JP2828495B2 - production management system - Google Patents

Description

The present invention relates to a production management system suitable for use in, for example, a production line for painting a body of an automobile.

2. Description of the Related Art In a line for painting a body of an automobile, usually, a large number of models of the body are mixed, and the designation of a painting color is also various. Therefore, it is necessary for the operator to perform an operation corresponding to the model and the designated color on each body. Therefore,
An identification card or the like in which a code indicating the model of the body, a designated color, or the like is written is attached to a body or a transfer hanger flowing in a line, and a worker performs a predetermined operation by visually checking the identification card.

By the way, in a predetermined process, the maximum number of bodies that can be put in the process (hereinafter referred to as the number of expired bodies) is predetermined. Therefore, if the number of expired vehicles is likely to exceed the number of expired vehicles for some reason, it is necessary to temporarily stay the body before the process. In addition, there is a portion on the body transfer line where it is necessary to make a certain number of empty spaces at the end of work. Even in such a case, a part for absorbing and retaining the body is necessary to make a space on the line.

Therefore, in such a portion, a night storage for retaining the body is provided. The body is transferred from the main line to the night storage by switching the trajectory of the hanger or the bogie for transferring the body by a predetermined switching device.

[Problems to be Solved by the Invention] By the way, conventionally, since the worker performs the switching work to the night storage while observing the work situation, it is necessary to arrange the worker in each switching part, which requires a lot of manpower. There was a problem. In addition, when the number of workers is small, it is necessary to go to each night storage to perform the switching work, which causes a problem that the work becomes complicated.

The present invention has been made in view of the above-described circumstances, and provides a production management system that can perform a switching operation to a night storage with a small number of persons (for example, one person) and can perform a batch switching by a remote operation. It is an object.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention, as shown in FIG.
Transport means d for transporting the transport means d, the identification code e assigned to each transport means d, and the identification code e of the transport means d
, A reading means f for reading information on the workpiece b to be placed, and an input means g for inputting information about the workpiece b to be placed. A storage unit h for storing the identification code e read by the reading unit f and the information input by the input unit g as a set
A branch transport path i arranged in parallel with a main transport path from the input section a to the delivery section c for temporarily retaining the transport means d, and the transport means provided on the entrance side of the branch transport path i switching means j for switching whether to transfer b to the main transport path or to the branch path i; operating means l for writing a branch instruction for transferring the transport means d to the branch path i in the storage unit h; A second reading unit m provided immediately before the switching unit j and reading an identification code e of the transport unit d;
The storage means h is searched based on the identification code e read by the second reading means m, and when a branch instruction is written, the switching means h is instructed to transfer to the branch path i. Means n. Also, in the present invention, the storage means includes a shift register for shifting the set of the identification code and the information one by one in accordance with the movement of the transport means, and the shift register includes a plurality of shift registers corresponding to the steps. The shift into a region and a shift from a certain region to a subsequent region is performed on condition that it is detected that the hanger plate has passed a predetermined position.

[Operation] A branch instruction is previously written in the storage means h by the operation means l. Then, the identification code of the transport means d is read by the second reading means m before the switching means j. If a branch instruction is written for this identification code, the switching means j is controlled by the processing of the determination means n, and the transport means d is transferred to the branch transport path i. In addition, since data is moved from one area of the shift register to the next area on condition that the hanger plate has passed the predetermined position, it is necessary to ensure that the actual movement of the hanger plate corresponds to the data movement. Can be.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A: Configuration of the Example Schematic of Production Line in Example FIG. 2 is a schematic configuration diagram showing a coating line in one example of the present invention. The steps of this coating line will be described below.

