Pillow packaging machine and method for adjusting tension of packaging material

Abstract

To provide a pillow packaging machine capable of maintaining the tension of a packaging material in a desired state, and suppressing the breakage of the film due to excessive tension and the generation of wrinkles due to looseness CONSTITUTION: The packaging machine includes a packaging machine body 11 for pillow packaging, and a packaging material supply device 12 for supplying a paper packaging material 15 to the packaging machine body. A feed roller 18 driven by a first motor 31 is provided on a packaging material feeder side, and a first pinch roller 21c and a second pinch roller 21d driven by a second motor 32 and a third motor 33 are provided on a packaging machine body side, as a constitution for applying carrying force to the packaging material. The control device 30 adjusts the rotation speed of the second motor from the torque of the first motor collected when the packaging material intermittently conveyed is temporarily stopped, and adjusts the speed of the third motor from the difference between the torque of the second motor 32 and the torque of the third motor 33.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pillow packaging machine and a method for adjusting tension of packaging material. [Background technology]

[0002] Patent Document 1 discloses a film supplying device that supplies packaging film unwound from a raw roll to a bag former in the main packaging machine body. The device includes a tension detection device that detects the tension of the film at a predetermined position on the transport path of the packaging film from the raw roll to the bag former, and a speed control device that receives an actual tension signal detected by the tension detection device, compares it with a preset reference value, and controls the speed of the drive motor for the raw roll so that the two values ​​match. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3575843 Summary of the Invention [Problem to be solved by the invention]

[0004] The device disclosed in Patent Document 1 has a tension detector equipped with a pressure sensor between the raw fabric roll and the bag making machine, but this has the problem of making the parts arrangement complicated and placing restrictions on the arrangement of other parts in order to secure space.

[0005] In addition, the tension in the film is detected as a current value from the torque of auxiliary rollers, etc., and this information is fed back to the motor on the original shaft to control the rotation speed so that the tension remains constant. However, due to the frictional resistance of the bag maker, the torque of auxiliary rollers, etc. cannot accurately determine the tension of the film upstream of the bag maker.

[0006] If the tension cannot be adjusted accurately and appropriately, there is a risk that the film will break due to excessive tension or wrinkles will occur due to slack.

[0007] The above-mentioned problems are described as being independent of each other, and the present invention does not necessarily have to solve all of the problems described, but it is sufficient if it can solve at least one of the problems. Furthermore, we intend to obtain rights to the configurations for solving these problems separately through divisional applications, amendments, etc. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the pillow packaging machine of the present invention comprises (1) a packaging machine main body that performs pillow packaging, and a packaging material supply device that pulls out a strip-shaped packaging material wound on a raw material roll and supplies the pulled-out packaging material to the packaging machine main body, wherein the packaging material supply device is configured to apply a conveying force to the packaging material by a feed roller driven by a first motor, and the packaging machine main body has a bag former that forms the packaging material into a cylindrical shape, a center seal device that seals both side edge portions of the packaging material formed into a cylindrical shape by the bag former, and a top seal device that is arranged downstream of the center seal device and seals and cuts the packaging material in a direction perpendicular to the conveying direction, and is configured to pinch and pull both side edge portions with a pair of first pinch rollers driven by a second motor, and is equipped with a control device that controls the rotational speed of the second motor so that the torque applied to the first motor becomes a first reference.

[0009] Because control is based on motor torque, the configuration for detecting the tension and tautness of the packaging material can be simple and compact, increasing the degree of freedom in the layout of the components that make up the packaging machine.In addition, because the tension state is determined based on the torque of the feed rollers located upstream of the bag maker, the tension state can be grasped with high accuracy, and the packaging material can be sent to the bag maker with the appropriate tension.

[0010] (2) The first pinch roller is arranged upstream of a center sealer that heats the both side edge portions of the center seal device, and a pair of second pinch rollers are provided downstream of the center sealer that pinch and pull the both side edge portions, and the control device may have a function to control the speed of the third motor based on the difference between the torque of the second motor and the torque of a third motor that drives the second pinch rollers.

[0011] In this way, in a pillow packaging machine having a first pinch roller and a second pinch roller at the front and rear along the conveying direction, the tensile force of the first pinch roller and the tensile force of the second pinch roller on the packaging material can be adjusted to a desired relationship depending on the thickness, properties, humidity, etc. of the packaging material and the usage environment, allowing the packaging material to be conveyed with appropriate tension between the first pinch roller and the second pinch roller. The control device may be composed of a single device or device, or may be composed of multiple devices or devices.

[0012] (3) The operating range of the speed ratio of the rotational speed of the second motor and the third motor to the rotational speed of the first motor is set as a second standard, and the control device may control the rotational speeds of the second motor and the third motor within a range that falls within the second standard.

[0013] By adjusting the speed of each motor within the second standard range in this way, the rotation speeds of the feed roller, first pinch roller, and second pinch roller can be balanced, and the tension of the packaging material can be stabilized.

[0014] (4) The packaging material may be configured to be conveyed intermittently, and the torque may be collected when the conveyance of the packaging material is stopped. In this way, variation in the collected torque is suppressed, and the tension state of the packaging material can be detected with high accuracy.

[0015] (5) The first standard may have a predetermined range, and the control device may be configured not to change the rotation speed of the second motor if the torque of the first motor is within the predetermined range. This can prevent frequent speed changes due to factors such as the surrounding environment (e.g., humidity) or uneven packaging quality.

