TR2024007093A2 - Supply apparatus. - Google Patents

Abstract

A supply apparatus includes a first conveyor, a second conveyor, a destination sensor, and a controller. The first conveyor separates a plurality of coils into individual coils and transports each coil. The second conveyor transports the coil sent from the first conveyor. The destination sensor detects the coil located at the destination position. One of the conditions for stopping the first conveyor includes determining that the coil is located at the destination position. If the second conveyor is operating, the controller determines that the coil is located at the destination position if a continuous detection time reaches a first threshold value. If the second conveyor is stopped, the controller determines that the coil is located at the destination position if a continuous detection time reaches a second threshold value. The first threshold value is longer than the second threshold value.

Description

DESCRIPTION SUPPLY APPARATUS Technical Field The present invention essentially relates to a supply apparatus for supplying a bobbin wrapped with a yarn spun by a spinning machine to a yarn winding machine, and to a yarn supply bobbin supply apparatus in State of the Art Patent Document 1, which includes a bobbin placing unit, a bobbin removal unit, and a tray placement unit. Bobbins carried in a container are placed on the bobbin placement unit. The bobbin removal unit receives the placed bobbins one by one, separates these bobbins into individual bobbins, and delivers these individual bobbins to the tray placement unit. The tray placement unit places the bobbins received from the bobbin removal unit on a tray. The bobbins placed on the tray are conveyed to a yarn winding machine by a conveyor. Patent Document 2 discloses a yarn supply bobbin supplying apparatus similar to that in Patent Document 1. The yarn supply bobbin supplying apparatus in Patent Document 2 includes bobbin detection sensors at various positions of a bobbin transport passage. Brief Description of the Invention Each bobbin detection sensor is used, for example, to determine whether or not a bobbin is allowed to be transported. Specifically, if it is determined that a bobbin is not present at a transport target, the bobbin is allowed to be transported. If it is determined that a bobbin is present at a transport target, the bobbin is not allowed to be transported. Therefore, a transport device is stopped until it is determined that there is no bobbin at the transport target. However, with such a method, the conveying device is stopped frequently, and as a result, the bobbin supply efficiency decreases. The present invention has been made considering the above conditions, and the main object of the invention is to provide a supply apparatus that can prevent a decrease in bobbin supply efficiency caused by frequent stops of a conveying device. The problem to be solved by the present invention is thus explained, and then, the means and their effects used to solve such a problem are explained. According to one aspect of the present invention, a supply apparatus having the following configuration is provided. That is, the supply apparatus supplies a yarn winding machine with a bobbin formed by winding a yarn spun by a spinning machine around a bobbin. The supply apparatus includes a first conveyor, a second conveyor, an arrival sensor, and a control device. The first conveyor separates multiple coils into individual coils and transports them individually. The second conveyor transports the coil received from the first conveyor. The arrival sensor detects the coil at a position on the second conveyor, which is the arrival position, where the coil is sent from the first conveyor. The controller determines whether the coil is in the arrival position based on a continuous detection time during which the coil is continuously detected at the arrival position. One of the conditions for stopping the first conveyor includes determining that the coil is in the arrival position. While the second conveyor is operating, the controller determines that the coil is in the arrival position after the continuous detection time reaches a first threshold value. When the second conveyor is stopped, the controller determines that the coil is in the arrival position after the continuous detection time reaches a second threshold value. The first threshold is longer than the second. While the second conveyor is operating, the coil is transported by the second conveyor, and thus, if a certain amount of time passes, the probability of the coil being transported from its destination position is high. Therefore, when the first threshold is set longer than the second threshold, the frequency with which the coil is detected at its destination position is reduced. Therefore, the first conveyor does not stop frequently, thus preventing a decrease in coil delivery efficiency. The aforementioned delivery apparatus preferably has the following configuration. That is, the delivery apparatus includes a transition sensor configured to detect the coil at a position on the second conveyor, which is a transition position, where the transition position is downstream of the coil's destination position in a conveying direction. When the second conveyor is operating, the controller determines that the coil is in the arrival position, regardless of whether the coil is in the transition position, and determines that the condition for stopping the first conveyor is met. When the second conveyor is stopped, the controller determines that the coil is in at least one of the arrival position and the transition position, and determines that the condition for stopping the first conveyor is met. When the second conveyor is operating, the coil in the transition position is immediately moved from the transition position to the downstream side. This prevents unnecessary stops of the first conveyor when a detection result from the transition sensor is ignored. The aforementioned delivery apparatus preferably has the following configuration. That is, the delivery apparatus includes a delivery sensor configured to detect the coil at a position on the first conveyor, which is the delivery position, where