JPH0425103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention provides a method for transporting workpieces between a plurality of processing stations along a transport route and a buffer station that pools work pallets using a transport cart running on the transport route. The present invention relates to a conveyance control device that performs the following operations.

<Prior art> In conventional FMS using a transport vehicle, in order to provide flexibility, there is a
Generally, conveyance control is performed in which a conveyance truck is run randomly to take out work pallets from a buffer station and supply them to a machine, and to transfer processed work pallets to the buffer station.

On the other hand, in the FMS for lot production, although it is possible to feed the workpieces in the same form until the type of workpiece is changed, such random conveyance does not allow the workpieces to be transferred from machine 1 to machine 1 one by one as shown in Figure 4. The discharged items have to be returned to the buffer station 2 and then loaded onto the transport vehicle 3 and transported to the machine 1, resulting in a lot of unnecessary movement of the transport vehicle, which not only reduces the efficiency of the system but also reduces the transport capacity. will also be connected.

<Means for Solving the Problems> Therefore, the present invention adjusts each machining process so that the machining time at each machining station is almost the same, and performs a workpiece loading/unloading cycle using a transport cart every predetermined takt time. Starting from the first process, the workpieces are sequentially transferred between each processing station in order of process, and workpieces are continuously loaded and unloaded to and from all processing stations. The workpieces are loaded and unloaded at the same time.

<Function> The machining cycle time of each machining station is set as the takt time, and the workpiece is carried in and out by the conveyor truck between machines at each takt time, and during the takt time, the buffer station is and loading
Since the workpieces are carried in and out of the unloading station, the conveyance control can be carried out efficiently and the down time of the machine can be reduced.

<Examples> Examples of the present invention will be described below based on the drawings. In FIG. 1, reference numeral 10 denotes a running line of a transport vehicle 11 on which a pallet P is loaded, and each of a plurality of processing stations ST1 to _STN provided along this running line 10 has a pallet loading/unloading device. Machine tools MT1 to MT _N
is installed. Further, a buffer station 15 is provided at a predetermined position along the conveyance line 10 to store a plurality of pallets P on which workpieces W are attached, and a loading/unloading station where an operator attaches and removes the workpieces to and from the pallets P. Stations 16 and 17 are provided.
A pair of pallet support stands 1 are mounted on the carrier 11.
1a and 11b are provided, and each machine tool MT1~
At MT _N , the processed pallet is attached to one support stand, and the pallet placed on the other support stand is carried into the machine tool.

Next, we will explain the second part about the control system that moves between each machine tool and carries in and out pallets every takt time.
This will be explained using figures. 21 is each machine tool MT1~
Numerical equipment provided corresponding to each of MT _N ,
22 is a transport vehicle control device that controls the traveling, positioning, etc. of the transport vehicle 11; The numerical control device 21 and the conveyance control device 22 are connected to the takt time setting means 2.
3. It is connected to a computer 26 that constitutes the transport operation starting means 24 and the transport control means 25.

The conveyance vehicle control device 22 controls the transfer of pallets by the conveyance vehicle 11, and also controls the loading/unloading stations 16, 1.
7 and the Banff station 15, and each machine tool.
It has a second transport mode for transporting pallets P between MT1 _{to MTN} .

That is, in the machining system of this embodiment, each machine tool MT1 to
In addition to transporting pallets P between MT _N and transporting them, pallets P are transferred from buffer station 15 to machine tool MT1, and machine tool
After transferring pallet P from MT _N to buffer station 15, each machine tool MT1~
The pallet P is transferred between the loading/unloading stations 16, 17 and the buffer station 15 in the first transfer mode until the processing by _MTN is completed.

When the conveyance vehicle control device 27 is supplied with the first conveyance command from the conveyance control means 25 achieved by the computer 26, it enters the first conveyance mode, and transfers the work W that has been internally processed on the pallet P of the buffer station 15. The pallet P to be supported is transferred to the loading/unloading stations 16, 17, and then it is checked whether there is a pallet P on which a new work W or a reworked work W is placed on the loading/unloading stations 16, 17. When it is determined that there is a loading/unloading station 16,1
The pallet P on the top 7 is transferred to the buffer station 15.

On the other hand, when the second conveyance command is given from the conveyance control means 25 every takt time, the second conveyance mode is entered, and the pallet P on which the unprocessed workpieces in the buffer station 15 are placed is transferred to the machine tool MT.
1, move pallet P in machine tool MT1 to machine tool
Repeat the transfer operation sequentially to MT2, machine tool MT
The pallets P in the machine tool MT _N are transferred to the buffer station 15 by moving between the machine tools MT _N -1.

