Advanced Materials Research Vol. 188 (2011) pp 104-109 Online available since 2011/Mar/29 at www.scientific.net © (2011) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.188.104
Module Partition and Application for Printed Circuit Board High Speed Drilling Machine H.Q. Tang1, 2, a, C.Y. Wang1, b *, B. Wang3, c, F. Su2, d, P. Ma 1, e and Y.X. Song1,f 1
2
Guangdong University of Technology, Guangzhou, P.R.China Key Laboratory of New Processing Technology for Nonferrous Metals and Materials, Ministry of Education, Guangxi University, Nanning, P.R.China 3
Nanjing Research Institute for Agriculture Mechanization, Nanjing, P.R.China a
[email protected],
[email protected],
[email protected],
b
c
d
[email protected], e
[email protected], f
[email protected]
Keywords: PCB high speed drilling machine, module partition, performance testing
Abstract. The target of this paper is to design a high speed drilling machine suitable for printed circuit board with micro-hole of 0.1 mm diameter, which has drilling force measuring function and rapid change spindle function. Therefore, in this paper, the main principles of module partition for drilling machine were analyzed. Module partition was conducted for high speed drilling machine of Printed Circuit Board (PCB), as well as using modular components combine PCB high speed drilling machine. Then, performance testing and simulation of dynamic modeling were carried out on the modular PCB high speed drilling machine. The results show that the modular PCB high speed drilling machine has good performance, enough stiffness, better stability and meeting the design requirements. The modular partition laid the foundation for further study on the module creation and reconfiguration of PCB drilling machine. Introduction The traditional process of mechanical design is from bottom to up, which depends on functional requirements for the product design, and then constitute a whole. There are also some requirements of overall design and coordination in this process, but mainly focuses on functional design and detailed design. On the contrary, modular design focuses on preliminary design rather than detailed design. That is, the functional analysis is the basis of product design, the total functional of product decomposition into several levels higher integrated units, and then according to different requirements, these integrated units are organized into several underlying cell of lower, interchangeable and independent. At present, module Partition methods have been studied by domestic and foreign scholars [1-5], but the high speed drilling machine for printed circuit board was studied little. From seeing the product structure in the world, PCB has become one of the biggest pillar industries in electronic components industry and support development of information-based society through assembling a complete electronic product. With the modular idea to construct machine tool products, not only improving the speed of product development, but also quickly responding to market demand. Therefore, modular design for PCB high speed drilling machine will be the future development of the PCB drilling machine design. The target of this paper is to design a high speed drilling machine suitable for printed circuit board with micro-hole of 0.1 mm diameter, which has drilling force measuring function and rapid change spindle function. Therefore, this paper mainly analyses the main principles of module partition for drilling machine and put into effect in PCB high speed drilling machine, as well as using modular components combine PCB high speed drilling machine. At last, performance testing and simulation of dynamic modeling were carried out on the modular PCB high speed drilling machine.
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Module partition on PCB high speed drilling machine Module is a basic unit of modular design and manufacturing. Module partition is the premise and foundation of modular design. Its result directly affects the function, performance as well as cost of modular design system. In order to be suitable for modular design of more product, its partition and design not only needs to guarantee the product design, manufacture and service, but also needs to obtain the most superior module structure quickly according to the variable design parameters. The level and scale of the function decomposes are the most important part for module partition. The general process of designing machine is from functional analysis to creating module, which is available between design duty decomposition and module decomposition. The main principles of module partition are as following: (1) Foundation principle. The material of basic parts of PCB high speed drilling machine such as machine tool bed and workbench is granite. It will take long time for making the basic parts and manufacturing, which will affect the rapid development of product. So, the module of basic parts must have the possibility of changing while ensuring product specification and performance. (2) Independence principle. The module, having relative independent function, is a part of product. The independent module can circulate in the market by itself. (3) Expandability principle. The module unit should consider the possibility for new technology application in the future. In order to realize other function or performance through adding some modules, a certain space should be left in the transmission module. According to the above principles and researching on drilling machine manufacturer of home and abroad, collection of function module can be constructed to satisfy general PCB high speed drilling machine, as shown in Table 1. Table 1 Module of PCB high speed drilling machine Modules Supporting Workbench Spindle box Transmission Tool storage Protective Auxiliary
Components and Parts Bed, Column, Guide rail Workbench Spindle Guide screw , Servo motor Robot manipulator, Tool storage Guide screw protective cover , Complete machine protective cover Press foot, Pneumatic and hydraulic components, Chip removal device, Cooling device, Electrical control equipment, Detection equipment
Selection and combination of modules for PCB high speed drilling The selection of PCB high speed drilling machine module is not only selecting the common module, but also modifying the base module and designing special module. Sometimes for adapting customer's demand, some personalized function and parameters should be added. And then, common module can be regarded as the base module and can be changed. Special module would be designed only for such unchanged module or uneconomical special function module.