[0016] The method for adjusting the tension of packaging material according to the present invention is (6) a method for adjusting the tension of packaging material in a pillow packaging method in which a strip-shaped packaging material is pulled out by a feed roller and supplied to a bag former of a packaging machine main body, the packaging material is formed into a tubular shape by passing through the bag former, both side edge portions of the packaging material formed into a tubular shape by the bag former are pinched by first pinch rollers while a conveying force is applied to the packaging material, both side edge portions of the packaging material formed into a tubular shape by the bag former are sealed by a center seal device, and the packaging material is sealed and cut in a direction perpendicular to the conveying direction downstream of the center seal device to produce a pillow package, and the rotational speed of a second motor that drives the first pinch roller is controlled so that the torque applied to a first motor that drives the feed roller becomes a first reference value.

[0017] (7) The first pinch roller is arranged upstream of a center sealer that heats the both side edge portions of the center seal device, and a pair of second pinch rollers that pinch and pull the both side edge portions are arranged downstream of the center sealer, and the speed of the third motor is controlled based on the difference between the torque of the second motor and the torque of a third motor that drives the second pinch rollers.

[0018] Furthermore, the configurations shown in (1) to (7) above can be configured by combining them as appropriate, and based on such combined configurations, it is advisable to combine the components described in the embodiments and drawings. [Effects of the Invention]

[0019] According to the present invention, the tension of the packaging material is maintained at a desired level, preventing film breakage due to excessive tension and wrinkles due to slack, thereby improving productivity. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram showing a preferred embodiment of a pillow packaging machine according to the present invention; [Figure 2] 4 is a flowchart showing the function of the control device 30. [Figure 3] 4 is a flowchart showing the function of the control device 30. [Figure 4] 4 is a flowchart showing the function of the control device 30. DETAILED DESCRIPTION OF THE INVENTION

[0021] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to these embodiments, and various changes, modifications, and improvements can be made based on the knowledge of those skilled in the art without departing from the scope of the present invention.

[0022] Figure 1 shows a preferred embodiment of the pillow packaging machine according to the present invention. The pillow packaging machine 10 of this embodiment pillow packages randomly supplied products 13 of different sizes. The products 13 may be, for example, a single item or a combination of multiple items. Products 13 of different sizes may include products of the same type, such as sandwich breads and other breads, each with different dimensions and shapes, or single items or collections of any number of the same items lined up one behind the other.

[0023] This pillow packaging machine 10 adjusts the cutting dimensions of the packaging material to match the product length, which is the length in the front-to-back direction along the conveying direction of the product 13, and produces a package with dimensions and shape that match the size of the product 13.

[0024] The pillow packaging machine 10 that sequentially packages various products 13 as described above includes a packaging machine main body 11 and a packaging material supply device 12 that continuously supplies strip-shaped packaging material 15 to the packaging machine main body 11. The packaging material 15 may be made of various materials, such as film or paper. In this embodiment, a paper packaging material 15 is used.

[0025] The packaging material supply device 12 supplies the packaging machine main body 11 with a strip-shaped packaging material 15 for wrapping the product 13. The pillow packaging machine 10 of this embodiment operates intermittently. Accordingly, the packaging material supply device 12 repeatedly conveys and pauses the packaging material 15.

[0026] The packaging material supply device 12, which intermittently conveys and supplies the packaging material 15 to the packaging machine main body 11 in this manner, includes a rotating shaft 17 that supports a web roll 16 on which the strip-shaped packaging material 15 has been wound into a roll, and a plurality of rollers that form a conveying path that guides the packaging material 15, which is continuously unwound from the web roll 16, to the packaging machine main body 11. The packaging material 15 is passed over rollers that are arranged at appropriate positions, and is guided to the packaging machine main body 11 through a predetermined path. These rollers include feed rollers 18 that apply drive to the strip-shaped packaging material 15, dancer rollers 19 that eliminate slack, and free rollers 14 that change the conveying direction of the strip-shaped packaging material 15 and guide its conveyance.

[0027] The feed roller 18 is configured to rotate by receiving a driving force from a first motor 31 and to apply a conveying force to the packaging material 15. The first motor 31 may be a speed-controllable motor such as a servo motor. The first motor 31 rotates at a predetermined speed based on a control signal from the control device 30. Furthermore, since the pillow packaging machine 10 operates intermittently, the control device 30 provides the first motor 31 with a predetermined control signal to cause the first motor 31 to repeatedly rotate at a predetermined rotational speed and pause. Furthermore, during the pause, the first motor 31 is controlled to maintain the angular position at the time of the pause.

[0028] The dancer roller 19 is disposed upstream of the feed roller 18. The dancer roller 19 is connected to a biasing means, such as a spring or an elastic member or a cylinder, and biases the strip-shaped packaging material 15 in the direction opposite to the slackening direction based on the biasing force of the biasing means, thereby preventing the packaging material 15 from slackening. That is, in this embodiment, the strip-shaped packaging material 15 moves as the feed roller 18 rotates, which in turn rotates the web roll 16 and pulls out the packaging material 15. When the rotation of the first motor 31 is temporarily stopped based on a command from the control device 30, the rotation of the feed roller 18 is also temporarily stopped. Therefore, the movement of the packaging material 15 by the feed roller 18 is also temporarily stopped. When slack occurs in the packaging material, the dancer roller 19 moves in a predetermined direction to absorb the slack. Furthermore, slack does not occur only when the packaging material is temporarily stopped as described above, but also during normal movement of the packaging material 15.