After being temporarily stored in the welding stock shop, the body B is placed on a hanger conveyor (see FIG. 4) and transported to the pre-processing section 1. Here, when the pretreatment is performed, the electrodeposition coating is performed through the steps of the electrodeposition unit 2 and the electrodeposition furnace 3. Next, a sealing process is performed on the seam portion of the iron plate by the sealer 4, and a process is performed on the lower portion of the floor by the undercoat portion 5. Then, it reaches the inspection unit 7 via the sealer furnace 6,
Here, the inspection of the electrodeposition coating is performed. After passing through the inspection unit 7, the intermediate coating process is performed through the intermediate coating unit 8 and the intermediate coating furnace 9. After the intermediate coating process, it reaches the inspection unit 11 via the color alignment storage 10,
Inspect the middle coat. Next, painting of the indicated color is performed in the overcoating section 12. Then, baking is performed in the top coating furnace 14, whereby the top coating process is completed. Various inspections are performed on the body B, on which the top coating has been completed, in the inspection section 15, and the coating B reaches the wax processing section 19 through the coating stock shop 18.
Here, wax is applied. The waxed body reaches the painting stockyard 20. In the paint stocking areas 18 and 20, rearrangement is performed to efficiently pay out the bodies B in the next step (car assembly line). In the vehicle assembly process, since the work in each process differs depending on the type of vehicle, destination, and options, high efficiency is required for the permutation of the bodies flowing through the line. Therefore, sorting is performed in the coating stock sites 18 and 20 in accordance with this request. In addition, rearrangement work is performed at the painting stock sites 18, 20
The reason is that the rearrangement cannot be performed in one place. The body B paid out from the paint stocking place 20 is temporarily reserved at the car set stocking place 21 and then shifts to a car set up process. The car stocking area 21 is 10
Approximately 0 bodies can be stored, and it is a buffer for the payout body. By providing the buffer function in this manner, it is possible to increase the parts procurement time in the assembly process or to cope with a change in the processing amount in the assembly process.

In addition, electrodeposition night 22, sealer night 23, middle coating night
24 and a topcoat night 25 are night storages for retaining the body, respectively.

Next, FIG. 3 is a block diagram showing a control system of this embodiment. In the figure, 30, 31, 32 and 33 are body B
Conveyor, which is provided in a charging step, a hand step, an automation step, and a dispensing step, respectively. The charging process refers to the process from "T1-ON" shown in FIG. 2 to before the pre-processing unit 1, the hand process refers to the inspection units 7, 11, and 15, and the automation process refers to the sealer 4, undercoat. Part 5, middle coat part 8, top coat part 12, and wax treatment part
19 and the like, and the dispensing process refers to the coating stock space 20. In FIG. 3, the input process, the hand process, the automation process, and the payout process are simply arranged serially for the sake of simplicity of explanation, but actually, the hand process and the automation process are alternately arranged as appropriate. Have been.

A large number of hangers 35 shown in FIG. 4 are attached to each of the hanger conveyors 30 to 33. The hanger 35 circulates in each of the hanger conveyors 30 to 33. However, the hanger 35 is actually the hanger conveyor 30
~ 33, but here,
For the sake of simplicity, it is assumed that it is placed on hanger conveyors 30 to 33.

A hanger plate 36 is attached to the hanger 35, and the hanger plate 36 is provided with eight windows as shown in FIG. These eight windows are weighted as "1", "2", "4", "8"..., And a predetermined identification code is determined according to whether the windows are open or closed. (Hereinafter referred to as hanger number). The hanger number is unique to the hanger and is not set to the same value. The hanger number is read by a hanger reader 40 (first reading means) shown in FIG. The hanger reader 40 is provided for each hanger conveyor 30.
The tip of the hanger plate 36 is detected by the photoelectric tube 41 as shown in FIG. 5, and the opening / closing of each window is checked at this timing.

The hanger conveyors 30, 31, 32, and 33 shown in FIG. 3 are provided in a coating line charging process, a hand process, an automation process (sealer, UDC, intermediate coating, top coating, WAX) and a dispensing process, respectively, and each has a conveyor control panel. The running is controlled by 50, 51, 52, 53. In the loading step, a card reader 55 is provided to read data from the magnetic card 56. The magnetic card 56 stores various information (hereinafter referred to as body information) regarding painting and assembly of the body B, and the magnetic card 56 is transported together with the body B to a painting process. Printer 57
Prints out the body information read by the card reader 55 so that the operator can visually check the body information. Reference numeral 58 denotes a transfer device for mounting the body on the hanger 35 of the hanger conveyor 30. When the body is mounted by the transfer device, the magnetic card 56 is moved by a card reader 55 by an operator.
Is inserted into. Then, the body information read from the card reader 55 is transferred to the host computer 60.
Reference numeral 61 denotes a file for storing data used by the host computer 60, processing data, and the like. Also the main computer
60 communicates with a computer (personal computer) 64 via modems 62 and 63. The computer 64 performs data communication with the sequencer 70, and further, the sequencer 70 communicates with the sequencer 71,
The sequencer 71 performs data communication with the sequencer 72, and the sequencer 72 performs data communication with the sequencer 73.

