production line

Abstract

To provide a manufacturing line capable of flexibly coping with fluctuations in tact times while suppressing a steep rise of equipment cost.SOLUTION: A manufacturing line 10 includes: a work line 12 for performing a predetermined work on a workpiece 11 while conveying the workpiece 11; an AGV13 movable on the work line 12 while holding the workpiece 11; and a speed setting unit 14 capable of stepwise setting a moving speed V of the AGV13 in a predetermined speed unit Vu. The speed setting unit 14 can vary the moving speed V upward and downward by detecting a plurality of to-be-detected objects 16 arranged on the work line 12 as the AGV13 moves.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a manufacturing line. [Background technology]

[0002] For example, in an automobile body assembly welding line, shell parts such as door panels are individually manufactured on the shell assembly line, and each shell part manufactured on the shell assembly line is supplied to the main assembly welding line, whereby the white body is assembled and welded (see, for example, Patent Document 1).

[0003] Furthermore, Patent Document 2 describes that, with the aim of reducing equipment costs by standardizing conveying equipment, workpiece transportation on the main body assembly line and workpiece transportation between the above-mentioned assembly lines are carried out using a common AGV (automated guided vehicle). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-272560 [Patent Document 2] Japanese Patent Application Publication No. 2019-14006 Summary of the Invention [Problem to be solved by the invention]

[0005] In a manufacturing line such as the one described above, multiple processes are performed, and workers in charge of each process may perform a specific task on the workpiece while moving along with the workpiece as it moves along the line. In this case, the workpieces on the line are transported at a predetermined speed so that the takt time (a standard work time per process, which refers to the work time common to all processes on the line to which the process belongs; the same applies hereinafter) is met. In other words, the speed at which the AGV transports the workpieces (i.e., the movement speed of the AGV) is controlled to a predetermined value so that the time required for the worker to perform a specific task on the workpiece while moving along with the workpiece, and then return to the start position after completing the task, is less than the takt time. On the other hand, from the perspective of minimizing worker waiting time, it is desirable to control the movement speed of the AGV to a constant value so that the time required for the above-mentioned series of operations is as close to the takt time as possible.

[0006] Here, if the takt time change is on the order of less than one minute (for example, a few seconds to several tens of seconds), the AGV movement speed is set to 10 -1 m / min, sometimes 10 -2 It becomes necessary to change the travel speed on the order of m / min. Changing the travel speed on the same order of magnitude requires an expensive AGV, which leads to a rise in equipment costs. Furthermore, if one AGV is to be used for both on-line workpiece transport and inter-line transport, as mentioned above, an AGV with a wide settable speed range and an extremely small speed increment compared to the speed range is required, which leads to an even higher rise in equipment costs.

[0007] In view of the above circumstances, the technical problem to be solved in this specification is to provide a manufacturing line that can flexibly respond to fluctuations in takt time while suppressing increases in equipment costs. [Means for solving the problem]

[0008] The above-mentioned problems are solved by a production line according to the present invention, which includes a work line for transporting workpieces and performing predetermined operations on the workpieces, and an AGV capable of moving along the work line while holding the workpieces, and further includes a speed setting unit that can set the movement speed of the AGV in stages in predetermined speed units, and the speed setting unit can vary the movement speed up and down by detecting multiple detectable objects arranged on the work line as the AGV moves.

[0009] In this way, in the present invention, when the movement speed of an AGV is set in stages in predetermined speed units, the AGV's movement speed can be changed up or down by utilizing the function that can change the movement speed when the AGV detects an object, so that the movement speed (average movement speed) of the AGV while moving along the work line can be set in units smaller than the speed units that the AGV can originally set. This makes it possible to fine-tune the average movement speed according to the takt time even with a general-purpose, inexpensive AGV, so it is possible to avoid a rise in equipment costs while minimizing worker waiting time and flexibly responding to changes in takt time.