[0029] In this embodiment, an operator manually places products 13 in a waiting area onto a supply conveyor (not shown), which supplies the products 13 to the packaging machine main body 11, whereupon the pillow packaging machine 10 automatically packages the supplied products 13 to produce packages 26. The packaging machine main body 11 operates intermittently at a fixed takt time, and supplies products 13 in accordance with its operation. Furthermore, the system is not limited to this manual supply of products 13 by an operator; a product supply conveyor may be provided upstream of the bag former 20, and products 13 continuously conveyed from the upstream side may be supplied to the bag former 20.

[0030] The packaging machine main body 11 is equipped with a bag former 20 that forms a cylindrical bag from the packaging material 15 supplied to its inlet side. The bag former 20 passes the strip-shaped packaging material 15 continuously supplied from the packaging material supply device 12, causing both side edge portions 15a of the packaging material 15 to come into contact (overlap) with each other and forming a cylindrical bag.

[0031] Furthermore, the packaging machine main body 11 is equipped with a center seal device 21 that is arranged downstream of the bag former 20 and joins both side edges of the packaging material 15 together, a top seal device 22 that is arranged downstream of the center seal device 21, and an output conveyor 23 that is arranged downstream of the top seal device 22. Furthermore, although not shown, it is preferable to arrange a belt or a bridge plate or the like that forms a conveying path between the center seal device 21 and the top seal device 22.

[0032] The center seal device 21 includes two upper plates 21a arranged at a predetermined distance from each other. The packaging material 15 is conveyed with both side edge portions 15a protruding downward from the gap between the upper plates 21a. The center seal device 21 also includes a pair of left and right bar sealers 21b arranged below the upper plates 21a to heat the both side edge portions 15a of the packaging material 15, a pair of left and right first pinch rollers 21c arranged upstream of the bar sealers 21b, and a pair of left and right second pinch rollers 21d arranged downstream of the bar sealers 21b. The pair of bar sealers 21b are configured to open and close so that the opposing heating surfaces move toward and away from each other. While the worker is inserting the product 13, the pair of bar sealers 21b preferably wait in an open state to avoid excessive heating of the packaging material 15. Once the product 13 has been inserted and the packaging material 15 begins to be conveyed, the bar sealers close and begin to heat the packaging material 15.

[0033] The first pinch roller 21c and the second pinch roller 21d pinch both side edge portions 15a of the packaging material 15 that come into contact with each other via the bag former 20 with a predetermined pressure, and by rotating in synchronization, apply a conveying force to the both side edge portions 15a and ultimately to the packaging material 15. The second pinch roller 21d also functions as a pressure roller that applies pressure to and cools the both side edge portions 15a of the packaging material 15 that have been heated by the bar sealer 21b to fuse and seal them. This sealed area becomes the center seal portion of the package 26.

[0034] The first pinch roller 21c and the second pinch roller 21d are linked to a second motor 32 and a third motor 33, respectively, which rotate at a predetermined speed based on the rotational output of each motor. Like the first motor 31, the second motor 32 and the third motor 33 are configured using speed-controllable motors such as servo motors. The control device 30 controls the rotation of the second motor 32 and the third motor 33. The control of the rotation of the second motor 32 and the third motor 33 is performed by providing the second motor 32 and the third motor 33 with predetermined control signals so that they alternately rotate at a predetermined rotational speed and pause, similar to the first motor 31. The timing and duration of the pause are set to be the same as those of the first motor 31, but the rotational speed is set to be different as appropriate. During the pause, the second motor 32 and the third motor 33 are controlled to maintain the angular position at the time of the pause.

[0035] The top sealing device 22 seals and cuts the cylindrical packaging material 15 containing the product 13 in a direction perpendicular to the conveying direction, parallel to the conveying surface, and transverse to the material. The top sealing device 22 has an upper top sealer 24 and a lower top sealer 25 above and below the packaging material 15, sandwiching it between them. The upper top sealer 24 and the lower top sealer 25 each have a built-in heater, which heats the sealing surfaces at their respective tips to a predetermined temperature. Furthermore, a cutter blade is built into the sealing surface 24a of the upper top sealer 24, for example, in the center in the front-to-back direction. The sealing surface 25a of the lower top sealer 25 also has a cutter groove in the center in the front-to-back direction.

[0036] In this embodiment, the upper top sealer 24 and the lower top sealer 25 approach and move away from each other with their sealing surfaces 24a, 25a facing each other. As they approach each other, the upper and lower sealing surfaces 24a, 25a sandwich and heat the packaging material 15 from above and below, and the cutter blades enter the cutter grooves to cut it. Thus, the top sealing device 22 seals and cuts a predetermined position (a portion where no product is present) of the center-sealed packaging material 15 laterally, forming a top seal portion that extends laterally. As a result, the leading end portion of the packaging material 15 (the portion containing the leading product 13) is separated from the following packaging material 15, and package 26 is produced.

[0037] The top sealing device 22 may be positioned, for example, at a position where the upper top sealer 24 and the lower top sealer 25 sandwich and cut the packaging material 15.

[0038] The pillow packaging machine 10 of this embodiment has a function of controlling the top sealing device 22 to seal and cut the packaging material 15 to a cut length that matches the length of the product when packaging products 13 of different sizes that are randomly supplied.

[0039] The control device 30 rotates the first motor 31, which has been temporarily stopped, at a predetermined speed according to a predetermined takt time, and rotates the feed roller 18 to start conveying the packaging material 15, and also starts operation of the packaging machine main body 11, which had been temporarily stopped due to intermittent operation. Then, as the packaging material 15 moves, the products 13 inside the packaging material 15, which have been made into cylindrical bags by the bag former 20, are also conveyed together with the packaging material 15.