Computers 65 to 67 shown in FIG. 3 are respectively a sequencer 70 to 73 and a LAN (local area network).
Is composed. Any one of the computers 65 to 67 has the same information to back up the sequencers 70 to 73.

The sequencers 70 to 73 control the hanger conveyors 30 to 33, respectively, and have a shift register 80 shown in FIG. In the first stage of this shift register 80,
The hanger number read by each hanger reader 40 is input.

Further, the hanger conveyor is provided with limit switches LS for detecting passage of the hanger 35 at predetermined intervals, and the storage area of the shift register 80 is partitioned corresponding to each limit switch LS. Sequencer 70-73
Recognizes the section divided by the limit switch LS as a zone, recognizes the entire section of the shift register 80 as a block, and further recognizes the position of each storage area of the shift register 80 as a position. The shift register 80 is a so-called first-stage type, and when a hanger number is supplied to the first stage, the shift register 80 sequentially shifts to the next stage as long as there is an empty area. However, shifts beyond the zone are hanger by the limit switch LS.
Only performed if 35 passes are detected. That is,
When the hanger passage is detected by the limit switch LS, the hanger number in the last storage area of the zone before the boundary corresponding to the limit switch LS is shifted to the first storage area of the next zone. ing.

80 shown in FIG. 3 is controlled by the conveyor control panel 51,
This is a display for performing various displays to the operator who works in the hand process. Reference numerals 81 and 82 denote a card reader and a printer, respectively, which have the same functions as the card reader 55 and the printer 57 described above. The body information read by the card reader 81 is transferred to the vehicle assembly line, which is the next step.

Next, robots 90, 91 and 92 perform various automatic operations in the automation process, and are controlled by robot control panels 93, 94 and 95, respectively. The stage master board 96 transfers a job number to each of the robot control boards 93, 94 and 95 as appropriate. Here, the job numbers are robots 90, 91,
This code specifies the operation of 92. The stage master boards 96 and 98 transfer job numbers to robot control boards (not shown) of other stages. The job number is from the model distribution board 100 to the line master board 99
, And the line master board 99 distributes it to each of the stage master boards 96 to 98 for transfer. The model distribution board 100
When body information is received from the conveyor control panel 52, the body information is converted into a job number with reference to an internal table, and transferred to the line master panel 99. The operation until the body information is output from the conveyor control panel 52 will be described later.

In the above configuration, the sequencers 70 to 73 and the personal computer 64 to
67 and terminal 68 are located in the main control room. Terminal 68
Displays management data such as the work volume and the number of process flows transferred from the management computer 67.

Here, a configuration of a track switching device that switches the hanger conveyor 30 from the main line to the night storages 22 to 25 will be described.

FIG. 10 is a plan view showing the configuration of the track switching device. In this figure, reference numeral 120 denotes a main line from the upstream to the downstream of the line, and 121 denotes a trolley. Trolley 121
Two hangers 35 are provided at a predetermined distance in the front-rear direction of the line with respect to one hanger 35, and the hangers 35 are suspended from these trolleys. Reference numeral 122 denotes a branch plate, which is rotatable around a fulcrum A, and is normally at a position shown by a solid line in the drawing. Branch plate
When 122 is at the position indicated by the solid line, the trolley 121 is conveyed to the main line conveyor and goes straight from the right end to the left end in the figure. Next, reference numeral 123 denotes a branch cylinder, which retracts the cylinder at the time of branch. When the cylinder is retracted, the driving force is transmitted to the branch plate 122 via the member 122a, and the branch plate 122 rotates counterclockwise to reach the position indicated by the dashed line. As a result, the trolley 121 is guided by the branch plate 122 and enters the night line 125. At this time, the dog 126 provided on the trolley 121 moves the actuator of the limit switch 127 provided on the entrance side of the night line 125. By turning on / off the limit switch 127, it is detected whether or not the trolley 121 has entered the night line 125. 130 is a cylinder having a claw 132 at the tip of the cylinder rod. This cylinder 130 has a trolley 121
When entering the cylinder 125, the cylinder rod is extended, the dog 126 is hooked by the claw 132, and then the cylinder rod is retracted to transfer the trolley 121 to the night line conveyor 131. Trolley 121 transferred to night line conveyor 131
Is transported by the night line conveyor 131 thereafter. In FIG. 10, a hanger reader 40 (second reading means) is provided at a position indicated by a broken line so that the hanger number of the hanger 35 that has entered can be read.

