METHOD AND CONTROL DEVICE FOR DETERMINING AT LEAST ONE FIXED ARMOR FOR A BUILDING LINE

Description

[0001] The invention relates to a method and a control device for determining at least one setup for a component assembly line equipped with a printed circuit board dual transport system, and to an associated computer program product.

[0002] A component placement line is set up to populate a printed circuit board (PCB) with a number of components. Such a line is used, for example, in... Figure 1The following example illustrates this process. In SMT (surface-mount technology), components are mounted and soldered onto printed circuit boards. A placement machine located at the assembly line comprises one or more placement heads, each configured to pick up components and position them at a predetermined location on the circuit board, which is mounted on a transport system. Several head types exist. For example, twin heads (TwinHead) are used according to the "pick and place" principle, which can accommodate a few large components. For example, turret heads are used according to the "collect and place" principle, which can accommodate many small components.

[0003] In manufacturing, the printed circuit board (PCB) types to be produced are divided into setup families ("clusters") for a planning horizon of approximately 1-5 days. A setup family is a set of PCB types that can be produced / manufactured on the assembly line with a predetermined number of components. The quantity of component types required for this is called the setup and is usually contained in a set of swap tables. A swap table is typically set up with the appropriate components during pre-production setup and then stripped down again afterward.

[0004] A placement line can be equipped with a dual PCB transport system. Dual PCB transport can significantly increase throughput. It enables the simultaneous (synchronous) or alternating / asynchronous transport of two printed circuit boards (PCBs) by a placement machine attached to the line. With asynchronous transport, a second PCB of the same type is fed into the placement machine while one is being placed, without any time difference. This completely eliminates the downtime caused by PCB transport. The expected increase in placement performance ranges from 10 to 30 percent, depending on the number of components on the PCB.

[0005] If double-sided printed circuit boards of a particular type are transported on this assembly line, then the first side (top) of the printed circuit board can be populated with components on the first transport lane, and the second side (bottom) of the printed circuit board can be populated with components on the second transport lane.

[0006] Typically, all printed circuit boards (PCBs) in a batch (PCB type with quantity to be produced; batch size is the number of PCBs of a given type to be produced) are first populated with components on one side (e.g., the top side). Then, all PCBs in the batch are populated with components on the other side (e.g., the bottom side). This assembly method is called asynchronous. This is usually done using a component setup on the assembly line.

[0007] If the assembly line has a synchronous dual transport, it is possible to place components on the top side of a batch of printed circuit boards on one transport track and simultaneously on the bottom side of the batch on the other transport track, thereby increasing the total number of components placed at the processing unit. This placement mode is called synchronous.

[0008] Synchronous operation can significantly reduce production times. This is based on the following two effects: (1) On a component placement line, there is a so-called external cycle time (e.g., due to a printer or kiln). In a manufacturing plant, this is typically 16 seconds. If the cycle time of one side of a printed circuit board is less than 16 seconds in asynchronous operation, this results in unproductive "waiting time" on the component placement line. This can be reduced in synchronous mode, thereby also reducing the overall production time. Simplified example: 1000 units.16s external line cycle time, top side 10s cycle time, bottom side 6s cycle time. Production time in asynchronous operation = 1000 * (16s + 16s) = 32,000s cycle time, top and bottom side in synchronous operation: 16s cycle time. Production time in synchronous operation = 1000 * 16s = 16,000s. (2) If the component load on one side is more turret-head-heavy (many small components) and the component load on the other side is more TwinHead-heavy (few large components), then only the placement heads of one head type on the placement line are utilized, while the other heads wait unproductively. In synchronous mode, this results in a more even and higher utilization of all placement heads on the placement line and thus a lower overall production time.

[0009] US 2010 / 0325860 A1 discloses a method comprising: capturing assembly information, including information on the component assembly operations to be performed by a pick-and-place machine; assessing, based on the assembly information obtained during capture, which production mode – synchronous or asynchronous – is suitable for the planned component assembly operations; or which production mode – alternating or independent – ​​is suitable for the planned component assembly operations; and selecting the production mode determined by the result of the assessment as the production mode to be performed by the pick-and-place machine.

