inputs, selects) each item on the tension setting screen according to, for example, the properties of the strip film Fw (e.g., rigidity, degree of elongation, etc.) and the operating conditions of the vertical form-fill-seal packaging machine 1 (e.g., the length of one bag Bp, feed speed, etc.). The settings made through the tension setting screen are commonly applied to each of the repeatedly executed sending processes.

As an example, in the case of a strip film Fw with high rigidity, the first control may be selected for the acceleration period A-C, and the second control may be selected for the deceleration period E-G. As another example, in the case of a strip film Fw with low rigidity, the second control may be selected for the acceleration period A-C, and the first control may be selected for the deceleration period E-G. However, the tension controls performed during each of the acceleration and deceleration periods are not limited to the combinations mentioned above.

The operation panel 74 accepts an operation to instruct, via the tension setting screen, whether to execute the first control or the second control during the acceleration period and the deceleration period. The operation panel 74 also accepts an operation to instruct, via the tension setting screen, the amount of tension increase β in the first control and the amount of tension decrease γ in the second control. The control device 70 then stores the operator's instruction received via the tension setting screen in the memory 72. Note that α, β, γ, and δ in this specification are all positive values.

The control device 70 controls the rotation speed, rotation torque, or rotation amount of the servo motors of the film supply device 10, the film transport device 20, the vertical sealing device 40, and the horizontal sealing device 50. More specifically, the control device 70 controls the rotation speed, rotation torque, or rotation amount of the servo motors by outputting a command current (pulse signal) through a servo amplifier.

The control device 70 repeatedly performs the process of forming bags Bp from the strip film Fw and filling them with products by operating the film supply device 10, film feed device 20, vertical sealing device 40, and horizontal sealing device 50 in conjunction with each other. This allows the vertical form fill packaging machine 1 to produce multiple bags Bp in sequence.

First, the control device 70 drives the film supply device 10 and the film advance device 20 to execute a sending process that sends out the strip film Fw. Next, the control device 70 drives the vertical sealing device 40 to sandwich and seal the overlapped ends of the strip film Fw between a pair of sealing blocks 41, 42, thereby forming the strip film Fw into a cylindrical shape. The control device 70 also sandwiches and seals the portion of the strip film Fw formed into a cylindrical shape that corresponds to the top of the first bag and the portion that corresponds to the bottom of the second bag immediately after the first bag between the sealing blocks 51, 52. Furthermore, the control device 70 cuts the boundaries between adjacent bags Bp.

The sending process is a process in which a strip of film Fw equivalent to the length of one bag Bp is sent in the feed direction for a predetermined time. More specifically, as shown in Figures 7 and 8, the sending process includes an acceleration period A-C in which the feed speed of the strip of film Fw is accelerated, a constant speed period D in which the feed speed of the strip of film Fw is kept constant, and a deceleration period E-G in which the feed speed of the strip of film Fw is decelerated.

That is, the control device 70 feeds the stopped strip film Fw according to a predetermined speed pattern, and stops the feeding when the length of one bag Bp has been fed. The control device 70 also increases or decreases the rotation speed of the feed servo motors 28L and 28R based on the feed amount detected by the feed amount sensor 73 so that the strip film Fw corresponding to the length of one bag Bp is fed in a predetermined time. Furthermore, the control device 70 intermittently and repeatedly executes the feeding process.

Figure 7 is a diagram showing an example of the relationship between the feed speed of the strip film Fw by the film feed device 20 and the tension applied to the strip film Fw by the tension mechanism 60. More specifically, Figure 7 shows a case where the first control is executed during the acceleration period A-C, and the second control is executed during the deceleration period E-F. That is, the process shown in Figure 7 is the process when, on the tension setting screen, a reference value α = 1.0 is entered in the text box 81, the option [Increase tension] is selected with the radio button 82, an increase amount β = 0.2 is entered in the text box 83, the option [Decrease tension] is selected with the radio button 85, and a decrease amount γ = 0.3 is entered in the text box 87.

The control device 70 controls the feed servo motors 28L and 28R to execute the feed process in the following procedure. First, the control device 70 feeds out the strip film Fw while accelerating the feed speed (acceleration period A-C). The acceleration period A-C includes a period A during which acceleration increases, a period B of constant acceleration, and a period C during which acceleration decreases. Next, the control device 70 feeds out the strip film Fw at a constant feed speed (constant speed period D). Next, the control device 70 feeds out the strip film Fw while decelerating the feed speed (deceleration period E-G). The deceleration period E-G includes a period E during which the original speed (negative acceleration) increases, a period F of constant deceleration, and a period G during which deceleration decreases.