the delivery position is the position from which the coil is delivered to the second conveyor. One of the conditions for stopping the first conveyor involves the supply sensor detecting a coil. If there is no coil at the supply position, no coil is supplied from the first conveyor to the second conveyor, even if the first conveyor is operated continuously. Therefore, when the above process is performed, it is possible to prevent unnecessary timing stops of the first conveyor. In the supply apparatus, the condition for restarting the stopped first conveyor preferably involves the controller determining that the coil is not at the arrival position or the transition position. Consequently, it is possible to restart the first conveyor at a time when the coils do not overlap on the second conveyor. The aforementioned supply apparatus preferably has the following configuration. That is, the period during which coils are not continuously detected at the arrival position or the transition position is referred to as the continuous non-detection time. When the second conveyor is operating, the condition for restarting the stopped first conveyor includes the arrival position and transition position continuous non-detection times reaching a first restart threshold. When the second conveyor is stopped, the condition for restarting the stopped first conveyor includes the arrival position and transition position continuous non-detection times reaching a second restart threshold. The first restart threshold is shorter than the second restart threshold. When the second conveyor is operating, the detected coil is immediately moved downstream, thus enabling rapid restart of the first conveyor when the continuous non-detection time is shortened. The aforementioned supply apparatus preferably has the following configuration. That is, the controller calculates an estimated coil count, which is an estimate of the number of coils in the upstream region, which is the region from one end of the upstream section to the middle section of the second conveyor. The controller stops the first conveyor when the estimated coil count consistently exceeds an upper limit threshold for a period of two. Consequently, if coils are likely to overlap in the upstream region, a situation where an additional coil is supplied to the second conveyor can be avoided. In the supply device described above, if the estimated coil count consistently exceeds an upper limit threshold for a period of two, the controller is preferred to reverse-drive the second conveyor to unload the coil in the upstream region. Consequently, if coils overlap in the upstream region, the device can eliminate the overlap. In the above-mentioned supply apparatus, when coils are supplied from the first conveyor to the second conveyor, it is preferable for the controller to increase the estimated number of coils by one. Consequently, it is possible to appropriately calculate an increase in the number of coils in the upstream region. The above-mentioned supply apparatus preferably has the following configuration. That is, as a result of the arrival sensor switching from a state in which a coil is detected to a state in which no coil is detected, the controller decreases the estimated number of coils by one. Consequently, it is possible to appropriately calculate a decrease in the number of coils in the upstream region. Brief Description of the Drawings Figure 1 is a side sectional view of a supply apparatus according to one embodiment of the present invention. Figure 2 is a sectional view of an individualization unit. Figure 3 is a perspective view of the individualization unit and a conveying unit. Figure 4 is a block diagram of a configuration in which a process is implemented for driving a first conveyor and a second conveyor. Figure 5 is a flow diagram illustrating a process for determining whether to stop the first conveyor while the first conveyor is operating. Figure 6 is a flow diagram illustrating a process for determining whether to restart operation of the first conveyor while the first conveyor is stopped. Figure 7 is a flow diagram illustrating a process for estimating the number of coils in an upstream region of the second conveyor. List of Reference Markings 1 supply apparatus receiving unit 11 holding part 12 limiting part 13 incline part individualization unit 21 first conveyor 22 first belt 23 rotating roller 24 first drive unit support leg 26 slit 27 separating element 29 incline surface adjusting unit 40 controller 50 transport unit 51 second conveyor 52 second belt 53 second drive unit 54 opening 61 first flat part 62 first protrusion 63 second flat part 64 second protrusion 71 stop position sensor 72 supply sensor 73 arrival sensor 74 transition sensor 90 housing body 91 coil 92 tray 93 transport path 25a end Description of Configurations In the following, configurations of the present invention will be described with reference to the figures. First, with reference to Figure 1 to Figure 4, an overview of a supply apparatus 1 will be explained. In the following description, an upstream and a downstream in the direction in which a bobbin 91 is conveyed are simply referred to as upstream and downstream. The supply apparatus 1 supplies the bobbin 91 to a yarn winding machine, such as an automatic winder. The bobbin 91 is a yarn supply bobbin 91 formed by winding a yarn spun by a spinning machine around a bobbin. The yarn winding machine winds the yarn wound around the bobbin 91 to form a package. As shown in Figure 1, the supply apparatus 1 includes a receiving unit 10, an individualization unit 20, an adjustment unit 30, a control device 40, and a conveying unit 50. A housing body 90 shown in Figure 1 houses a plurality of bobbins 91 formed by a spinning machine. The housing body 90 is a box-shaped member with an opening 54 formed at its top. When the housing body 90 is tilted by an operator or a loading device not shown in the figures with the opening 54 facing downward, the plurality of bobbins 91 housed in the housing body 90 are loaded into the receiving unit 10. The receiving unit 10 comprises a holding piece 11, a limiting piece 12, and a beveling piece 13. Each coil 91 loaded from the housing body 90 is temporarily held in