[0010] In addition, in the production line according to the present invention, the speed setting unit may be capable of alternately switching the movement speed between a first movement speed and a second movement speed that is greater than the first movement speed by one speed unit, depending on the cumulative number of detections of the object to be detected.

[0011] In this way, by varying the travel speed up or down based on the cumulative number of detected objects by the AGV, the average travel speed of the AGV can be easily fine-tuned without complex settings such as changing the type or placement of the detected objects. Furthermore, by alternately increasing or decreasing the travel speed by a speed unit, the average travel speed can be fine-tuned efficiently. Therefore, this configuration makes it possible to flexibly respond to takt time more simply and at low cost.

[0012] Furthermore, when the movement speed is changed up or down by a speed unit, in the production line of the present invention, the speed setting unit may adjust the ratio of the set time of the second movement speed to the set time of the first movement speed.

[0013] In this way, by adjusting the ratio of the set times of the first and second movement speeds, which differ by a speed unit, the average movement speed of the AGV can be accurately set. In other words, the ratio of the set times of the first and second movement speeds while the AGV is moving on the work line is the magnitude of the average movement speed as the ratio of the first movement speed to the second movement speed, so by setting the average movement speed in this way, it is possible to fine-tune the average movement speed more easily and accurately.

[0014] In this case, in the production line according to the present invention, the speed setting unit may be capable of setting the movement speed so that the time periods of the first movement speed and the time periods of the second movement speed are evenly distributed in time series.

[0015] As described above, when workers in charge of each process on a production line move with their workpieces while working, they can intuitively grasp the progress of the work they are currently performing based on their own standing position. However, for example, if the time period when the second movement speed, which is relatively faster, is concentrated in the latter half of the process, the relationship between the worker's own standing position and the actual progress of the work becomes different from the previous relationship, making it difficult to grasp the progress of the work in the same intuitive manner as before. In response to this, by allowing the first and second movement speeds to be alternately switched so that the time periods of the first movement speed and the second movement speed are evenly distributed in chronological order, it is possible to avoid a situation where one of the movement speeds becomes biased. Therefore, workers can grasp their own progress (standing position) in the same intuitive manner as before. Therefore, it is possible to flexibly respond to takt time while maintaining the worker's workability.

[0016] In the production line according to the present invention, the plurality of detection objects may be arranged at equal intervals on the work line.

[0017] In this way, by arranging multiple detectable objects at equal intervals, it is possible to easily grasp the time it takes to move at a constant speed (=disposition interval of detectable objects / moving speed). Therefore, the average moving speed can be calculated instantly and accurately according to the fluctuation history of the moving speed, making it possible to fine-tune the average moving speed of the AGV more easily and accurately.

[0018] In addition, in the manufacturing line according to the present invention, the AGV may be a path-guided AGV that can move along guides on the work line, and the speed setting unit may be capable of varying the movement speed up and down when detecting multiple guides as detection objects arranged intermittently along the work line.

[0019] In this way, a route-guided AGV that can move along a guide is a general-purpose AGV and can be obtained inexpensively. Furthermore, if a guide is used as the object to be detected, the guide can be used as the object to be detected using the functions that route-guided AGVs normally have. Therefore, it is possible to build a manufacturing line with the above configuration inexpensively. [Effects of the Invention]

[0020] As described above, according to the present invention, it is possible to provide a manufacturing line that can flexibly respond to fluctuations in takt time while suppressing increases in equipment costs. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a plan view of a main part of a manufacturing line according to an embodiment of the present invention; [Figure 2] 2 is a graph showing an example of a history of speeds set by the speed setting unit shown in FIG. 1 for the AGV. [Figure 3] 10 is a graph showing another example of the speed history set by the speed setting unit shown in FIG. 1 . DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, the contents of a manufacturing line according to one embodiment of the present invention will be described with reference to the drawings.