In addition, the control device 70 adjusts the tension applied to the strip film Fw by the tension mechanism 60 in parallel with the sending process. First, before starting the sending process, the control device 70 sets the tension applied to the strip film Fw by the tension mechanism 60 to a reference value α.

Next, the control device 70 increases the torque of the tension servo motor 65 during period A, thereby increasing the tension applied to the strip film Fw. Next, the control device 70 stops increasing the torque of the tension servo motor 65 at the timing when the tension applied to the strip film Fw has increased by an increment β from the reference value α, and maintains the tension at a constant value, thereby making the tension (=α+β) applied to the strip film Fw constant during period B. Next, the control device 70 reduces the torque of the tension servo motor 65 during period C, thereby reducing the tension applied to the strip film Fw to the reference value α. This process is an example of the first control.

Next, the control device 70 maintains the tension applied to the strip film Fw at the reference value α by stopping the reduction in the torque of the tension servo motor 65 during the constant speed period D and keeping it constant. This process is an example of reference control. However, the length of the constant speed period D may be as close to 0 as possible. In other words, the deceleration period E-G may begin immediately after the end of the acceleration period A-C.

Next, the control device 70 reduces the tension applied to the strip film Fw by reducing the torque of the tension servo motor 65 during period E. Next, the control device 70 stops the reduction in the torque of the tension servo motor 65 and holds it constant when the tension applied to the strip film Fw has decreased by the reduction amount γ from the reference value α, thereby keeping the tension (=α-γ) applied to the strip film Fw constant during period F. Next, the control device 70 increases the torque of the tension servo motor 65 during period G, thereby increasing the tension applied to the strip film Fw to the reference value α. This process is an example of the second control.

Next, the control device 70 drives the vertical sealing device 40 and the horizontal sealing device 50 during the period H during which the feeding of the strip film Fw is stopped. This forms a bag Bp (first bag) filled with the product. Next, the control device 70 executes the feeding process again to form the next bag Bp (second bag immediately after the first bag). The control device 70 also executes the tension control set through the tension setting screen (i.e., first control during the acceleration period and second control during the deceleration period) during the feeding process for the second bag.

In the delivery process, the feed servo motors 28L and 28R are driven to follow a predetermined target speed pattern (solid line in FIG. 7) in order to deliver the strip film Fw equivalent to the length of one bag Bp in a specified time. However, the actual feed speed of the strip film Fw (dashed line in FIG. 7) may deviate from the target speed pattern. Therefore, the control device 70 increases or decreases the rotation speed of the feed servo motors 28L and 28R based on the feed amount detected by the feed amount sensor 73.

For example, when the tension applied to the strip film Fw is increased, as in period A of the sending process for the first bag in Figure 7, the actual feed speed may fall below the target speed pattern. In this case, the control device 70 temporarily makes the actual feed speed faster than the target speed pattern by increasing the rotation speed of the feed servo motors 28L and 28R. Then, the control device 70 causes the actual feed speed to converge to the target speed pattern when the delayed feed amount is made up.

Then, as shown in FIG. 7, when the control device 70 temporarily increases the rotation speed of the feed servo motors 28L, 28R to make up for the delay in the feed amount in the sending process for the first bag, the control device 70 reduces the tension increase amount β in the first control by the correction amount δ during the acceleration period A-C of the sending process for the second bag. That is, the control device 70 applies a tension (α+β-δ) to the strip film Fw obtained by adding the increase amount β to the reference value α and subtracting the correction amount δ during the first control during the acceleration period A-C of the sending process for the second bag. The other processing is the same as in the sending process for the first bag. This makes it possible to bring the actual feed speed closer to the target speed pattern in the sending process for the second bag.

Figure 8 is a diagram showing another example of the relationship between the feed speed of the strip film Fw by the film feed device 20 and the tension applied to the strip film Fw by the tension mechanism 60. More specifically, Figure 8 shows a case where the second control is executed during the acceleration period A-C, and the first control is executed during the deceleration period E-F. That is, the process shown in Figure 8 is the process when, on the tension setting screen, a reference value α = 1.0 is entered in the text box 81, the option [Decrease tension] is selected with the radio button 82, a decrease amount γ = 0.3 is entered in the text box 84, the option [Increase tension] is selected with the radio button 85, and an increase amount β = 0.2 is entered in the text box 86.

