JP4897346B2 - Sealing quality judgment method in automatic packaging machine - Google Patents

Description

  The present invention relates to an automatic packaging machine that determines whether or not a foreign object is caught in the horizontal seal portion when the packaging material formed into a cylindrical shape by the vertical seal portion is laterally sealed in the transverse direction including the vertical seal portion. The present invention relates to a seal pass / fail judgment method.

  Conventionally, in vertical bag making and packing machines and pillow wrapping machines, web-shaped packaging materials are formed into cylindrical packaging materials, and bags are made from the cylindrical packaging materials while the packages are loaded and filled therein. By doing, a bag packaging body can be manufactured continuously. This type of wrapping machine seals the cylindrical packaging material transversely to form a vertical sealing means for sealing the side edge portion of the web-shaped packaging material into a cylindrical shape and the bag bottom or bag top. Horizontal sealing means. In the above-mentioned lateral sealing means, the seal portion is detected by detecting the thickness of the seal portion based on the distance by the photoelectric sensor, the magnitude of the torque that drives the seal bar as a load required for sealing, or the delay in the rotation angle of the sealer. It has been proposed to detect the biting of the product into the seal portion during the operation of the bar and to exclude the abnormal seal product due to the biting from the normal bag packaged product.

As an example of a bag making and packaging machine that can detect the biting of articles into such a seal part, it detects the pulse value generated corresponding to the rotation amount of the servo motor that contacts and separates a pair of seal jaws After the separable seal jaw starts approaching at time t1, it contacts the torque t at time t2 and shifts to torque control, and then the pulse value P detected by the encoder at time t3 after a predetermined time Td is obtained. There has been proposed an apparatus that determines the biting of an article into a seal portion based on the result of reading and comparing the pulse value P with a preset threshold value P0 (see Patent Document 1). In this case, if the pulse value P is greater than the threshold value P0, it is determined to be normal, and if it is smaller, it is determined to be abnormal.
JP 2005-104512 A ([0037] to [0040], FIG. 7)

In addition, as a method for determining the presence or absence of inclusions that have entered the seal part of the packaging material, such as products to be packaged or fragments thereof, the package is inserted for a predetermined time when the packaging machine starts operating. Without sealing, the packaging material is sealed to form several empty bags, and data proportional to the average thickness of the sealed portion is stored as standard data. By detecting data proportional to the thickness of the sealed portion at the time of normal packaging sealing, and comparing this data with the previously stored standard data, Some determine the presence or absence (see Patent Document 2). This determination method is intended to detect the presence or absence of wrinkles or the like of the packaged material or the packaging material that has entered the sealing portion without being affected by variations in the thickness seen in the longitudinal direction of the packaging material.
Japanese Patent No. 3473861 ([0011] to [0014], FIGS. 1 to 2)

  In the method of detecting the entry of foreign matter etc. in the seal part, the operation pattern is recorded as a reference operation pattern during normal operation of the servo motor, and the subsequent operation pattern of the servo motor is compared with the recorded reference operation pattern. Some have detected foreign object biting in the seal portion by detecting abnormal operation of the servo motor.

  By the way, when detecting the abnormal operation of the servomotor, the heat sealer biting detection level is strictly set as a threshold value for distinguishing between normal operation and abnormal operation (that is, even if the servomotor driving current is slightly high, When the packaging operation of the packaging machine is temporarily stopped for maintenance or the like and then restarted, the transverse sealing means sandwiches the transverse region of the packaging material including the longitudinal sealing portion already formed by the longitudinal sealing means. In some cases, a false detection that a foreign object is caught may occur. This is because the vertical seal portion provided by the vertical seal means is initially heated and soft, so it is lying down against the bag, but the vertical seal portion is cooled while the packaging operation is stopped. This is because the softness is lost and the bag tends to get up. When the packaging operation is resumed, when the vertical seal portion with increased hardness is sandwiched between the horizontal seal means, the vertical seal portion is not crushed to a thickness equal to or less than the threshold value, so that a foreign object is erroneously detected. If such a false detection occurs, it is determined that the seal is defective. Therefore, the packaging machine is immediately stopped to deal with foreign matter, that is, starting from checking for the presence of foreign matter, investigating the cause of the defective seal, removing the cause, and improving it. It is necessary to take a series of response operations such as this, and it is inevitable that the operating rate of the packaging machine will decrease.

