JP2951075B2 - Cassette layout selection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette placement selecting apparatus for selecting an optimized placement of a tape cassette in a chip component mounting apparatus.

[0002]

2. Description of the Related Art A high-speed chip component mounting device is a device for mounting a surface mounting component mainly composed of chip components on a printed circuit board at a high speed and has a configuration as shown in FIG. The chip components are wound around a tape for each type, placed in a cassette 1 and arranged on a reel shaft 2. The operation when the chip component is mounted on the printed circuit board is as follows. First, the cassette 1 of the component to be mounted is moved to the component pick-up position 3, and among the suction nozzles 5 arranged around the index table 4, the suction nozzle 5 located at the pick-up position 3 is suctioned by vacuum. The index table 4 rotates intermittently at the pitch at which the suction nozzles 5 are arranged. During this intermittent rotation, the reel shaft 2 is moved (or stopped) to position the cassette 1 of the component to be supplied next at the component pick-up position 3. Then, the component is sucked by the new suction nozzle 5 sent to the component removal position 3 by the intermittent rotation. In this way, components are continuously supplied from the reel shaft 2 to the index table 4.

On the other hand, the XY table 8 holding the printed circuit board 7 is horizontally moved in the front-rear and left-right directions while the components vacuum-adsorbed to the suction nozzles 5 by the intermittent rotation of the index table 4 are sequentially carried to the electronic component mounting position 6. A predetermined position on the printed circuit board 7 where electronic components are to be mounted is moved to the electronic component mounting position 6. Then, the component carried to the electronic component mounting position 6 is mounted.

[0004] Such an operation is controlled by a program based on NC data. Such NC data is created by a program creating device.

[0005] In this case, depending on how the cassette is arranged on the reel shaft and in what order the components are to be mounted, it is possible to eliminate unnecessary movements of the reel shaft and the XY table and to set the time for mounting. Can be shortened.

In the chip component mounting apparatus, the movement of the XY table, the rotation of the index table, and the movement of the reel axis are performed in parallel. Time to move the axis, time to rotate the index table,
This is the maximum value of the three times of moving the XY table. Therefore, in order to efficiently mount components at high speed, it is necessary to consider three factors: the reel axis, the rotation of the index table, and the moving time of the XY table.

In the chip component mounting apparatus, one operation is represented by a unit having a time width of tact as shown in FIG. For example, when the XY table is moved by 25 mm, it takes one tact, and when it is moved by 40 mm, it takes 2 tacts.
Tact. In addition, moving the reel shaft by one cassette is one tact, and moving the reel shaft by two cassettes is two tacts. The rotation of the index is determined by the type of parts, and when carrying a part that needs to be rotated at a low speed, three tacts are required to rotate the index from FIG.

Considering the above, the following case is considered. In FIG. 4, the rotation speed of the index table is set to be high, the time required for the movement of the cassette and the movement of the XY table is assumed to be FIG. If the component type is B, a1, a2, a3, a4, b5, b6, b7,
When b8 is hit, the movement time of the XY table takes 13 tacts, but as shown in FIG. 5, a1, b5, a2, b6, a3,
You can hit b7, a4, b8 in 7 tacts. In this case, since the cassettes of the component A and the component B are adjacent to each other, the moving time of the reel shaft is 7 tacts. When the cassettes are not adjacent to each other, for example, if the cassettes are separated by three pitches as shown in FIG. 6, the movement time of the XY table is 7 tacts, but the movement time of the reel axis is 3 tacts each time.
One tact. Thus, in order to shorten the mounting time, it is necessary to optimally arrange the cassettes.

Although this optimization problem is considered to be one of the combination problems, when calculating all the combinations,
Assuming that the type of parts is m and the number of places for mounting parts is n, the arrangement of the cassettes is m! , Mounting order is n! There is a combination of m!・ N! Becomes a huge number,
It is impossible to calculate every case. Therefore, an approximate optimal solution has been conventionally obtained. As one of them, there is a method presented at the 35th System Control Information Society Research Presentation Lecture 5008. (FIG. 7 shows the mounting positions of the components on the printed circuit board, and a1 to a
4, b1 to b3 and c1 to c3 represent the same kind of parts. In this conventional method, the following operation is performed.

