METHOD AND CONTROL DEVICE FOR THE PROCESSING-TIME-OPTIMIZED PRODUCTION OF PRINTED CIRCUIT BOARDS ON A PICK-AND-PLACE LINE

Abstract

Provided is a transmission device for feedback-free unidirectional transmission of data from a first network zone into a second network zone for evaluation at a remote application server, containing:a data export device which is arranged in the first network zone and is to detect the data transmitted in a network data format in the first network zone and to transform the data from the network data format into a transport data format,a unidirectional data transmission unit, to transmit the data in the transport data format into the second network zone unidirectionallya data import device which transforms the data from the transport data format back into the network data format and to transmit the data to an application server, wherein the data import device and the application server are arranged in a second network zone remote from the first zone, and to a corresponding method.

Claims

1. A method for the processing-time-optimized production of printed circuit boards on a pick-and-place line, wherein the printed circuit boards each have a production cycle time and are divided into groups known as clusters, wherein each cluster is fabricated by a setup, wherein the setup is achieved by shuttle tables that are attachable to the pick-and-place lines, which each comprise at least one feed device for providing stores of components wherein a quantity of shuttle tables necessary per setup is designated as shuttle table set and an empty shuttle table set comprises shuttle tables whose feed devices are empty, under the conditions that a setup is temporarily set up on empty shuttle table sets and dismantled after production of printed circuit boards by the assembly thereof, and that one of the shuttle table sets can only be used in production if it has been completely set up in a preliminary setup area and the shuttle table set can only be set up again when the production performed with the shuttle table set has ended and the shuttle table set has been dismantled again in the preliminary setup area, wherein the method comprises the following steps: a) sensing a quantity of clusters, b) sensing a number of empty shuttle table sets, c) sensing the respective time for creating the setup for a cluster, d) sensing a number of printed circuit boards within a cluster, e) determining the cumulative cycle times of the printed circuit boards within a cluster, wherein the determined result corresponds to the production time for a cluster, f) selecting an order for using the shuttle table sets for setting up in the preliminary setup area with the aim of avoiding waiting times in production in which these shuttle table sets are used for producing printed circuit boards, g) setting an order of the printed circuit boards within a cluster in ascending order according to the cycle times of the individual printed circuit boards, h) optimizing the order of the clusters taking into account the selected order for using the shuttle table sets, i) wherein the average processing time of the printed circuit boards from all the sensed clusters is minimized, j) carrying out the production of the printed circuit boards with the aid of the set and optimized orders of the printed circuit boards and the clusters thereof.

2. The method as claimed in claim 1, wherein in order to minimize the average processing times of the printed circuit boards of the clusters, the sum of the number of printed circuit boards of a cluster multiplied by the starting time of the cluster is minimized over all the clusters.

3. The method as claimed in claim 1, wherein in addition changeover times are sensed and taken into account in the production time, which changeover times occur as a result of changing the shuttle table sets on transition from one setup to another setup.

4. The method as claimed in claim 1, wherein steps h) and i) are carried out with the aid of mixed integer linear optimization.

5. The method as claimed in claim 1, wherein different types of setups are used, wherein a first type corresponds to a fixed setup, which remains unchanged after setting up once and is not dismantled and set up before production and a shuttle table set is provided per fixed setup, wherein a second type corresponds to a variant setup, which is variable as claimed in claim 1 and at least one shuttle table set is provided for the variant setups and wherein the printed circuit boards of each cluster are fabricated with a setup of a predefinable type of the said types.

6. The method as claimed in claim 1, wherein one cluster with a fixed setup split and introduced multiple times into the order of the clusters.

7. The method as claimed in claim 1, wherein in order to minimize the average processing times of the printed circuit boards of the clusters, a cost function is taken into account.

