Transport System

Abstract

A conveyance system is provided that can stop some of a plurality of synchronously driven servo motors while maintaining the synchronous relationship. [Solution] The conveying system includes a first conveying mechanism driven by a first servo motor, a second conveying mechanism driven by a second servo motor, and a control device that synchronously controls the first and second servo motors. A processor in the control device constructs a virtual control system in accordance with a program, with a first virtual axis (M1) as the master axis and the first and second servo motors as first and second slave axes (S1, S3), respectively. A second slave axis (S3) and a second virtual axis (S6) are connected to the first virtual axis (M1), and the second slave axis (S3) and the second virtual axis (S6) operate in accordance with the first virtual axis (M1). A first slave axis (S1) is connected to the second virtual axis (S6), and the first slave axis (S1) operates in accordance with the second virtual axis (S6).

Description

[Technical Field]

[0001] The present disclosure relates to a transport system. [Background technology]

[0002] For example, Japanese Patent Application Laid-Open No. 2009-90984 (Patent Document 1) discloses a packaging machine equipped with multiple servo mechanisms for packaging products manufactured by the manufacturing machine in units of a certain number, and a control means for controlling the servo motors of each servo mechanism.

[0003] In Patent Document 1, a virtual control system is used as a control system for controlling multiple servo motors that are driven synchronously. In the virtual control system, multiple servo mechanisms are connected to the same virtual axis. The control means synchronizes the operating speed of the packaging machine with the operating speed of the manufacturing machine by setting the rotation speed of the virtual axis to match the operating speed of the manufacturing machine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-90984 Summary of the Invention [Problem to be solved by the invention]

[0005] In a virtual control system, if some of the multiple servo motors that are driven synchronously include a servo motor that you want to stop operating by canceling synchronization with the virtual axis, you can stop the operation of that servo motor by cutting off the transmission of rotation from the virtual axis to that servo motor in parallel with controlling the remaining servo motors to synchronize with the virtual axis.

[0006] However, since a stopped servo motor is asynchronous with the virtual axis, when restarting the servo motor, a program must be prepared to resynchronize the servo motor with the virtual axis. As the number of servo motors to be stopped increases, there is a concern that the program for synchronization control will become more complex. Furthermore, since there is no synchronization relationship between stopped servo motors, it may be impossible to maintain synchronization accuracy between multiple servo motors after restarting.

[0007] The present disclosure has been made to solve such problems, and an object of the present disclosure is to provide a conveying system that can stop some of multiple synchronously driven servo motors while maintaining the synchronous relationship. [Means for solving the problem]

[0008] A conveying system according to one aspect of the present disclosure is a conveying system for sequentially conveying a plurality of articles, and includes a first conveying mechanism driven by a first servo motor, a second conveying mechanism driven by a second servo motor, and a control device for synchronously controlling the first and second servo motors. The control device includes a processor and a memory for storing a program executed by the processor. The processor, in accordance with the program, establishes a virtual control system in which a first virtual axis serves as a master axis and the first and second servo motors serve as first and second slave axes, respectively. In the virtual control system, a second slave axis and a second virtual axis are connected to the first virtual axis, and the second slave axis and the second virtual axis operate in accordance with the first virtual axis. The second virtual axis is connected to the first slave axis, and the first slave axis operates in accordance with the second virtual axis. [Effects of the Invention]

[0009] In the present disclosure, a first servo motor, which is to be desynchronized with a first virtual axis and stopped, is connected to a second virtual axis that is connected to the first virtual axis. By stopping the rotation of the second virtual axis, the first servo motor can be stopped while maintaining its synchronous relationship with the second virtual axis. Therefore, it is sufficient to prepare a program for synchronizing the second virtual axis with the first virtual axis. Furthermore, after restarting the first servo motor, the synchronization between the first and second servo motors can be maintained with high precision. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a container transport system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a control configuration of the container transport system. [Figure 3] FIG. 2 is a diagram for explaining synchronous control by a control device. [Figure 4] 10A and 10B are diagrams for explaining synchronous control during normal operation of the container transport system. [Figure 5] FIG. 10 is a diagram for explaining synchronization control when a container shortage occurs. [Figure 6] FIG. 10 is a diagram for explaining synchronization control when a container shortage occurs. [Figure 7] FIG. 10 is a diagram for explaining synchronization control when a container shortage occurs. [Figure 8] 10A and 10B are diagrams for explaining synchronization control at the time of restart after a container shortage occurs. [Figure 9] 10 is a flowchart showing the flow of processing by the control device when a container shortage occurs. [Figure 10] 10 is a diagram for explaining synchronization control when an abnormality occurs in the container transport system. FIG. [Figure 11] 10 is a diagram for explaining synchronization control when an abnormality occurs in the container transport system. FIG. [Figure 12]10A and 10B are diagrams for explaining synchronization control at the time of restarting the container transport system after an abnormality has occurred in the system. [Figure 13] 10 is a flowchart showing the flow of processing by the control device when an abnormality occurs in the container generating system. [Figure 14] FIG. 10 is a block diagram showing a virtual control system according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings will be denoted by the same reference numerals, and their description will not be repeated in principle.

[0012] <Conveyor system configuration> First, a configuration example of a conveying system according to this embodiment will be described with reference to Fig. 1. The conveying system according to this embodiment is a conveying system that sequentially conveys a plurality of articles, and can be applied to, for example, a container conveying system that sequentially conveys a plurality of containers and coats each container with a label.

[0013] Fig. 1 is a schematic diagram of a container transfer system according to the present embodiment. As shown in Fig. 1, the container transfer system includes three transfer mechanisms CV1 to CV3, and is configured to transfer a container 50 sequentially from transfer mechanism CV1 to transfer mechanism CV2 and transfer mechanism CV3.

[0014] The container 50 is a bottle made of synthetic resin such as a PET bottle, etc. The container 50 is not limited to this, and glass containers, flow containers, delaminated bottles, etc. can be used as appropriate.

[0015] (Transport mechanism CV1) The conveying mechanism CV1 is disposed on the most upstream side in the conveying direction of the containers 50. A plurality of containers 50 are continuously conveyed in the direction indicated by the arrow AR1 by an upstream conveyor or the like (not shown) and supplied to the conveying mechanism CV1.

[0016] The conveying mechanism CV1 is a mechanism (container supply mechanism) for correcting the posture of multiple continuously conveyed containers 50, adjusting the spacing between adjacent containers 50, and sequentially supplying them to the next process. The conveying mechanism CV1 is configured to include screws 10 and 12, a star wheel 14, and a discharge device 16.

[0017] The screws 10 and 12 are arranged in parallel across the conveying path of the container 50. The screws 10 and 12 are driven by servo motors (not shown) that are independent of each other. The screws may be arranged on only one side of the conveying path.

[0018] The screws 10 and 12 are configured to guide and transport the container 50 along the transport path at a predetermined transport pitch. Specifically, the screws 10 and 12 are rod-shaped members with spiral grooves (not shown) of a fixed pitch formed on their sides. The screws 10 and 12 rotate in opposite directions, and are driven to rotate in opposite directions, thereby sandwiching and transporting the container 50 between the opposing spiral grooves.

[0019] The star wheel 14 is provided downstream of the screws 10 and 12 in the conveying direction of the containers 50. The star wheel 14 is driven by a servo motor (not shown) and rotates in the direction indicated by arrow AR2. The star wheel 14 has a circular shape in a plan view, and is provided at its outer circumferential end with a plurality of holding devices for holding the containers 50. The plurality of holding devices are arranged in a line in the circumferential direction of the star wheel 14.

[0020] The containers 50 transported sequentially by the screws 10, 12 are delivered to the star wheel 14. The star wheel 14 transports the multiple containers 50 by rotating while holding the multiple containers 50 at equal intervals using multiple holding devices. As the star wheel 14 rotates, the multiple holding devices sequentially reach the transfer position PA. In this way, the multiple containers 50 are transported sequentially to the transfer position PA.

[0021] The discharge device 16 is a device for discharging a container 50 from the transfer mechanism CV1 without transferring it to the transfer mechanism CV2. The discharge device 16 is used when an abnormality occurs in the container transfer system 100 or when there is a shortage of containers 50 supplied to the transfer mechanism CV1. The discharge device 16 includes a conveyor and a recovery device. The conveyor receives the container 50 from the star wheel 14 and transports the received container 50 to the recovery device.