[0010] As shown in FIG. 8, for the same type of component, a component mounting path connecting the mounting positions on the printed circuit board in the shortest time is obtained.

[0011] A type having the largest number of components is selected, two types of other types of components along the mounting path are selected, and a set of three types of components is created (FIG. 9).

[0012] Repeat from the one with the largest number of parts.

[0013] By connecting the end points of the set of parts determined in (1), the set of parts is arranged to be the shortest (FIG. 10).

[0014] The cassettes are arranged in the order determined in.

[0015]

SUMMARY OF THE INVENTION The present invention seeks to improve the above-mentioned prior art to determine a more efficient cassette arrangement.

[0016]

According to the present invention, there is provided a portion for recording a shortest path for each type of component, and a cassette pair recording section for recording cassettes which need to be adjacent to each other. A means for calculating the sum of the movement times of the XY table when mounting along the shortest path; a part selecting means for selecting a component of the largest type having an average mounting time when mounting along the shortest path; In the shortest path of a part of the different type, if it takes two tacts to move from the part to the next part, an area that can be moved in one tact from both parts is set between the part and the next part. If three tacts are required to move from one part to another, set an area that can be moved by one tact from one part and two tacts from the other part. Many included And a cassette pair selecting means for creating a set of component types with the component types and the component types selected by the component selecting means, and selecting cassettes of these component types so as to be adjacent to each other. The cassette pair selection operation is repeated except for the parts selected for the cassette pair.

[0017]

In the shortest path, the component type having the longest average mounting time (total of XY table movement time along the shortest path / total number of components of the type) is selected, so that more efficient cassette arrangement is possible. Can be performed.

[0018]

Embodiments of the present invention will be described below.

FIG. 1 is a block diagram of a cassette arrangement selecting apparatus according to the present invention. Reference numeral 7 denotes a component data recording unit for storing data such as the type and mounting position of each component. Reference numeral 8 denotes a shortest path for recording the shortest path for each component. A path recording unit 9 is a cassette pair recording unit that records cassettes that need to be adjacent to each other, 10 is a cassette arrangement recording unit that records the determined cassette arrangement, and 11 is an arithmetic unit.

In the prior art, a combination of parts that can be placed next to each other is created by giving priority to a type having a large number of parts. However, in the present invention, a combination of parts having a lot of waste in moving the XY table is given priority. In order to create a good set, priority is given to those having the largest average mounting time (total of XY table movement times along the shortest path / total number of components of the type).

In the prior art, when counting other types of components along the mounting path, a square having the path as one side is drawn around the center of the path, and the other components in the square are counted. (FIGS. 11 and 13) However, in this case, an efficient cassette order may not always be determined.

On the other hand, according to the present invention, when counting other types of components along the mounting path, when the components are transferred in two tacts, the other points within a range of one tact from both ends of the line segment of the path. (Fig. 12). When moving with three tacts, the parts within two tacts from one end and one tact from the other end are counted.

In the present invention, the following procedure is used in order to select components of a cassette which are more efficient if they are placed next to each other.

The shortest path is selected for each component type.

[0025] In the shortest route obtained in the above, the average wearing time (total of XY table moving time along the shortest route /
Select the type of component that has the largest number of components of that type.

[0026] Along the path of the part determined in
When moving by tact, the parts (a1, a
Count other types of parts in the range from 2) to 1 tact. (FIG. 12) This is because if another part (b1) is placed in this area, two parts (a1-b1-a2) are placed in two tacts.

When moving by three tacts, other types of parts within the range of two tacts from one end and one tact from the other end are counted (FIG. 14). This is because if other parts are put in this area, it takes 3 tacts and (a1-b1-a2 or a
1-b2-a2). Other types of parts, which are the most abundant in such an area, are selected next to each other.

The process after removing the parts of the type selected next to each other is repeated. If the above operations are performed next to each other, an efficient cassette can be selected.