[0010] When forming the aforementioned setup families for synchronous assembly lines, it is best to choose printed circuit board types that maximize the production time savings compared to operating the printed circuit board assembly in asynchronous mode.

[0011] The object of the invention is to provide a method and a control device that are improved compared to the prior art mentioned at the outset.

[0012] This task is solved by independent claims. Advantageous further training is the subject of dependent claims.

[0013] The invention claims a method for determining at least one fixed setup for a component placement line equipped with a dual-transport printed circuit board system, the first transport track of which transports double-sided printed circuit boards of a printed circuit board type, the first side of which is populated, and the second transport track of which transports double-sided printed circuit boards of the printed circuit board type (especially of the same printed circuit board type), the second side of which is populated, wherein each fixed setup comprises a number of component types sufficient for populating the printed circuit boards of a fixed setup family of printed circuit board types assigned to this fixed setup, wherein the at least one fixed setup remains unchanged during the planning horizon and can be used multiple times on the component placement line, wherein the method comprises the following steps: Recording a set of printed circuit board types, each with assigned double-sided PCBs to be assembled on the assembly line within the planning horizon; recording a set of component types with their space requirements in tracks in at least one component feeding device; recording the production time for simultaneous, synchronous assembly of the first and second sides of each assigned double-sided PCB on the first and second transport tracks; recording the production time for staggered, asynchronous assembly of the first and second sides of each assigned double-sided PCB on the first and second transport tracks;Identifying a number of fixed setup families, wherein each fixed setup family comprises a set of printed circuit board (PCB) types whose PCBs can be populated with the components of the component types of the fixed setup on the assembly line; assigning PCB types to each fixed setup family, wherein all components for populating a PCB of a PCB type of the assigned PCB types have space available in the tracks in the fixed setup with respect to their space requirements and are installed in the fixed setup; and optimizing the assignment such that the production time savings, which are determined from the identified production times of synchronous and asynchronous placement across all assigned double-sided PCBs, are maximized.

[0014] Due to the need to set up changeover tables and the additional equipment required, a placement line can only be operated efficiently in synchronous mode in practice if there is only fixed setup (preferably only one) and no variable setups need to be set up.

[0015] A fixed-gear setup family comprises a set of printed circuit board types whose circuit boards can be populated with the components of the fixed-gear component types on the assembly line.

[0016] A further development of the invention provides that, for each fixed-assembly assembly family, the printed circuit boards of the assigned printed circuit board types have the same printed circuit board width so that the printed circuit boards fit into the transport track with respect to the transport track width.

[0017] Therefore, only printed circuit boards of a single width should be used to avoid width variations on the assembly line. Furthermore, it is particularly advantageous to produce a high quantity of these printed circuit boards.

[0018] The sum of the production times of the printed circuit board types of a fixed-gear setup family should fall below a predefinable upper limit and / or exceed a predefinable lower limit.

[0019] Optimization is preferably performed using mixed integer programming.

[0020] Ultimately, the printed circuit boards can be populated on the assembly line using at least one fixed setup. Preferably, printed circuit boards should be populated on the assembly line using only one fixed setup.

[0021] The economic benefits, as well as savings in equipment and production time, are very high.

[0022] Another aspect of the invention provides for a control device. The control device, orThe control device is designed to determine at least one fixed setup for a placement line equipped with a dual-transport printed circuit board system, the first transport track of which transports double-sided printed circuit boards of one type, the first side of which can be populated, and the second transport track of which can transport double-sided printed circuit boards of the (same) type, the second side of which can be populated, wherein each fixed setup comprises a number of component types sufficient for populating the printed circuit boards of a fixed setup family of printed circuit board types assigned to that fixed setup, wherein the at least one fixed setup remains unchanged during the planning horizon and can be used multiple times on the placement line, wherein the control device is designed to perform the following steps: . Recording a set of printed circuit board types, each with assigned double-sided PCBs to be assembled on the assembly line within the planning horizon; recording a set of component types with their space requirements in tracks in at least one component feeding device; recording the production time for simultaneous, synchronous assembly of the first and second sides of each assigned double-sided PCB on the first and second transport tracks; recording the production time for staggered, asynchronous assembly of the first and second sides of each assigned double-sided PCB on the first and second transport tracks;Identifying a number of fixed setup families, wherein each fixed setup family comprises a set of printed circuit board (PCB) types whose PCBs can be populated with the components of the component types of the fixed setup on the assembly line; assigning PCB types to each fixed setup family, wherein all components for populating a PCB of a PCB type of the assigned PCB types have space available in the tracks in the fixed setup with respect to their space requirements and are installed in the fixed setup; and optimizing the assignment such that the production time savings, which are determined from the identified production times of synchronous and asynchronous placement across all assigned double-sided PCBs, are maximized.