[0040] The control device 30 then controls the top sealing device 22, and the packaging material 15 is sandwiched between the upper top sealer 24 and the lower top sealer 25, and sealed and cut.

[0041] In this embodiment, the control device 30 controls the first motor 31 to rotate at a constant speed, so that the feed roller 18 rotates at a constant speed and moves the packaging material 15 at a constant speed.

[0042] Furthermore, the control device 30 instructs the second motor 32 and the third motor 33 to repeatedly pause and rotate at the same timing as the first motor 31. As described above, the first motor 31 rotates at a constant speed during rotation, and operates to move the packaging material 15 at the same set speed.

[0043] The packaging material 15 of this embodiment is made of paper, and is characterized by being thicker and harder than resin film. As described above, the packaging material 15 is made into a tubular bag as it passes through the bag former 20. However, the direction of travel of the packaging material 15 is suddenly bent, particularly at the entrance, and the packaging material 15 comes into contact with the surface of the bag former 20. As a result, the resistance to movement is greater near the bag former 20 than elsewhere, and the packaging material tends to sag more easily on the upstream side of the bag former 20. This slack is absorbed to some extent by the dancer roller 19. To prevent slack from occurring, first pinch roller 21c and second pinch roller 21d pinch both side edge portions 15a of the packaging material 15 and rotate to apply a predetermined conveying force to the packaging material 15.

[0044] The control device 30 controls the rotation speeds of the second motor 32 and the third motor 33 so as to balance the force pulling the packaging material 15 by the first pinch roller 21c and the second pinch roller 21d with the conveying force of the feed roller 18. When the rotation speeds of the motors are appropriately adjusted, the packaging material 15, which receives the conveying force from the feed roller 18 and moves along the movement path under a predetermined tension, is supplied to the packaging machine main body 11. On the other hand, if this adjustment is not appropriate and the conveying force of the first pinch roller 21c and the second pinch roller 21d is weak compared to the conveying force of the feed roller 18, the packaging material 15 will slacken. Conversely, if the conveying force of the first pinch roller 21c and the second pinch roller 21d is relatively strong, the packaging material 15 will be pulled too hard, causing wrinkles in the packaging material 15. Furthermore, because the packaging material 15 is made of paper, excessive tension may cause the packaging material 15 to break.

[0045] Therefore, the control device 30 determines the tension of the packaging material 15, and if the tension is weak, increases the rotation speed of the second motor 32 and controls the rotation speed of the first pinch roller 21c. On the other hand, if the tension of the packaging material 15 is strong, the control device 30 controls the rotation speed of the second motor 32 and controls the rotation speed of the first pinch roller 21c to decrease. This balances the pulling force on the packaging material 15 by the first pinch roller 21c with the conveying force on the packaging material 15 by the feed roller 18, stabilizes the tension of the packaging material 15, and allows the packaging material 15 to move without sagging, meandering, or breaking.

[0046] To perform this control, the control device 30 controls the rotation speed of the second motor 32 so that the torque applied to the first motor 31 that drives the feed roller 18 becomes equal to a first reference torque. The first reference torque is a torque that allows the packaging material 15 to be conveyed with appropriate tension, and may be set to a specific value, such as -5, or may have a predetermined range, such as -5 to -10.

[0047] Regarding the relationship between torque and tension of the packaging material 15, if the rotation direction (counterclockwise in the example of FIG. 1) for conveying the packaging material 15 by the drive shaft of the feed roller 18 (the right-hand roller connected to the first motor 31 in the example of FIG. 1) is considered to be a positive direction, then if the torque of the first motor 31 is smaller than a first reference value, it is presumed that the packaging material 15 between the bag former 20 and the feed roller is somewhat tense. In this case, the rotation speed of the second motor 32 is slowed down so as to reduce the speed ratio of the first pinch roller 23c to the feed roller 18. On the other hand, conversely, if the torque of the first motor 31 is greater than the first reference value, the tension of the packaging material 15 between the bag former 20 and the feed roller is weak, and the rotation speed of the second motor 32 is increased so as to increase the speed ratio of the first pinch roller 23c to the feed roller 18.

[0048] If the mounting direction of first motor 31 is changed so that clockwise rotation becomes positive in the example of Figure 1, the torque magnitude relationship with respect to the first reference and the increase / decrease in speed control for second motor 32 will be reversed. In the following explanation, it is assumed that first motor 31 is linked so that the rotation direction (counterclockwise rotation in the example of Figure 1) for conveying packaging material 15 with the drive shaft of feed roller 18 becomes positive. Similarly, second motor 32 and third motor 33 attached to first pinch roller 21c and second pinch roller 21d are also linked so that the rotation direction of each pinch roller in the direction of conveying packaging material 15 becomes positive.

[0049] Based on the above assumptions, the control device 30 increases the rotation speed of the second motor 32 when the torque of the first motor 31 is large. That is, when the torque of the first motor 31 is large, the packaging material 15 between the bag former 20 and the first pinch roller 21c is loose and slack, so by increasing the speed of the second motor 32, the pulling force and conveying speed of the first pinch roller 21c are increased, and adjustments are made to eliminate the slack. On the other hand, when the torque of the first motor 31 is small, the control device 30 decreases the rotation speed of the second motor 32. That is, when the torque of the first motor 31 is small, the packaging material 15 is excessively pulled, so by decreasing the speed of the second motor 32, the pulling force and conveying speed of the first pinch roller 21c are reduced, and adjustments are made to eliminate the excessive pulling state.