8. The method as claimed in claim 1, wherein the cost function expresses inventory costs of printed circuit boards.

9. A control device, for the processing-time-optimized production of printed circuit boards on an pick-and-place line, wherein the printed circuit boards each have a production cycle time and are divided into groups known as clusters, wherein each cluster is fabricated by setup, wherein the setup is achieved by shuttle tables that are attachable to the pick-and-place lines, which each comprise at least one feed device for providing stores of components, wherein a quantity of shuttle tables necessary per setup is designated as shuttle table set and an empty shuttle table set comprises shuttle tables whose feed devices are empty, under the conditions that a setup is temporarily set up on empty shuttle table sets and is dismantled after production of printed circuit boards by the assembly thereof, and that one of the shuttle table sets can only be used in production if it has been completely set up in a preliminary setup area and the shuttle table set can only be set up again when the production performed with the shuttle table set has ended and the shuttle table set has been dismantled again in the preliminary setup area, wherein the control unit comprises the following sensing devices: a) for sensing a quantity of clusters, b) for sensing a number of empty shuttle table sets, c) for sensing the respective time for creating the setup for a cluster, d) for sensing a number of printed circuit boards within a cluster, and e) means for determining the cumulative cycle times of the printed circuit boards within a cluster, wherein the determined result corresponds to the production time for a cluster, f) means for selecting an order for using the shuttle table sets for setting up in the preliminary setup area with the aim of avoiding waiting times in production in which these shuttle table sets is used for producing printed circuit boards, g) means for setting an order of the printed circuit boards within a cluster in ascending order according to the cycle times of the individual printed circuit boards, and h) means for optimizing the order of the clusters taking into account the selected order for using the shuttle table sets, i) wherein the average processing time of the printed circuit boards from all the sensed clusters is minimized, and j) means for carrying out the production of the printed circuit boards with the aid of the set and optimized orders of the printed circuit boards and the clusters thereof.

10. The control device as claimed in claim 1, wherein in order to minimize the average processing times of the printed circuit boards of the clusters, the sum of the number of printed circuit boards of a cluster multiplied by the starting time of the cluster is minimized over all the clusters.

11. The control device as claimed in claim 1, wherein the control device additionally has means for sensing changeover times, which are taken into account in the production time and which occur as a result of changing the shuttle table sets on transition from one setup to another setup.

12. The control device as claimed in claim 10, wherein the means from steps h) and i) in claim 9 are configured by means for mixed integer linear optimization.

13. The control device as claimed in claim 9, wherein different types of setups is used, wherein a first type corresponds to a fixed setup, which remains unchanged after setting up once and is not dismantled and set up before production and a shuttle table set is provided per fixed setup, wherein a second type corresponds to a variant setup, which is variable as claimed in claim 9 and at least one shuttle table set is provided for the variant setups and wherein the printed circuit boards of each cluster is fabricated with a setup of a predefinable type of the said types.

14. A computer program product, comprising a computer readable hardware storage device having computer readable program code stored therein, said program code executable by a processor of a computer system to implement a method with program code for carrying out the method as claimed in claim 1, when it runs on a control device as claimed in claim 9 or is stored on a computer-readable medium.

Description

BRIEF DESCRIPTION

[0045] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0046] FIG. 1 shows a pick-and-place system for example with a pick-and-place line;

[0047] FIG. 2 shows the processing time of an assembly r of the setup family or cluster v;

[0048] FIG. 3 shows an example that waiting times increase the processing time; and

[0049] FIG. 4 shows an example for improving the processing time with an assumed constant total throughput.

DETAILED DESCRIPTION

[0050] FIG. 1 shows an exemplary pick-and-place system 100. The pick-and-place system 100 comprises a pick-and-place line 110 and a processing or control device 115. Each pick-and-place line 110 comprises an optional transport system 125 as well as one or more automatic pick-and-place machines 130. Each automatic pick-and-place machine 130 comprises one or more pick-and-place heads 135, which are each adapted to receive components 155 from a setup table 140 and position them at a predetermined location on the printed circuit board or assembly 120, which is located on the transport system 125. During the pick-and-place process, the printed circuit board 120 is usually stationary in relation to the automatic pick-and-place machine 130.

[0051] The setup tables 140 each comprise a plurality of feed devices 150, of which only one is shown as an example in FIG. 1. Each feed device 150 holds in readiness a supply of components 155 of a predetermined component type 160. For the components 155, the feed device 150 usually has a capacity, which can be expressed in tracks. A track is usually 8 mm wide and the number of tracks of a setup table 140 is limited, for example, to 40. Components 155 of the same component type 160 are usually held in readiness in a belt, on a tray or in a tube. Each component type 160 requires a predetermined number of tracks on the feed device 150 and on the setup table 140, which tracks usually adjoin one another.

[0052] Usually a feed device 150 can be configured to hold in readiness components 155 of different component types 160 and usually different feed devices 150 can be attached to a setup table 140. In the present case, it is assumed for simplicity that a supply of components 155 of a component type 160 on a feed device 150 is almost infinitely large so that retrofitting is not necessary.

