JPS5848300B2 - Workpiece conveyance device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a workpiece conveyance device that connects a plurality of numerically controlled machine tools arranged in the order of machining processes, and is capable of variably conveying cycle time according to the maximum machining time in each machining process. The purpose is to control.

Workpiece conveyance devices that connect machine tools in group control of machine tools usually carry out conveyance operations individually, and a buffer is generally provided in front of a processing station.

For this reason, the structure of the workpiece conveyance apparatus is not only large-scale and complicated, but also the control of the workpiece conveyance apparatus is complicated, leading to an increase in cost.

The purpose of providing a buffer by asynchronously operating the workpiece transport devices between each process is to reduce the waiting time for workpieces between each process and increase the machine operating rate. The effect will not be fully realized unless the scheduling is done very well, such as in what order the parts are visited and processed.

Moreover, when only a limited number of workpieces are prepared, optimal scheduling cannot be performed, and the scheduling and machining of only the limited number of prepared workpieces are forced.

In such cases, even with a workpiece transfer device that has a buffer function, processes with long machining cycle times become a bottleneck, and processes before and after the process have to wait for machining or workpieces, which unavoidably reduces the machine's engagement ratio. As a result, the functions of such transport devices are often not fully utilized.

In view of the above, the present invention employs a synchronous transport method for the workpiece transporting device, so that the transporting operation is performed at an optimal cycle according to the type of workpiece placed at each processing station, and the workpiece transporting device is configured. and to simplify control.

The present invention will be explained below with reference to Examples.

In Fig. 1, MTI to MT4 are numerically controlled machine tools;
ST1 to ST4 are the processing stations of each machine tool, ST
O is a loading station where workpieces W are attached and removed, C■1 to OV5 are workpiece conveyance devices that connect each station and convey workpieces W, and C is a workpiece conveyance device that simultaneously performs the conveyance operations of Cv1 to C■5. The controlling transport control devices DT1 to DT4 are detectors that detect the type of workpiece W located at each station.

The machine tools MT1 to MT4 have detectors DT1 to DT4.
Tools are replaced and a NO program for machining is selected in accordance with the workpiece signal detected by the machine, and different machining steps are performed for each workpiece.

Therefore, although this machining system can simultaneously process many types of workpieces, the machining time at each machining station varies.

Therefore, the conveyance devices OVI to OV5 are controlled by the conveyance control device C so that they simultaneously start their conveyance operations after completing the process that requires the longest machining time.

Such control involves registering the machining time individually for each workpiece and each process, detecting the type of workpiece located at each machining station ST1 to ST4 using the detectors DT1 to DT4, and controlling the machining time for each process. The time is checked and the conveyance operations of each conveyance device are performed at once in the maximum machining time period.

At the same time, the machining operations of each machine tool are started at the same time.

For example, the transport control device C can also be used as a group control computer.

In this case, machining times are stored for each work and each process in the memory of the computer, and a machining time table as shown in FIG. 2 is registered.

The detectors DT1 to DT4 detect the type of work carried to the processing station, that is, the work number, and inform the computer of this.

Once the workpiece number at each processing station is known, the maximum processing time is found by referring to the processing time table for each step, and this is stored in a register.

For example, processing stations STI, ST2, ST3
, the work numbers detected in ST4 are 10, 11, 10.
．． If it is 12, the maximum machining time is 5 minutes, and this value is stored in the register.

The computer is given a program as shown in FIG.

This program is executed by an internal clock generated at one minute intervals.

The i step is processed by an internal clock, and the i step is processed by an internal clock.
At step i, the value stored in the register (maximum machining time) is set to -1.

In step iii, it is determined whether the stored value of the register has become O, and if it is not 0, the process returns to the main routine.
The program of this routine will not be executed until the next internal clock is generated.

If 5 minutes have passed after the start of machining operation, the value stored in the register will be 0.
Then, the following steps are executed.

In steps iv, vi, viii, and
In steps x and xi, an abnormality is reported for the machine tool whose machining has not been completed.

If processing is completed, this abnormality will be notified V, vii
, ix, and xi are not executed.

In the Xii step, it is determined whether all process processing has been completed.
Workpiece conveyance device CV1 only when all process processing is completed
~C■5 transport operation start is commanded, and the process returns to the main routine.

If there is even one piece of machining that has not been completed, the main routine is returned to without issuing a command to start the transport operation, so the transport operation is not performed.

In this way, the workpiece transport device is controlled, and it is possible to notify abnormalities of each machine tool and to transport the processed workpieces to the next process all at once.

Then, the detectors DT1 to DT4 detect the workpiece number placed at each processing station again, refer to the processing time table for each process, find the maximum processing time, store it in the register, and set the start time of the next transport cycle. is controlled.

Even if the machining time differs for each process, all the conveying devices start the conveying operation at the same time at the maximum machining time period.

Furthermore, the machining operations of each machine tool are started simultaneously after the transfer of the workpiece to each machining station is completed.

In this way, when the maximum machining time in the next machining cycle has elapsed, the workpiece conveyance operation is performed again, and no matter what kind of workpieces are given in what order, the workpiece conveyance device will transfer the workpiece according to the process that takes the longest machining time. The movement is controlled in each case.

Therefore, compared to a system with a fixed transport cycle time, the mechanical transfer ratio is greatly improved, and compared to a system that is equipped with a buffer and performs transport operations asynchronously, the structure of the transport system is simpler, and the control Not only is this extremely simple, but it is also possible to maintain almost the same mechanical transfer rate as in the case of an asynchronous conveyor.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a plan view of a processing system, FIG. 2 is a diagram showing an example of a processing time table, and FIG. 3 is a flowchart when a computer is used as the conveyance control device. It is a chart. MT1~MT4...Numerical control machine tool, ST1
~ST4...Processing station, OV1~OV
5... Workpiece transfer device, C... Transfer control device, DTI to DT4... Detector.

Claims (1)

[Scope of Claims] 1. In a workpiece transfer device that interconnects a plurality of numerically controlled machine tools arranged in the order of machining steps and capable of machining different types of workpieces, the machining time of each workpiece and each process in the machine tools is a device for storing the maximum machining time; a device for checking the type of workpiece located at each machining station of the machine tool and searching for the maximum machining time from the machining time storage device; A workpiece conveyance device comprising: a conveyance control device that instructs the conveyance device to start a conveyance operation after a dog machining time has elapsed. 2. The workpiece transfer device according to claim 1, wherein the transfer control device instructs to start the transfer operation if all of the machine tools have completed machining when the maximum machining time has elapsed.