The control device 70 reduces the tension applied to the strip film Fw by reducing the torque of the tension servo motor 65 during period A. Next, the control device 70 stops the reduction in the torque of the tension servo motor 65 and holds it constant when the tension applied to the strip film Fw has decreased by the reduction amount γ from the reference value α, thereby keeping the tension (=α-γ) applied to the strip film Fw constant during period B. Next, the control device 70 increases the torque of the tension servo motor 65 during period C, thereby increasing the tension applied to the strip film Fw to the reference value α. This process is an example of the second control.

The control device 70 also increases the torque of the tension servo motor 65 during period E, thereby increasing the tension applied to the strip film Fw. Next, the control device 70 stops increasing the torque of the tension servo motor 65 and holds it constant when the tension applied to the strip film Fw has increased by an increment β from the reference value α, thereby keeping the tension (=α+β) applied to the strip film Fw constant during period F. Next, the control device 70 reduces the torque of the tension servo motor 65 during period G, thereby reducing the tension applied to the strip film Fw to the reference value α. This process is an example of the first control.

Next, the control device 70 drives the vertical sealing device 40 and the horizontal sealing device 50 during the period H during which the feeding of the strip film Fw is stopped. This forms a bag Bp (first bag) filled with the product. Next, the control device 70 executes the feeding process again to form the next bag Bp (the second bag immediately after the first bag). The control device 70 also executes the tension control set through the tension setting screen (i.e., the second control during the acceleration period and the first control during the deceleration period) during the feeding process for the second bag.

Here, for example, if the tension applied to the strip film Fw is reduced, as in period A of the sending process for the first bag in FIG. 8, there is a possibility that the actual feed speed (dashed line in FIG. 8) will exceed the target speed pattern (solid line in FIG. 8). In this case, the control device 70 temporarily makes the actual feed speed slower than the target speed pattern by reducing the rotation speed of the feed servo motors 28L, 28R. Then, the control device 70 causes the actual feed speed to converge to the target speed pattern when the excess feed amount has been absorbed.

Then, as shown in FIG. 8, when the control device 70 temporarily reduces the rotational speed of the feed servo motors 28L, 28R to absorb the excess feed amount in the sending process for the first bag, the control device 70 reduces the tension reduction amount γ in the second control by the correction amount δ during the acceleration period A-C of the sending process for the second bag. That is, the control device 70 applies tension (α-γ+δ) to the strip film Fw, which is obtained by subtracting the reduction amount γ from the reference value α and adding the correction amount δ, during the second control during the acceleration period A-C of the sending process for the second bag. The other processes are the same as those in the sending process for the first bag. This makes it possible to bring the actual feed speed closer to the target speed pattern in the sending process for the second bag.

The above embodiment provides the following advantages:

According to the above embodiment, the first control or the second control is switched between during the acceleration period A-C depending on the properties of the strip film Fw and the operating conditions of the vertical form-fill-seal packaging machine 1, so that an appropriate tension can be applied to the strip film Fw during the acceleration period A-C, when the feed of the strip film Fw is likely to become unstable. In addition, the use of the tension servo motor 65 makes it easy to fine-tune the tension.

In addition, according to the above embodiment, the first control or the second control is switched between during the deceleration period E-G, so that the strip film Fw can be stopped at the timing when the length equivalent to one bag Bp has been fed out. This prevents the strip film Fw from being excessive or insufficient for forming the bag Bp, and also prevents the date printing position by the date printing device 15 from being misaligned.

In addition, according to the above embodiment, the operator sets each item through the tension setting screen, which allows appropriate settings to be made to obtain the desired results. However, instead of the tension setting screen, the control device 70 may use a sensor to detect the properties of the strip film Fw wound around the winding roll 11, and read and execute settings corresponding to the detected properties from the memory 72.

In addition, according to the above embodiment, the tension increase amount β or decrease amount γ in the sending process for the second bag is corrected depending on the deviation of the actual feed speed from the target speed pattern in the sending process for the first bag. This makes it possible to level out the feed amount of the strip film Fw in the sending processes that are repeatedly executed.

The method of determining the correction amount δ is not particularly limited as long as it is a value smaller than the increase amount β or decrease amount γ. As one example, the control device 70 may calculate the correction amount δ by multiplying the increase amount β or decrease amount γ by a coefficient less than 1 (e.g., 0.1). As another example, the control device 70 may set the correction amount δ to a larger value as the deviation of the actual feed speed from the target speed pattern increases.