(a)
(b)
Fig.1 Bed structure
(c)
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Supporting module. (1) Bed. Through investigating on the PCB drilling bed, there have three types as shown in Fig.1. According to the function demand and the technical parameters of this design drilling machine, the structure in Fig.1 (c) is the best. The size of drilling bed depends on (a) (b) the size of beam, workbench and column. (2) Fig.2 Column structure Column. The size of column depends on the length of X and Y workbench and operating stroke of Z-axis. There are two types of column structure, as shown in Fig.2. The goal of designing machine in this paper is for studying on measuring force and temperature etc. Adding stroke of Z-axis to ensure dynamometer can be installed on the X-workbench. So the column structure as Fig.2 (b) was adopted in this paper design. (3) Guide rail. Guide rail is used to support and pilot the movement of some parts. It withstands the quality and cutting force of supported movement part and the work piece (or cutting tool).There is two types of guide rail, rolling guide and sliding guide. Rolling guide has accurate location, smooth movement and little wearing etc. Now, the main corporations of rolling guide are Japan's THK, NSK, IKO Corporation, Sweden's SKF Corporation, Germany's INA Corporation and US's Thomsen Company. In order to obtain higher pointing accuracy, higher repetition pointing accuracy and smaller feeding in this designing machine, Japan's IKO rolling guide is suitable. Workbench module. Workbench should be considered from two aspects: (1) workbench should keep balance of forces to guarantee unchangeable for long-term; (2) The material of workbench should have high stiffness and not easy for changing. In this design, the material of PCB high speed drilling machine is granite and the designing size of workbench should have enough space for installing all kinds of measuring device. Spindle box module. In order to satisfy the demands of drilling small hole with the diameter of 0.1 mm and accuracy requirement for high speed drilling, UK westwind D1733-12 type spindle with 250 K RPM was used in this design. The performance of this type spindle can meet the experimental requirements. Transmission module. (1) Guide screw. Guide screw is the most common transmission part. The main function is transforming the rotary motion into the linear motion, or transforming the torque into the repeatedly axial action. Guide screw consists of screw, nut, recycle system, and so on. Japan NSK ball bearing lead screw is used in this design because it has high smoothness, precise localization, low torque, high rigidity and ultra static sound etc. (2) Servo motor. Servo motor provides power for equipment. It can receive the feed command signal of sending out by numerical control system and transform it into the angular displacement or the straight line displacement, then driving execution unit to realize movement requests. High dynamic AC servo motors are used in X-axis, Y-axis and Z-axis. The common servo electrical machinery in the market is Japan's YASKAWA, Panasonic, SANYO, Europe's and America's Baldor and Kollmorgen, and so on. Japanese products have higher cost performance. Sanyo ac servo motor is used in this design.
(a)
(b)
(c)
Fig.3 Layout of robot manipulator and Tool storage Tool storage module. Many holes of different size decide the massive drill bits are needed in the processing of PCB. Therefore, robot manipulator and tool storage must be settled in general PCB high speed machine. Robot manipulator always adopted pneumatic type. This will shorten the assistant time of tool changing and enhance the drilling machine efficiency.