[0050] By performing such control, the pulling force on the packaging material 15 by the first pinch roller 21c is balanced with the conveying force on the packaging material 15 by the feed roller 18, the tension of the packaging material 15 is stabilized, and the packaging material 15 can move without sagging, meandering, or breaking.

[0051] Furthermore, in this embodiment, the control device 30 calculates the tension of the packaging material 15 between the first pinch roller 21c and the second pinch roller 21d by calculating the difference in torque between the second motor 32 and the third motor 33, and adjusts the speed of the third motor 33 so that the calculated torque difference is kept constant at a set value. For example, a torque difference of 0 is desirable because it means that the packaging material 15 is being pulled by the first pinch roller 21c and the second pinch roller 21d without any tension. Alternatively, the pulling force on the side of the second pinch roller 21d may be slightly increased (the torque of the second motor 32 may be increased) so that the packaging material 15 is conveyed in a slightly taut state. By controlling in this manner, the packaging material 15 can be conveyed with appropriate tension applied to it.

[0052] It is preferable that the conveying speed of the packaging material 15 by the first pinch roller 21c and the second pinch roller 21d be approximately the same. When each pinch roller applies a conveying force to the packaging material 15 without slippage, the torque difference between the second motor 32 and the third motor 33 is basically zero. However, there are cases where a difference is required depending on the thickness or humidity of the packaging material 15. Furthermore, as will be described later, even when controlling so that the torque difference is zero, it is advisable to provide a certain margin above and below.

[0053] As described above, the control device 30 of this embodiment controls the speed of the second motor 32 based on the torque of the first motor 31, and controls the speed of the third motor 33 based on the torque difference between the second motor 32 and the third motor 33. In this embodiment, the first motor 31, the second motor 32, and the third motor 33 are servo motors, and the servo motors have a torque detection function. Therefore, the control device 30 collects the torque values ​​output from each motor using the torque detection function to perform predetermined control.

[0054] In this embodiment, the speed of the first motor 31 is fixed, and the speeds of the second motor 32 and the third motor 33 are adjusted by the control described above. However, it is also possible to set a second standard, which is an appropriate range of the speed ratio of the second motor 32 and the third motor 33 to the rotational speed of the first motor 31, and control the rotational speeds of the respective motors within the second standard. The second standard speed ratio may be determined, for example, by determining an appropriate speed ratio range for each packaging material and storing it in the control device 30. The speeds of the second motor 32 and the third motor 33 may be adjusted within the second standard range, and speed changes that exceed the second standard may be avoided. The second standard is the range within which each motor can operate with an appropriate torque. If speed correction of the second motor 32 based on the torque of the first motor 31 or speed correction of the third motor 33 based on the torque difference between the second motor 32 and the third motor 33 would exceed the second standard, the control device 30 may perform a predetermined error process without making the correction. The error can be handled, for example, by stopping operation of the pillow packaging machine 10 and reporting a state in which the second standard has been exceeded. That is, the second standard is a range in which stable, normal operation is possible, and control that exceeds this range may indicate some kind of problem with the pillow packaging machine 10, so the device should be stopped and a manual check should be performed. Adjusting the speed of each motor within the range of the second standard in this way makes it possible to balance the rotational speeds of the feed roller 18, first pinch roller 21c, and second pinch roller 21d, thereby stabilizing tension.

[0055] Furthermore, in this embodiment, the torque of each motor is collected when the motors are stopped during intermittent operation. This is because measuring torque while the packaging material 15 is being fed would result in some resistance being applied to the packaging material 15, for example, as the packaging material 15 moves while in contact with the bag former 20, resulting in greater variation in the collected torque. Furthermore, in this embodiment, the dimensions, shape, and weight of the products 13 to be packaged vary each time, and therefore the load applied by the products 13 to the packaging material 15 during transport also varies each time. These factors also contribute to variation in the torque collected while the packaging material 15 is moving. In contrast, measuring torque when the motors are stopped prevents the above-mentioned problem from occurring, and makes it possible to accurately determine the current force pulling the packaging material 15 at the installation position of the rollers connected to each motor.

[0056] Then, when the next movement starts, the control device 30 controls the motors so that they rotate at a rotation speed adjusted based on the torque of each motor collected while the motors were stopped.

[0057] The control device 30 for performing the above control may, for example, have a function to execute the flowchart shown in Fig. 2. First, the control device 30 waits for the top sealers (upper top sealer 24 and lower top sealer 25) of the top sealing device 22 to start operating (S1), and once operation has started, collects the value of M1 torque, which is the torque of the first motor 31 (S2). That is, the pillow packaging machine 10 of this embodiment operates intermittently, and while the packaging material 15 is being conveyed, the upper top sealer 24 and the lower top sealer 25 stop at a standby position where they are separated from each other, and after the conveyance of the packaging material 15 is temporarily stopped, the upper top sealer 24 and the lower top sealer 25 start operating. Therefore, the control device 30 does not collect the M1 torque value until the top sealers start operating, but collects it after they have started, thereby making it possible to obtain the torque value when the conveyance of the packaging material 15 is stopped during intermittent operation. In addition, the determination of whether the top sealer has started operating can be made, for example, by detecting the operation of the drive source or drive mechanism that moves the top sealer, or by providing a sensor that detects the movement of the top sealer and basing it on the detection output of that sensor.