[0022] In the transport mechanism CV1, the screws 10 and 12 and the star wheel 14 constitute rotating bodies. Although Fig. 1 illustrates an example in which the number of rotating bodies included in the transport mechanism CV1 is three, the number of rotating bodies included in the transport mechanism CV1 is not limited to three. The number of rotating bodies included in the transport mechanism CV1 may be two or less, or four or more.

[0023] (Transport mechanism CV2) The transport mechanism CV2 is provided downstream of the transport mechanism CV1 in the transport direction. The transport mechanism CV2 is a mechanism (label attachment mechanism) for attaching labels to the containers 50 transported from the transport mechanism CV1.

[0024] The label is formed from a shrink film made of, for example, polyethylene, polypropylene, PVC, etc. The label is formed into a cylindrical shape by joining both ends, then wound into a roll, and the film is cut to a predetermined length while being unwound. In the conveying mechanism CV2, the label is opened by an opening device (not shown) and applied to the container 50.

[0025] The conveying mechanism CV2 is configured to include star wheels 20 and 22, a labeler (label attachment device) 24, and a star wheel 26, which are arranged in this order from the upstream side in the conveying direction. The star wheels 20 and 22 form a container carrying-in section that sequentially carries in a plurality of containers 50 to the labeler 24, and the star wheel 26 forms a container carrying-out section that sequentially carries out the containers 50 to which labels have been attached by the labeler 24.

[0026] The labeler 24 is a rotary label attachment device configured to attach a label to each container 50 while transporting multiple containers 50 in a line on a circular transport path. The circular transport path of the labeler 24 is provided with a transfer position P2 for receiving containers 50 from a container carry-in section, and a transfer position P3 for delivering the containers 50 with the labels attached to them to a container carry-out section.

[0027] The star wheels 20 and 22 that make up the container loading section rotate in the directions indicated by arrows AR3 and AR4, respectively. Each of the star wheels 20 and 22 has a circular shape in a plan view, and is provided at its outer circumferential end with a plurality of holding devices for holding containers 50. The plurality of holding devices provided on each star wheel are arranged in a row in the circumferential direction of the star wheel.

[0028] Star wheel 20 is disposed adjacent to star wheel 14 of transport mechanism CV1. Star wheel 14 and star wheels 20, 22 rotate in the same direction at the transfer position of container 50. Each of the multiple holding devices provided on star wheel 14 and each of the multiple holding devices provided on star wheel 20 sequentially arrive at transfer position PA as star wheel 14 and star wheel 20 rotate, and at transfer position PA, container 50 is transferred from the holding device provided on star wheel 14 to the holding device provided on star wheel 20.

[0029] Similarly, each of the multiple holding devices provided on star wheel 20 and each of the multiple holding devices provided on star wheel 22 sequentially arrives at transfer position P1 as star wheel 20 and star wheel 22 rotate, and at transfer position P1, container 50 is transferred from the holding device provided on star wheel 20 to the holding device provided on star wheel 22.

[0030] The labeler 24 is driven by a servo motor (not shown) and rotates in the direction indicated by arrow AR5. A plurality of holding devices for holding the containers 50 are provided on the outer peripheral end of the labeler 24. The plurality of holding devices are arranged in a line in the circumferential direction of the labeler 24.

[0031] The labeler 24 is disposed adjacent to the star wheel 22. The star wheel 22 and the labeler 24 rotate in the same direction at a transfer position P2 for the container 50. Each of the multiple holding devices provided on the star wheel 22 and each of the multiple holding devices provided on the labeler 24 sequentially reach the transfer position P2 as the star wheel 22 and the labeler 24 rotate, and at the transfer position P2, the container 50 is transferred from the holding device provided on the star wheel 22 to the holding device provided on the labeler 24.

[0032] The circular conveyance path of the labeler 24 is further provided with a receiving position for receiving labels from a label conveyance mechanism (not shown). The label conveyance mechanism conveys the labels produced by the label production mechanism to the receiving position and hands them over to the labeler 24. The labeler 24 attaches the received labels to containers 50.

[0033] The star wheel 26 that constitutes the container carrying-out section rotates in the direction indicated by the arrow AR6. The star wheel 26 has a circular shape in a plan view, and is provided with a plurality of holding devices on its outer circumferential end for holding the containers 50. The plurality of holding devices provided on the star wheel 26 are arranged in a line in the circumferential direction of the star wheel 26.

[0034] The star wheel 26 is disposed adjacent to the labeler 24. The labeler 24 and the star wheel 26 rotate in the same direction at a transfer position P3 for the container 50. Each of the multiple holding devices provided on the labeler 24 and each of the multiple holding devices provided on the star wheel 26 sequentially reach the transfer position P3 as the labeler 24 and the star wheel 26 rotate, and at the transfer position P3, the container 50 is transferred from the holding device provided on the labeler 24 to the holding device provided on the star wheel 26.

[0035] In the conveying mechanism CV2, the rotation shaft of the labeler 24 and the rotation shafts of the star wheels 20, 22, and 26 are connected by a gear mechanism (not shown). When the rotation shaft of the labeler 24 is rotationally driven by a servo motor, the rotational force of the servo motor is transmitted from the labeler 24 to the star wheels 20, 22, and 26 by the gear mechanism. Therefore, the star wheels 20 and 22 rotate in conjunction with the rotation of the labeler 24, and the container 50 is transferred from the star wheel 22 to the labeler 24 at transfer position P2. Furthermore, the star wheel 26 rotates in conjunction with the rotation of the labeler 24, and the container 50 is transferred from the labeler 24 to the star wheel 26 at transfer position P3.

[0036] The rotational speeds of the star wheels 20, 22, and 26 are adjusted so that the peripheral speed is the same as the peripheral speed of the labeler 24. The transport speed of the container 50 by the star wheels 20, 22, and 26 and the transport speed of the container 50 by the labeler 24 are synchronized.

[0037] The transport mechanism CV2 further includes a discharge device 28. The discharge device 28 is a device for discharging the container 50 in the transport mechanism CV2 from the transport mechanism CV2 without transferring it to the transport mechanism CV3. The discharge device 28 is used when an abnormality occurs in the container transport system 100 or when the containers 50 downstream of the transport mechanism CV3 become full. The discharge device 28 includes a conveyor and a recovery device. The conveyor receives the container 50 from the star wheel 26 and transports the received container 50 to the recovery device.

[0038] In the transport mechanism CV2, the star wheels 20, 22, 26 and the labeler 24 constitute a rotating body. In FIG. 1, the container loading section includes two rotating bodies and the container unloading section includes one rotating body, but this is not limited to this. The number of rotating bodies included in each of the container loading section and the container unloading section may be one or more. The transport mechanism CV2 corresponds to one example of the "first transport mechanism."

[0039] (Transport mechanism CV3) The conveying mechanism CV3 is provided downstream of the conveying mechanism CV2 in the conveying direction. The conveying mechanism CV3 is a mechanism (heat shrinking mechanism) for heat-shrinking the label covering the container 50 conveyed from the conveying mechanism CV2 to adhere it to the container 50. The conveying mechanism CV3 is configured to include a rotary heater 30 and a star wheel 32 arranged in this order from the upstream side in the conveying direction.

[0040] The rotary heater 30 is disposed adjacent to the star wheel 26 of the transfer mechanism CV2. The rotary heater 30 is driven by a servo motor (not shown) and rotates in the direction indicated by the arrow AR7. The rotary heater 30 is provided with a plurality of holding devices for holding the containers 50. The plurality of holding devices are arranged in a line in the circumferential direction of the rotary heater 30.

[0041] The star wheel 26 and the rotary heater 30 rotate in the same direction at a transfer position PB for the container 50. Each of the multiple holding devices provided on the star wheel 26 and each of the multiple holding devices provided on the rotary heater 30 sequentially arrive at the transfer position PB as the star wheel 26 and the rotary heater 30 rotate, and at the transfer position PB, the container 50 is transferred from the holding device provided on the star wheel 26 to the holding device provided on the rotary heater 30. In this way, containers 50 covered with unshrunk labels are sequentially carried into the rotary heater 30 from the conveying mechanism CV2.

[0042] The rotary heater 30 is a rotary shrink tunnel. The rotary heater 30 includes a rotary transport path along which the containers 50 are transported, and a tunnel-shaped heating device (heating tunnel) that is installed along the transport path and heats the labels. The rotary heater 30 transports multiple containers 50 in a line on the transport path, and heats the labels as the containers 50 pass through the heating tunnel, causing them to adhere to the containers 50. Steam, hot air, or the like can be used as a heat medium for heating the labels.