[0023] The units or facilities that are set up to carry out such procedural steps can be implemented in hardware, firmware and / or software.

[0024] Another aspect of the invention is a computer program (product) with program code means for carrying out the method according to one of the preceding method claims, if it runs on a control device of the type mentioned above or is stored on a computer-readable storage medium.

[0025] The computer program or product can be stored on a computer-readable storage medium. The computer program or product can be written in a common programming language (e.g., C++, Java). The processing equipment can comprise a standard computer or server with appropriate input, output, and storage capabilities. This processing equipment can be integrated into the control unit or its components.

[0026] The control device and the computer program (product) can be further developed or trained analogously to the above-mentioned procedure and its further developments.

[0027] Further advantages, details and developments of the invention will become apparent from the following description of exemplary embodiments in conjunction with the drawings.

[0028] The figure shows a machining system for processing workpieces.

[0029] Figure 1Figure 1 shows a placement system 100. The placement system 100 comprises one or more placement lines 110 and a control unit 115. Each placement line 110 comprises a transport system 125 and one or more placement machines 130. Each placement machine 130 comprises one or more placement heads 135, each configured to pick up components 155 from a shuttle table 140 and position them at a predetermined position on the printed circuit board 120 located on the transport system 125. The transport system is preferably configured as a dual-carrying printed circuit board transport system, the first transport track 201 of which transports double-sided printed circuit boards 120 of a printed circuit board type 122, the first side of which is populated, and the second transport track 202 of which transports double-sided printed circuit boards 120 of a printed circuit board type 122, the second side of which is populated.

[0030] During the placement process, the printed circuit board 120 is usually stationary relative to the placement machine 130. The changeover tables 140 each comprise a plurality of feeding devices 150, of which in Figure 1 Only one example is shown. Each component feeder 150 holds a supply of components 155 of a predetermined component type 160. The component feeder 150 has a capacity for the components 155, which is usually expressed in tracks. A track is usually 8 mm wide, and the number of tracks in each component feeder 150 is limited, for example, to 40. Components 155 of the same component type 160 are usually provided in a tape, on a tray, or in a tube. Each component type 160 requires a predetermined number of tracks on the component feeder 150, which must usually be adjacent to each other.

[0031] Each component feeder 150 can be configured to hold different components 155, and different component feeders 150 can typically be mounted on a shuttle table 140. If a component 155 of a component type 160 is required on the pick-and-place machine 130, and this component is not present on one of the shuttle tables 140, then, as a rule, one of the mounted shuttle tables 140 is not equipped with the required components 155, but rather the entire shuttle table 140 is replaced with another one that is already equipped accordingly. Upgrading a shuttle table 140 being replaced with components 155 is called pre-loading and can require several hours of processing time.

[0032] Since changing the tables 140 on the assembly line 110 usually involves a production stoppage, the aim is to perform changes of the tables 140 as infrequently as possible.

[0033] To populate a predetermined quantity of printed circuit boards 120, setups can be formed, each comprising stocks of components 155 of predetermined component types 160, whereby each of the printed circuit boards 120 in the quantity can be fully populated with components 155 from the setup. A setup can be implemented by a number of changeover tables 140. In the representation of Figure 1 A fixed setup 165, whose transfer tables 140 are attached to the assembly line 110, and a variant setup 170, whose transfer tables 140 are separate from the production line 110, are formed. One or more fixed setups can be provided. A preferred scenario is to operate without variant setups 170, particularly when a dual printed circuit board transport system is used in synchronous operation.