[0053] If a component 155 of a component type 160, which is not present on one of the setup tables 140, is required on the automatic pick-and-place machine 130, usually the assignment of components 155 on one of the attached setup tables 140 is therefore not changed but the setup table 140 is completely exchanged for another suitably equipped setup table 140. The equipping of a setup table 140 not attached to the pick-and-place line 110 with components 155 is known as preliminary setup and can require a processing time in the range of one or several hours, for example, about 6-8 hours.

[0054] Since a change of setup tables 140 on the pick-and-place line 110, a so-called setup change, is usually associated with a production standstill, it is desirable to carry out a change of setup tables 140 as infrequently as possible. Since furthermore the setup tables 140 are costly and the changeover of a setup table 140 can be time-consuming and tedious, attempts are also made to form as few setups as possible in order to fabricate a predetermined production quantity of printed circuit boards 120 of predetermined printed circuit board types 122. The production quantity here comprises several printed circuit board types 122, of which in each case one predetermined number of printed circuit boards 120 should be equipped with components 155 of predetermined component types 160. For example, 300 printed circuit boards 120 of a first printed circuit board type 122 and 200 printed circuit boards 120 of a second printed circuit board type 122 can be equipped.

[0055] A setup 165, 170 comprises a quantity of component types 160 and is achieved by one or more setup tables 140, which in the case of several setup tables, form a shuttle table set and are each provided with supplies of components 155 of the component types 160 of the setup 165, 170 and are attached to the pick-and-place line 110.

[0056] The setup 165, 170 is assigned a setup family 175, which comprises printed circuit board types 122, of which printed circuit boards 120 can be equipped by means of components 155 of the component types 160 of the setup 165, 170. One setup family 175 is assigned to precisely one setup 165, 170 and conversely.

[0057] In order to increase the capacity of a pick-and-place line 110 or reduce a requirement for setup tables 140, it is therefore crucial how setup families 175 are formed on the basis of the printed circuit boards types 122 to be equipped. When forming setups 165, 170 or setup families 175, it may be necessary to observe auxiliary conditions, for example, maintaining a limited capacity of a setup table 140 for component types 160 or a grouping of predetermined printed circuit board types 160 in the same setup family 175, possibly for reasons of using lead-containing or lead-free tin solder.

[0058] The setups can be distinguished into fixed setups 165 and variant setups 170, wherein a fixed setup 165 is provided to remain set up unchanged on a number of shuttle tables 140 over a predetermined planning period while a shuttle table 140 of a variant setup 170 is prospectively changed over within the planning period with components 155 of different component types 160. The planning period can, for example, be 6 to 12 months. A variant setup 165 consists in a predetermined arrangement usually substantially shorter than the planning period, for example, over several hours or days, but usually not over more than one week.

[0059] The setups 165, 170 can be exchanged if required on the pick-and-place line 110. In order to achieve a fixed setup 165 or a variant setup 170, usually a setup table 140, while it is not attached to the pick-and-place line 110, is set up with supplies of components 155 of predetermined component types 160. Components 155 of unrequired component types 160 which have already been set up can be dismantled first. This changeover can comprise a considerable proportion of manual work and can be time-consuming.

[0060] In order to minimize the effort associated with a variant setup 170, attempts are made to accommodate as many printed circuit board types 122 as possible in the fixed setups 165. However, a desired case without variant setups 170 is barely achievable in practice.

[0061] In the course of the control of the pick-and-place system 100, the control device 115 assigns to one setup family 175 in each case, printed circuit board types 122, whose assigned printed circuit boards 120 are to be equipped on the pick-and-place line 100, wherein fixed-setup setup families 175, which are each assigned to a fixed setup 165, and variant-setup setup families 175, which are each assigned to a variant setup 170, can be formed.

[0062] A special case of optimization methods is linear optimization. This is concerned with the optimization of linear target functions over a quantity which is limited by linear equations and inequations. This is the basis of the solution method of (mixed) integer linear optimization. A so-called solver is a collective designation for special mathematical computer programs, which can numerically solve mathematical problems. In connection with MILP (mixed integer linear programing), standard solvers such as, for example, CPLEX, Scip, Gurobi, Xpress can be used for IP programs (integer optimization models).