[0043] The containers 50 are carried out from the rotary heater 30 by the star wheel 32. That is, the star wheel 32 constitutes a container carrying section that sequentially carries out the containers 50 coated with labels by the rotary heater 30.

[0044] The star wheel 32 is disposed adjacent to the rotary heater 30. The star wheel 32 rotates in the direction indicated by the arrow AR8. The star wheel 32 has a circular shape in a plan view, and is provided with a plurality of holding devices at its outer circumferential end for holding the containers 50. The plurality of holding devices provided on the star wheel 32 are arranged side by side in the circumferential direction of the star wheel 32.

[0045] The rotary heater 30 and the star wheel 32 rotate in the same direction at a transfer position P4 for the container 50. Each of the multiple holding devices provided on the rotary heater 30 and each of the multiple holding devices provided on the star wheel 32 sequentially reach the transfer position P4 as the rotary heater 30 and the star wheel 32 rotate, and at the transfer position P4, the container 50 is transferred from the holding device provided on the rotary heater 30 to the holding device provided on the star wheel 32.

[0046] In the transfer mechanism CV3, the rotation shaft of the rotary heater 30 and the rotation shaft of the star wheel 32 are connected by a gear mechanism (not shown). The rotation shaft of the rotary heater 30 is driven to rotate by a servo motor (not shown). The rotational force of the servo motor is transmitted from the rotary heater 30 to the star wheel 32 by the gear mechanism. Therefore, the star wheel 32 rotates in conjunction with the rotation of the rotary heater 30, and the container 50 is transferred from the rotary heater 30 to the star wheel 32 at the transfer position P4.

[0047] The rotation speed of the star wheel 32 is adjusted so that the peripheral speed is the same as the peripheral speed of the rotary heater 30. The transport speed of the container 50 by the star wheel 32 and the transport speed of the container 50 by the rotary heater 30 are synchronized.

[0048] The transfer mechanism CV3 further includes a discharge device 34. The discharge device 34 is a device for discharging the container 50 from the transfer mechanism CV3 without passing it on to the next process. The discharge device 34 is used when the containers 50 on the downstream side of the transfer mechanism CV3 become full. The discharge device 34 includes a conveyor and a recovery device. The conveyor receives the container 50 from the star wheel 32 and transports the received container 50 to the recovery device.

[0049] In the transfer mechanism CV3, the rotary heater 30 and the star wheel 32 constitute a rotating body. Although the container unloading unit includes one rotating body in the example illustrated in Fig. 1, the container unloading unit may include multiple rotating bodies.

[0050] The containers 50 coated with labels by the transport mechanism CV3 are transported from the transport mechanism CV3 to the next process. In FIG. 1, a star wheel 40 constituting a downstream transport mechanism is arranged adjacent to the star wheel 32 of the transport mechanism CV3. The star wheel 40 rotates in the direction indicated by the arrow AR9. The star wheel 40 has a circular shape in a plan view, and a plurality of holding devices for holding the containers 50 are provided on its outer circumferential end. The plurality of holding devices are arranged in a line around the circumferential direction of the star wheel 40.

[0051] The star wheel 32 and the star wheel 40 rotate in the same direction at a transfer position PC for the container 50. Each of the multiple holding devices provided on the star wheel 32 and each of the multiple holding devices provided on the star wheel 40 sequentially arrive at the transfer position PC as the star wheels 32 and 40 rotate, and at the transfer position PC, the container 50 is transferred from the holding device provided on the star wheel 32 to the holding device provided on the star wheel 40. The transport mechanism CV3 corresponds to one embodiment of a "second transport mechanism."

[0052] <Control configuration of the transport system> Next, the control configuration of the container transport system 100 shown in FIG. 1 will be described.

[0053] Fig. 2 is a block diagram showing the control configuration of the container transfer system 100. As shown in Fig. 2, the container transfer system 100 includes a plurality of servo drivers 70-78, a plurality of servo motors 80-88, and a control device 60 as a configuration for controlling the rotation of a plurality of rotating bodies included in the transfer mechanisms CV1-CV3.

[0054] The servo motor 80 drives and rotates the rotary heater 30 of the transfer mechanism CV3. The servo driver 70 controls the servo motor 80. The star wheel 32 rotates in conjunction with the rotation of the rotary heater 30. The servo motor 80 corresponds to one embodiment of the "second servo motor."

[0055] The servo motor 82 rotates and drives the labeler 24 of the conveying mechanism CV2. The servo driver 72 controls the servo motor 82. The star wheels 20, 22, and 26 rotate in conjunction with the rotation of the labeler 24. The servo motor 82 corresponds to one example of a "first servo motor."

[0056] The servo motor 84 rotates and drives the star wheel 14 of the transport mechanism CV1. The servo driver 74 controls the servo motor 84. The servo motor 86 rotates and drives the screw 10 of the transport mechanism CV1. The servo driver 76 controls the servo motor 86. The servo motor 88 rotates and drives the screw 12 of the transport mechanism CV1. The servo driver 78 controls the servo motor 88.

[0057] The multiple servo drivers 70-78 are communicatively connected to a control device 60 via a network 90. ​​The control device 60 comprehensively controls each part of the container conveyance system 100. For example, the control device 60 is configured to include, as main components, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and HDD (Hard Disk Drive). The CPU executes programs. The RAM is used as a working area for the CPU. The ROM stores programs executed by the CPU. The HDD stores data in a non-volatile manner. Note that some or all of the functions provided by the CPU executing programs may be implemented using dedicated hardware circuits (for example, an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array)).

[0058] 2, the control device 60 includes a PLC (Programmable Logic Controller) 62, which is a sequence controller, and a motion controller 64. The PLC 62 has a built-in sequence program, and controls the motion controller 64 based on the program.

[0059] The motion controller 64 has a built-in motion program and controls the multiple servo drivers 70-78 based on that program. Specifically, the motion controller 64 sends control commands to each servo driver and receives information about the control status of each servo motor from each servo driver. For the network 90, it is preferable to use a network that performs fixed-cycle communication and guarantees data arrival time.

[0060] In the conveying mechanism CV1, the conveying speed of the container 50 by the screws 10, 12 and the conveying speed by the star wheel 14 are controlled to be the same. In addition, the conveying speed is synchronized with the speed at which the star wheel 20 of the conveying mechanism CV2 receives and conveys the container 50 at the delivery position PA.

[0061] In the conveying mechanism CV2, the conveying speed of the container 50 by the star wheels 20, 22, the conveying speed of the container 50 by the labeler 24, and the conveying speed of the container 50 by the star wheel 26 are the same, and the conveying speed is synchronized with the speed at which the rotary heater 30 of the conveying mechanism CV3 receives and conveys the container 50 at the transfer position PB.

[0062] In the conveying mechanism CV3, the conveying speed of the container 50 by the rotary heater 30 and the conveying speed of the container 50 by the star wheel 32 are the same, and the conveying speed is synchronized with the speed at which the star wheel 40 receives the container 50 at the transfer position PC.

[0063] Therefore, the conveying speeds of the screws 10 and 12, the star wheel 14, the labeler 24, and the rotary heater 30 are controlled to be synchronized. In this embodiment, the control device 60 synchronously controls, via a plurality of servo drivers 70 to 78, a plurality of servo motors 80 to 88 that drive the screws 10 and 12, the star wheel 14, the labeler 24, and the rotary heater 30, respectively.

[0064] In the synchronous control of the plurality of servo motors 80-88, as will be described later, one axis different from the plurality of servo motors 80-88 to be controlled is designated as a main axis, and the plurality of servo motors 80-88 are designated as slave axes, and the plurality of slave axes are synchronized with the main axis. In the following description, servo motor 82 is also referred to as "slave axis S1." Servo motor 84 is also referred to as "slave axis S2." Servo motor 80 is also referred to as "slave axis S3." Servo motor 86 is also referred to as "slave axis S4." Servo motor 88 is also referred to as "slave axis S5."

[0065] <Synchronous control> 3 is a diagram for explaining synchronous control by the control device 60. In this embodiment, a virtual control system is used for the control system of the plurality of servo motors 80 to 88. The virtual control system is a control system constructed using virtual mechanical modules such as virtual axes and virtual clutches as components. The virtual control system is realized by the control device 60 executing a program stored in a memory or a hard disk.