  Therefore, in an automatic packaging machine equipped with a vertical sealing means, when the packaging operation is stopped and then restarted, even if the vertical seal portion cools and rises with respect to the bag, a horizontal detection caused by a false detection of foreign object biting occurs. There is a problem to be solved in terms of avoiding an erroneous determination of a sealing failure during a sealing operation.

  An object of the present invention is to erroneously determine a seal failure based on a false detection due to a foreign object biting during a lateral sealing operation when the vertical sealing portion is cooled and the bag rises when the packaging operation is stopped and restarted thereafter. By avoiding the above, it is possible to improve the accuracy of the seal failure detection and to prevent the unnecessary operation stop in advance and to improve the operating rate of the packaging machine. Is to provide.

  In order to solve the above-mentioned problems, the seal quality determination method in the automatic packaging machine according to the present invention is a longitudinal packaging method in which a web-shaped packaging material is bent and subjected to vertical sealing on both side edges brought close to each other to form a cylindrical packaging material. Sealing means, transverse sealing means driven by a servo motor to form a bag by sandwiching a transverse region including a longitudinal sealing portion of the cylindrical packaging material to form a bag, detection means for detecting the drive current of the servo motor, and And determining means for determining a seal failure caused by foreign object biting in the lateral sealing means based on comparing a deviation between the driving current detected by the detecting means and a reference driving current of the servo motor with a threshold value. In the automatic packaging machine, the threshold value is changed according to a packaging operation parameter after the operation of the automatic packaging machine is stopped.

  According to the sealing quality determination method in this automatic packaging machine, as an automatic packaging machine, the vertical sealing means bends the web-shaped packaging material and performs vertical sealing on both side edges that are brought close to each other to form a cylindrical packaging material. Then, the horizontal seal means driven by the servo motor applies a horizontal seal to the transverse region including the vertical seal portion of the cylindrical packaging material to form a bag. The detecting means detects the sandwiching resistance of the packaging material generated during the transverse sealing operation by the transverse sealing means by detecting the driving current of the servo motor. The judging means detects the driving current detected by the detecting means and the servo motor. Based on the comparison of the deviation from the reference driving current with a threshold value, a sealing failure due to the foreign object biting in the lateral sealing means is determined. The present invention further adopts a measure for changing the threshold according to the packaging operation parameter after the automatic packaging machine is stopped. After the operation of the automatic packaging machine is stopped, the vertical seal portion already formed by the vertical seal means is cooled to increase the hardness and show a tendency to get up from a sleeping state. According to the present invention, after the packaging operation is resumed, when the horizontal sealing means performs the horizontal sealing in the direction crossing the vertical sealing portion, the threshold value for detecting the abnormality of the driving current is changed, so that the cooling state Even when the drive current supplied to the servo motor is increased when the vertical seal portion is crushed, the lateral seal portion is prevented from being determined to have a poor seal due to foreign object biting. Can do.

  In the sealing quality determination method in the automatic packaging machine, the packaging operation parameter may be an elapsed time after the operation stop. As the elapsed time after the operation stops, the degree of cooling of the vertical seal portion increases, the hardness increases, and the possibility that it is determined that the seal is defective due to foreign object pinching increases. Therefore, the longer the elapsed time after the operation stop, the larger the threshold change amount can be set.

  In the sealing quality determination method in the automatic packaging machine, the packaging operation parameter may be the number of the bags manufactured after the operation is resumed. As the elapsed time after resuming operation passes, the cooled bag with the vertical seal passes through the horizontal sealing means, and the bag with the high temperature vertical seal newly formed by the vertical sealing means passes. Will come. Therefore, when the number of production bags immediately after the restart of operation is small, that is, when the temperature of the already created vertical seal portion is low and the temperature of the horizontal seal means does not reach saturation, the threshold change amount is increased. After that, as the operation resumes, the vertical seal portion newly formed by the vertical seal means is manufactured until the horizontal seal is applied by the horizontal seal means whose temperature has risen to the steady state. As the number of bags increases, it is possible to take a measure that the change amount is set to be smaller to the normal threshold value.