the holding piece 11. The holding piece 11 has an inclined surface whose height decreases towards the downstream side, thus enabling the coil 91 to be transported by its own weight. It should be noted that the coil 91 can also be transported using a conveyor instead of the inclined surface 29. The limiting piece 12 is provided between the holding piece 11 and the beveling piece 13 in the direction of transport of a coil 91. The limiting piece 12 can be raised and lowered by a mechanism described later. As the limiting piece 12 is raised and lowered, the limiting piece 12 changes position between a raised and a lowered state. When the limiting piece 12 is raised, movement of the coil 91 is prevented. When the limiting piece 12 is lowered, movement of the coil 91 is permitted. When the limiting piece 12 transitions between the raised and lowered states at a predetermined timing, it is possible to adjust the quantity of coils 91 to be supplied from the holding piece 11 to the inclined piece 13. The inclined piece 13 has a sloping surface whose height decreases towards the downstream side. The inclined piece 13 supports the coil 91 by its own weight. The coil 91 rolls or slides on the incline piece 13 in a state where the coil 91 is down and supplied to the individualization unit 20. The downward state of the coil 91 means that the coil 91 is not standing upright on a carrying surface (e.g., an inclined surface) and an axial direction of the coil 91 is parallel or substantially parallel to the carrying surface. The individualization unit 20 separates the multiple coils 91 supplied from the incline piece 13 of the receiving unit 10 into individual coils 91 and transports each coil 91 individually. The coil 91 transported by the individualization unit 20 is transported to the adjustment unit 30 via the carrying unit 50. As shown in Figures 2 and 3, the individualization unit 20 includes a first conveyor 21 configured to convey coils 91 upwards. The first conveyor 21 includes a first belt 22, two rotating rollers 23 arranged above and below, and a first drive unit 24. The first belt 22 is a band-shaped (plate-shaped) element. The first belt 22 bridges the two rotating rollers 23 in a loop-like manner. The upper rotating roller 23 is rotationally driven by the first drive unit 24. In the present configuration, the first drive unit 24 is a stepper motor. The controller 40 drives the first drive unit 24 by transmitting a control command. The rotation of an output shaft of the stepper motor is transmitted to the upper rotating cylinder 23 via a drive transmission belt or the like. Consequently, the first belt 22 is driven to run in a vertical direction. A support leg 25 is provided on an outer surface of the first belt 22. The support leg 25 comprises a plurality of support legs 25, each provided at equal intervals along a longitudinal direction of the first belt 22. The support leg 25 moves integrally with the first belt 22 in a vertical direction. The support leg 25 receives the coil 91, which is loaded by the bevel piece 13, into the individualization unit 20. Consequently, the coil 91 is placed on the support leg 25. The support leg 25 supports the coil 91 placed thereon and carries the coil 91 upwards. The support leg 25 has a rectangular surface so that the coil 91 in a fallen state can be placed on it. Such a rectangular support leg 25 is attached to the first belt 22 such that a longitudinal direction of the support leg 25 extends along a width direction of the first belt 22. A slot 26 is formed in the support leg 25. The slot 26 includes a plurality of slits 26 formed side by side in the longitudinal direction of the support leg 25. A separation element 27 passes through each of the plurality of slits 26. The separation element 27 is, for example, a metal wire. However, the separation element 27 is not limited to a metal wire. As shown in Figure 2, the separation element 27 comprises, from the bottom, a first flat portion 61, a first protrusion 62, a second flat portion 63, and a second protrusion 64. The first flat part 61 prevents the coil 91, loaded by the bevel part 13, from contacting the first belt 22. The first protrusion 62 projects toward a distal end of the support leg 25, compared to the first flat part 61. When two of the plurality of coils 91 are placed on the support leg 25, the position of the coil 91 placed on the top side is disturbed by the first protrusion 62, and thus the coil 91 placed on the top side falls. As a result, one coil 91 is placed on a support leg 25 on the first conveyor 21 (i.e., the coils 91 are individualized). The second flat part 63 is located closer to the root side of the support leg 25, compared to the first protrusion 62. The second protrusion 64 projects towards the distal end 25a of the support leg 25, in comparison with the second flat part 63. The second protrusion 64 causes the coil 91, which is placed on and carried on the support leg 25, to fall. The coil 91, which is dropped by the second protrusion 64, is carried by an inclined surface 29 to the transport unit 50. As shown in Figure 3, one end 25a of the support leg 25 in the longitudinal direction is located outside an area where the coil 91 is carried. The individualization unit 20 includes a stop position sensor 71 configured to detect the end 25a. The stop position sensor 71 is not attached to the first belt 22, but to a frame or the like of the individualization unit 20. The stop position sensor 71 is, for example, a contact-type sensor or a non-contact-type sensor (such as a magnetic sensor or an optical sensor). The stop position sensor 71 transmits a detection result to the controller 40. In a state where the first belt 22 is driven, the tip 25a moves together with the first belt 22, but a position of the stop position sensor 71 remains unchanged. Therefore, the stop position sensor 71 detects the tip 25a only at a timing when the tip 25a reaches a predetermined position. A position of the support leg 25 when the stop position sensor 71 detects the tip 25a is referred to as a stoppable position. In the individualization unit 20, the fact that the support leg 25 is in a stoppable position is one of the conditions for stopping the first conveyor 21. One reason for