[0066] As shown in Fig. 3, the virtual control system includes two virtual axes M1 and S6, six virtual clutches CL1 to CL6, and five slave axes S1 to S5. In the virtual control system, the virtual axis M1 is the main axis, and the five slave axes S1 to S5 are directly or indirectly connected to the virtual axis M1. As described in Fig. 2, each slave axis includes a servo motor that rotates and drives each rotating body.

[0067] A slave axis S3 and a virtual axis S6 are connected to a virtual axis M1 (main axis). As will be described later, the virtual axis S6 is a virtual slave axis that moves in accordance with the virtual axis M1. The slave axis S3 and the virtual axis S6 move in accordance with the virtual axis M1. The virtual axis M1 corresponds to an example of a "first virtual axis," and the virtual axis S6 corresponds to an example of a "second virtual axis." The slave axis S3 corresponds to an example of a "second slave axis."

[0068] A virtual clutch CL3 is provided between the virtual axis M1 and the driven shaft S3 to transmit the rotation of the virtual axis M1 to the driven shaft S3. The virtual clutch CL3 is configured to be able to switch between transmitting and blocking rotation. When the virtual clutch CL3 is in an ON state, the rotation is transmitted from the virtual axis M1 to the driven shaft S3, and when the virtual clutch CL3 is in an OFF state, the transmission of rotation from the virtual axis M1 to the driven shaft S3 is blocked.

[0069] A virtual clutch CL6 is provided between the virtual axis M1 and the virtual axis S6 to transmit the rotation of the virtual axis M1 to the virtual axis S6. The virtual clutch CL6 is configured to be able to switch between transmitting and blocking the rotation. When the virtual clutch CL6 is in an ON state, the rotation is transmitted from the virtual axis M1 to the virtual axis S6, and when the virtual clutch CL6 is in an OFF state, the transmission of the rotation from the virtual axis M1 to the virtual axis S6 is blocked. The virtual clutch CL6 corresponds to one embodiment of a "first virtual clutch."

[0070] Four slave axes S1, S2, S4, and S5 are connected to the virtual axis S6 (slave axis). The four slave axes S1, S2, S4, and S5 operate in accordance with the virtual axis S6.

[0071] A virtual clutch CL1 is provided between the virtual axis S6 and the driven shaft S1 to transmit the rotation of the virtual axis S6 to the driven shaft S1. The virtual clutch CL1 is configured to be able to switch between transmitting and blocking rotation. When the virtual clutch CL1 is in the ON state, rotation is transmitted from the virtual axis S6 to the driven shaft S1, and when the virtual clutch CL1 is in the OFF state, transmission of rotation from the virtual axis S6 to the driven shaft S1 is blocked. The driven shaft S1 corresponds to one example of a "first driven shaft."

[0072] A virtual clutch CL2 is provided between the virtual axis S6 and the driven shaft S2 to transmit the rotation of the virtual axis S6 to the driven shaft S2. The virtual clutch CL2 is configured to be able to switch between transmitting and blocking rotation. When the virtual clutch CL2 is in an ON state, the rotation is transmitted from the virtual axis S6 to the driven shaft S2, and when the virtual clutch CL2 is in an OFF state, the transmission of rotation from the virtual axis S6 to the driven shaft S2 is blocked.

[0073] A virtual clutch CL4 is provided between the virtual axis S6 and the driven shaft S4 to transmit the rotation of the virtual axis S6 to the driven shaft S4. The virtual clutch CL4 is configured to be able to switch between transmitting and blocking rotation. When the virtual clutch CL4 is in an ON state, the rotation is transmitted from the virtual axis S6 to the driven shaft S4, and when the virtual clutch CL4 is in an OFF state, the transmission of rotation from the virtual axis S6 to the driven shaft S4 is blocked.

[0074] A virtual clutch CL5 is provided between the virtual axis S6 and the driven shaft S5 to transmit the rotation of the virtual axis S6 to the driven shaft S5. The virtual clutch CL5 is configured to be able to switch between transmitting and blocking rotation. When the virtual clutch CL5 is in an ON state, the rotation is transmitted from the virtual axis S6 to the driven shaft S5, and when the virtual clutch CL5 is in an OFF state, the transmission of rotation from the virtual axis S6 to the driven shaft S5 is blocked.

[0075] In this way, the driven shafts S1, S2, S4, and S5 are indirectly connected to the driven shaft M1 (main shaft) via the driven shaft S6. Therefore, when the virtual clutches CL6, CL1, CL2, CL4, and CL5 are all in the ON state, the rotation of the driven shaft M1 is transmitted to the driven shafts S1, S2, S4, and S5 via the driven shaft S6. As a result, the driven shafts S1, S2, S4, and S5 operate in accordance with the driven shaft M1. When the virtual clutch CL6 is turned OFF in this state, the transmission of rotation from the driven shaft M1 to the driven shaft S6 is interrupted, and the transmission of rotation to the driven shafts S1, S2, S4, and S5 is interrupted, causing the operation of the driven shafts S1, S2, S4, and S5 to stop.

[0076] Since virtual clutches CL1, CL2, and CL4 are provided between the virtual axis S6 and the driven axes S1, S2, S4, and S5, respectively, it is possible to individually switch between transmitting and cutting off rotation to each driven axis by turning on and off the virtual clutches CL1, CL2, CL4, and CL5 independently of one another. Therefore, for example, while the driven axis S1 is operating in synchronization with the virtual axis S6 (i.e., the virtual axis M1), the virtual clutches CL2, CL4, and CL5 can be turned off to stop the operation of the driven axes S2, S4, and S5.

[0077] On the other hand, in contrast to the driven shafts S1, S2, S4, and S5, the driven shaft S3 is directly connected to the virtual shaft M1. Therefore, even if the virtual clutch CL6 is turned off and the driven shafts S1, S2, S4, and S5 are stopped from operating, the driven shaft S3 can continue to operate in synchronization with the virtual shaft M1 as long as the virtual clutch CL3 is turned on.

[0078] In the virtual control system, when all of the virtual clutches CL1-CL6 are in the ON state, when the virtual axis M1 rotates one revolution (360°) by a virtual servo motor (not shown), each of the slave axes S1-S5, which are directly or indirectly connected to the virtual axis M1, moves for one designed cycle (one conveyance pitch). In other words, each cycle is 360°, and each slave axis is configured to repeat its operation in synchronization with each other every time the virtual axis M1 rotates one revolution. This allows the container conveyance system 100 to convey multiple containers 50 continuously supplied from the upstream side at a constant speed via the conveyance mechanisms CV1, CV2, and CV3 in sequence.

[0079] Here, assume that during normal operation of transporting multiple containers 50, an abnormality occurs within the container transport system 100 or on the upstream or downstream side of the container transport system 100. In this case, it is necessary to quickly stop the transport of the containers 50.

[0080] For the transfer mechanisms CV1 and CV2, all rotating bodies can be stopped after dispensing the containers 50 from each transfer mechanism. On the other hand, for the transfer mechanism CV3, the rotary heater 30 cannot be stopped and must continue to operate. This is because stopping the rotary transfer path included in the rotary heater 30 could cause the containers 50 remaining in the tunnel-shaped heating device (heating tunnel) and the components inside the heating device to continue to heat, potentially resulting in damage. To prevent damage to the containers 50 and components, it is necessary to continue rotating the transfer path, even at a speed slower than the normal rotation speed, without completely stopping the rotation of the transfer path.

[0081] In the above-described synchronous control, in order to continue the operation of only the slave axis S3 that drives the rotary heater 30, it is conceivable to configure the virtual control system so that five slave axes S1 to S5 are directly connected to a virtual axis M1, which is the master axis, as shown in Fig. 14. In the configuration shown in Fig. 14, five virtual clutches CL1 to CL5 are provided between the virtual axis M1 and the five slave axes S1 to S5, respectively.

[0082] If an abnormality occurs in the container conveying system 100, the virtual clutch CL3 between the virtual axis M1 and the driven axis S3 is kept on, and the virtual clutches CL1, CL2, CL4, and CL5 between the virtual axis M1 and the remaining driven axes S1, S2, S4, and S5 are turned off. This allows the operation of the remaining driven axes S1, S2, S4, and S5 to be stopped while the operation of the driven axis S3 is maintained.