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There are three main types of layout for robot manipulator and tool storage, as shown in Fig. 3. The first is manipulator installs in front of Y-axis workbench and the tool storage installs nearby the spindle, as shown in Fig. 3(a). Disadvantage of this type can not guarantee the precise installation for tools. The second is the tool storage installs in the front of Y-axis workbench, as shown in Fig. 3(b). And cutting tool is grasped by spindle directly instead of manipulator. Disadvantage of this type is that the quantity of drill bits is fewer. The third is manipulator installs nearby the spindle, and the tool storage installs in front of Y-axis workbench, as shown in Fig. 3(c). This type can guarantee the precise installation for tools and have more drill bits to put in the tool storage, but need to install shrink-ring. In order to enhance the precise installation for tools, avoiding hitting and increasing the quantity of cutting tool, the third type in Fig.3(c) is used in this design. Protective module. Protective cover is made of iron, additional color protective paint. The color of drill machine is gray-white. Auxiliary module. (1) Press foot. Convertible press foot is adopted in this design which can ensure Machining accuracy for all kinds of small holes and prevent micro-drill broken. (2) Pneumatic and hydraulic components. Pneumatic drive system is an important component for PCB drilling machine. This pneumatic system mainly includes air station and two big return routes, i.e., tool change loop and air flotation spindle loop. (3) Chip removal device. The automatic dust exhaust apparatus are generally used in the processing of PCB drilling. The inflow system of exhaust apparatus was connected by a pipe joint on the pressure foot. (4) Cooling device. The temperature, rate of flow and press of cooling water are controlled strictly for high speed air float electrical spindle. The main functions of cooling device are providing cooling water to decrease the heat produced by spindle working. (5) Electrical control equipment. The high revolving speed of high speed air float electrical spindle can be realized through frequency converter. SIEB&MEYER frequency converters of series FC80 is the most widely used in PCB drilling machine industry and is used in this design. (6) Detection equipment. Tool monitor equipment comprises the detection of tool diameter, tool length, broken tool and drilling depth. The equipment adopts contacted broken tool detection and RENISHAW laser tool inspection device. Special function module. (1) Drilling force measuring function. In order to measure drilling force, we should enlarge the space in Z-axis direction, increasing the length of column and lengthening Z-axis guide screw. The installation and configuration of Z-axis must be carefully. (2) Rapid change spindle function. The spindle is clamped in two ways, as shown in Fig.4. One is integral type, the other is split type. The disadvantages of first type remove inconveniently, easily wear or rust and not (a) integral type (b) split type easily replacing. So the second type is adopted in this Fig.4 Spindle Clamp Method design. Modular high-speed drilling performance testing Spindle performance testing. After setting spindle parameters through control software of frequency converters, we should test spindle performance including spindle motor voltage, motor electric current, motor rotational speed, and so on. The detection curves are observed when the spindle rotates separately by 30K rpm, 60K rpm, 90K rpm, 120K rpm, 150K rpm, 180K rpm, 210K rpm and 250K rpm. Some results are shown in Fig.5. The results (red lines in figures) show that each testing value maintains stability. Therefore, the spindle has better performance. Spindle partial pendulum performance testing. The non-contact acceleration sensor was adjacent to the spindle clamp and close to the Z axis terminal. The vibration signals produced by micro-drill rotating were received when the driving spindle rotated with different speed (i.e., 30K rpm, 50K rpm, 80K rpm, 110K rpm,140K rpm,170K rpm,200K rpm,230K rpm and 250K rpm).Vibration signals are shown in Fig.6. The testing results indicate that under the definite clamp
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condition and along with rotational speed enhancing, spindle has very low vibration. The vibration magnitude maintains about 2.5 microns, which explain that spindle has fine partial pendulum performance.