Also, when the transfer of the hanger 35 is switched from the night storage to the main line, the same device as described above is used. In this case, the operation is the reverse of the operation described above.

Next, the internal configuration of the computer 64 will be described with reference to FIG.

In the figure, reference numeral 105 denotes a CPU that controls each unit of the apparatus, and operates according to a program in a program memory 101.
M is a memory in which a hanger number and body information are stored, and the storage procedure will be described later. 102 is C
It is a keyboard that gives various instructions to PU 105, 103 is
This is a CRT display device that performs various displays under the control of the CPU 105. 104 is a communication interface, and the sequencer 70
To 73, and controls communication between the computers 65 to 67 and the CPU 105. The CPU 105 reads out each shift register 80 in the sequencers 70 to 73 via the communication interface 104,
Writing is performed.

Further, respective output signals are supplied to the CPU 105 from the limit switch 127 and the hanger reader 40 shown in FIG. In addition, the CPU 105
In addition, the expansion and contraction of the branch cylinder 123 is controlled. A hanger reader enclosed by a chain line in FIG.
A combination U consisting of 40, a limit switch 127, a cylinder 130 and a branch cylinder 123 is provided on the entrance side and the exit side of each night storage.

The other computers 65, 66, and 67 have the same configuration as described above.

B: Operation of Embodiment Next, the operation of this embodiment having the above-described configuration will be described with reference to FIG.

2. Tracking of Hanger Number First, the body is placed on the hanger 35 at the loading section of the hanger conveyor 30 by the transfer device 58a from the WBS shown in FIG. At this time, the operator inserts the magnetic card 56 of the body into the card reader 55. As a result, the body information is transferred to the host computer 60, and further transferred to the computer 64 via the modems 62 and 63. On the other hand, the hanger reader 40 provided at the loading section of the hanger conveyor 30
(See FIG. 4) reads the hanger number from the hanger plate 36 and transfers it to the sequencer 70. The sequencer 70 writes the transferred hanger number in the first-stage storage area of the first zone of the register 80, and transfers it to the computer 64. When the hanger number is supplied, the computer 64 stores the hanger number in combination with the body information in an internal memory. As a result, the relationship between the body and the hanger on which it is placed is stored as data. Thereafter, each time the body B is transferred to the hanger 35 by the transfer device 58a, the above-described processing is performed.
The internal memory stores the correspondence between the body and the hanger number. Here, assuming that the hanger number read by the hanger reader 40 is, for example, ..., the internal memory of the computer 64 stores the correspondence as shown in FIG. In the figure, M indicates an internal memory, and A1, A2,... Indicate its storage areas. For example, the storage area A1 stores body information indicating that a domestic body, a vehicle type is A, and the color is red, and a hanger number of a hanger on which the body is mounted is stored.

On the other hand, the shift register 80 in the sequencer 70 performs the following processing. First, as shown in FIG. 8 (a), the hanger number is input to the first-stage storage area. This hanger number is sequentially shifted to the subsequent stage, and reaches the last stage of the zone (see FIG. 2B). Next, when the hanger number is input, it shifts to the subsequent stage in the same manner as described above, and is stored in the storage area immediately before the last stage of the zone (see FIG. 3C). As described above, the hanger number input to the shift register 80 is sequentially shifted to the subsequent stage as long as there is an empty area. However, no shift beyond the zone is performed in the above case. And the hanger 35 of the number moves, and the first limit switch LS
When the passage is detected, the detection signal of the limit switch LS is transferred to the sequencer 70. As a result, the sequencer 70 shifts the hanger number to the first-stage storage area of the next zone as shown in FIG. The hanger number thus shifted is sequentially shifted to the subsequent stage in the next zone. Also, in the previous zone, the hanger number,..., Is shifted to the subsequent stage by one stage since the last stage storage area becomes empty.