[0083] However, with the corresponding virtual clutches disengaged, each of the four slave axes S1, S2, S4, and S5 becomes asynchronous with the virtual axis M1. Therefore, when restarting the transport mechanisms CV1 and CV2, it is necessary to execute a process to resynchronize each of the slave axes S1, S2, S4, and S5 with the virtual axis M1. To do this, it becomes necessary to prepare a program for each slave axis to synchronize with the virtual axis M1. Furthermore, because there is no synchronization between the stopped slave axes S1, S2, S4, and S5, it may be impossible to maintain synchronization accuracy between the slave axes S1 to S5 after restarting.

[0084] To address these concerns, in this embodiment, the multiple slave axes S1 to S5 are divided into slave axis S3, whose operation is not permitted to stop, and slave axes S1, S2, S4, and S5, whose operation is permitted to stop. As shown in Fig. 3, the slave axis S3 is connected to a virtual axis M1 (main axis), while the slave axes S1, S2, S4, and S5 are connected to a virtual axis S6 that is different from the virtual axis M1, and the virtual axis S6 is connected to the virtual axis M1.

[0085] According to this embodiment, the slave axes S1, S2, S4, and S5 operate in synchronization with the virtual axis S6. Therefore, when the virtual clutch CL6 between the virtual axis M1 and the virtual axis S6 is disengaged, the operation of the slave axes S1, S2, S4, and S5 can be stopped while maintaining synchronization with the virtual axis S6. Therefore, in order to restart the transport mechanisms CV1 and CV2, it is sufficient to prepare a program for synchronizing the virtual axis S6 with the virtual axis M1. Furthermore, because the synchronous relationship between the stopped slave axes S1, S2, S4, and S5 is maintained, it is possible to improve the synchronization accuracy between the slave axes S1 to S5 after restart.

[0086] Next, the synchronous control by the virtual control system shown in FIG. 3 will be described. (1) Normal operation 4 is a diagram for explaining synchronous control during normal operation of the container transport system 100. During normal operation of the container transport system 100, the virtual clutches CL1 to CL6 are all in the ON state. Therefore, the rotation of the virtual axis M1 (main axis) is transmitted to all of the slave axes S1 to S5. When the virtual axis M1 rotates once (360°), each of the slave axes S1 to S5 performs one designed cycle (one transport pitch).

[0087] Specifically, a detector (not shown) for detecting the position of the virtual axis M1 (rotation angle from the reference position (0°)) is provided at one end of the virtual axis M1. The time for one cycle (one transfer pitch) of the slave axes S1 to S5 is set to one rotation of the virtual axis M1. Based on the position information of the virtual axis M1 acquired from the detector, the control device 60 controls the positions of the slave axis S3 and the virtual axis S6 (slave axes) connected to the virtual axis M1 so that the respective positions of the slave axis S3 and the virtual axis S6 follow the position of the virtual axis M1.

[0088] Furthermore, a detector (not shown) for detecting the position of the virtual axis S6 is provided at one end of the virtual axis S6. Based on the position information of the virtual axis S6 acquired from the detector, the control device 60 controls the positions of the slave axes S1, S2, S4, and S5 connected to the virtual axis S6 so that each of the slave axes S1, S2, S4, and S5 follows the position of the virtual axis S6. In this way, the control device 60 drives and controls the slave axis S3 and the virtual axis S6 based on the position information of the virtual axis M1, and drives and controls the slave axes S1, S2, S4, and S5 based on the position information of the virtual axis S6.

[0089] In this specification, for two axes in a master-slave relationship, acquiring position information of the master axis so that the slave axis operates in synchronization with the master axis is defined as "synchronization on." On the other hand, operating the slave axis without synchronization with the master axis is defined as "synchronization off."

[0090] The "synchronization on" state includes a state in which a virtual clutch provided between two axes in a master-slave relationship is on, and a state in which the virtual clutch is off. The "synchronization on and virtual clutch on" state refers to a state in which position information of the main shaft is acquired and the position of the slave shaft is controlled to follow the acquired position of the main shaft. The "synchronization on and virtual clutch off" state refers to a state in which position information of the main shaft is acquired, but the operation of the slave shaft is stopped and the position of the slave shaft does not follow the position of the main shaft.

[0091] During normal operation, the virtual axis M1 and the slave axis S3 are in a "synchronization on and virtual clutch on" state. The virtual axis M1 and the virtual axis S6 are in a "synchronization on and virtual clutch on" state. Furthermore, the virtual axis S6 and each of the slave axes S1, S2, S4, and S5 are in a "synchronization on and virtual clutch on" state. By repeating the operation of each slave axis in synchronization with each other every time the virtual axis M1 rotates once, the container conveying system 100 can convey multiple containers 50 continuously supplied from the upstream side at a constant speed via the conveying mechanism CV1, the conveying mechanism CV2, and the conveying mechanism CV3 in sequence.

[0092] (2) When there is a shortage of containers 5 to 8 are diagrams for explaining the synchronization control when a shortage of containers 50 supplied to the transport mechanism CV1 occurs.

[0093] 1, a sensor (not shown) is installed on the conveyor upstream of the transfer mechanism CV1 to detect a shortage of containers 50. The control device 60 detects whether or not a shortage of containers 50 has occurred based on the output signal of the sensor.

[0094] If a shortage of containers 50 is detected during normal operation, the control device 60 dispenses the containers 50 from the transfer mechanisms CV1 and CV2, and then stops the operation of the transfer mechanisms CV1 and CV2. On the other hand, the control device 60 continues the operation of the transfer mechanism CV3 to prevent damage to the containers 50 and the rotary heater 30 components.

[0095] Specifically, when a shortage of containers 50 is detected upstream of the transfer mechanism CV1, the control device 60 first stops the operation of the transfer mechanism CV1. As shown in Fig. 5, the control device 60 turns off the virtual clutches CL2, CL4, and CL5 in the virtual control system, thereby interrupting the transmission of rotation from the virtual axis S6 to the driven axes S2, S4, and S5.

[0096] The control device 60 transitions the virtual axis S6 and the slave axes S2, S4, and S5 from the "synchronization on and virtual clutch on" state to the "synchronization on and virtual clutch off" state. That is, the control device 60 acquires the position information of the virtual axis S6, but stops the slave axes S2, S4, and S5, so that the positions of the slave axes S2, S4, and S5 do not follow the position of the virtual axis S6.

[0097] In response to the virtual clutches CL2, CL4, and CL5 being turned off, the driven shafts S2, S4, and S5 decelerate. At the transfer position PA, the control device 60 discharges the container 50 from the star wheel 14 to the discharge device 16 without transferring the container 50 from the holding device provided on the star wheel 14 to the holding device provided on the star wheel 20.

[0098] The control device 60 stops the operation of the driven shafts S2, S4, and S5 after moving the driven shafts S2, S4, and S5 a predetermined distance. The distance of movement of the driven shafts S2, S4, and S5 is determined by the product of the rotational speed of the driven shafts S2, S4, and S5 and the time from when the virtual clutches CL2, CL4, and CL5 are disengaged until the driven shafts S2, S4, and S5 stop. The distance of movement of the driven shafts S2, S4, and S5 is set so that all containers 50 in the transport mechanism CV1 can be discharged to the discharge device 16.

[0099] Because the virtual clutch CL1 is in the ON state, the rotation of the virtual axis S6 is transmitted to the slave axis S1. In other words, the virtual axis S6 and the slave axis S1 are maintained in a "synchronized ON and virtual clutch ON" state. The slave axis S1 operates in accordance with the virtual axis S6, thereby sequentially transporting the containers 50 in the transport mechanism CV2 to the transport mechanism CV3.

[0100] When all the containers 50 in the transport mechanism CV2 have been dispensed, the control device 60 then turns off the virtual clutch CL6, as shown in FIG. 6, thereby interrupting the transmission of rotation from the virtual axis M1 to the virtual axis S6. The control device 60 transitions the virtual axis M1 and the virtual axis S6 from the "synchronization on and virtual clutch on" state to the "synchronization on and virtual clutch off" state. That is, the control device 60 acquires position information of the virtual axis M1, but stops the virtual axis S6 so that the position of the virtual axis S6 does not follow the position of the virtual axis M1. Note that the virtual axis S6 and the slave axis S1 are maintained in the "synchronization on and virtual clutch on" state.