[0063] An example is described hereinafter, in which by means of an MILP model (mixed integer linear programming), the optimal time setup sequences of predefined setup families to be fabricated can be calculated with a minimal average processing time of a printed circuit board. In addition, an optimal time sequence can be calculated for use of the set-up shuttle table sets (variant setup) and optionally of the fixed-setup shuttle table sets on the pick-and-place line.

[0064] Furthermore, a sequence of assemblies is specified in ascending order according to their cycle times.

[0065] FIG. 2 shows in pictorial form that the processing time Dlz of an assembly r of the setup family v is

beginSetup.sub.v+t.sub.v.sup.r

[0066] In FIG. 3 it is shown schematically how waiting times can have a negative influence on the processing time. For example, four printed circuit boards with a cycle time of one time unit 1 each are shown on the pick-and-place line 110. The average processing time Dlz here is 2.5 without waiting time and 3.5 with waiting time.

[0067] In FIG. 4 it is shown that for different cycle times of the assemblies, the sequence of the assemblies within a setup family has an effect on the average processing time. In one example it is found that Dlz=6. In another example and optimized case, it is found that Dlz=4.

[0068] In the formulation of the optimization model in the form of an MILP model, the following designations apply:

[0069] Target function: [0070] BeginSetup.sub.v Beginning of fabrication of the setup family v [0071] t.sub.v.sup.r Sum of waiting time of the assembly r after beginning of production of the setup family and cycle time of r

[0072] The processing time of an assembly r of the setup family v is (see FIG. 2):

beginSetup.sub.v+t.sub.v.sup.r

[0073] If RecipeCount.sub.v is the number of assemblies in the setup family v, the sum of the processing times of all the assemblies of a setup family v is then:

[00002]${\mathrm{sumDlz}}^v=\underset{rv}{.Math.}.Math..Math.{\mathrm{beginSetup}}_v+t_v^r={\mathrm{RecipeCount}}_v.Math.{\mathrm{beginSetup}}_v+\underset{rv}{.Math.}.Math.t_v^r$

[0074] The last term is a constant for optimization of the production sequence of the setup families. The target function for minimizing the sum of the processing times of the assemblies and therefore also for minimizing the average processing time of the assemblies is as follows:

Minimize .sub.vV RecipeCount.sub.v beginSetup.sub.v

Designations:

[0075] In the MILP formulation the following designations apply.

Indices

[0076] V Quantity of setup families to be fabricated
P P={1, . . . , |V|}, positions for the setup families, in the production sequence
T Quantity of table sets
P.sub.S Quantity of positions classified in ascending order at which table set sT is used.

Parameters

[0077] PTime.sub.v Production time for the setup family v
RTime.sub.v Time for creating the setup of setup family v
EarliestBegin.sub.L Earliest possible beginning of production on the pick-and-place line
EarliestBegin.sub.R Earliest possible beginning of setup in the preliminary setup area
EarliestBegin.sub.S Earliest possible use for table set s
RecipeCounty Number of assemblies in the setup family v

M M:=max{EarliestBegin.sub.L, EarliestBegin.sub.R, EarliestBegin.sub.S: ST}+.sub.vV(RTime.sub.v+PTime.sub.v) [0078] Variables [0079] assign.sub.v,p Variable which specifies whether the setup family v is produced at the p-th position of the fabrication sequence. (In this case, the variable has the value 1, otherwise the value 0). [0080] beginP.sub.p Beginning of fabrication of the setup family at the p-th position of the fabrication sequence [0081] beginSetup.sub.v Beginning of fabrication of the setup family v [0082] beginV.sub.p . . . Beginning of creation of the setup for the setup family at the p-th position of the fabrication sequence in the preliminary setup area [0083] endP.sub.p End of fabrication of the setup family at the p-th position of the fabrication sequence [0084] endV.sub.p End of creation of the setup for the setup family at the p-th position of the fabrication sequence in the preliminary setup area
IP formulation:
Target function: [0085] Minimize vV RecipeCount.sub.v beginSetup.sub.v

Auxiliary Conditions:

[0086] (1) Each setup family must be assigned a position.

[00003]$\underset{pP}{.Math.}.Math.{\mathrm{assign}}_{v,p}=1,vV$

(2) A setup family must be assigned to each position.