specifying such a condition is that the individualization unit 20 is designed such that, if the first conveyor 21 is stopped while the support leg 25 is in a stoppable position, the support leg 25 configured to deliver the coils 91 will stop in the optimal position for delivery. The stop position sensor 71 is also used as a sensor configured to detect when the first conveyor 21 is not operating normally. That is, in a state where the first belt 22 is driven, the stop position sensor 71 alternately repeats the detection and non-detection of the end 25a. On the other hand, in a state where the first belt 22 is not driven, the detection result of the stop position sensor 71 remains unchanged. That is, the stop position sensor 71 maintains a state in which the end 25a of the stop position sensor 71 continues to detect, or maintains a state in which the end 25a of the stop position sensor 71 does not detect. If the detection result of the stop position sensor 71 remains unchanged, the controller 40 cannot detect the operation of the first conveyor 21. In such a case, it is determined that the reason why the coil 91 is not supplied to the arrival position is that the coil 91 interferes with the mechanical parts and cannot operate normally, and the first conveyor 21 is reversed. Consequently, it is possible to eliminate this interference and restart normal operation. As shown in Figure 2, a supply sensor 72 is provided in a region where the coil 91 placed on the support leg 25 is transported and also in a region where the second flat piece 63 is supplied. The supply sensor 72 is a contact-type sensor configured to detect the coil 91 supported by the support leg 25. The supply sensor 72 is provided in a position passing through the slot 26 and does not contact the support leg 25, but contacts the coil 91 placed on the support leg 25. The supply sensor 72 is not limited to a contact-type sensor but can also be a non-contact type sensor. A position of the coil 91 supported by the individualization unit 20, which is a position around the second protrusion 64, is referred to as a supply position. In a state where the coil 91 is in the supply position, the coil 91 is supplied to the transport unit 50 by the second protrusion 64 in a short time. The supply sensor 72 detects whether the coil 91 is present at the supply position and transmits a detection result to the controller 40. The conveying unit 50 transports the coils 91 supplied from the individualization unit 20 to the adjustment unit 30. As shown in Figure 3, the conveying unit 50 includes a second conveyor 51. The second conveyor 51 includes a second belt 52 and a second drive unit 53. When a pulley not shown in the figures is driven by a power generated by the second drive unit 53, the second belt 52 wrapped around the pulley is driven. Consequently, the second conveyor 51 transports the coil 91 on the second belt 52 to transfer the coil 91. The second drive unit 53 is controlled by the controller 40. It should be noted that a direction indicated by a thick arrow in Figure 3 is a driving direction of the second belt 52 as the coil 91 is conveyed towards the adjustment unit 30. In the following, such a direction will be referred to as a forward direction and the opposite direction as a reverse direction. When a control command is transmitted, the controller 40 can move the second conveyor 51 in either a forward or a reverse direction. One reverse end of the second conveyor 51 is formed by an opening 54 through which the coil 91 is dropped and returned to the incline piece 13. A position on the second conveyor 51, a position where the coil 91 supplied from the individualization unit 20 arrives, is referred to as a destination position. That is, the destination position is a position on the second conveyor 51 close to the incline surface 29. Near the arrival position, an arrival sensor 73 is provided configured to detect whether the coil 91 is in the arrival position. A position on the second conveyor 51, which is a position downstream from the arrival position, is referred to as a transition position. Near the arrival position, a transition sensor 74 is provided configured to detect whether the coil 91 is in the transition position. The arrival sensor 73 and the transition sensor 74 are non-contact sensors, i.e., optical sensors. The arrival sensor 73 and the transition sensor 74 may be cameras. The arrival sensor 73 and the transition sensor 74 may be contact sensors. The arrival sensor 73 and the transition sensor 74 transmit the detection results to the controller 40. A region from an upstream end to a middle section of the second conveyor 51 is referred to as an upstream region. The arrival position and the transition position are included in the upstream region. The setting unit 30 places the bobbin 91 supplied from the individualization unit 20 on the tray 92. The tray 92 can be moved along a conveyor path 93 configured with a conveyor or the like. The bobbin 91 moves along the conveyor path 93 while being placed on the tray 92 and is supplied to a yarn winding machine. The control device 40 shown in Fig. 4 includes an arithmetic device such as a CPU, a RAM, and a storage area. The storage area is an HDD, SSD, flash memory, or the like. The storage area stores data such as a program associated with the supply apparatus 1 and a condition necessary for the execution of such a program. The arithmetic device reads the program stored in the storage area into RAM and executes such a program. Consequently, the controller 40 performs various checks for the limiting piece 12, the individualization unit 20, and the adjustment unit 30. Next, a process for starting and stopping the first conveyor 21 will be described. The controller 40 modifies the starting and stopping of the second conveyor 51 depending on a conveying condition of the coil 91 located downstream of the conveyor unit 50 or in the adjustment unit 30, or the like. For example, if the number of coils 91 located on the downstream side of the conveying unit 50 or in the adjusting unit 30 is greater than a threshold value, or if coil 91 is already present at a conveying destination of the second conveyor 51, the second conveyor 51 is temporarily stopped. Therefore, even if