[0023] Fig. 1 shows a plan view of a manufacturing line 10 according to this embodiment. As shown in Fig. 1, this manufacturing line 10 mainly comprises a work line 12 for performing a predetermined operation on a workpiece 11, an AGV 13 that can move on the work line 12 while holding the workpiece 11, and a speed setting unit 14 that can set the speed of the AGV 13.

[0024] The work line 12 has work areas A (A1, A2...An) for carrying out a plurality of processes S (S1, S2...Sn). In each work area A, a worker W (W1, W2...Wn) in charge of each process S is located. In this embodiment, the workpiece 11 carried into each work area A by the AGV 13 moves along the flow direction X of the work line 12, and the worker W of each process S performs a predetermined task on the workpiece 11 while moving on the work line 12 together with the workpiece 11.

[0025] In this embodiment, the working areas A of the respective processes S have the same dimensions in the flow direction X of the working line 12 .

[0026] In this embodiment, the AGV 13 is a path-guided AGV, and is capable of moving along guides (first guides 15) that are continuously arranged on the work line 12. In this embodiment, as shown in FIG. 1, the first guides 15 are continuously arranged along the work line 12. The first guides 15 are arranged so as to pass through all work areas A (A1, A2...An) on the work line 12. The AGV 13 detects the first guides 15 with a sensor (not shown), and is capable of moving on the first guides 15 in the direction in which the first guides 15 extend.

[0027] Additionally, second lead-in elements 16, which are lead-in elements for setting the speed, are intermittently arranged along the first lead-in elements 15 on the work line 12. These multiple second lead-in elements 16 correspond to the detection objects according to the present invention. In this embodiment, a predetermined number (10 in FIG. 1 ) of second lead-in elements 16 are arranged per process S. Furthermore, these multiple second lead-in elements 16 are arranged at equal intervals in the flow direction X. The AGV 13 detects the second lead-in elements 16 using a sensor (not shown) and transmits the detection information to the speed setting unit 14.

[0028] From the viewpoint of cost, magnetic materials such as magnetic tape are suitable for the first and second inductors 15 and 16, but the present invention is not limited to this. Induction methods (inductors) using non-magnetic media, such as optical reflection and magnetic induction, may also be used.

[0029] The speed setting unit 14 can set the movement speed V of the AGV 13 according to a preset takt time T. When the work area A of each process S has dimensions equal to the flow direction X as described above, the movement speed V of the AGV 13 is set to an appropriate magnitude so that the time from time t1 when the work 11 being transported by the AGV 13 starts to be carried into the work area A to time t2 when the work 11 starts to be carried out from the work area A (passage time t2-t1 through the work area A) is less than the takt time T and is as close to the takt time T as possible.

[0030] Here, the AGV 13 is configured so that the travel speed V can be set in stages using a predetermined speed unit Vu. In this case, the travel speed V of the AGV 13 can be set within a range of multiples of the speed unit Vu, which is set to a predetermined magnitude in advance. Therefore, the speed setting unit 14 first sets the travel speed V within the settable range so that one work area A can be passed through in the same time as the takt time T. Then, if it is not possible to set a travel speed V that can pass through one work area A in the same time as the takt time T, the speed setting unit 14 sets a first travel speed V1 to a value obtained by adding the minimum speed Vm of the AGV 13 to the largest multiple of the speed unit Vu so that one work area A can be passed through in a time slightly longer than the takt time T. Then, the speed setting unit 14 sets a second travel speed V2 to a value that is larger than the first travel speed V1 by the speed unit Vu.

[0031] Then, the ratio of the time period of the first moving speed V1 to the time period of the second moving speed V2 is set so that the transit time t2-t1 through one work area A is shorter than the takt time T and as close to the takt time T as possible. For example, in the present embodiment, when multiple second guides 16 are arranged at ten equally spaced locations per work area A (see FIG. 1), and the set moving speed V is the intermediate value between the first moving speed V1 and the second moving speed V2, the speed history of each moving speed V1 and V2 is set so that there are five time periods for the first moving speed V1 and five time periods for the second moving speed V2, as shown in FIG. 2. As a result, the average moving speed VA, which is the moving speed of the AGV 13 while it is moving on the work line 12, is set to a value outside the value obtained by adding the lower limit speed Vm to a multiple of the speed unit Vu. Specifically, the average moving speed VA is set to the average value (V1 + V2) / 2 of the first moving speed V1 and the second moving speed V2.