  In the sealing quality determination method in the automatic packaging machine, the packaging operation parameter can be a combination of the elapsed time after the operation stop and the number of the bags manufactured after the operation is resumed. The amount of change in the threshold value can be determined in a map by the elapsed time after the operation is stopped and the number of bags manufactured after the operation is resumed.

  In the sealing quality determination method in the automatic packaging machine, the packaging operation parameter and the threshold value after the operation of the automatic packaging machine is stopped are determined as a plurality of discrete packaging operation parameters and the threshold value corresponding thereto. The threshold for the packaging operation parameters other than the discrete packaging operation parameters can be determined by interpolation. When storing the combination of the packaging operation parameter and the threshold value as data, the number of stored data can be reduced by storing them as discrete values. Arbitrary points other than the discrete values can be supplemented by an interpolation method such as linear interpolation.

  In the sealing quality determination method in the automatic packaging machine, it is preferable that the relationship between the packaging operation parameter and the threshold value can be set while being displayed on a display unit. By displaying the packaging operation parameter and the threshold value on the display means such as a display, the packaging operation parameter and the threshold value are set so that the operator can easily confirm the relationship between the two.

  Since the sealing quality determination method in the automatic packaging machine according to the present invention is configured as described above, after the operation of the automatic packaging machine is stopped, the servo motor is driven during the operation of the lateral sealing means according to the packaging operation parameter. The threshold value for evaluating the deviation of the drive current from the reference current is changed in order to detect the current and determine the seal failure. Therefore, the vertical seal part already formed by the vertical seal means is cooled after the operation of the automatic packaging machine is stopped and shows a tendency to rise from the state where the hardness is increased and lies in the packaging bag. Even if horizontal sealing is applied to the cylindrical packaging material in the transverse direction crossing the vertical sealing portion by the horizontal sealing means, the threshold value is changed to a large value, so that the vertical sealing portion in the cooled state is a foreign object for the horizontal sealing means. Therefore, it is not determined that the seal is defective. As a result, after resuming the packaging operation, when forming the horizontal seal portion by the horizontal seal means, the false detection that the vertical seal portion itself is a foreign object is avoided, enabling more accurate seal failure determination, It is possible to prevent unnecessary operation stop caused by erroneous detection of foreign matters and improve the operating rate of the packaging machine.

  Hereinafter, an embodiment of a sealing quality determination method in an automatic packaging machine according to the present invention will be described based on the attached drawings. FIG. 1 is a graph showing an example of a time variation of a deviation pulse and an output current of a servo motor that operates a sealing mechanism, FIG. 2 is a block diagram for determining whether or not a seal is good in an automatic packaging machine, and FIG. It is a graph which shows an example of the time change of the electric current value in the case of the closing operation of a means. FIG. 4 is a graph showing an example of a change in threshold value according to the packaging operation parameter. FIG. 5 is a diagram showing a display example in which the packaging operation parameter and the threshold value are displayed. FIG. 6 is a perspective view showing an example of a vertical bag making filling and packaging machine to which the sealing quality determination method according to the present invention can be applied.

  The vertical bag making and filling machine 1 as an example of the automatic packaging machine shown in FIG. 6 has a known structure, but the web-like packaging material Fw fed out from the packaging material roll R around which the web-like packaging material is wound. Is supplied to a former 11 of a bag making filling and packaging machine through several guide rollers 9 and a tension applying mechanism 10. Necessary printing is applied to the web-shaped packaging material that is being supplied. Further, the mark on the packaging material is read by the sensor, and the packaging material is supplied to the former 11 at the timing of the formation of the bag and the filling of the product into the bag. The vertical bag making filling and packaging machine 1 further includes a vertical heat sealer 15 as a vertical sealing means for forming a cylindrical packaging material Ft by applying a vertical seal to both side edges of the cylindrical packaging material Fw. Horizontal heat sealers 16 and 16 are provided as horizontal sealing means which are driven by a servomotor and sandwich a horizontal region including a vertical seal portion of the cylindrical packaging material Ft to form a bag by applying a horizontal seal.