[0034] The fixed setup 165 is designed to remain unchanged with regard to its component types 160, at least during a planning horizon, which may be, for example, six months or one year. Thus, while components 155 can be replenished at the changeover tables 140 of the fixed setup 165 as needed, the assignment of component types 160 to the tracks of the changeover tables 140 remains unchanged. If several fixed setups 165 are planned, these can be exchanged for each other or for one of the variant setups 170 within the planning horizon.

[0035] A variant setup 170, on the other hand, is designed to accommodate components 155 of different component types 160 during the planning horizon, but is only temporary. For this purpose, the changeover tables 170 are typically, while not attached to the assembly line 110, stripped of components 155 of predetermined component types 160 and restocked with components 155 of other component types 160. This changeover can involve a significant amount of manual work and be time-consuming.

[0036] The control unit 115 assigns printed circuit board types 122, whose associated printed circuit boards 120 are to be assembled on the assembly line 110, to a setup family. A setup family is a set of printed circuit board types 122, whose printed circuit boards 120 can be fully populated with components 155 provided in the assigned setup 165, 170. A setup family is typically assigned to exactly one setup 165, 170 and vice versa.

[0037] Figures 2 and each shows a section of a printed circuit board dual transport system with two transport tracks 201 and 202, which is carried out by a pick-and-place machine 130. In Figure 2 The asynchronous operation described at the beginning will be demonstrated. Figure 3 The synchronous operation explained at the beginning will be shown.

[0038] The following optimization method can be used to assign printed circuit board types to one or more fixed-setup families, whereby all components for mounting a printed circuit board of a printed circuit board type of the assigned printed circuit board types have space in the tracks available in the fixed-setup with regard to their space consumption and are mounted in the fixed-setup.

[0039] Linear optimization is a special case of optimization methods. It deals with the optimization of linear objective functions over a set constrained by linear equations and inequalities. It forms the basis of the solution methods for (mixed-)integer linear optimization. A solver is a collective term for specialized mathematical computer programs that can solve mathematical problems numerically. In the context of MILP (mixed-integer linear programming), standard solvers such as CPLEX, Scip, Gurobi, and Xpress can be used for IP programs (integer optimization models).

[0040] Typically, an initial configuration is specified, which is then iteratively optimized to achieve a target result. In this example, the goal is to maximize the production time savings, which is determined from the recorded production times of synchronous and asynchronous assembly across all assigned double-sided printed circuit boards.

[0041] The following proposes a MILP model for determining fixed setup families for a given assembly line operating in synchronous mode. The approach is based on mixed-integer linear optimization.

[0042] The setup families for synchronous operation of the line are configured to maximize production time savings compared to manufacturing the assemblies in asynchronous mode. Various restrictions must be observed in this process: Adherence to a minimum production time ensures that the line is not underutilized. Adherence to a maximum production time ensures that the line is not overloaded. No different PCB widths may be present within a single setup family. The component setup of a setup family must be capable of being set up on the line.

[0043] The following terms apply in the MILP formulation. Indices

[0044] C Quantity of component types R Number of assemblies (synchronous boards with top and bottom sides) RC Quantity of assemblies with component type c Cl Number of fixed installations / fixed installation families Cl parameter

[0045] Width c Space requirement of a component type c in traces LineCap Number of tracks of component types that can fit in the armor of an armor family UpperTimeLimit Upper production time limit of all items assigned to the assembly line Assemblies LowerTimeLimit Lower production time limit of all assemblies assigned to the assembly line TimeSync r Total production time of the assembly r , if it is manufactured in synchronous mode TimeASync r Total production time of the top and bottom surfaces of the assembly r , if these are manufactured in asynchronous mode BoardWidth r PCB width of the assembly r Binary variables

[0046] assign r,cl Variable indicating whether a component r is assigned to the setup family cl. (In this case, it takes the value 1; otherwise, the value 0.) setup c, cl Variable indicating whether the component type c must be equipped in the armor of the armor family cl. (In this case, it takes the value 1; otherwise, the value 0.) Objective function:

[0047] Maximiere ∑ cl ∈ Cl ∑ r ∈ R assign r , cl TimeAsync r − TimeSync r Conditions:

[0048] (1) Each assembly type may be assigned to no more than one setup family. ∑ cl ∈ Cl assign r , cl ≤ 1 r ∈ R (2) The component types of the assemblies of an armor family must fit into an armor. ∑ c ∈ C Width c setup c , cl ≤ LineCap cl ∈ Cl (3) All component types of an armor family must be equipped in the armor of the armor family. ∑ r ∈ R c assign r , cl ≤ R c setup c , cl c ∈ C , cl ∈ Cl (4)The sum of the production times of the assembly types of a setup family must not exceed the upper production time limit. ∑ cl ∈ Cl ∑ r ∈ R assign r , cl Time r ≤ UpperTimeLimit (5) The sum of the production times of the assembly types of a setup family must not fall below the lower production time limit. ∑ cl ∈ Cl ∑ r ∈ R assign r , cl Time r ≥ LowerTimeLimit (6) All assemblies assigned to a kit family must have the same printed circuit board width assign r , cl + assign r ′ , cl ≤ 1 cl ∈ Cl , r , r ′ ∈ R , BoardWidth r ≠ BoardWidth r ′ (7) Variable restrictions assign r , cl ∈ 0 1 r ∈ R , cl ∈ Cl setup c , cl ∈ 0 1 c ∈ C , cl ∈ Cl

[0049] In the example, two out of 15 assembly lines could be saved in a printed circuit board production plant due to the production time reductions achieved with the inventive method.

[0050] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without leaving the scope of protection of the invention.

[0051] The implementation of the processes or procedures described above can be carried out using instructions stored on computer-readable storage media or in volatile computer memory (hereinafter collectively referred to as computer-readable memory). Examples of computer-readable memory include volatile memory such as caches, buffers, or RAM, as well as non-volatile memory such as removable media, hard drives, etc.

[0052] The functions or steps described above can be represented in the form of at least one instruction set in / on computer-readable memory. These functions or steps are not bound to a specific instruction set, a specific form of instruction sets, a specific storage medium, a specific processor, or specific execution schemes, and can be executed by software, firmware, microcode, hardware, processors, integrated circuits, etc., either independently or in any combination. Various processing strategies can be employed, such as serial processing by a single processor, multiprocessing, multitasking, or parallel processing, etc.

[0053] The instructions can be stored in local memory, but it is also possible to store the instructions on a remote system and access them via a network.

[0054] In the context of the invention, "computer-aided" can, for example, be understood to mean an implementation of the method in which, in particular, a processor, which may be part of the control device or unit, performs at least one process step of the method.

[0055] The terms "processor," "central signal processing," "control unit," or "data processing device," as used herein, encompass processing devices in the broadest sense, including, for example, servers, general-purpose processors, graphics processors, digital signal processors, application-specific integrated circuits (ASICs), programmable logic circuits such as FPGAs, discrete analog or digital circuits, and any combination thereof, including all other processing devices known to those skilled in the art or which may be developed in the future. Processors may consist of one or more devices, units, or components. If a processor consists of several devices, these may be designed or configured for parallel or sequential processing or execution of instructions. In the context of the invention, a "memory unit" may, for example, refer to a memory in the form of main memory (RAM).Random-Access Memory (RAM) or a hard drive.