[0032] In addition, in this embodiment, the speed setting unit 14 can alternately switch the movement speed V between a first movement speed V1 and a second movement speed V2 depending on the cumulative detection number of the second guide 16. In the case of this embodiment, when the cumulative detection number of the second guide 16 in one work area A is odd, the movement speed V of the AGV 13 can be switched to the first movement speed V1, and when the cumulative detection number of the second guide 16 is even, the movement speed V of the AGV 13 can be switched to the second movement speed V2.

[0033] In this case, from the viewpoint of making it easier for the worker W to intuitively grasp the progress of the work, the speed history of each of the movement speeds V1 and V2 may be set so that each of the movement speeds V1 and V2 is evenly distributed in time series. Fig. 2 illustrates an example in which the movement speed V of the AGV 13 is varied up and down so that five time periods of the first movement speed V1 and five time periods of the second movement speed V2 alternate.

[0034] In any case, the movement speed V of the AGV 13 is set within an appropriate range, taking into consideration that the worker W works on the workpiece 11 while moving. As an example, the movement speed V is set to 0.5 m / min or more and 3.0 m / min or less.

[0035] The effects of the present invention will be explained below mainly based on Tables 1 and 2. Tables 1 and 2 show the verification results when the flow direction dimension of the work area A (the moving distance of one process S of the AGV 13) is 2.5 m and the speed unit Vu of the AGV 13 is 0.15 m / min. [Table 1] [Table 2]

[0036] First, consider the downtime of the AGV 13 when it moves through each work area A on the work line 12 at a constant speed V, as in the conventional case. As shown in Table 1, when the takt time T is changed in increments of 0.05 minutes (3 seconds), the speed setting unit of the conventional AGV 13 sets the speed V in steps at a predetermined speed unit Vu (here, 0.15 m / min) as a constant speed while passing through the work area A. Therefore, for example, when the takt time T is 2.4 minutes, the downtime of the AGV 13 can be kept to about 1 second by setting the speed V to 1.05 m / min. However, when the takt time T is reduced by 0.05 minutes from 2.4 minutes (when the takt time T is set to 2.35 minutes), the speed V of the AGV 13 must be increased by the speed unit Vu, resulting in a significant increase in downtime.

[0037] In contrast, in the production line 10 according to the present embodiment, the AGV 13 is able to change its movement speed V by utilizing a function that allows the AGV 13 to change its movement speed V when it detects the second inductor 16 (see FIG. 2). This allows the movement speed V (average movement speed VA) of the AGV 13 while it moves along the production line 12 to be set in units smaller than the speed unit Vu that the AGV 13 can originally set (in this embodiment, a value 0.1 times Vu). For example, as shown in Table 2, if the takt time T is reduced by 0.05 minutes from 2.4 minutes to 2.35 minutes, the average movement speed VA can be set to 1.065 m / min, thereby significantly reducing the downtime of the AGV 13. Thus, according to the production line 10 according to the present embodiment, even when a general-purpose, inexpensive AGV is used as the AGV 13, the average movement speed VA can be fine-tuned according to the takt time T. This allows the AGV 13 to flexibly respond to changes in the takt time T by minimizing the waiting time of the worker W while avoiding increases in equipment costs.

[0038] In addition, in this embodiment, the speed setting unit 14 can alternately switch the movement speed V between the first movement speed V1 and the second movement speed V2, which is larger than the first movement speed V1 by the speed unit Vu, according to the cumulative number of detections of the second induction device 16. Therefore, the average movement speed VA of the AGV 13 can be set to a desired value with a minimum fluctuation in the movement speed V. This makes it difficult for the worker W to notice the fluctuation in the movement speed V, thereby ensuring the same workability as before.