the first conveyor 21 supplies coil 91 to the destination position, coil 91 is not immediately transported to the downstream side when the second conveyor 51 is stopped. If the first conveyor 21 supplies another coil 91 to the destination position while coil 91 is present at the arrival position, a problem may arise because there are two coils 91 at the arrival position. In the following description, it should be noted that a situation in which two or more coils 91 are in a predetermined position on the second conveyor 51 is referred to as overlap of coils 91. In order to prevent overlap of coils 91, when the controller 40 detects that coil 91 is in the arrival position, it temporarily stops the first conveyor 21. However, switching between starting and stopping the first conveyor 21 can be time-consuming, and therefore, if the first conveyor 21 is stopped frequently, the coil 91 supply efficiency decreases. Specifically, in the present configuration, if the first conveyor 21 is temporarily stopped, a stop position of the support leg 25 is determined based on a control relationship. Therefore, the time required to switch between starting and stopping the first conveyor 21 is long, and therefore the supply efficiency of the coil 91 is likely to decrease. As explained above, by reducing the stop frequency of the first conveyor 21, it is possible to prevent a decrease in the supply efficiency of the coil 91. Whether the coil 91 is in the arrival position is determined based on the detection result of the arrival sensor 73. To prevent a malfunction, the controller 40 determines that the coil 91 is in the arrival position when the time it takes the arrival sensor 73 to detect the coil 91 exceeds a threshold value. Here, if the second conveyor 51 is running, even if the arrival sensor 73 detects the coil 91, there is a high probability that the coil 91 will immediately move downstream and the coil 91 will move out of its arrival position. On the other hand, when the second conveyor 51 is stopped and the coil 91 is in its arrival position, there is a high probability that the coil 91 will continue to be in its arrival position. Considering the above, in the present configuration, the above threshold value is made different depending on whether the second conveyor 51 is running or stopped. Specifically, a first threshold value, which is a threshold value when the second conveyor 51 is running, is longer than a second threshold value, which is a threshold value when the second conveyor 51 is stopped. For example, when the second conveyor 51 is operating, the normal time for the arrival sensor 73 to detect coil 91 is preferably shorter than the first threshold value. Consequently, if coil 91 is normally transported while the second conveyor 51 is operating, the first conveyor 21 will not, in principle, stop. As explained above, the frequency of stops of the first conveyor 21 is reduced, thus preventing a decrease in the efficiency of supplying coil 91. Referring to the flow diagram in Figure 5, the process for determining whether operation of the first conveyor 21 should be stopped will be explained below. The process shown in Figure 5 is carried out by the controller 40. Controller 40 determines whether coil 91 is present in the supply position (5101). Such a determination is made based on the detection result of the supply sensor 72. If the supply sensor 72 does not detect the coil 91, the controller 40 determines that there is no coil 91 in the supply position. If there is no coil 91 in the supply position, there is no possibility of overlapping the coils 91, and therefore there is no need to stop the first conveyor 21. Therefore, the controller 40 does not perform any subsequent processes. On the other hand, if the supply sensor 72 detects the coil 91, the controller 40 determines that the coil 91 is present in the supply position. If there is a coil 91 in the supply position, the coils 91 may overlap. Therefore, the controller 40 performs the following process. The controller 40 determines whether the support leg 25 is in a stoppable position (5102). Such a determination is made based on the detection result of the stop position sensor 71. As explained above, when the stop position sensor 71 detects the tip 25a, the support leg 25 is in the stop position. Therefore, the controller 40 performs the following process. The controller 40 determines whether the second conveyor 51 is operating (5103). The controller 40 drives the second conveyor 51, and thus the controller 40 can determine whether the second conveyor 51 is operating based on the control command. As explained above, such a process is a process for determining whether the first or the second threshold value is used when determining whether the coil 91 is present at the arrival position. If the second conveyor 51 is operating, the controller 40 determines that a period of time during which the arrival sensor 73 continuously detects the presence of the coil 91 at the arrival position (referred to below as the continuous detection period at the arrival position) reaches the first threshold value 5104. If the continuous detection period at the arrival position reaches the first threshold value, the controller 40 determines that the coil 91 is at the arrival position and stops the first conveyor 21 5105. As explained above, the first threshold value is longer than the second threshold value, and therefore, it is unlikely that a situation will occur in which the first conveyor 21 is stopped. On the other hand, if the continuous detection time at the arrival position does not reach the first threshold value, the coil 91 may not be present at the arrival position, or the coil 91 may be present for such a short time that the coil 91 is immediately moved downstream. Therefore, the controller 40 does not stop the first conveyor 21. If the second conveyor 51 is not running, the controller 40 determines whether the continuous detection time at the arrival position has reached the second threshold value (5106). If the continuous detection time at the arrival position reaches the second threshold value, the controller 40 determines that the coil 91 is present at the arrival position and stops the first conveyor 21 (5105). On the