Claims

1. Method for determining at least one fixed setup (165) for an assembly line (110) which is configured with a printed circuit board double transport system (125) of which the first transport track (201) transports double-sided printed circuit boards (120) of a printed circuit board type (122) of which the first side is populated, and of which the second transport track (202) transports double-sided printed circuit boards of the printed circuit board type of which the second side is populated, wherein each fixed setup comprises a number of component types (160) that is sufficient to populate the printed circuit boards of a fixed-setup setup family, which is associated with this fixed setup, of printed circuit board types, wherein the at least one fixed setup remains unchanged during a planning horizon and can be used several times on the assembly line, wherein the method comprises the following steps: - detecting a set of printed circuit board types each with allocated double-sided printed circuit boards which are intended to be populated on the assembly line within the planning horizon; - detecting a set of component types together with their space requirement in tracks in at least one component feed device (150) ; - detecting a production time for simultaneous, referred to as synchronous, population of the first and second side of each allocated double-sided printed circuit board on the first and second transport track; - detecting a production time for staggered, referred to as asynchronous, population of the first and second side of each allocated double-sided printed circuit board on the first and second transport track; - detecting a number of fixed-setup setup families, wherein each fixed-setup setup family comprises a set of printed circuit board types of which the printed circuit boards can be populated with the components of the component types of the fixed setup on the assembly line; - assigning printed circuit board types to each fixed-setup setup family, wherein all the components for populating a printed circuit board of a printed circuit board type of the assigned printed circuit board types have the space they require in the tracks available in the fixed setup and are set up in the fixed setup; and - optimizing the assignment process in such a way that a production time saving, which is identified from the detected production times of the synchronous and asynchronous population over all the allocated double-sided printed circuit boards, is maximized.

2. Method according to the preceding claim, characterized in that, for each fixed-setup setup family, the printed circuit boards of the assigned printed circuit board types have the same printed circuit board width, so that the printed circuit boards fit into the transport track with respect to the transport track width.

3. Method according to either of the preceding claims, characterized in that printed circuit boards with only one fixed setup are populated on the assembly line.

4. Method according to one of the preceding claims, characterized in that a sum of production times of the printed circuit board types of a fixed-setup setup family falls below a pre-specifiable upper limit.

5. Method according to one of the preceding claims, characterized in that the sum of production times for the printed circuit board types of a fixed-setup setup family exceeds a pre-specifiable lower limit.

6. Method according to one of the preceding claims, characterized in that optimization is carried out by means of mixed integer programming.

7. Control device (115) for determining at least one fixed setup (165) for an assembly line (110) which is configured with a printed circuit board double transport system (125) of which the first transport track (201) is configured so as to transport double-sided printed circuit boards (120) of a printed circuit board type (122) of which the first side can be populated, and of which the second transport track (202) is configured so as to transport double-sided printed circuit boards of the printed circuit board type of which the second side can be populated, wherein each fixed setup comprises a number of component types (160) that is sufficient to populate the printed circuit boards of a fixed-setup setup family, which is associated with this fixed setup, of printed circuit board types, wherein the at least one fixed setup remains unchanged during a planning horizon and can be used several times on the assembly line, wherein the control device is designed to execute the following steps: - detecting a set of printed circuit board types each with allocated double-sided printed circuit boards which are intended to be populated on the assembly line within the planning horizon; - detecting a set of component types together with their space requirement in tracks in at least one component feed device (150) ; - detecting a production time for simultaneous, referred to as synchronous, population of the first and second side of each allocated double-sided printed circuit board on the first and second transport track; - detecting a production time for staggered, referred to as asynchronous, population of the first and second side of each allocated double-sided printed circuit board on the first and second transport track; - detecting a number of fixed-setup setup families, wherein each fixed-setup setup family comprises a set of printed circuit board types of which the printed circuit boards can be populated with the components of the component types of the fixed setup on the assembly line; - assigning printed circuit board types to each fixed-setup setup family, wherein all the components for populating a printed circuit board of a printed circuit board type of the assigned printed circuit board types have the space they require in the tracks available in the fixed setup and are set up in the fixed setup; and - optimizing the assignment process in such a way that a production time saving, which is identified from the detected production times of the synchronous and asynchronous population over all the allocated double-sided printed circuit boards, is maximized.

8. Control device according to the preceding claim, characterized in that, for each fixed-setup setup family, the printed circuit boards of the assigned printed circuit board types have the same printed circuit board width, so that the printed circuit boards fit into the transport track with respect to the transport track width.

9. Computer program product with program code means for carrying out the method according to one of the preceding method claims when it is executed by a processor, in particular of the control device according to the preceding claim.