FIG. 15 shows the positions of the components on the printed circuit board.
Assuming that the index table rotation speed of each component is high, a cassette that should be placed next to another is determined as follows.

First, the arithmetic unit 11 reads information from the component data recording unit 7 which records the mounting position of the component and the like,
The shortest path for each part is obtained, and this is entered in the shortest path recording unit 8 for each part. Next, the type A of the component having the longest average mounting time is selected, and the area described in the procedure is set along the route, as shown in FIG. When counting other types of components in this area, there are many components of B and C. Therefore, it is determined that the cassettes of B and C are to be adjacent to the cassette of A and the cassette pair recording unit is entered.

FIG. 17 shows the result of selecting the component D having the longest average mounting time, excluding the components A, B, and C, and setting the area as described in the procedure. If other types of parts are counted, E and F are large. Therefore, D, E and F are added to the cassette recording unit.

When all the parts have been put into the cassette pair recording section, the process ends.

When the cassette arrangement is determined in this way, the component mounting order is determined. Next, a method of selecting the component mounting order will be described.

First, when the number of components to be mounted on the printed circuit board is large, the cassette on the reel shaft is divided into a plurality of groups, and an optimum mounting order is determined for each divided group. At this time, it is appropriate that the number of parts in each divided group is about 50.

In the dividing method, as shown in FIG. 18, one pair of cassettes is added to the divided group according to the reel moving path, and this is continued until the number of parts in the group exceeds 50. In order to provide a connection between the division groups, the mounting order of the components of the cassette before and after the division boundary is made continuous as shown in FIG. Then, the mounting order is optimized for each of the divided groups. The optimization of the target mounting order means that the path in which the weight of the mounted component is the length of the branch is the shortest. The weight between the mount components uses the sum of three tact times of reel movement, XY table movement, and switching of the positioning position. As conditions for the mounting path, if the number of components is n (including the origin), the following three are required (the origin is a component at the reel position 1, the XY coordinates (0, 0), and the positioning position 1).

A. The path connects all parts.

B. The path is composed of n branches.

C. Two branches intersect all parts.

Of these conditions, the condition c is relaxed, and only two branches from the starting point and the ending point are set at the origin. A graph with such a condition and having the smallest sum of the technique weights is obtained by the following procedure.

A minimum tree connecting all parts except the origin is obtained (n-2).

Select parts to be the start and end points (FIG. 1)
8).

By adding two branches from the start point and end point to the origin, n branches are obtained.

The obtained graph is called a minimum 1-tree (FIG. 1)
9). The mount path is the minimum one-tree, but the minimum one-tree does not necessarily hold because the condition c is relaxed. Therefore, a modification is made to the minimum 1-tree so as to satisfy the condition c. Next, the procedure will be described.

(1) List all parts having an odd number of branches in the minimum-tree. There are even numbers (2k). The black circle in FIG. 19 corresponds to this.

(2) The k branches connecting such a pair of parts are selected such that the sum of the weights of the branches is minimized. Such a set of branches is called optimal matching, and is obtained by a greedy method. When the optimal matching branch is added as shown in FIG.
Every part has an even number of branches.

(3) In this graph, all branches can be visited in a single-stroke manner. Starting from the origin, follow a single-stroke route, but skip the same part more than once and skip ahead. FIG. 21 shows this state.
As a result, the mounting order is obtained.

The minimum tree, the optimal matching, and the greedy method are defined as follows.

A minimum tree is a tree connecting all parts and having a minimum sum of branch weights.

Optimal matching: Matching in which no two branches of a branch set share a part is called matching. When the number of parts is 2k, the sum of the weights of the k branches is minimized.

Greedy method: A method of directly constructing a possible solution based on local evaluation indicating the goodness of the objective function value.

The mounting order obtained in this way is further modified using an iterative improvement method.

The iterative improvement method is a method in which an approximate optimum solution obtained by some method is examined in the vicinity thereof, that is, another solution obtained by making a slight change, and if it can be improved, the solution is replaced. This iterative improvement method is described below.

