Field Trial of Optical Fibre Cable-TV System Optical Fibre System for ...

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181 drawings must at present be fed into the local system in the Kristianstad factory manually for further processing, fig. 2. Tool design using computer aid A moulding tool is built up of standard components. They are modified by means of different processes to suit the application in question. The parts that shape the plastic detail are usually loose steel inserts that are fitted into the moulding tool. The parts that determine the geometry of the plastic detail have to be modified because of the shrinkage of the plastic material, which means a conversion of the measurements of the plastic detail. With computer aid this design work is an interactive process. The relevant standard components, which are stored in a data base, are retrieved and built up into a mould. Mould inserts are designed on the basis of the product geometry built up by the designer, with compensation for the shrinkage of the plastic material. Drawings are produced to the extent required for each individual design. The system has standard forms for this purpose which are displayed on the screen. This is laso an interactive process, as are the defining of positions and generation of a parts list. Component library The standard components required for the tool design are stored in a data base, which has been provided by one of our suppliers. It contains 25 000 items, for example screws, guide pins, ejectors and mould plates. The graphic display is two-dimensional. An order list is created automatically when components are selected. Calculations Strength calculations Strength calculations are often necessary in order to be able to judge whether the tool can function satisfactorily. Injection moulding pressure in the order of 1000bar/cm 2 can easily cause displacements in the tool. With tolerances of a few hundredths of a millimetre the tool must be self-supporting and be deformed by a maximum of a few thousandths of a mm. The CAD/CAM method, together with the finite element method, has meant that the mechanical function of the moulding tool can be assessed more easily and earlier, during the design stage. The finite element method (FEM) is a general means of approximating differential equations in connection with strength calculations, The method is based on a grind, whereby the object to be investigated is divided into a number
Fig. 4 Product geometry displayed on a screen and used to generate programs for numerical control Fig.3 Manufacturing a model tor verification of finite elements. The calcualtion is then carried out for each individual element, for which differential equations can be set up and solved. The separate solutions are combined into an approximation for the whole object. Temperature calculations In order to obtain a product that is the optimum with respect to technology and economy it is necesary to devote great care to the tempering system of the tool. During the interrupt stage the heat from the plastic melt must be dispersed by a tempering medium consisting of water or oil. The positions of the channels are extremely important in order to obtain the optimum result. FEM permits advanced analysis, but this is a laborious task. Instead the Kristianstad factory usesaprogram, MOLD TEMP, which dimensions and positions the channels efficiently. However, the calculations require great simplification of the shape of the mould space. Mould fill calculation The position of the intake, suitable material thickness, and suitable product design are obtained by means of mould fill simulation, for examle by means ol the program MOLS FILL. The piece is divided into sections, which in their turn are divided into elements. The calculation provides information regarding pressure drop and gives temperature and speed profiles. The results of the calculation provide a good idea of what product quality can be expected. Fig. 5 Manufacture of a graphite spark tooling electrode using numerical control based on the geometry shown in fig. 4 Fig. 6 The finished product, an intercom ERICOM Direct DEE 401 01
Page 1 and 2: ERICSSON REVIEW 4 1985 Field Trial
Page 3 and 4: Trial of Optical Fibre Cable-TV Sys
Page 5 and 6: Head end (HC] 280 Mbit/s Farsta aut
Page 7 and 8: 158 Switching equipment Fig. 7 Futu
Page 9 and 10: 160 Fig. 10 The teleconference room
Page 11 and 12: GERHARD GOBL Public Telecommunicati
Page 13 and 14: Fig. 5, above left Two-channel A/D
Page 15 and 16: Digital input signals Digital outpu
Page 17 and 18: Power ZAV 280/4 has individual powe
Page 19 and 20: Wavelength Division Multiplexing fo
Page 21 and 22: 172 Subscriber side BP-890 Controll
Page 23 and 24: Fig. 8 Transmission characteristics
Page 25 and 26: Most computer cabinets are 19" wide
Page 27 and 28: 178 Fig. 5 Modems in Series 7 Modem
Page 29: Computer Aided Production of Plasti
Page 33 and 34: Rectifier for Mobile Telephone Syst
Page 35 and 36: I OR | OFU OS I CMUP HlsHi W±±±h
Page 37 and 38: 188 Fig. 6 The rectifier with the o
Page 39 and 40: Fig. 9 Rectifier BMJ A01 001 with t
Page 41 and 42: The Renewal of the London Undergrou
Page 43 and 44: 194 Rickmansworth, and the Loughton
Page 45 and 46: 196 Fig. 5 Optical fibre cable rout
Page 47 and 48: 198 In planning the optical fibre n
Page 49 and 50: Fig. 9 The digital telephone DIAVOX
Page 51 and 52: 202 Fig. 11 Transmission equipment
Page 53 and 54: 204 Fig. 2 Automatic testing of mul
Page 55 and 56: 206 Relative occurrence for F Fig.
Page 57 and 58: Fig. 5 Field testing of a 140 Mbit/
Page 59 and 60: 210 Fig. 7 The system down time as
Page 61 and 62: MTBF (years) Equipment 2-5 Transmul

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