[0058] The control device 30 determines whether the position of the top sealer is outside the collection range (S3), and if it is within the collection range (No in S3), returns to S2 and collects the M1 torque value. In this way, the control device 30 collects the M1 torque value at a predetermined sampling period until it falls outside the collection range. The collection range may be, for example, until the sealing surface of the top sealer contacts the packaging material 15, until the packaging material 15 is slightly pushed in after contact, or until the sealing surfaces of the upper top sealer 24 and the lower top sealer 25 come into contact with each other via the packaging material 15. Whether it is outside the collection range may be determined, for example, by detecting the operation of the drive source or drive mechanism that moves the top sealer, or by providing a sensor that detects the movement of the top sealer and basing the detection output of that sensor.

[0059] If the position of the top sealer is outside the collection range (No in S3), the control device 30 calculates the average value of the M1 torque collected up to that point (M1 average torque) (S4). Then, it is determined whether the calculated M1 average torque is outside a first set range (S5). If the M1 average torque is outside the first set range (Yes in S5), the control device 30 performs a correction process for the speed of the second motor 32 (S6). On the other hand, if the M1 average torque is within the first set range (No in S5), the correction process for the second motor 32 is not performed.

[0060] This first set range may be, for example, a predetermined width (a range from a first minus set value to a first plus set value) with a predetermined margin provided above or below the reference torque when the packaging material 15 is at the target tension. The upper and lower margins from the reference torque may be equal or different. Also, one or both of the first minus set value and the second plus set value may be the same as the reference torque. If both are the same, the first set range becomes a single point of the reference torque, and it is determined whether the M1 torque is the same as the reference torque (first set value), and if they are different, a predetermined correction process is performed.

[0061] The correction process in processing step S6 is a process to increase the rotational speed of second motor 32 when M1 average torque is large and equal to or greater than the first positive set value, and a process to decrease the rotational speed of second motor 32 when M1 average torque is small and equal to or less than the first negative set value. These processes may be performed by immediately changing the speed of second motor 32 the next time operation is resumed, or by monitoring a state outside the first set range rather than immediately, and actually changing the speed if the state continues to exceed the first set range. In the former case, the tension of packaging material 15 can be quickly adjusted. In the latter case, the speed is actually changed if the state continues to exceed the first set range, which prevents frequent speed changes.

[0062] Next, the control device 30 calculates the difference (torque difference) between the M2 torque, which is the torque of the second motor 32, and the M3 torque, which is the torque of the third motor 33 (S7), and determines whether the calculated torque difference is outside a second set range (S8). If the torque difference is outside the second set range (Yes in S8), the control device 30 performs a correction process for the speed of the third motor 33 (S9). If the torque difference is within the second set range (No in S8), the correction process for the third motor 33 is not performed.

[0063] The motor torques of the second motor 32 and the third motor 33 for which the torque difference is to be calculated may be, for example, the torques obtained at the time of execution of process step S7, but it is also preferable to obtain the motor torques of the second motor 32 and the third motor 33 at the same time as collecting the M1 torque value in process step S2, and calculate the torque difference based on the torques of the second motor 32 and the third motor 33 obtained at the same time. Furthermore, if the torques of the second motor 32 and the third motor 33 are collected multiple times, it is preferable to average the torque differences calculated for each pair as described above, and use the averaged torque difference to make the determination in process step S8.

[0064] The second set range may be a predetermined width (a range from a second minus set value to a second plus set value) with a predetermined margin provided above or below the target second set value for the torque difference, or both. The upper and lower margins for the second set value may be equal or different. In addition, one or both of the second minus set value and the second plus set value may be the same as the second set value. If both are the same, the second set range becomes a single point at the second set value, and it is determined whether the torque difference is the same as the second set value. If they are different, a predetermined correction process is performed.

[0065] As an example of a specific numerical value for the second setting range, for example, if the second setting value is set to 0 and there is a margin of 5 above and below, the second positive setting value is +5 and the second negative setting value is -5, and the second setting range is within ±5. Also, a negative setting value means the negative side of the setting value, and for example, if the second setting value is +6 and the margin is ±5 as above, the second positive setting value is +11 and the second negative setting value is +1. In this way, the packaging material 15 is conveyed with a slight tension applied by the second pinch roller 21d.

[0066] When setting the second setting range, in the above example, the margins are the same on the plus side and the minus side, such as ±5, but they may be different.

[0067] The correction process in processing step S8 is preferably a process to reduce the rotational speed of the third motor 33 if the torque difference is equal to or greater than the upper limit of the second set range, and a process to increase the rotational speed of the third motor 33 if the torque difference is equal to or less than the lower limit of the second set range. These processes may be performed by immediately changing the speed of the third motor 33 the next time operation is restarted, or by monitoring a state outside the second set range and actually changing the speed if that state continues to be outside the range. In the former case, the tension of the packaging material 15 can be quickly adjusted. In the latter case, the speed is actually changed if the state continues to exceed the range, which prevents frequent speed changes.

[0068] FIG. 3 shows an example of a more specific processing flow of processing steps S5 and S6 for controlling the rotation speed of the second motor 32, and is an example of a pattern in which the speed is not changed immediately even if the M1 average torque falls outside the first set range.