  In the bag making and filling and packaging supply 10, an input cylinder 12 for introducing and guiding a product into the former 11 is disposed so as to penetrate, and an upper portion of the input cylinder 12 is a hopper 13 having an enlarged cross section. The packaging material bent into a cylindrical shape by the former 11 is guided so as to surround the periphery of the input cylinder 12, and a pair of left and right belt feeding mechanisms 14 and 14 for feeding the packaging material are operated synchronously. Paper is intermittently fed downward. While the packaging material bent into the cylindrical shape is traveling downward around the charging cylinder 12, the edges are heat-sealed by the vertical heat sealer 15 while the intermittent operation is stopped. The vertical heat sealer 15 includes a pair of heat seal bars that perform heat sealing with the edges of the packaging material sandwiched between the palms in the case of palm-to-palm bonding. The packaging material bent into a substantially cylindrical shape is thermally welded by the vertical heat sealer 15 and formed into the cylindrical packaging material Ft.

  The cylindrical packaging material Ft is sent downward from the lower end of the input cylinder 12. In the cylindrical packaging material into which the product is charged and filled, the top heat seal portion of the bag and the bottom seal portion S of the next bag are formed by the horizontal heat sealers 16 and 16. The packaging material is sequentially supplied intermittently, and the bag package P in which the product is packaged is sequentially manufactured.

  As shown in FIG. 1, the operation of the horizontal heat sealing mechanism is roughly divided into three stages, and consists of a closing operation period, a sealing section immediately after that, and a subsequent opening operation period. 1A is a graph of the motor speed, and FIG. 1B is a graph of the output current value. The output current value changes greatly when the motor speed accelerates or decelerates during the opening operation or the closing operation, and shows a large value in the seal section. The output current value indicates the current supplied to the motor in order to operate the servo motor, and the current value varies depending on the movement and load of the motor.

  FIG. 2 is a block diagram for performing seal quality determination in an automatic packaging machine. As shown in FIG. 2, a servo motor 20 for driving the lateral seal means 16 and a detection means 21 for detecting the drive current are provided in association with the control means. The detection means 21 detects the pinching resistance of the packaging material that occurs during the lateral sealing operation by the lateral sealing means 16 by detecting the drive current of the servo motor 20. In addition, setting means 23 that can set a threshold value for determining that the foreign object is caught by comparing the driving current with the reference driving current in association with the display means 22 such as a display is provided. In the setting means 23, the threshold value can be set according to the packaging operation parameter after the operation is resumed after the automatic packaging machine is stopped. In the control unit 24, the threshold value set by the setting unit 23 is stored in the storage unit 25 as data such as a table, a map, or an expression. The determination unit 26 determines a seal failure in the lateral seal unit 16 based on comparing the deviation between the drive current detected by the detection unit 21 and the reference drive current of the servo motor 20 with a threshold value. The determination result of the determination unit 26 is output to the horizontal seal drive unit 27 that drives the horizontal seal unit 16, and the horizontal seal drive unit 27 drives the horizontal seal unit 16 according to the determination result of the determination unit 26.