other hand, if the continuous detection time at the arrival position does not reach the second threshold value, it is assumed that there is no coil 91 at the arrival position, but there may be coil 91 at the transition position, and thus, the controller 40 performs the following process. The controller 40 determines whether the continuous detection time at the transition position reaches the third threshold value (5107). The third threshold value is used to determine the presence of coil 91 when the second conveyor 51 is not operating, and therefore, the third threshold value can be the same as the second threshold value. However, the third threshold value and the second threshold value can be different values. If the continuous detection time at the transition position reaches the third threshold value, the controller (40) determines that the coil (91) is present at the transition position and stops the first conveyor (21) (5108). On the other hand, if the continuous detection time at the transition position does not reach the third threshold value, it is assumed that coil 91 is not present at both the arrival position and the transition position, and therefore, there is no need to stop the first conveyor 21. In the current configuration, if the second conveyor 51 is running, the presence of coil 91 at the transition position is determined before determining whether the first conveyor 21 should be stopped. This is because, even if coil 91 is present at the transition position, the second conveyor 51 transports coil 91 downstream, so the coils 91 are almost never overlapped. On the other hand, if the second conveyor 51 is stopped, there is a possibility that the coil 91 in the transition position will continue to be in the transition position, and therefore, even if the coil 91 is in the transition position, the controller 40 will stop the first conveyor 21. Therefore, in the current configuration, the prerequisites for stopping the first conveyor 21 are 1. the coil 91 in the supply position and 2. the support leg 25 in the stoppable position. Another condition is that, if the second conveyor 51 is running, 3. the continuous detection time at the arrival position reaches the first threshold value. If the second conveyor 51 is stopped, another condition is 4. the continuous detection time at the arrival position reaches the second threshold value or 5. the continuous detection time at the transition position reaches the third threshold value. These conditions are merely examples, and for example, conditions 1, 2, or 5 above could be omitted. The order in which these conditions are determined is merely an example and can be varied. For example, the fulfillment of any of conditions 3 to 5 could be determined first, and then the first conveyor 21 could be stopped at a time when condition 2 is determined to be met. Next, with reference to the flow diagram in Figure 6, a process for restarting temporarily stopped operation of the first conveyor 21 will be described. A flow diagram in Figure 6 is implemented by the controller 40. If operation of the first conveyor 21 is restarted in a state where coil 91 is in the arrival position or transition position, coils 91 may overlap. Therefore, if controller 40 detects that coil 91 is not present at the arrival position or transition position, controller 40 restarts operation of first conveyor 21. Determining that coil 91 is not present is similar to determining that coil 91 is present. That is, if controller 40 reaches a restart threshold for a period during which coil 91 is not continuously detected at the arrival position or transition position, it determines that coil 91 is not present at the arrival position or transition position. If second conveyor 51 is operating, coil 91 is transported downstream by second conveyor 51 from a period during which coil 91 is no longer detected at the arrival position and transition position. Therefore, if the second conveyor 51 is operating, the coils 91 may overlap, even if the first conveyor 21 restarts operation at a relatively early timing after coil 91 is no longer detected at the arrival position and the transition position. Therefore, in the current configuration, the aforementioned restart threshold is made different depending on whether the second conveyor 51 is operating or not. Specifically, the first restart threshold, which is the restart threshold when the second conveyor 51 is operating, is shorter than the second restart threshold, which is the restart threshold when the second conveyor 51 is stopped. As a result, it is possible to restart the operation of the first conveyor 21 at an early timing, thereby preventing a decrease in the supply efficiency of coils 91. A process will be described below according to a flow diagram shown in Figure 6. Controller 40 determines whether second conveyor 51 is operating (5201). Such a process is used to differentiate the restart threshold used when determining whether coil 91 is present at the arrival position and the transition position. If second conveyor 51 is operating, controller 40 determines whether a period during which coil 91 is not continuously detected at the arrival position and the transition position (referred to below as the continuous non-detection period at the arrival position and the transition position) has reached the first restart threshold 5202. If the continuous non-detection time at the arrival position and the transition position reaches the first restart threshold, controller 40 determines that coil 91 is not present at the arrival position and the transition position and restarts operation of the first conveyor 21 (5204). If the second conveyor 51 is not present, controller 40 determines that the continuous non-detection time at the arrival position and the transition position has reached the second restart threshold (5203). If the continuous non-detection time at the arrival position and the transition position reaches the second restart threshold, controller 40 determines that coil 91 is not present at the arrival position and the transition position and restarts operation of the first conveyor 21 (5204). In the current configuration, the restart threshold value is made different depending on whether the second