[0069] First, in this example, the upper limit of the first setting range is the first positive setting value, and the lower limit is the first negative setting value. The first positive setting value is greater than the first negative setting value, and the first setting range has a predetermined width. The control device 30 then determines whether the calculated M1 average torque is equal to or greater than the first positive setting value (S5a). If it is equal to or greater than the first positive setting value (Yes in S5a), the control device 30 increments the M2 correction count by 1 (S6a). The control device 30 then determines whether the incremented M2 correction count is equal to or greater than a set value (S6b). If the M2 correction count is less than the set value (No in S6b), the current correction process for the second motor 32 ends, and the process proceeds to step S7.

[0070] On the other hand, if the M2 correction count is equal to or greater than the set value (Yes in S6b), the rotational speed of the second motor 32 is corrected in a positive direction, i.e., increased (S6c). This positive correction can be achieved by changing the rotational speed command value. As a result, when the sealing and cutting process in the top sealing device 22 is completed and the next product 13 is supplied, and the conveyance of the packaging material 15 is resumed, the control device 30 provides the second motor 32 with the positively corrected command value. Therefore, the second motor 32 rotates at the increased rotational speed from the next conveyance, and the first pinch roller 21c rotates at the speed and torque associated with that rotation.

[0071] Thereafter, the control device 30 clears the M2 correction count and the M3 correction count (S6d), and ends this processing.

[0072] On the other hand, if the branch determination in process step S5a is No, the control device 30 proceeds to process step S5b, where it determines whether the calculated M1 average torque is equal to or less than a first negative set value (S5b). If it is equal to or less than the first negative set value (Yes in S5b), the control device 30 increments the M2 correction count by 1 (S6e). Next, the control device 30 determines whether the incremented M2 correction count is equal to or greater than a set value (S6f). If the M2 correction count is less than the set value (No in S6f), the current correction process for the second motor 32 ends, and it proceeds to process step S7.

[0073] On the other hand, if the M2 correction count is equal to or greater than the set value (Yes in S6f), the rotational speed of the second motor 32 is negatively corrected, i.e., slowed down (S6g). This negative correction can be achieved by changing the rotational speed command value. As a result, when the sealing and cutting process in the top sealing device 22 is completed and the next product 13 is supplied, and the transport of the packaging material 15 is resumed, the control device 30 provides the negatively corrected command value to the second motor 32. Therefore, the second motor 32 rotates at the reduced rotational speed from the next transport, and the first pinch roller 21c rotates at the speed and torque associated with that rotation.

[0074] Thereafter, the control device 30 clears the M2 correction count and the M3 correction count (S6h), and ends this processing.

[0075] Furthermore, the correction value when making the above-mentioned positive and negative corrections to the rotation speed of M2 may be, for example, a fixed value or a value according to the amount of deviation from the set value. When a fixed value is used, the speed changes gradually, allowing for smooth control. When a value according to the amount of deviation is used, corrections can be made quickly.

[0076] FIG. 4 shows an example of a more specific processing flow of processing steps S8 and S9 for controlling the rotation speed of the third motor 33, and is an example of a pattern in which the speed is not changed immediately even if the torque deviation falls outside the second set range.

[0077] In this example, the upper limit of the second setting range is the second positive setting value, and the lower limit is the second negative setting value. The second positive setting value is greater than the second negative setting value, and the second setting range has a predetermined width. If the second setting range is set to ±5 with 0 as the base, the second positive setting value will be +5 and the second negative setting value will be -5. Also, if the range is set to ±5 with +5 as the base, the second positive setting value will be +11 and the second negative setting value will be +1.

[0078] The control device 30 then determines whether the calculated torque difference is equal to or greater than a second positive set value (S8a). If it is equal to or greater than the first positive set value (Yes in S8a), the control device 30 increments the M3 correction count by 1 (S9a). The control device 30 then determines whether the incremented M3 correction count is equal to or greater than a set value (S9b). If the M3 correction count is less than the set value (No in S9b), the current correction process for the third motor 33 is completed after only processing the M3 correction count.

[0079] On the other hand, if the M3 correction count is equal to or greater than the set value (Yes in S9b), the rotational speed of the third motor 33 is negatively corrected, i.e., slowed down (S9c). This negative correction can be achieved by changing the rotational speed command value. As a result, when the sealing and cutting process in the top sealing device 22 is completed and the next product 13 is supplied, and the conveyance of the packaging material 15 is resumed, the control device 30 gives the negatively corrected command value to the third motor 33. Therefore, from the next conveyance, the third motor 33 rotates at the reduced rotational speed, and the second pinch roller 21d rotates at the speed and torque associated with that rotation.

[0080] Thereafter, the control device 30 clears the M2 correction count and the M3 correction count (S9d), and ends this processing.

[0081] On the other hand, if the branch determination in processing step S8a is No, the control device 30 proceeds to processing step S8b, where it determines whether the calculated torque difference is equal to or less than a second negative set value (S8b). If it is equal to or less than the second negative set value (Yes in S8b), the control device 30 increments the M3 correction count by 1 (S9e). Next, the control device 30 determines whether the incremented M3 correction count is equal to or greater than a set value (S9f). If the M3 correction count is less than the set value (No in S9f), the current correction process for the third motor 33 is completed after only processing the M3 correction count.

[0082] On the other hand, if the M3 correction count is equal to or greater than the set value (Yes in S9f), the rotation speed of the third motor 33 is corrected in a positive direction, i.e., increased (S9g). This positive correction can be achieved by changing the rotation speed command value. As a result, when the sealing and cutting process in the top sealing device 22 is completed and the next product 13 is supplied, and the conveyance of the packaging material 15 is resumed, the control device 30 gives the positively corrected command value to the third motor 33. Therefore, from the next conveyance, the third motor 33 rotates at the increased rotation speed, and the second pinch roller 21d rotates at the speed and torque associated with that rotation.