[0101] When the virtual clutch CL6 is turned off, the transmission of rotation from the virtual axis M1 to the driven axis S1 is interrupted, causing the driven axis S1 to decelerate. The control device 60 stops the operation of the driven axis S1 after moving the driven axis S1 by a predetermined amount. This stops the operation of the transport mechanism CV2.

[0102] During the period in which the driven shafts S2, S4, S5 and the driven shaft S1 are sequentially decelerated and stopped in this manner, the virtual clutch CL3 is in the ON state, so the driven shaft S3 operates following the virtual shaft M1. Therefore, the conveying mechanism CV3 labels the containers 50 sequentially conveyed from the conveying mechanism CV2 and conveys them sequentially to the next process.

[0103] When all containers 50 in the transport mechanism CV3 have been dispensed, the control device 60 turns on the virtual clutches CL2, CL4, and CL5 while keeping the virtual clutch CL6 in the off state, as shown in FIG. 7. The control device 60 transitions the virtual axis S6 and the slave axes S2, S4, and S5 from a "synchronization on and virtual clutch off" state to a "synchronization on and virtual clutch on" state. That is, the control device 60 acquires position information for the virtual axis S6 and controls the positions of the slave axes S2, S4, and S5 to follow the position of the acquired virtual axis S6. However, because the rotation of the virtual axis S6 has stopped, the operation of the slave axes S1, S2, S4, and S5 has also stopped.

[0104] The control device 60 further transitions the virtual axis M1 and the virtual axis S6 from the "synchronization on and virtual clutch off" state to the "synchronization off and virtual clutch off" state. In other words, the virtual axis S6 is brought into a state where it operates without following the virtual axis M1.

[0105] In this state, the control device 60 causes the transfer mechanism CV3 to perform standby operation, in which the transfer mechanism CV3 continues to operate without transferring the containers 50. During standby operation, the control device 60 causes the virtual axis M1 to rotate at a constant speed that is lower than the rotational speed during normal operation. Because the virtual axis M1 and the slave axis S3 are maintained in a "synchronized on and virtual clutch on" state, the slave axis S3 also operates at a low speed following the virtual axis M1. Therefore, the rotary heater 30 in the transfer mechanism CV3 can continue to operate even during standby operation, preventing damage to the components of the rotary heater 30.

[0106] When the shortage of containers 50 is resolved and the transfer mechanisms CV1 and CV2 are restarted, the control device 60 transitions the virtual axes M1 and S6 from the "synchronization off and virtual clutch off" state to the "synchronization on and virtual clutch on" state, as shown in Fig. 8. In other words, the control device 60 acquires position information of the virtual axis M1, and controls the position of the virtual axis S6 so that it follows the position of the acquired virtual axis M1.

[0107] Here, before turning on the virtual clutch CL6, the control device 60 temporarily stops the virtual axis M1, which is in standby operation (low-speed operation), and moves the position of the virtual axis M1 to the reference position (0°). This is to re-establish a synchronous relationship between the virtual axis M1 and the stopped virtual axis S6 and the slave axes S1, S2, S4, and S5. Because the virtual axis S6 and the slave axes S1, S2, S4, and S5 are stopped at positions corresponding to the reference position (0°) of the virtual axis M1, the position of the virtual axis M1 is reset to the reference position (0°) to re-synchronize with these slave axes.

[0108] The temporary stop of the virtual axis M1 also causes the slave axis S3 to temporarily stop. The time for which the virtual axis M1 is temporarily stopped is set to a time that does not affect the components of the rotary heater 30.

[0109] After moving the position of the virtual axis M1 to the reference position (0°), the control device 60 synchronizes the virtual axis M1 with the virtual axis S6 and turns on the virtual clutch CL6, thereby transitioning the virtual axis M1 and the virtual axis S6 to a "synchronization on and virtual clutch on" state.

[0110] FIG. 9 is a flowchart showing the flow of processing by the control device 60 when a situation occurs in which the number of containers 50 supplied to the transport mechanism CV1 is insufficient.

[0111] As shown in Fig. 9, in step S01, the control device 60 executes synchronization control during normal operation of the container conveyance system 100. In S01, the control device 60 turns on all of the virtual clutches CL1 to CL6 in the virtual control system, as shown in Fig. 4. The control device 60 also turns on the virtual axis M1, the slave axis S3, and the virtual axis S6 in a synchronized on state, and turns on the virtual axis S6 and the slave axes S1, S2, S4, and S5 in a synchronized on state. Therefore, the positions of the slave axis S3 and the virtual axis S6 are controlled to follow the position of the virtual axis M1, and the positions of the slave axes S1, S2, S4, and S5 are controlled to follow the position of the virtual axis S6.

[0112] By having each slave axis repeat its operation in synchronization every time the virtual axis M1 rotates once, the container conveying system 100 conveys multiple containers 50 continuously supplied from the upstream side at a constant speed via conveying mechanism CV1, conveying mechanism CV2, and conveying mechanism CV3 in sequence.

[0113] During normal operation, in step S02, the control device 60 detects whether or not there is a shortage of containers 50 upstream of the transfer mechanism CV1 based on the output signal of a sensor for detecting a shortage of containers 50. If a shortage of containers 50 is not detected (NO in S02), the control device 60 continues the processing of step S01.

[0114] When a shortage of the container 50 is detected (YES in S02), the control device 60 first turns off the virtual clutches CL2, CL4, and CL5 in step S03, as shown in FIG. 5. This blocks the transmission of rotation from the virtual axis S6 to the driven axes S2, S4, and S5. The control device 60 transitions the virtual axis S6 and the driven axes S2, S4, and S5 from a "synchronization on and virtual clutch on" state to a "synchronization on and virtual clutch off" state. In other words, the control device 60 stops the operation of the driven axes S2, S4, and S5 while maintaining synchronization with the virtual axis S6.

[0115] In response to the virtual clutches CL2, CL4, and CL5 being turned off, the driven shafts S2, S4, and S5 decelerate. While the screws 10 and 12 and the star wheel 14 are decelerating, the control device 60 discharges the container 50 from the star wheel 14 to the discharge device 16 in step S04. In step S05, the control device 60 moves the driven shafts S2, S4, and S5 by a predetermined amount and then stops the operation of the driven shafts S2, S4, and S5. This stops the operation of the transport mechanism CV1.

[0116] Next, in step S06, the control device 60 operates the slave axis S1 in response to the virtual axis S6, thereby delivering the containers 50 in the transport mechanism CV2 to the transport mechanism CV3. When all of the containers 50 in the transport mechanism CV2 have been delivered, the control device 60 turns off the virtual clutch CL6 in step S07, as shown in FIG. 6. This blocks the transmission of rotation from the virtual axis M1 to the virtual axis S6. The control device 60 transitions the virtual axes M1 and S6 from a "synchronization on and virtual clutch on" state to a "synchronization on and virtual clutch off" state. That is, the control device 60 stops the rotation of the virtual axis S6 while maintaining synchronization with the virtual axis M1, and stops the operation of the slave axis S1 while maintaining synchronization with the virtual axis S6.

[0117] In response to the virtual clutch CL6 being turned off, the driven shaft S1 decelerates. In step S08, the control device 60 moves the driven shaft S1 by a predetermined movement amount and then stops the operation of the driven shaft S1. This stops the operation of the transport mechanism CV2.

[0118] Next, in step S09, the control device 60 operates the slave axis S3 in response to the virtual axis M1, thereby delivering the containers 50 in the transfer mechanism CV3 to the next process. When all of the containers 50 in the transfer mechanism CV3 have been delivered, the control device 60 turns on the virtual clutches CL2, CL4, and CL5 in step S10, while keeping the virtual clutch CL6 in the off state, as shown in FIG. 7. The control device 60 transitions the virtual axis S6 and the slave axes S2, S4, and S5 from a "synchronization on and virtual clutch off" state to a "synchronization on and virtual clutch on" state.

[0119] Furthermore, in step S11, the control device 60 transitions the virtual axes M1 and S6 from the "synchronization on and virtual clutch off" state to the "synchronization off and virtual clutch off" state.

[0120] Next, in step S12, the control device 60 causes the transfer mechanism CV3 to perform standby operation. In S12, the control device 60 causes the virtual axis M1 to rotate at a constant speed that is lower than the rotational speed during normal operation. By having the slave axis S3 also operate at a low speed following the virtual axis M1, the rotary heater 30 in the transfer mechanism CV3 can continue to operate even during standby operation. This prevents damage to the components of the rotary heater 30.