[0039] 2, in this embodiment, the movement speed V is switched so that the time period of the first movement speed V1 and the time period of the second movement speed V2 are evenly distributed in time series, which makes it possible to avoid a situation in which the time period of one movement speed (for example, the second movement speed V2) is concentrated in the first half or second half of the process S. This allows the worker W to grasp his or her own progress (position) in the same way as before. Therefore, it becomes possible to flexibly respond to the takt time T while maintaining the workability of the worker W.

[0040] Although one embodiment of the present invention has been described above, the manufacturing line according to the present invention can also have other configurations than those described above without departing from the spirit of the invention.

[0041] FIG. 3 shows a graph related to the speed history of an AGV according to another embodiment of the present invention. In this embodiment, the speed setting unit 14 can set the speed history of the AGV 13 in a manner different from the speed history shown in FIG. 2. More specifically, if the average movement speed VA of the AGV 13 to be set according to the takt time T is closer to the first movement speed V1 than to the second movement speed V2, the speed history of each movement speed V1, V2 is set so that the time period of the first movement speed V1 is longer than the time period of the second movement speed V2, as shown in FIG. 3. In this illustrated example, the movement history of each movement speed V1, V2 is set so that the ratio of the time period of the first movement speed V1 to the time period of the second movement speed V2 is 7:3.

[0042] Also in this embodiment, the speed history of each of the movement speeds V1 and V2 is set so that the movement speeds V1 and V2 are evenly distributed in time series, from the viewpoint of making it easier for the worker W to intuitively grasp the progress of the work. As shown in Fig. 3, when the time period of the second movement speed V2 is shorter than the time period of the first movement speed V1, it is desirable to fluctuate the movement speed V of the AGV 13 up and down so that the time period of the first movement speed V1 and the time period of the second movement speed V2 alternate at a ratio of 2:1, for example, as shown in the figure.

[0043] 2 and 3 are merely examples. The speed setting unit 14 can set any speed history for the movement speed V, as long as it is possible to set the movement speed V (average movement speed VA) of the AGV 13 while it moves on the work line 12 in units smaller than the speed unit Vu that the AGV 13 originally has by varying the movement speed V up and down.

[0044] Furthermore, in the above embodiment, a case where a route-guided AGV is used as the AGV 13 has been exemplified, but of course, this is not limited to this. For example, an AGV of a type that does not require the guide 15 (16), such as an autonomous mobile type, may also be used. In this case, it is essential that a detection object for setting the speed be disposed on the work line 12. Of course, if there is space available for installation other than the floor surface of the work line 12, such as the side of the work line 12, the detection object may be disposed on a surface other than the floor surface (such as the ceiling surface). [Explanation of symbols]

[0045] 10 production lines 11 Work 12 working lines 13 AGV 14 Speed ​​setting section 15 First derivative 16 Second derivative A Work Area S process T takt time V Movement speed V1 Primary movement speed V2 Secondary Movement Speed VA average moving speed Vm lower limit speed Vu velocity units W Worker X conveying direction

Claims

1. a work line for carrying out a predetermined operation on the work while transporting the work; an AGV capable of moving on the work line while holding the workpiece, a speed setting unit that can set the movement speed of the AGV in stages in predetermined speed units; A manufacturing line characterized in that the speed setting unit varies the movement speed of the AGV up and down by detecting multiple objects arranged on the work line as the AGV moves, thereby making it possible to adjust the average movement speed of the AGV while it is moving on the work line to be smaller than the specified speed unit that can be set by the speed setting unit.

2. 2. The manufacturing line according to claim 1, wherein the speed setting unit is capable of alternately switching the moving speed between a first moving speed and a second moving speed that is greater than the first moving speed by the speed unit, depending on the cumulative number of detections of the object to be detected.

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