Next, the transport of the body B proceeds, and the hanger conveyor 30
Will be described. For example, when the hanger of the hanger number reaches the delivery section of the hanger conveyor 30, the body is moved to the transfer device 58b.
Transported up. At this time, the hanger number is stored in the last storage area of the shift register 80, but the shift register 80 discards the hanger number with the transfer of the body B. Therefore, the shift register
Each hanger number in 80 is shifted by one step toward the next step.

An identification number is set in advance in the transfer device 58b, and this identification number is assigned to the sequencer 70 or the computer 64.
Is stored within. Then, when the body B is transferred, a signal indicating the transfer is supplied to the computer 64 via the sequencer 70, whereby the computer 64 stores the hanger number in the storage area A1 shown in FIG.
Rewrite with the identification number of For example, the identification number is "100"
Would be rewritten to "100".
Next, the body B is transferred from the transfer device 58b to the hanger conveyor 31.
Is transferred to the hanger 35 in the loading section of Then, the hanger number of the hanger 35 is detected by the hanger reader 40 in the loading section of the hanger conveyor 31 and transferred to the sequencer 71. If a hanger number is detected, the hanger number is transferred to the sequencer 71. The sequencer 71 transfers the hanger number to the computer 64 via the sequencer 70 and inputs the hanger number to the internal shift register 80. As a result, the computer 64 rewrites the hanger number in the storage area A1 shown in FIG. 7 from “100”. The shift register 80 in the shift register 71 performs the same shift operation as the shift register 80 of the sequencer 70 described above.

The above operation is similarly performed when the body B is transferred to another hanger conveyor. That is, when the hanger on which the body is placed is changed, the computer 64 rewrites the hanger number in the corresponding storage area in the memory M with a new one. Therefore, by referring to the memory M, it is possible to know what body is mounted on each hanger.

Monitoring of tracking data As described above, each shift register in sequencers 70 to 73
80 shifts the hanger number in response to the movement of the hanger. That is, tracking of the hanger number is performed. Each of the sequencers 70 to 73 has a body B
Transfer the contents of the shift register 80 to the computers 65 to 67 at the timing when the data is transferred to the hanger conveyor on the downstream side. This transfer is performed to at least one of the computers 65 to 67, whereby the hanger number (tracking data) in each shift register 80 is duplicated and held. And sequencer 70 ~
If any one of 73 goes down, hanger number data is transferred from any of the computers 65 to 67 to the shift register 80 of the sequencer. As a result, restoration is performed quickly.

Further, the computer 64 can recognize the block and the zone where the body exists by referring to the contents of each shift register 80 and the contents of the memory M.

Automatic branch processing At the end of work or when the number of post-processes of the night storage increases, the operator in the main control room performs the following processing.

First, the line status is displayed on the CRT display device 103 (FIG. 11) of the computer 64. This display is performed based on the recognition of the position of each body obtained by monitoring the tracking data described above. Then, the body to be switched from the front screen to the night storage (electroplated night 22, sealanite 23, middle coat night 24, or top coat night 25) is confirmed, and the hanger number of the hanger 35 on which the body is placed is displayed on the keyboard 102. And a command to switch the hanger 35 to the night storage. As a result, "1" is set in the predetermined flag of the area of the memory M where the hanger number is stored. Thereafter, the operator performs the same processing as described above on the hanger 35 to be switched to the night storage. Incidentally, the operator may recognize the body to be switched to the night storage by looking at the actual painting line.

Next, the hanger flagged by the above process
When 35 is transferred to the vicinity of the night storage, the hanger reader 40 shown in FIG. 10 reads the hanger number.
The read hanger number is supplied to the CPU 105,
U105 searches the memory M using the hanger number as a key. When this search detects that a flag is set for the hanger, the CPU 105 outputs a control signal for retracting the branch cylinder 123. As a result, the branch cylinder 123 is retracted, the branch plate 122 rotates, and the hanger 35 is guided to the night line 125. And hanger 35 guided to night line 125
Is detected by the limit switch 127, and a detection signal is supplied from the limit switch 127 to the CPU 105. As a result, control for instructing extension is supplied to the CPU 105 cylinder 130, and the cylinder 130 extends the cylinder rod, hooks the dog 126 with the claw 132 at the tip, and draws it into the night line 125. As a result, the hanger 35 will be
It is conveyed by 125 conveyors, and the switching is completed.