（a）30K rpm
（b）180K rpm
（c）250K rpm
Fig.5 Spindle performance testing
Fig.6 Relationship between speed and vibration magnitude Drilling position accuracy. The drilling machine position accuracy refers to the position accuracy of each moving parts including positioning accuracy and repeated positioning accuracy. Positioning accuracy is detected by inspection equipments. Detecting instrument always adopts RENISHAW laser interferometer. The results indicate that the position accuracy of X-axis and Y-axis are ±0.005 mm, and the repeated positioning accuracy is ±0.0025 mm. Drilling Hole position accuracy. The hole position accuracy is the pointing accuracy for Z-axis, which is expressed with the inner ring width of drilling hole. The hole position accuracy with different diameter drill was tested under certain drilling conditions. The final results indicated that the hole position accuracy is ±0.0254mm when using the diameter 1.6 mm drill bit to drill single-layer PCB. Modular drilling machine dynamical performance simulation. The steps of dynamical simulation for modular drilling machine are as following: (1) Building parts of 3D model in Pro/E software and assembling these parts. (2) Importing 3D model to ADAMS software and defining constrained relationship between various parts. (3) Importing drill bit model to ANSYS software, meshing model in pre-processing of ANSYS and creating the file of mnf format which can be identified by ADAMS software. (4) Importing beam, workbench, and column parts to ADAMS / Flex to mesh directly and creating the file with .mnf format. (5) Importing .mnf file separately to replace corresponding parts, and then exerting constraints. (6) Simulating in ADAMS／Vibration. The simulation model and simulation analysis chart are shown in Fig.7 and Fig.8. Using Pro/E to build parts of 3D model
Using Pro/E to assemble and importing to ADAMS
Using ANSYS Geom command to create .anf file for flexible part Importing the .mnf file to ADAMS to replace the rigid part
Using ANSYS to mesh the .anf file for creating .mnf file Dynamical simulation by using ADAMS/Vibration
Fig.7 The Flow Chart of ADAMS Simulation Forced vibration analysis is established and executed in ADAMS/Vibration. The processes of ADAMS／Vibration analysis are as following: (1) Taking the drill bit (i.e., z direction) as the incentives and establishing one input channel. (2) Taking the displacement of reference point (tool
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nose of drill bit) as response and establishing three output channels(X direction, Y direction and Z direction). (3) Because the response of Z direction is the biggest, we mainly discuss the response of Z direction when the frequency ranges 1～1000Hz. The result of Z-direction response is shown in Fig.9.
Fig.8 ADAMS Simulation Model Fig.9 Response curve of frequency and magnitude From Fig.9, we can see that the response curve has peak values in the low frequency area below 100 Hz and other frequencies are smooth. These peak values explain that the energy of this range is especially centralized, which created mainly by modality natural frequency. In a word, the modular machine has enough stiffness, better stability and can meet design requirements. Summary and Conclusion 1. The main principles of module partition for drilling machine are foundation principle, independence principle and expandability principle. 2. According to these main principles, PCB high speed drilling machine could be divided into six main modules (i.e., supporting module, workbench module, spindle box module, transmission module, tool storage module, protective module and auxiliary module). 3. One PCB high speed drilling machine could be combined with modular components. The test results show that the modular PCB high speed drilling machine has better spindle performance (i.e., fine spindle partial pendulum performance, enough stiffness and better stability). The position accuracy of X-axis and Y-axis is ±0.005mm, the repeated positioning accuracy is ±0.0025mm and the hole position accuracy is ±0.0254 mm when using the diameter 1.6 mm drill bit to drill single-layer PCB. 4. To further study the PCB drilling machine, the modular PCB high speed drilling machine laid the foundation for modular machine creating and reconfigurable machine building. Acknowledgement This project supported by the Key Program of NSFC-Guangdong Joint Fund, China (Grant No. U0734007) and Foundation of Key laboratory for New Processing Technology for Nonferrous Metals and Materials, Ministry of Education, Guangxi University, China (No. GXKFJ-11) and Guangxi University Natural Fund, China (No. X081030) References [1] Reuven Katz: The International Journal of Advanced Manufacturing Technology, 34(5-6), 2007, pp. 430-439 [2] Y.Q. Fei and X.F. Zhao : Journal of Intelligent & Robotic Systems, 43(2-4), 2005, pp. 147-159 [3] Z.M. Bi, Sherman Y.T. Lang, M.Verner et al. : The International Journal of Advanced Manufacturing Technology, 39(11-12), 2008, pp. 1227-1251 [4] B.Wang, C.Y.Wang, H.Q.Tang ,et al.: Tool Engineering, 43 (12), 2009, pp. 3-10 (In Chinese) [5] H.Q.Tang, C.Y.Wang and B.Wang: Machine Tool & Hydraulics, 38 (16), 2010, pp. 1-5 (In Chinese) * correspondent author: C.Y. Wang,
[email protected]
High Speed Machining doi:10.4028/www.scientific.net/AMR.188 Module Partition and Application for Printed Circuit Board High Speed Drilling Machine doi:10.4028/www.scientific.net/AMR.188.104