conveyor 51 is running, but the same restart threshold value can be used regardless of whether the second conveyor 51 is running. Another condition can be added for restarting the first conveyor 21. Next, a process for estimating the number of coils 91 located in the upstream region will be described. The processes described above make it difficult for coils 91 to overlap, but it may not be possible to completely avoid coils 91. Therefore, the controller 40 estimates the number of coils 91 located in the upstream region and, based on such estimation, performs a process for eliminating coils 91 overlap. In the following, an estimated value of the number of coils 91 present in the upstream region will be referred to as an estimated number of coils 91. The controller 40 determines whether coil 91 is supplied from the first conveyor 21 to the second conveyor 51 (5301). For example, the controller 40 determines that coil 91 is supplied from the first conveyor 21 to the second conveyor 51 if the stop position sensor 71 detects the tip 25a after the supply sensor 72 detects coil 91 while the first conveyor 21 is operating. Alternatively, the controller 40 may determine, from a state in which the arrival sensor 73 does not detect the coil 91, that the coil 91 is supplied from the first conveyor 21 to the second conveyor 51 if the arrival sensor 73 detects the coil 91. If it is determined whether the coil 91 is supplied from the first conveyor 21 to the second conveyor 51, the controller 40 increments the estimated coil 91 count by one (5302). Next, the controller 40 determines whether a state in which the arrival sensor 73 detects the coil 91 (ON state) has been changed to a state in which the arrival sensor 73 does not detect the coil 91 (OFF state) (S303). When coil 91 is delivered to the arrival position, arrival sensor 73 detects coil 91 (in the ON state). Subsequently, when coil 91 is conveyed by the second conveyor 51, a state is created in which arrival sensor 73 does not detect coil 91 (OFF state). Therefore, step S303 is the process of determining whether coil 91 has passed over the arrival position. If arrival sensor 73 is detected to have switched from the ON state to the OFF state, controller 40 decreases the estimated number of coils 91 by one (5304). Controller 40 then determines whether a period in which the estimated number of coils 91 is two or more has reached an upper limit threshold (S305). If the estimated number of coils 91 is two or more, two coils 91 are located in the upstream region. In such a case, coils 91 overlap or are likely to overlap. Therefore, if it is determined that the time during which the estimated number of coils 91 is two or more reaches the upper limit threshold, controller 40 performs a process to eliminate such a situation. First, controller 40 stops the first conveyor 21 (S306). Consequently, no new coils 91 are supplied to the upstream region, and thus the number of coils 91 located in the upstream region does not increase. Controller 40 then moves the second conveyor 51 in the reverse direction until the arrival sensor 73 and the transition sensor 74 are turned OFF (S307). As a result, the bobbin 91 located in the upstream region falls through the opening 54 onto the slope piece 13 and is returned. This eliminates the possibility of overlapping or potential overlapping of the bobbins 91. Controller 40 then changes the estimated number of bobbins 91 to 0 (S308). Controller 40 then restarts the operation of the first conveyor 21 and moves the second conveyor 51 forward (S309). Consequently, the supply of bobbin 91 to the yarn winding machine is restarted. Instead of reversing the second conveyor 51, a process can be performed to notify the operator that two or more bobbins 91 are in the upstream region. Instead of returning the bobbin 91 to the incline part 13 using the second belt 52 and the opening 54, the controller 40 can use another element, such as an arm, to return the bobbin 91 to the incline part 13 or to another position. The transition sensor 74 can be omitted, and only the arrival sensor 73 can be used to calculate the estimated number of bobbins 91. As explained above, the supply apparatus 1 supplies a yarn winding machine with a bobbin 91 formed by winding a yarn spun by a spinning machine around a bobbin. The supply apparatus 1 includes the first conveyor 21, the second conveyor 51, the arrival sensor 73, and the controller 40. The first conveyor 21 separates the plurality of coils 91 into individual coils 91 and transports each coil 91. The second conveyor 51 transports the coil 91 sent from the first conveyor 21. The arrival sensor 73 detects the coil 91 at a position on the second conveyor 51, which is an arrival position, where the arrival position is a position from which the coil 91 was sent from the first conveyor 21. The controller 40 determines whether the coil 91 is in the arrival position based on the continuous detection time during which the coil 91 is continuously detected in the arrival position. One of the conditions for stopping the first conveyor 21 includes determining that the coil 91 is in the arrival position. When the second conveyor 51 is operating, the controller 40 determines that the coil 91 is in the arrival position when the continuous detection time reaches the first threshold value. When the second conveyor 51 is stopped, the controller 40 determines that the coil 91 is in the arrival position when the continuous detection time reaches the second threshold value. The first threshold value is longer than the second threshold value. If the second conveyor 51 is operating, the coil 91 is carried by the second conveyor 51, and therefore, as time passes, the probability that the coil 91 will be carried from the arrival position is high. Therefore, when the first threshold value is set to a time longer than the second threshold value, the frequency with which the coil 91 is determined to be in the arrival position decreases. Therefore, the first conveyor 21 does not stop frequently, thus preventing a decrease in the coil 91 supply efficiency. The supply apparatus 1 of the present configuration includes the transition sensor 74 configured to detect the position of the second conveyor 51 at a transition