Switching is performed in the same manner as described above for a hanger with a flag set, and when a hanger without a flag is set, the branch plate comes to a position shown by a solid line in FIG. Go straight on 120. In this way, only hangers for which a flag has been set in advance are drawn into the night line 125. The retracted hanger 35 is sequentially transported in the night line 125, and when the leading hanger 35 reaches the vicinity of the exit of the night line 125, its movement is regulated by a stopper (not shown). The movement of the subsequent hanger 35 is restricted when the hanger 35 approaches the previous hanger 35.

Next, when switching the hanger 35 in the night storage to the main line, the operator uses the keyboard 102 to instruct the CPU 105 to that effect. As a result, a device similar to the device shown in FIG. 10 performs the reverse operation to the above-described case, and sequentially transfers the hanger 35 to the main line.

C: Modifications In the embodiment described above, the following modifications are possible.

Although the shift register 80 is divided into a plurality of zones corresponding to the limit switch LS, the shift register 80 need not be divided unless it is particularly necessary.

In the embodiment, a plurality of blocks are provided. However, when the scale of a production line is small, a single block may be used.

In the embodiment, the rewriting of the memory M at the time of transfer between the blocks of the body B is performed once by the transfer devices 58a and 58b.
A new hanger number is written after rewriting the identification number. On the other hand, the identification number of the transfer device may be omitted, and the new body B may be replaced with the new hanger number when the new body B is mounted on the hanger.

[Effects of the Invention] As described above, according to the present invention, there is an advantage that the switching operation to the night storage can be performed by a small number of people and the switching can be performed collectively by remote operation.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention, FIG. 2 is a schematic configuration diagram showing a configuration of a coating line according to an embodiment of the present invention, and FIG. 3 is a control block showing a control system of the embodiment. FIG. 4, FIG. 4 is a schematic configuration diagram showing the vicinity of a loading section of a hanger conveyor, FIG. 5 is a front view showing a configuration of a hanger plate, FIG. 6 is a conceptual diagram showing a shift register provided in a sequencer, FIG. 8 is a memory map showing storage contents of the memory M of the computer 64, FIG. 8 is an explanatory diagram for explaining a shift operation of the shift register 80, FIG. 9 is a schematic configuration diagram showing a configuration near the robot 90, and FIG. Plan view showing the configuration of a switching device for switching the transfer line of
FIG. 11 is a block diagram showing a configuration of the computer 64. 35: hanger (transporting means), 36: hanger plate (identification code), 40: hanger reader (first reading means, second reading means), 55: card reader (input means), M ... ... Memory (storage means), 102 ... Keyboard (operation means), 105 ... CPU (judgment means), 120 ... Main line (main conveyance path), 122 ... Branch plate (switching means), 123 ... Branch Cylinder (switching means), 125 ... Knight line (branch transport path).

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G05B 19/418 G05B 15/02 B23Q 41/02

Claims (1)

(57) [Claims] 1. A plurality of transport means for transporting a workpiece placed in an input section to a sending section via a plurality of processes; and a plurality of transport means attached to each of the transport means and corresponding to the transport means. A hanger plate on which an identification code is stored; first reading means for reading the identification code of the transport means in the input section; input means for inputting information on a workpiece to be placed; A storage unit configured to store a set of the identification code read by the first reading unit and the information input by the input unit each time a workpiece is placed; A branch transport path which is arranged in parallel with a main transport path connecting the steps between the processes and temporarily holds the transport means, and a transport means provided on an entrance side of the branch transport path to transfer the transport means to the main transport path. Transfer or Switching means for switching whether to transfer to a road, operating means for writing a branching instruction for transferring the transporting means to a branch path in the storage means, and based on an identification code of the transporting means provided immediately before the switching means. Determining means for searching the storage means and instructing the switching means to transfer to a branch path when a branch instruction is written, wherein the storage means A shift register for shifting the set of the identification code and the information one by one correspondingly, the shift register is divided into a plurality of areas corresponding to the process, and a shift from a certain area to a subsequent area is performed. A production management system which is executed on condition that it is detected that the hanger plate has passed a predetermined position.