The control in the second transport mode and the first transport mode will be explained based on the flowchart of FIG. 3.
The processing shown in this flowchart is periodically executed in real time. First, it is assumed that the walking control by the transport vehicle has not yet started and the takt time has not been set.The process proceeds from steps (1) to (2) to (3), and the next takt time is determined. Calculations are made. For example, if the processing cycle time is 25 minutes and the time required to move between each machine is 5 minutes, then 25 minutes - 5
Minutes = 20 minutes is the takt time, and this is set in step (4). The takt time is the time from when the conveyance cart completes the transfer between the machines until it starts the next transfer, during which the first transfer mode and other controls are performed. After the takt time has been set, the process proceeds to step (2) → (5), where it is determined whether the set takt time has exceeded, and if the takt time has exceeded, the process proceeds to step (6), where the takt time is started. A request flag is set, and a second conveyance command is sent together with this. At this stage, the transport vehicle is not in operation, so the process proceeds from (8) to (9) to create a transport pattern for the transport vehicle to move between stages.
In (10), it is possible to know which machine to move to by referring to this transport pattern. In steps (11) and (12), it is determined whether all the machines to be moved have been switched to individual operation or whether any machines are down, and if all machines are operating normally, the "OK" flag is set. and then returns through step (14). Thereafter, when this routine is executed again, the process proceeds to steps (1)→(7)→(15), and a control command to sequentially move between the machines specified in the transport pattern is sent to the transport vehicle control device 22. When the transport control in the second transport mode is performed, the loading/unloading operation of the transport vehicle is completed, so the takt time is calculated and set again in steps (1)→(2), and takt time overs are monitored. . The takt time start request flag is not set.
(8)→(16)→(17) are executed, and the transport vehicle is moved to the first
It can be redirected to other transport control depending on the transport mode.

Next, a case where a machine failure occurs will be explained. Machine down shall also include the case where automatic operation is switched to individual operation, and will be determined in steps (11) and (12). When it is determined that the machine is down, takt time extension processing is performed in step (20) to extend the already set takt time by the down time. If multiple machines are down, the takt time setting is changed to extend the downtime by the longest downtime. Thereafter, in steps (21) and (22), the takt time start request flag is cleared and the NG flag is set. By setting this NG flag, the process proceeds to steps (14) → (23), where the conveyance pattern is cleared, and then the process proceeds to step (16), where if there are other control requests, a conveyance pattern that matches them is created. Ru. Therefore, in a state where another control transport pattern has been set, that transport pattern is referred to in step (15) to control the transport of the transport carriage. Therefore, the first transport mode will be executed.

<Effects of the Invention> As described above, according to the present invention, each machining process is adjusted so that the machining time at each machining station is approximately the same, and the workpieces are moved by the conveyor cart at each takt time corresponding to the machining time. The loading/unloading cycle starts from the first process, and the workpieces are sequentially transferred to and from the machine during the machining process, and workpieces are loaded/unloaded continuously to all processing stations. Since it is designed to carry in and out workpieces, it is suitable for lot production.
It is extremely suitable for FMS, increasing the efficiency of conveyance control and reducing machine downtime. Therefore, there is an advantage that there is no need to provide a margin for random transport, and the number of connected machines can be increased to the maximum transport system capacity.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; Fig. 1 is a diagram conceptually showing the processing system, Fig. 2 is a functional block diagram of the control system, and Fig. 3 is a flowchart for controlling the transport vehicle. , FIG. 4 is a diagram showing a conventional example of random conveyance. 11... Transport vehicle, 15... Buffer station, ST1~ST _N ... Processing station, MT
1～MT _N ...Machine tool, 21...Numerical control device,
22... Transport vehicle control device, 23... Takt time setting means, 24... Transport operation starting means, 25...
...transport control means, 26...computer.

Claims (1)

[Scope of Claims] 1 Machine tools are arranged at a plurality of processing stations along a conveyance path, and a buffer station that pools a plurality of work pallets and a loading/unloading station that attaches and detaches workpieces to and from the pallets are provided. In a processing system in which a workpiece pallet is transferred between a plurality of processing stations, a loading/unloading station, and a buffer station by a transport vehicle running on the transport path, the processing time at each processing station is numerical control means for controlling each machining process so that the processing times are substantially the same; takt time setting means for setting the takt time of the transport vehicle according to the machining time; - A first transport mode in which workpieces are loaded into and unloaded from the unloading station, a second transport mode in which workpieces are loaded into and unloaded from all processing stations by sequentially moving through the processing stations in process order, and a set tact. A tact conveyance control device comprising: a conveyance operation start means for starting a second conveyance mode every time a time elapses. 2. The tact conveyance control device according to claim 1, wherein the takt time setting means includes means for changing the setting of the takt time according to the time required for the conveyance cart to move between machines. 3. The transport operation starting means has means for collecting the down time of each machine and delaying the start of the transport operation by the transport vehicle by the down time of the machine that has been down for the longest time. Tact transfer control device.