position downstream of the arrival position of the coil 91 in the transport direction. If the second conveyor 51 is operating, the controller 40 determines that the coil 91 is in the arrival position, regardless of whether the coil 91 is in the transition position, while determining that the condition for stopping the first conveyor 21 is met. If the second conveyor 51 is stopped, the controller 40 determines that the coil 91 is in at least one of the arrival position and the transition position, while determining that the condition for stopping the first conveyor 21 is met. If the second conveyor 51 is operating, the coil 91 in the transition position is immediately moved from the transition position to the downstream side. Therefore, it is possible to avoid unnecessary timing stops of the first conveyor 21 when the detection result of the transition sensor 74 is ignored. The supply apparatus 1 of the present configuration includes the supply sensor 72 configured to detect the position of the first conveyor 21 in the supply position from which the coil 91 is sent to the second conveyor 51. One of the conditions for stopping the first conveyor 21 involves the supply sensor 72 detecting the coil 91. If the coil 91 is not in the supply position, the coil 91 is not supplied from the first conveyor 21 to the second conveyor 51, even if the first conveyor 21 continues to operate. Therefore, when the above process is carried out, it is possible to prevent the first conveyor 21 from stopping at an unnecessary time. In the supply apparatus 1 of the current configuration, the condition for restarting the operation of the stopped first conveyor 21 consists in the controller 40 determining that coil 91 is not in the arrival position or in the transition position. Consequently, it is possible to restart the operation of the first conveyor 21 at a time when the coils 91 do not overlap on the second conveyor 51. In the supply apparatus 1 of the current configuration, the period during which coil 91 is not continuously detected in the arrival position or in the transition position is referred to as the continuous non-detection time. If the second conveyor 51 is running, the condition for restarting the stopped first conveyor 21 includes the continuous non-detection time at the arrival position and the transition position reaching the first restart threshold value. If the second conveyor 51 is stopped, the condition for restarting the stopped first conveyor 21 includes the continuous non-detection time at the arrival position and the transition position reaching the second restart threshold value. The first restart threshold value is shorter than the second restart threshold value. If the second conveyor 51 is running, the detected coil 91 is immediately moved to the downstream side, so that when the continuous non-detection time is shortened, it is possible to quickly restart the operation of the first conveyor 21. In the supply apparatus 1 of the present configuration, the controller 40 calculates the estimated number of coils 91, which is an estimated value of the number of coils 91 present in the upstream region, which is the region from the upstream end to the middle of the second conveyor 51. The controller 40 stops the first conveyor 21 if the estimated number of coils 91 exceeds the upper limit threshold value for the period in which two coils are present. Consequently, it is possible to avoid a situation where another coil 91 is supplied to the second conveyor 51 if there is a possibility of overlap of coils 91 in the upstream region. In the supply apparatus (1) of the current configuration, if the estimated number of coils (91) exceeds the upper limit threshold value continuously for the time period in which two coils are supplied, the controller (40) drives the second conveyor (51) in the reverse direction and discharges the coil (91) located in the upstream region. Consequently, if coils (91) overlap in the upstream region, it is possible to eliminate the overlap of coils (91) on the apparatus side. In the supply apparatus (1) of the current configuration, when coils (91) are supplied from the first conveyor (21) to the second conveyor (51), the controller (40) increases the estimated number of coils (91) by one. As a result, it is possible to calculate appropriately the number of coils 91 present in the upstream region. In the supply apparatus 1 of the current configuration, when the arrival sensor 73 goes from the state in which coil 91 is detected to the state in which coil 91 is not detected, the controller 40 decreases the estimated number of coils 91 by one. Consequently, it is possible to calculate appropriately the decrease in the number of coils 91 present in the upstream region. 9: L22 627V\ î 13 O Q_ 2 61xê: :J Position Sisiai xiçxiîlýis..! Stop Position Sensor k Supply Sensor k_ Arrival Sensor k Transition Sensor Controller First Conveyor First Drive Unit _ Second Conveyor Second Drive Unit \ is there a coil in the supply position? is the support leg in a stoppable position? Is the second conveyor running? Has the continuous S1 06 detection time at the arrival position reached the first threshold? Has the continuous detection time at the arrival position reached the second threshold? Has the continuous detection time at the transition position reached the third threshold? Determine that there is a coil at the arrival position and stop the first conveyor. S1 05 Determine that there is a coil at the transition position J. Stop the first conveyor. Is the second conveyor running? Has the continuous non-detection time at the arrival position and at the transition position reached the first restart threshold? / Has the continuous detection at the arrival position and at the QEÇIS Yes position reached the restart threshold? Restart the operation of the first conveyor i_/SZO4 Supply coils from the first conveyor to the second conveyor. Arrival sensor on/off? Has the upper limit threshold been reached for a longer time? Stop the first conveyor /\__ Change the second estimated coil count to 0 until the 8306 arrival sensor and transition sensor are closed. Restart the operation of the first conveyor and drive the second conveyor in the forward direction. TR TR TR TR TR