JPH0721725B2 - NC mounting machine cassette layout optimization method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for optimizing a cassette layout when mounting components on an NC mounting machine.

[Prior Art] NC mounters have come to be used as component mounters that automatically mount components when a large number of printed boards are produced. In this case, the NC mounter sets the mounting components in the cassette in advance, and the head automatically picks up the components based on the instructions from the numerical controller and moves them to the mounting location on the printed circuit board, It is an automatic component mounter configured to be mounted on.

[Problems to be Solved by the Invention] When using this type of NC mounter, shortening the component mounting time is an important issue for cost reduction.

This is because recently, the unit price of the component has become low, and the cost of mounting one component by the NC mounting machine is higher than the cost of one component.

In order to reduce the component mounting time of the NC mounting machine, it is a priori to reduce the head moving time. There is a minimum cycle time distance in the operation of the head, and the NC mounting machine has the property that when moving within this distance, the required time is always constant (same) regardless of the size of the movement distance (this required time Is called the minimum cycle time).

However, if the moving distance of the head exceeds the amount that can be moved in the minimum cycle time, it takes extra time due to the excess (this is called overtime).

The movement of the head includes movement for mounting the same type of component and movement required for starting the mounting of another type of component. Therefore, the total component mounting time on the NC mounter is the sum of the overtime caused by component-to-component movement (hereafter referred to as component-to-component movement) for the same type of component, and the next time after the component of a certain type has been mounted. It is the total time of the sum of the overtime and the sum of the minimum cycle time caused by the movement (hereinafter, referred to as the movement to a different type of component) when mounting various types of components.

By the way, in the conventional mounting by the NC mounter, automatic optimization by the computer is attempted for the total sum of the overtime of movement between components, but optimization for the total sum of overtime of movement to different parts (that is, cassette Layout optimization) is not automated. In the past, this was done by the intuition and experience of the operator. It is known that this optimization is simply a problem of finding an optimum combination, and therefore it takes a huge amount of time to find an optimum solution using a computer.

Normally, the operator decides the cassette layout in advance, and under this fixed condition, the mounting order (route) of the parts
Only the optimization of is carried out. Therefore, there is a problem that sufficient optimization is not performed.

The object of the present invention has been made in view of such a point, and at the same time as optimizing the mounting route of the components in the NC mounting machine, the component cassette layout is also optimized, and the overall component mounting time is minimized. It is to provide a method for optimizing the cassette layout of an NC mounter that can achieve the above.

[Means for Solving Problems] In order to achieve such an object, the present invention provides a method for automatically determining a component cassette layout in an NC mounting machine, in which a maximum of M types of component types are selected. A step of determining an optimum path, and a path when the value of the following evaluation function D becomes the minimum among the maximum M paths obtained for each part type, and a different part set in the next cassette. It is characterized by comprising the steps of sequentially determining.

D = (overtime when moving to the next dissimilar part) + α · (overtime when moving the next dissimilar part between parts) where α is a coefficient depending on the number of parts of the next dissimilar part.

EXAMPLES The present invention will be described in detail below with reference to the drawings. FIG. 1 is a principle flow according to the method of the present invention. The steps will be described below in order.

(1) A maximum of M routes (M is an integer) are determined as optimum routes for each component. Note that, as an example, a case where the maximum number of routes is eight will be described.

More specifically, in the present invention, the mounting path is optimized for each component of the same type, and a maximum of eight optimized paths (there may be eight or less depending on the number of parts). At the same time, the overtime is calculated for each route.

For example, if the number of parts is N for a certain kind of parts,
There are N! Routes, but the following method is used to select a maximum of 8 optimal routes.

Place the mounting start part on the upper left, lower left, and
Limited to 4 in the upper right and lower right (4 ways).

To determine the mounting route, SORTING is performed by position coordinates, but horizontal and vertical sorting is performed (two ways).

With the above execution, up to 4x2 for the same type of parts
= 8 routes (this is the optimized route) are required.

(2) Next, the head of the mounting machine is initially located at the machine origin, and the first cassette is determined based on a predetermined evaluation function.

That is, the following evaluation function D is defined, and one of the optimum routes is selected from the eight routes related to the type of component so as to minimize it, and at the same time, the unmounted component ( Among different types of parts), the part (different type of parts) to be set in the next cassette is determined.

