Glass-Technology International 6/1999

Transcription

1 161 Founded in August 1971, Glasstech Inc. was launched to design and build flat-glass tempering systems in order to satisfy the rapidly expanding requirement for safety glass in the architectural market, particularly in buildings accessible to the public. The author of this article discusses the technological progress which Glasstech has made in developing machinery for the production of architectural and automotive glass, with particular attention given to the bending and tempering furnaces now produced. Jay K. Molter* GLASSTECH INC. Glasstech headquarters, Perrrysburg, Ohio, USA

2 162 ISTORICAL MILESTONES When Glasstech manufactured its first horizontal glass tempering system, it was unique in that it pioneered the use of fused silica rollers to transport the glass through the furnace. The first Glasstech horizontal flat glass tempering systems were the continuous type, suitable for the mass production of tempered glass products such as patio doors. The continuous flat glass tempering system was well received because safety codes in place at the time in the United States, required safety glass to be used in certain areas, such as doors of public buildings. That system was an early forerunner of the sophisticated and innovative automotive and architectural glass systems that have earned Glasstech the reputation for being among the world s leaders in bending and tempering technology. PROGRESS HAS BEEN MADE The company s research and development activities are determined by listening and reacting to the automotive and architectural industry which it serves. This innovative spirit has proven successful over the years. Glasstech s sales base of more than 400 furnace systems includes virtually all major glassmakers in the world, and its systems are in use in more than 40 countries on five continents. Glasstech is at the forefront of technology in the design and manufacture of microprocessorcontrolled glass bending and tempering systems and its technology is covered by more than 700 patents and patent filings world-wide. RECENT TECHNOLOGICAL ACHIEVEMENTS In the past few years, a wide range of improvements and technological advancements have been completed in response to customer needs. The Forced-Convection Heater (FCH) is one of Glasstech s latest developments. It is an architectural glass tempering system with an advanced, gas-fired, forced-convection heater. It was designed in response to specific industry needs. The architectural sector of the glass industry for years was seeking new processing techniques for a range of reflective and low-e glass products. Traditional electric radiant heaters struggle to pass heat through the reflective surface and many of the coatings partially or completely decompose at the processing temperature. Moreover, the throughput rate compared with standard clear float glass is dramatically reduced, typically by 50 per cent or more, which makes the tempering process less economical. Glasstech, and other manufacturers of radiant heating systems, introduced convectionassisted radiant heaters which, although improving the quality and economy of coated glass processing, did not fully address the throughput shortcomings. The FCH system, developed by Glasstech with the sponsorship of the Gas Research Institute, reduces the heating time required to bring a piece of glass up to tempering temperature. The FCH substantially reduces energy costs and produces significantly higher throughput than a radiant heater. The benefits of the gas-fired FCH system include: faster heating of all types of glass; heats low-e and clear products in a similar heating time, thus enabling the FCH systems to be twice as productive as radiant systems for low-e products; improved glass surface quality resulting from lower residence time in the heater; considerable energy cost savings resulting from the use of gas fuel for the heating process; ability to process super low-e glasses. Glasstech s FCH systems enable glass processors to confidently offer temperable low-e products to their customers at a reasonable processing cost. OTHER ARCHITECTURAL TRENDS Another trend during the last ten years has been to use curved or bent glass for buildings and other applications, creating more challenges for the industry. Glass bending and tempering systems capable of making bends in larger sheets either of cylindrical contour or combined cylindrical and flat contours, have been adopted by some processors for building glazing, shop fronts, display cases, shower enclosures, furniture panels and appliance glass.

3 163 Glasstech, for example, produces three bending systems of different widths and capabilities which can be supplied with either the traditional radiation heater or the new FCH. Tight radius bending and tempering system Glasstech s new generation Tight-Radius Bending and Tempering System (TRCB), which bends and tempers glass quickly, easily and without tong marks, can produce an extended range of available shapes. The unit possesses a more precise motion control system for improved repeatability, reduced part set-up and change-over times and a PLC for heat control. The system can process glass into cylindrical curves, tight-radius V shapes, configurations with three flats and two small radii, and a wide variety of other shapes, both symmetrical and asymmetrical. The advanced TRCB, whose modular design permits total system flexibility and adaptability to any production setting, is particularly advantageous for the needs of the growing display-case glass market. DB4 system which reduces part changeover time to less than 90 minutes Advanced bending and tempering system for architectural glass Glasstech s advanced bending and tempering system for architectural glass produces custom-specific curves with contours ranging from a slight curve to curves with a minimum radius of 20 inches (500 mm). Capable of processing sheets of up to 84 inches (2,140 mm) wide by 144 inches (3,660 mm) long, in thicknesses from 5 to 19 mm, this innovative system allows architects and designers to use high quality, curved architectural glass for a multitude of applications. Architectural cylindrical bending and tempering system The architectural cylindrical bending and tempering system produces a wide range of constant radius bends from a 27-inch (600 mm) minimum radius to flat. Thickness ranges from 3 to 8 mm on the architectural bender system, and shapes of the same thickness are changed from one radius to another in a matter of seconds through Glasstech s microprocessor control system.