[0121] During standby operation, the control device 60 determines whether or not a restart command for the transfer mechanisms CV1 and CV2 has been received in step S13. If a restart command has not been received (NO in S13), the control device 60 continues the processing of step S12.

[0122] When the restart command is received (YES in S13), the control device 60 temporarily stops the virtual axis M1, which is operating at low speed, in step S14. Next, in step S15, the control device 60 moves the position of the virtual axis M1 to the reference position (0°).

[0123] After moving the position of the virtual axis M1 to the reference position (0°), the control device 60 synchronizes the virtual axis M1 with the virtual axis S6 in step S16, and turns on the virtual clutch CL6 in step S17. This causes the virtual axis M1 and the virtual axis S6 to transition to a "synchronization on and virtual clutch on" state.

[0124] Next, in step S18, the control device 60 activates the virtual axis M1. The control device 60 controls the positions of the slave axes S3 and S6 so that they follow the position of the virtual axis M1, and also controls the positions of the slave axes S1, S2, S4, and S5 so that they follow the position of the virtual axis S6. Therefore, the container transport system 100 returns to normal operation (FIG. 4).

[0125] As described above, when a shortage of containers 50 occurs upstream of the container conveying system 100, first, the virtual clutches CL2, CL4, and CL5 are turned off to stop the operation of the slave axes S2, S4, and S5 (i.e., the operation of the conveying mechanism CV1), and then the virtual clutch CL6 is turned off to stop the operation of the slave axis S1 (i.e., the operation of the conveying mechanism CV2). These slave axes S1, S2, S4, and S5 are stopped while maintaining synchronization with the virtual axis S6. Meanwhile, the slave axis S3 continues to operate in accordance with the virtual axis M1.

[0126] Therefore, when restarting the container conveyance system 100, synchronization between the virtual axis M1 and the virtual axis S6 can be resumed, thereby resuming synchronization between the virtual axis M1 and the slave axes S1, S2, S4, and S5. In other words, a program for synchronizing each slave axis with the virtual axis M1 is no longer necessary, and it is sufficient to prepare a program for synchronizing the virtual axis S6 with the virtual axis M1.

[0127] Furthermore, since the synchronous relationship between the stopped slave axes S1, S2, S4, and S5 is maintained, the synchronization between the slave axes S1 to S5 can be maintained with high precision even after synchronization with the virtual axis M1 is resumed.

[0128] (3) When an abnormality occurs in the container transport system 10 to 12 are diagrams for explaining synchronous control when an abnormality occurs in the container transport system 100. Abnormalities in the container transport system 100 include a situation in which one of the multiple sensors installed in the system detects an abnormality, and a situation in which an operator detects an abnormality and operates an emergency stop button. The synchronous control described below can also be applied when a situation occurs in which the containers 50 downstream of the transport mechanism CV3 become full.

[0129] 1, if an abnormality occurs during normal operation, the control device 60 stops the operation of the transfer mechanisms CV1 and CV2 after discharging the containers 50 from the transfer mechanisms CV1 and CV2. On the other hand, the control device 60 continues the operation of the transfer mechanism CV3 to prevent damage to the components of the rotary heater 30.

[0130] Specifically, when an abnormality occurs in the container conveyance system 100, first, as shown in FIG. 10, the virtual clutch CL6 is turned off to interrupt the transmission of rotation from the virtual axis M1 to the virtual axis S6. The control device 60 transitions the virtual axis M1 and the virtual axis S6 from a "synchronization on and virtual clutch on" state to a "synchronization on and virtual clutch off" state. In other words, the position information of the virtual axis M1 is acquired, but the position of the virtual axis S6 does not follow the position of the virtual axis M1. Note that the virtual axis S6 and the slave axes S1, S2, S4, and S5 are maintained in a "synchronization on and virtual clutch on" state.

[0131] When the virtual clutch CL6 is turned off, the transmission of rotation from the virtual axis M1 to the virtual axis S6 is interrupted, causing the virtual axis S6 to decelerate. The driven axes S1, S2, S4, and S5 also decelerate following the virtual axis S6. The control device 60 stops the rotation of the virtual axis S6 after moving the virtual axis S6 a predetermined distance. The movement distance of the virtual axis S6 is determined by the product of the rotational speed of the virtual axis S6 and the time from when the virtual clutch CL6 is turned off until the virtual axis S6 stops. The movement distance of the virtual axis S6 is set so that the driven axes S1, S2, S4, and S5 can discharge all of the containers 50 in the transfer mechanisms CV1 and CV2 to the discharge devices 16 and 28.

[0132] Since the virtual axis S6 and the slave axes S1, S2, S4, and S5 are maintained in the "synchronization on and virtual clutch on" state, the slave axes S1, S2, S4, and S5 stop while maintaining synchronization with the virtual axis S6.

[0133] When the rotation of the virtual axis S6 stops, the control device 60 transitions the virtual axis M1 and the virtual axis S6 from the "synchronization on and virtual clutch off" state to the "synchronization off and virtual clutch off" state, as shown in Fig. 11. In other words, the virtual axis S6 is brought into a state where it operates without following the virtual axis M1.

[0134] During the period when the virtual axis S6 and the slave axes S1, S2, S4, and S5 are decelerated and stopped in this manner, the virtual clutch CL3 is in the ON state, so the rotation of the virtual axis M1 is transmitted to the slave axis S3. In other words, the virtual axis M1 and the slave axis S3 are maintained in a "synchronized ON and virtual clutch ON" state. As the slave axis S3 operates in accordance with the virtual axis M1, the containers 50 in the transfer mechanism CV3 are sequentially transferred to the next process. Note that if the containers 50 are full downstream of the container transfer system 100, the containers 50 in the transfer mechanism CV3 are discharged to the discharge device 34.

[0135] Once all the containers 50 in the transfer mechanism CV3 have been dispensed, the control device 60 puts the transfer mechanism CV3 into standby mode. During standby mode, the control device 60 rotates the virtual axis M1 at a constant speed that is lower than the rotational speed during normal operation. Because the virtual axis M1 and the driven axis S3 are maintained in a "synchronized on and virtual clutch on" state, the driven axis S3 also rotates at a low speed following the virtual axis M1. Therefore, the rotary heater 30 in the transfer mechanism CV3 can continue to operate even during standby mode, preventing damage to the rotary heater 30's components.

[0136] When restarting the transport mechanisms CV1 and CV2, the control device 60 transitions the virtual axes M1 and S6 from the "synchronization off and virtual clutch off" state to the "synchronization on and virtual clutch on" state, as shown in Fig. 12. That is, the control device 60 acquires position information of the virtual axis M1, and controls the position of the virtual axis S6 so that it follows the acquired position of the virtual axis M1.

[0137] 8, before turning on the virtual clutch CL6, the control device 60 temporarily stops the virtual axis M1, which is in standby operation (low-speed operation), and moves the position of the virtual axis M1 to the reference position (0°). Because the virtual axis S6 and the slave axes S1, S2, S4, and S5 are stopped at positions corresponding to the reference position (0°) of the virtual axis M1, the position of the virtual axis M1 is reset to the reference position (0°) to regain synchronization with these slave axes.

[0138] After moving the position of the virtual axis M1 to the reference position (0°), the control device 60 synchronizes the virtual axis M1 with the virtual axis S6 and turns on the virtual clutch CL6, thereby transitioning the virtual axis M1 and the virtual axis S6 to a "synchronization on and virtual clutch on" state.

[0139] Fig. 13 is a flowchart showing the flow of processing by the control device 60 when an abnormality occurs in the container transport system 100. In the flowchart of Fig. 13, steps S03 to S11 in the flowchart of Fig. 9 are replaced with steps S02A to S07A.

[0140] As shown in Fig. 13, in step S01, which is the same as in Fig. 9, the control device 60 executes synchronization control during normal operation of the container conveyance system 100. In S01, the control device 60 turns on all of the virtual clutches CL1 to CL6 in the virtual control system, as shown in Fig. 4. The control device 60 also turns on the virtual axis M1, the slave axis S3, and the virtual axis S6 in a synchronized on state, and turns on the virtual axis S6 and the slave axes S1, S2, S4, and S5 in a synchronized on state. Therefore, the positions of the slave axis S3 and the virtual axis S6 are controlled to follow the position of the virtual axis M1, and the positions of the slave axes S1, S2, S4, and S5 are controlled to follow the position of the virtual axis S6.