1...Vertical bag making, filling and packaging machine, 10...Film supply device, 11...Winding roll, 12a-12h...Fixed guide roll, 14...Cylinder maker, 15...Date printing device, 16...Date inspection device, 20...Film feed device, 21A, 21B...Guide shaft, 22L, 22R...Feed unit, 23L, 23R...Base plate, 24L, 24R, 66...Drive pulley, 25L, 25R, 67...Driven 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, 42, 51, 52...seal block, 50...horizontal sealing device, 60...tension mechanism, 61L, 61R...levers, 62, 63...movable guide rolls, 64...oscillating shaft, 65...tension servo motor, 68...belt, 70...control device, 71...CPU, 72...memory, 73...feed amount sensor, 74...operation panel, 81, 83, 84, 86, 87...text boxes, 82, 85...radio buttons

Claims (8)

A form-fill-seal packaging 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-shaped packaging material from the winding roll;
a tension mechanism that is disposed on a feed path of the strip packaging material from the winding roll to the feed device and that applies tension to the strip packaging material fed from the winding roll by a tension servo motor;
a cylinder former for overlapping both ends of the strip packaging material fed by the feeding device in the width direction to form a cylinder;
a first sealing device for sealing both ends of the strip-shaped packaging material overlapped by the tube former;
a second sealing device that seals the portions of the strip-shaped 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;
a control device for controlling the operation of the feeding device and the tension mechanism,
The control device includes:
a first control for increasing the tension applied to the strip packaging material by the tension mechanism from a reference value during an acceleration period in which the feed speed of the strip packaging material by the feed device is accelerating;
a second control in which the tension applied by the tension mechanism to the strip-shaped packaging material is reduced below the reference value during the acceleration period, or The bag making, filling and packaging machine according to claim 1,
The control device is further configured to be capable of switching between executing the first control and the second control during a deceleration period in which the feed speed of the strip packaging material by the feed device is decelerating. The bag making, filling and packaging machine according to claim 2,
The control device performs reference control to set the tension applied by the tension mechanism to the strip-shaped packaging material at the reference value during a constant speed period between the acceleration period and the deceleration period. The bag making, filling and packaging machine according to claim 2,
an operation device that receives an operation for instructing whether the first control or the second control is to be executed during each of the acceleration period and the deceleration period,
The form-fill-seal machine, wherein the control device executes controls received through the operation device during each of the acceleration period and the deceleration period. The bag making, filling and packaging machine according to claim 4,
the operation device accepts an operation for instructing an increase amount of tension in the first control and an decrease amount of tension in the second control,
The control device includes:
In the first control, the tension is increased from the reference value by the increase amount received through the operation device,
a tension reducing unit that reduces the tension from the reference value by the reduction amount received through the operation device in the second control. The bag making, filling and packaging machine according to claim 1,
The control device includes:
a feed servo motor provided in the feed device is operated at a rotation speed to intermittently repeat a feed process for feeding a length of the strip of packaging material corresponding to a bag in a predetermined time;
a form-fill-seal packaging machine, characterized in that the first control or the second control is executed during the acceleration period of each of the repeatedly executed feeding processes. The bag making, filling and packaging machine according to claim 6,
The feeding device further includes a feeding amount sensor for detecting the amount of the strip-shaped packaging material fed by the feeding device,
a control device for controlling a feeding speed of a second bag immediately after the first bag from a first position in a bag-making, filling and packaging machine, the control device being configured to reduce an increase in tension in the first control during the acceleration period of the feeding process for a second bag immediately after the first bag when the rotational speed of the feed servo motor is increased to make up for a delay in the feed amount detected by the feed amount sensor in the feeding process for a first bag. The bag making, filling and packaging machine according to claim 6,
The feeding device further includes a feeding amount sensor for detecting the amount of the strip-shaped packaging material fed by the feeding device,
a control device for controlling the feeding of a bag by a second bag after the first bag, the control device controlling the feeding of a bag by a second bag after the first bag, the control device controlling the feeding of a bag by a second bag after the first bag, the control device controlling the feeding of a bag by a second bag after the first bag, the control device controlling the feeding of a bag by a second bag after the first bag, the control device controlling the feeding of a bag by a second bag after the first bag, the control device controlling the feeding of a bag by a second bag after the first bag, the control device controlling the feeding of a bag by a second bag after the first bag,

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