4 164 AUTOMOTIVE GLASS APPLICATIONS Trends in the automotive industry have also influenced glass processors designs. Although the FCH design was initially directed at architectural uses, its benefits can also be used for automotive glass processing. Coating or coloured glass is being specified increasingly for automotive applications and Glasstech has introduced a forced convection heater, which can be supplied for use on new bending and tempering systems, or which can be retrofitted to existing systems for automotive glass. CRB (Cylindrical bending and tempering system) Other trends in the 1990s in the automotive sector are shorter glass part production runs, justin-time delivery and reduction of part inventories. In certain facilities, part changeovers are required at least once a day and sometimes once a shift or more. Automotive glass processors are under great pressure from automobile manufacturers not only to hold down, but even to reduce, glass prices. As a result, the glass processors are seeking systems which can achieve high productivity, low downtime, high yield and rapid part changeover at little or no tooling cost. Glasstech s advanced cylindrical bending and tempering system (CRB), for example, does not require part-dedicated tooling and can be changed from one radius to another in a matter of seconds for parts of the same thickness, or in minutes for parts of varying thicknesses. The CRB enhances uptime with its fast changeover abilities. The system is ideal for long and short Original Equipment Manufacture (OEM) glass runs, and the typically very short Automotive Replacement Glass (ARG) runs. The system s modular design minimizes installation time for earlier start-ups. The CRB can also produce single parts with cylindrical bends on thin glass with highly repeatable shapes suitable for subsequent lamination. The CRB is available with fully programmable logic controller (PLC) systems, with either electricradiation or forced-convection heaters, and with equal applicability for production of single-unit or high volume parts. The CRB system is economical to install and operate and is ideal for the production of side windows, sunroofs and some back windows. DB4, QUICK CHANGE AND M2 IN-LINE FORMING Many back windows and fixed sidewindows, however, cannot be produced on simple bending and tempering systems. Such complex shapes and precise design demands require part-dedicated tooling and are often difficult to be achieved satisfactorily. Glasstech s deep bend (DB4) with its quick tool change system, reduces part changeover time to less than 90 minutes. Glass produced on DB4 systems has exceptional optical quality and uniformity of shape. Coated and tinted glass can be processed without difficulty. These systems are unsurpassed in creating complex back windows, side windows and quarter windows to US and international fracture standards. The M2 complex forming and tempering system provides the automotive glass industry with the highest degree of accuracy and repeatability available in the world today. The M2 system produces back windows, side windows and quarter windows up to 500 mm (20 inches) deep at cycle times of 16 to 30 seconds for 4 mm thick glass. The M2 forming and annealing version produces windscreen glasses at cycle rates as low as 15 seconds. These technology advancements from Glasstech are examples of how the glass processing industry is continually engineering new answers for the challenges posed by glass users. Prototypes of four systems - FCH, CRB, DB4 and M2 In-Line Forming have been installed at Glasstech headquarters in Perrysburg, Ohio, United States for development and demonstration purposes. SHAPE MODELLING Glasstech has developed the computer-driven Shape Modelling programmes, both for automotive glass manufacturers and automotive designers. Shape Modelling is the company s internally developed, proprietary system which can predict the shape and optical quality - both transmitted and reflected - of a given surface design, and if necessary, calculate a modified surface design to minimize optical distortion.

5 165 CUSTOMER SERVICE PROGRAMME Most recently, Glasstech has unveiled a new customer service agreement for users of Glasstech furnaces, incorporating proactive services with priority access to resources. The new service helps maintain systems in top operating condition through proactive assistance. With the reduction in downtime and improvements in throughput being high-priority production objectives in the glass-processing industry, the company s goal is to help maintain operational Glasstech systems in peak condition so that uptime and productivity are maximized, thereby reducing the cost of the tempered glass product for customers. Glasstech s new after market agreement is comprised of three separate service programmes: Technical Services Programme, which includes breakdown troubleshooting, preventive maintenance plans, software maintenance, remote system monitoring, operator training, equipment status audits and productivity improvement assistance; Tooling Programme, consisting of part predictive shape modelling services, tooling design services, tooling manufacture and Glasstech cylindrical bending and tempering system prove-out at Glasstech, and, if required, tooling installation and prove-out at user site; Spare Parts Programme, which includes stock-holding recommendations, stock audits, direct telephone and fax lines, deliveryperiod guarantee and spare parts and roller package deals. FUTURE OUTLOOK Glasstech aims to continue to deliver to its expanding base of customers both state of the art systems for the bending, tempering and annealing of glass, as well as increasing the scope of its customer service offerings. The company is also committed to developing leading-edge technology for new products and services as well as for improving existing designs and systems. *Director of marketing, administration and aftermarket sales GLASSTECH - USA Entire content 1999 by Artech Publishing S.r.l.