  FIG. 3 shows the state from the open state to the closed state of the transverse sealer means when the power is turned off to stop the operation of the automatic packaging machine 1 and then the power is turned on again to restart the packaging operation of the automatic packaging machine 1. Examples of current values consumed in each of the three closing operations (a), (b), and (c) performed at intervals are shown. In FIG. 3, the elapsed time from when the power is turned on again to when it restarts is long in the order of (a), (b), and (c). It can be seen that the current value consumed in the final stage among the current values consumed in the closing operation of the horizontal sealer means decreases as the time elapsed after the power is turned on again. This is because the temperature of the components constituting the horizontal sealer gradually rises due to continuous heating by the heater, and the meshing position of the horizontal sealer slightly changes due to thermal expansion. Further, as shown in the graph of (a), the operation data of the sealing operation when a foreign object is bitten with respect to the operation data (reference drive current) of the normal sealing operation, that is, The change of the drive current is indicated by an imaginary line. It can be seen that the drive current (sealer drive current) rises momentarily as indicated by the range A, due to the biting of foreign matter near the end point of the closing operation of the lateral sealer means. This instantaneous increase in the drive current data is a fluctuation that exceeds the normal range and is not updated as the reference drive current data. In addition, when an abnormal value occurs, the packaging material and the horizontal sealer are inspected, and measures such as removal of foreign substances are taken. Furthermore, to protect the sealing mechanism, the operation of the lateral sealing means can be stopped when abnormal operation data is detected, and damage to the sealing mechanism due to the biting of hard products such as frozen food can be avoided. it can.

  The drive current (current value) of the servo motor required for the operation of the lateral seal means changes as the operating time elapses after the lateral seal means is turned on, so the drive current during the closing operation of the lateral heat sealer (operation data) Is updated and recorded as a reference drive current (operation data). The reference driving current at the time of power-on can be recorded as an average driving current when manufacturing some empty bags in which no product is sealed, but is not limited to this, and an appropriate method is adopted. be able to. Even if the drive current that has fluctuated is normal, an error may occur if a fixed reference drive current that does not update the reference drive current is used. However, the updated drive current is updated by updating the reference drive current. If the drive current is within a normal range based on the reference drive current, an error is avoided.

  When the automatic packaging machine is restarted after the operation is stopped, the threshold value for determining that the change amount (increase amount) of the drive current caused by the foreign object biting is related to the seal failure is determined according to the packaging operation amount. Be changed. As shown to Fig.4 (a), the change of a threshold value is defined according to the elapsed time after the operation stop as a packaging operation amount. As the elapsed time after the operation stops, the degree of cooling of the vertical seal part advances, so that the vertical seal part with high hardness that has risen due to temperature drop passes through the position of the horizontal seal means for a while. Therefore, when the elapsed time after the restart of operation is short, it is necessary to increase the amount of change of the threshold value. As the elapsed time becomes longer, the high temperature vertical seal portion just sealed by the vertical seal means passes, so that the amount of change can be set small to the normal threshold value.

  As shown in FIG. 4B, the packaging operation parameter may be the number of the bags manufactured after the operation is resumed. Immediately after resuming the packaging operation, the temperature of the already created vertical seal portion is low and the temperature of the horizontal seal means does not reach saturation. Therefore, when the number of manufacturing bags immediately after resuming operation is small, the threshold change amount is set to be large so that even if the low-temperature vertical seal part is difficult to collapse even when heated from the horizontal seal part, false detection will not occur. Can do. As the elapsed time after the resumption of operation passes, the cooled bag having the vertical seal portion is sealed by the horizontal sealing means and passes. Thereafter, the bag having a high temperature vertical seal portion newly formed by the vertical seal means is sealed by the horizontal seal means having a sufficiently high heating temperature. Therefore, as the number of bags to be manufactured increases with the progress of the packaging operation, it is possible to take a measure of setting the change amount to a normal threshold value. Furthermore, both the elapsed time after stopping the packaging operation and the number of bags can be reflected in the change amount of the threshold value.

  In this way, even when the reference drive current data is fixed, the threshold is set large so that the changed drive current data when sandwiching the hard vertical seal portion is determined to be normal without being determined to be abnormal. As a result, the allowable range is widened and it is not determined to be abnormal. Therefore, even after the operation of the automatic packaging machine is stopped, the vertical seal portion already formed by the vertical seal means is cooled, and even though the hardness tends to increase, the threshold value is changed after the packaging operation is resumed. Even if the drive current at the time of crushing the vertical seal part becomes high when the horizontal seal is applied to the cylindrical packaging material in the transverse direction across the vertical seal part by means, it is determined that the vertical seal part is a foreign matter. Can be avoided.