D = (overtime when moving to the next dissimilar part) + α ・ (overtime when moving the next dissimilar part between parts) where α is a coefficient depending on the number of parts of the next dissimilar part,
This is the optimum value obtained from the measured data.

According to the experiment, when α = 0, a large number of parts may be selected first, and a route having a large overtime may be selected from the eight optimum routes.

Further, when α = 1, a large number of parts were selected last.

However, in both cases, when the number of parts is large, the overtime at the time of moving to the next dissimilar part is small, and the overtime at the time of moving the dissimilar parts between parts is large. Conceivable.

As described above, when α = 0 or α = 1, the optimum layout is not obtained when the variation in the number of similar components is large.

Therefore, I set α = 0.1 / N (N is the number of different parts to be set next) and obtained relatively good results.

From such experimental results, α is preferably set to 0.1 / N. However, it goes without saying that the present invention does not limit α to this value.

(3) The evaluation in (2) above is repeated for all types of parts. However, the initial position of the head of the mounting machine in that case shall be the end position of the front part.

As described above, the optimum cassette layout and the optimum path for each component are simultaneously obtained.

FIG. 2 is a diagram showing an example of functional blocks for realizing such an optimization method. 1 is an optimal route determination block that determines a maximum of 8 optimal routes for each component, 2
Is an evaluation function calculation block that evaluates the evaluation function in order to determine different parts to be set in the next cassette according to the given evaluation function and the optimum path that minimizes the overtime. 3 is a control block. 4 is various data. Is a memory for storing signals, and 5 is a bus for transmitting signals and data of each unit.

The control block 3 controls each part according to a predetermined procedure.

In such a configuration, the control block 3 first activates the optimum path determination block 1 to determine a maximum of eight optimum paths for all types of parts. The control block 3 stores the component type and the optimum route obtained by the optimum route determination block in the memory 4 via the bus 5.

Next, the control block 3 activates the evaluation function calculation block 2 to first determine the type of parts to be stored in the first cassette. That is, in the evaluation function calculation block 2, it is assumed that the initial position of the mounting machine head is at the machine origin, and based on the component type read from the memory 4 via the bus 5 by the control block 3 and the route data of the component type. Then, the evaluation function is evaluated to obtain the type of part to be stored in the first cassette and one optimum path for the type of part.

The component type and the optimum route thus obtained are stored in the memory 4 in association with the cassette number each time.

When the type of component to be set in the first cassette and its mounting route are obtained as described above, the type of component to be set in the second cassette and its mounting route are then determined. That is, the component type and its optimum route are determined in the evaluation function calculation block 2 in the same manner as described above. The obtained component type and optimum route are stored in the memory 4 in association with the cassette number as in the above.

The control block 3 controls so that the above evaluation is repeated until there are no unmounted components.

The control block 3 terminates this processing when the optimum paths and cassette layouts are obtained for all the parts in this way.

The information about the optimum path and the cassette layout for each component thus obtained and stored in the memory 4 can be appropriately read and used.

[Effects of the Invention] As described in detail above, the present invention has the following effects.

(1) Since the optimum mounting path is limited to M ways in advance, the processing time for determining the cassette layout can be shortened.

(2) As the evaluation function for determining the cassette layout, both the overtime when the mounter head moves between parts and the overtime when the mounter head moves between different parts are taken into consideration, so that the number of mounted parts is large. Can be obtained at the beginning or the end, and the cassette layout can be obtained so that the total mounting time can be minimized.

[Brief description of drawings]

FIG. 1 is a flowchart showing the principle of the present invention, and FIG. 2 is a diagram showing an example of functional blocks for implementing the method of the present invention. 1 ... Optimal route determination block, 2 ... Evaluation function calculation block, 3 ... Control block, 4 ... Memory, 5 ... Bus.

Claims (1)

[Claims] 1. A method for automatically determining a component cassette layout in an NC mounting machine, the step of determining a maximum of M optimum routes for each component type, and the maximum M determined for each component type. A method for optimizing a cassette layout of an NC mounter, which comprises sequentially determining a path when the value of the following evaluation function D is the smallest and a different component to be set in the next cassette from each path. D = (overtime when moving to the next dissimilar part) + α · (overtime when moving the next dissimilar part between parts) where α is a coefficient depending on the number of parts of the next dissimilar part.