[0141] During normal operation, in step S02A, the control device 60 detects whether or not an abnormality has occurred in the container transport system 100 based on output signals from multiple sensors in the container transport system 100. If no abnormality has occurred in the container transport system 100 (NO in S02A), the control device 60 continues processing in step S01.

[0142] When an abnormality in the container conveying system 100 is detected (YES in S02A), the control device 60 first turns off the virtual clutch CL6 in step S03A, as shown in FIG. 10. This blocks the transmission of rotation from the virtual axis M1 to the virtual axis S6. The control device 60 transitions the virtual axis M1 and the virtual axis S6 from a "synchronization on and virtual clutch on" state to a "synchronization on and virtual clutch off" state. However, the control device 60 maintains the virtual axis S6 and the slave axes S1, S2, S4, and S5 in a "synchronization on and virtual clutch on" state.

[0143] In response to the virtual clutch CL6 being disengaged, the rotation of the virtual shaft S6 is decelerated. As the virtual shaft S6 is decelerated, the driven shafts S1, S2, S4, and S5 are also decelerated. In step S04A, while the screws 10 and 12 and the star wheel 14 are decelerating, the control device 60 discharges the containers 50 from the star wheel 14 to the discharge device 16. Also, while the labeler 24 is decelerating, the control device 60 discharges the containers 50 from the star wheel 26 to the discharge device 28.

[0144] In step S05A, the control device 60 moves the virtual axis S6 by a predetermined movement amount and then stops the rotation of the virtual axis S6, thereby stopping the operation of the transfer mechanisms CV1 and CV2.

[0145] Next, in step S06A, the control device 60 transitions the virtual axis M1 and the virtual axis S6 from the "synchronization on and virtual clutch off" state to the "synchronization off and virtual clutch off" state.

[0146] Next, in step S07A, the control device 60 operates the slave axis S3 following the virtual axis M1 to dispense the containers 50 from the transfer mechanism CV3. Once all of the containers 50 from the transfer mechanism CV3 have been dispensed, the control device 60 causes the transfer mechanism CV3 to enter standby mode in step S12, the same as in FIG. 9. In S12, the control device 60 rotates the virtual axis M1 at a constant speed that is lower than the rotational speed during normal operation. By operating the slave axis S3 at a low speed following the virtual axis M1, the rotary heater 30 in the transfer mechanism CV3 can continue to operate even during standby mode. This prevents damage to the components of the rotary heater 30.

[0147] During standby operation, the control device 60 determines whether or not a restart command for the transfer mechanisms CV1 and CV2 has been received in step S13, which is the same as in Fig. 9. If a restart command has not been received (NO in S13), the control device 60 continues the processing of step S12.

[0148] When a restart command is received (YES determination in S13), the control device 60 temporarily stops the virtual axis M1, which is operating at low speed, in step S14, which is the same as in Fig. 9. Next, in step S15, which is the same as in Fig. 9, the control device 60 moves the position of the virtual axis M1 to the reference position (0°).

[0149] After moving the position of the virtual axis M1 to the reference position (0°), the control device 60 synchronizes the virtual axis M1 with the virtual axis S6 in step S16, which is the same as in Fig. 9, and turns on the virtual clutch CL6 in step S17, which is the same as in Fig. 9. This causes the virtual axis M1 and the virtual axis S6 to transition to a "synchronization on and virtual clutch on" state.

[0150] Next, in step S18, which is the same as in Fig. 9, the control device 60 activates the virtual axis M1. The control device 60 controls the positions of the slave axes S3 and S6 so that they follow the position of the virtual axis M1, and also controls the positions of the slave axes S1, S2, S4, and S5 so that they follow the position of the virtual axis S6. Therefore, the container transport system 100 returns to normal operation (Fig. 4).

[0151] As described above, when an abnormality occurs in the container transport system 100, first, the virtual clutch CL6 is turned off and the rotation of the virtual axis S6 is stopped. By stopping the rotation of the virtual axis S6, the operation of the slave axes S2, S4, S5 (i.e., the operation of the transport mechanism CV1) and the operation of the slave axis S1 (i.e., the operation of the transport mechanism CV2) are stopped. These slave axes S1, S2, S4, S5 are stopped while maintaining synchronization with the virtual axis S6. Meanwhile, the slave axis S3 continues to operate in accordance with the virtual axis M1.

[0152] Therefore, when the transfer mechanisms CV1 and CV2 are restarted, the synchronization between the virtual axis M1 and the virtual axis S6 is resumed, thereby allowing the synchronization between the virtual axis M1 and the slave axes S1, S2, S4, and S5 to be resumed. In other words, a program for synchronizing each slave axis with the virtual axis M1 is no longer necessary; it is sufficient to prepare a program for synchronizing the virtual axis S6 with the virtual axis M1. Furthermore, because the synchronous relationship between the stopped slave axes S1, S2, S4, and S5 is maintained, it is possible to maintain high precision synchronization between the slave axes S1 to S5 after synchronization with the virtual axis M1 is resumed.

[0153] <Modification> In the above description, the container transport system 100 is configured such that the transport mechanism CV2 is a "first transport mechanism" driven by a first servo motor, and the transport mechanism CV3 is a "second transport mechanism" driven by a second servo motor. In a virtual control system for synchronously controlling the first and second servo motors, the second servo motor (second slave shaft) and the second virtual shaft S6 are connected to the first virtual axis M1, and the first servo motor (first slave shaft) is connected to the second virtual axis S6. However, in the transport system of the present disclosure, the "first transport mechanism" and the "second transport mechanism" are not limited to the above embodiment. In the transport system of the present disclosure, the "first transport mechanism" may include a rotating body that allows the first slave shaft to stop operating, and the "second transport mechanism" may include a rotating body that does not allow the second slave shaft to stop operating.

[0154] In the above explanation, a container conveying system was shown as an example of application of the conveying system of the present disclosure, but the conveying system of the present disclosure can be applied to various systems configured to sequentially convey items by synchronously driving multiple servo motors, such as shrink labelers, cartoning machines, pouch bag making machines, and tack labelers.

[0155] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0156] 10,12 Screw, 14,20,22,26,32,40 Star wheel, 16,28,34 Discharge device, 24 Labeler, 30 Rotary heater, 50 Container, 60 Control device, 62 PLC, 64 Motion controller, 70,72,74,76,78 Servo driver, 80,82,84,86,88 Servo motor, 90 Network, 100 Container conveying system, CV1~CV3 Conveying mechanism, M1,S6 Virtual axis, S1~S5 Slave axis.

Claims

1. A conveying system that sequentially conveys a plurality of items, a first conveying mechanism driven by a first servo motor; a second conveying mechanism driven by a second servo motor; a control device that synchronously controls the first servo motor and the second servo motor, the control device includes a processor and a memory that stores a program executed by the processor, and the processor constructs a virtual control system in accordance with the program, in which a first virtual axis is a master axis and the first and second servo motors are first and second slave axes, respectively; In the virtual control system, the second slave axis and the second virtual axis are connected to the first virtual axis, and the second slave axis and the second virtual axis operate in accordance with the first virtual axis; The first slave shaft is connected to the second virtual shaft, and the first slave shaft operates in accordance with the second virtual shaft.

2. the virtual control system includes a first virtual clutch that is provided between the first virtual axis and the second virtual axis and is configured to be switchable between an ON state in which rotation of the first virtual axis is transmitted to the second virtual axis and an OFF state in which transmission of rotation from the first virtual axis to the second virtual axis is interrupted, During normal operation of the conveyance system, the control device 2. The conveyance system according to claim 1, wherein the first virtual clutch is set to an ON state, the second virtual axis and the second slave axis are drive-controlled based on position information of the first virtual axis, and the first slave axis is drive-controlled based on position information of the second virtual axis.

3. When an abnormality occurs in the transport system during the normal operation, the control device 3. The conveyance system according to claim 2, wherein the first virtual clutch is set to an OFF state, and the operation of the first slave axis is stopped while maintaining synchronization with the second virtual axis, while the second slave axis is operated to follow the first virtual axis.

4. the first transport mechanism includes a rotating body that allows the first slave shaft to stop moving, The transfer system according to claim 1 , wherein the second transfer mechanism includes a rotating body that does not allow the second slave shaft to stop moving.

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