[0083] Thereafter, the control device 30 clears the M2 correction count and the M3 correction count (S9h), and ends this processing.

[0084] Furthermore, by deleting the processing for the correction count from the processing steps in the flowcharts of Figures 3 and 4, the processing flow becomes one in which control is performed to quickly change the rotation speed of the corresponding second motor 32 or third motor 33 when it falls outside the set range.

[0085] In the above-described embodiment, the pillow packaging machine 10 is described as a packaging machine that operates intermittently and repeatedly conveys and pauses the packaging material 15, but the packaging machine may also be a type that conveys the packaging material 15 without pausing. In this case, the torque of each motor is collected at an appropriate timing while the packaging material 15 is being conveyed, and a predetermined correction process is performed when the collected torque or torque difference falls outside a set range. Furthermore, in a packaging machine that operates intermittently as in the above-described embodiment, torque may be collected while the packaging material 15 is being conveyed, and correction process may be performed based on the collected torque.

[0086] Furthermore, in the above-described embodiment, the individual products 13 have different lengths, but products 13 of the same size may be supplied to the bag former 20 and packaged.

[0087] In addition, in this embodiment, the packaging material 15 is made of paper, but it may be made of a resin film.

[0088] While various aspects of the present invention have been described above using embodiments thereof, it should be noted that these embodiments and descriptions are provided to aid in understanding the present invention, and are not intended to limit the scope of the present invention. The scope of the present invention is not limited to the structures and manufacturing methods explicitly described in the specification, but also encompasses combinations of various aspects of the present invention disclosed herein. While the structures of the present invention that are sought to be patented are specified in the appended claims, it is hereby expressly stated that structures not currently specified in the claims may be claimed in the future as disclosed herein. [Explanation of symbols]

[0089] 10: Pillow packaging machine 11: Packaging machine body 12: Packaging material supply device 13:Product 14: Free roller 15: Packaging material 15a: Side edge 16: Raw roll 18: Feed roller 19: Dancer Lola 20: Bag making machine 21: Center seal device 21b: Basira 21c: First pinch roller 21d: Second pinch roller 22: Top seal device 24: Upper top sealer 25: Lower top seal 26: Packaging 27: Product detection sensor 28: Packaging 30: Control device 31: First motor 32: Second motor 33: Third motor

Claims

1. A packaging machine body for pillow packaging; a packaging material supply device that pulls out a strip-shaped packaging material wound around a raw roll and supplies the pulled-out packaging material to the packaging machine main body; Equipped with the packaging material supply device is configured to apply a conveying force to the packaging material by a feed roller driven by a first motor, The packaging machine main body has a bag former that forms the packaging material into a cylindrical shape, a center seal device that seals both side edge portions of the packaging material formed into a cylindrical shape by the bag former, and a top seal device that is disposed downstream of the center seal device and seals and cuts the packaging material in a direction perpendicular to the conveying direction, and is configured so that both side edge portions are pinched and pulled by a pair of first pinch rollers driven by a second motor, A pillow packaging machine comprising a control device that controls the rotational speed of the second motor so that the torque applied to the first motor becomes a first reference value.

2. the first pinch roller is disposed upstream of a center sealer that heats both side edge portions of the center seal device; a pair of second pinch rollers disposed downstream of the center sealer to pinch and pull the both side edge portions; The pillow packaging machine according to claim 1, wherein the control device has a function of controlling the speed of the third motor based on the difference between the torque of the second motor and the torque of a third motor that drives the second pinch roller.

3. setting an operating range of a speed ratio of the rotation speed of the second motor and the third motor to the rotation speed of the first motor as a second reference; The pillow packaging machine according to claim 2 , wherein the control device controls the rotation speeds of the second motor and the third motor within a range that satisfies the second standard.

4. The packaging material is configured to be intermittently conveyed, The pillow packaging machine according to any one of claims 1 to 3, wherein the torque is collected when the transport of the packaging material is stopped.

5. the first criterion has a predetermined range; 5. The pillow packaging machine according to claim 4, wherein the control device does not change the rotation speed of the second motor when the torque of the first motor is within the predetermined range.

6. The strip-shaped packaging material is pulled out by the feed roller and fed to the bag making device of the packaging machine body. The packaging material is formed into a cylindrical shape by passing through the bag former, The packaging material formed into a cylindrical shape by the bag making machine is pinched at both side edge portions by first pinch rollers, and a conveying force is applied to the packaging material; A method for adjusting tension of a packaging material in a pillow packaging method in which both side edge portions of the packaging material formed into a cylindrical shape by the bag making machine are sealed by a center seal device, and the packaging material is sealed and cut in a direction perpendicular to a conveying direction downstream of the center seal device to produce a pillow package, comprising: A method for adjusting tension of a packaging material, comprising controlling the rotation speed of a second motor that drives the first pinch roller so that the torque applied to the first motor that drives the feed roller is equal to a first reference value.

7. The first pinch roller is disposed upstream of a center sealer that heats the both side edge portions of the center seal device, and a pair of second pinch rollers that pinch and pull the both side edge portions are disposed downstream of the center sealer, 7. The method for adjusting tension of a packaging material according to claim 6, wherein the speed of the third motor is controlled based on a difference between the torque of the second motor and the torque of a third motor that drives the second pinch roller.

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