  As shown in FIGS. 4A and 4B, the packaging operation amount and the threshold value after the automatic packaging machine is stopped are defined as a plurality of discrete packaging operation amounts and corresponding threshold values. When storing the combination of the packaging operation amount and the threshold value as data, the number of stored data can be reduced by storing them as discrete values. The threshold value for the wrapping operation amount other than the plotted discrete wrapping operation amount can be determined by an interpolation method such as linear interpolation.

  Furthermore, it is preferable that the relationship between the packaging operation amount and the threshold value can be set while being displayed on the display means. It is possible to work without error by displaying the packaging operation parameter and the threshold value on a display means such as a display so that the operator can easily confirm the setting. FIG. 5 shows a display example in which packaging operation parameters and threshold values are displayed. In the display example shown in FIG. 5, the numerical value 100 shown as the threshold value is a set value of the threshold value, and a case where the deviation from the reference value exceeds the set value 100 is determined as a seal failure.

It is a graph which shows an example of the time change of the deviation pulse and output current of the servomotor which operates a seal mechanism. It is a block diagram for performing the sealing quality detection in an automatic packaging machine. It is a graph which shows an example of the time change of the electric current value in the case of a horizontal sealing operation | movement when it restarts after stopping the operation | movement of a packaging machine. It is a graph which shows the example of the change of the threshold value according to a packaging operation parameter. It is a figure which shows the example of a display which displayed the packaging operation parameter and the threshold value. It is a perspective view which shows an example of the vertical bag making filling packaging machine with which the sealing quality determination method by this invention can be applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vertical bag making filling packaging machine 9 Guide roller 10 Tension | tensile_strength imparting mechanism 11 Former 12 Input cylinder 13 Hopper 14, 14 Belt feed mechanism 15 Vertical heat sealer (vertical sealing means) 16 Horizontal heat sealer (horizontal sealing means)
20 Servo motor 21 Detection means 22 Display means 23 Setting means 24 Control means 25 Storage means 26 Determination means 27 Horizontal seal drive means R Packaging material roll Fw Web-like packaging material Fw Cylindrical packaging material S Top seal part of bag and next bag Bottom seal part P

Claims (6)

  Longitudinal sealing means for forming a cylindrical packaging material by longitudinally sealing both sides of the web-shaped packaging material that are bent close to each other, a transverse region that is driven by a servo motor and includes the vertical sealing portion of the cylindrical packaging material A horizontal seal means for forming a bag by sandwiching the sheet, a detection means for detecting a drive current of the servo motor, and a deviation between the drive current detected by the detection means and a reference drive current of the servo motor In an automatic packaging machine provided with a determination means for determining a sealing failure caused by foreign object biting in the lateral sealing means based on contrasting with a threshold value, according to a packaging operation parameter after the automatic packaging machine is stopped. A sealing quality determination method in an automatic packaging machine, wherein the threshold value is changed.   The sealing quality determination method for an automatic packaging machine according to claim 1, wherein the packaging operation parameter is an elapsed time after the operation stop.   The sealing quality determination method for an automatic packaging machine according to claim 1, wherein the packaging operation parameter is the number of the bags manufactured after the operation is resumed.   2. The seal quality determination method for an automatic packaging machine according to claim 1, wherein the packaging operation parameter is an elapsed time after the operation stop and a number of the bags manufactured after the operation is resumed.   The packaging operation parameter and the threshold value after the operation of the automatic packaging machine is stopped are determined as a plurality of discrete packaging operation parameters and the corresponding threshold value, and other than the discrete packaging operation parameter. 5. The seal quality determination method for an automatic packaging machine according to claim 1, wherein the threshold value corresponding to the packaging operation parameter is determined by interpolation.   The seal quality determination method for an automatic packaging machine according to any one of claims 1 to 5, wherein the relationship between the packaging operation parameter and the threshold value can be set in a state of being displayed on a display means. .

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