The mounting order is corrected for each speed group. The correction is performed in the following procedure.

(1) The branch having the maximum weight is selected from the branches that have not been replaced.

(2) The operation of exchanging with this branch is performed for all the branches except the branches at both ends of this branch, and this branch is regarded as already operated.

(3) The replacement with the branch whose improvement is the largest as a result of the replacement is actually performed as shown in FIG.

(4) The operations of (1) to (3) are repeated until all the branches have been operated or the maximum weight of the unoperated branch becomes equal to the minimum weight in the speed.

By using the iterative improvement method with the final mount component as the origin, it is possible to correct the reel return mounting order.

[0059]

As described above, the cassette arrangement selecting apparatus according to the present invention can determine the arrangement of cassette pairs more effectively than in the conventional case, so that the component mounting time can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cassette arrangement selecting device of the present invention.

FIG. 2 is a configuration diagram of a chip component mounting apparatus.

FIG. 3 is a diagram showing correspondence of time required for movement of a reel axis, movement of an XY table, and rotation of an index table.

FIG. 4 is an explanatory diagram illustrating a mounting order and cassette arrangement of electronic components.

FIG. 5 is an explanatory diagram illustrating a mounting order and cassette arrangement of electronic components.

FIG. 6 is an explanatory diagram illustrating a mounting order and cassette arrangement of electronic components.

FIG. 7 is an explanatory diagram for explaining a conventional cassette arrangement selecting method.

FIG. 8 is an explanatory diagram for explaining a conventional cassette arrangement selecting method.

FIG. 9 is an explanatory diagram for explaining a conventional cassette arrangement selecting method.

FIG. 10 is an explanatory diagram for explaining a conventional cassette arrangement selecting method.

FIG. 11 is an explanatory diagram illustrating a search area according to a conventional method.

FIG. 12 is an explanatory diagram illustrating a search area according to the method of the present invention.

FIG. 13 is an explanatory diagram illustrating a search area according to a conventional method.

FIG. 14 is an explanatory diagram illustrating a search area according to the method of the present invention.

FIG. 15 is an explanatory diagram for explaining a process of finding a cassette which should be placed side by side in the present invention.

FIG. 16 is an explanatory diagram for explaining a process of finding a cassette which should be placed side by side in the present invention.

FIG. 17 is an explanatory diagram for explaining a process of finding a cassette which should be placed side by side in the present invention.

FIG. 18 is an explanatory diagram for explaining reel division.

FIG. 19 is an explanatory diagram illustrating a procedure for determining an optimal component mounting order.

FIG. 20 is an explanatory diagram for describing a procedure for determining an optimal component mounting order.

FIG. 21 is an explanatory diagram for explaining a procedure for determining an optimal component mounting order.

FIG. 22 is an explanatory diagram illustrating a procedure for determining an optimal component mounting order.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 cassette 2 reel axis 3 component take-out position 4 index table 5 suction nozzle 6 electronic component mounting position 7 component data recording unit 8 shortest path recording unit 9 cassette pair recording unit 10 cassette arrangement recording unit 11 arithmetic unit

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05K 13/00-13/04

Claims (1)

(57) [Claims] 1. A part for recording a shortest path for each type of component and a cassette pair recording unit for recording cassettes that need to be placed next to each other, and a shortest mounting path for each type of component and mounting along this shortest path Means for calculating the sum of the movement times of the XY table when performing the operation, component selection means for selecting the type of component having the largest average mounting time when mounting along the shortest path, and If the movement from one part to the next part requires two tacts, an area that can be moved by one tact from both parts is set between the part and the next part, and the movement from one part to the next part requires three tacts. In this case, an area that can be moved by one tact from one part and two tacts from the other part is set between the part and the next part, and other types of parts that are most often included in these areas And above parts selection Cassette pair selecting means for creating a set of component types with the types of components selected by the selecting means, and selecting the cassettes of these component types to be adjacent to each other. A cassette arrangement selecting apparatus wherein a cassette pair selecting operation is repeated except for parts.