[00004]$\underset{vV}{.Math.}.Math.{\mathrm{assign}}_{v,p}=1,pP$

(3) The production of a setup family at position p can only begin when the setup is created in the preliminary setup area.

endV.sub.pbeginP.sub.p pP

(4) The setup process for the setup family at position p can only begin when the setup process for the setup family at position p1 is completed.

endV.sub.p-1beginV.sub.p p=2, . . . , |P|

(5) The setup process for the setup family at position p in the preliminary setup area can only begin when the assigned shuttle table set is free.

endP.sub.pbeginV.sub.p p directly follows pin P.sub.s, sT

(6) Allowance for the production times

[00005]$e.Math.n.Math.d.Math.P_p={\mathrm{beginP}}_p+\underset{vV}{.Math.}.Math.\mathrm{PTim}.Math.e_v.Math..Math.{\mathrm{assign}}_{v,p}.Math..Math.pP$

(7) Allowance for the setup times in the preliminary setup area

[00006]${\mathrm{endV}}_p={\mathrm{beginV}}_p+\underset{vV}{.Math.}.Math.{\mathrm{RTime}}_v.Math..Math.{\mathrm{assign}}_{v,p}.Math..Math.pP$

(8) The production of a setup family at position p can only begin when the production of the setup family at position p1 is completed

endV.sub.p-1beginV.sub.p p=2, . . . , |P|

(9) The production at the pick-and-place line can initially only begin when the pick-and-place line is available for this.

EarliestBegin.sub.LbeginP.sub.1

(10) The setup creation in the preliminary setup area can initially only begin when the pick-and-place line is available for this.

EarliestBegin.sub.VbeginV.sub.1

(11) The setup creation in the preliminary setup area can initially only begin when the pick-and-place line is available for this.

EarliestBegin.sub.sbeginV.sub.p p first element in P.sub.s

(12) The beginning of production of the setup family v is less than or equal to the beginning of production of the setup family at the ascribed position

beginSetup.sub.vbeginP.sub.p.sup.L+M(1assign.sub.v,p) vV,pP

(13) The beginning of production of the setup family v is greater than or equal to the beginning of production of the setup family at the ascribed position

beginSetup.sub.vbeginP.sub.pM(1assign.sub.v,p) vV,pP

(14) Variable restrictions

assign.sub.v,p{0,1} vV,pP

beginP.sub.p.sup.L0 pP

beginV.sub.p0 pP

beginSetup.sub.v0 vV

endP.sub.p0 pP

endV.sub.p0 pP

[0087] Further Developments/Embodiments:

[0088] Guarantee of Throughput Optimality

[0089] If the average processing time of the assemblies is minimized, undesired and avoidable waiting times can therefore possibly occur. These can be avoided by determining in a first optimization firstly the minimum fabrication time T.sub.min of all the setup families and then including the following restriction in the presented method:

endP.sub.|P|T.sub.min

[0090] Order Transfer of the Assemblies after the End of Fabrication

[0091] If after the end of fabrication of the assemblies, the assemblies are not delivered individually to the next processing station or automatic pick-and-place machines but they wait only until an entire order (consisting of one assembly type and the number of items to be fabricated) is complete, therefore the target function must be modified as follows to minimize the average processing time of an order:

minimize .sub.vV RecipeTypeCountT.sub.v beginSetup.sub.v

wherein RecipeTypeCount.sub.v comprises the number of assembly types which are contained in the setup family.

[0092] More General Cost Function

[0093] The target function can also contain a more general cost function Cost.sub.v, by means of which, for example, inventory costs can be depicted more accurately.

minimize .sub.vV Cost.sub.v, beginSetup.sub.v

[0094] Allowance for Fixed Setups

[0095] Fixed setups and the associated setup families can be integrated in the MILP approach. They can be used as a buffer between the variant setup families in order to avoid downtimes on account of times for the creation of setups being too long.

[0096] The following associated extensions are also possible:

[0097] Allowance for Changeover Times

[0098] Changeover times which occur on changing from one setup to the next setup can also be taken into account in the optimization approach.

[0099] Fixed Setup at the End

[0100] For the reason described in (1) it is also favorable to fabricate a fixed setup at the end. To this end, a target function component with a small weighting can be included in the minimization target function.

[0101] Possible Division of a Fixed Setup

[0102] The optimal solution can possibly be further improved if it is assumed that a fixed-setup setup family is not fabricated in one piece but can be divided into several parts, which can then be used as a buffer in each case between variant setup families. Then however, a corresponding changeover time is incurred for each part of the fixed-setup setup family.

[0103] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0104] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.