AIR-EXHAUSTING AND PRE-PRESSING APPARATUS FOR LAMINATED GLASS SHEETS

Abstract: The invention relates to an air-exhausting and pre-pressing apparatus for laminated glass sheets. In the manufacture of laminated windscreens, the glass sheets are carried on a conveyor (4) in a substantially upright position through a heating tunnel. The suction tubes included in a suction track adjacent to the conveyor are coupled with suction rings surrounding the edges of laminated glass sheets. A preheating station (1), a heating station (2) and a recooling station (3) are set successively to define together a heating tunnel, said conveyor (4) being extended therethrough. Preheating station (1) and recooling station (3) are linked with each other by at least two air circulation ducts (7, 8) for circulating air from recooling station (3) to preheating station (1) and from the latter back to recooling station (3). The arrangement saves heating energy and achieves a uniform heating and cooling of glass sheets.

Description: Air-exhausting and re-pressing apparatus for laminated glass sheets. The present invention relates to an air-exhausting and pre-pressing apparatus for laminated glass sheets, com¬ prising - a conveyor, fitted with means for supporting laminated glass sheets in a substantially upright position on the conveyor, - a pre-heating station, a heating station and a recool¬ ing station set successively to define together a heat¬ ing tunnel for carrying said conveyor therethrough, - a suction track, mounted adjacent to the conveyor and also extending through the heating tunnel and provided with suction tubes that can be coupled with suction rings surrounding the edges of laminated glass sheets, and - air circulation ducts, included in the heating station and having their ends fitted with blasting and suction ports on opposite sides of the heating tunnel for blasting the heating air between glass sheets, as well as - fans and heating elements associated with the air cir¬ culation ducts. This type of equipment is generally used in the manufac¬ ture of laminated windscreens. Heating is used to pro¬ vide a preliminary adhesion between glass sheets to be laminated and a plastic film therebetween while suction is applied to exhaust the air from between glass sheets. Heating mechanisms for glass laminates have been de¬ scribed e.g. in German publications DE 2 209 642, DE 2 050 033 and DE 2 241 754. A drawback in these prior known mechanisms is high energy consumption in relation to production capacity. An object of the invention is to provide an improved apparatus capable of substantially saving heating energy while increasing production capacityand performing the heating and cooling of a glass sheet effectively and uniformly. This object is achieved on the basis of the character¬ izing features set forth in the annexed claim 1. The invention will now be described in more detail with reference made to the accompanying drawings, in which fig. 1 shows an apparatus of the invention in a schema¬ tic perspective view; fig. 2 shows an apparatus of the invention in a side view and fig. 3 shows the apparatus of fig. 2 in a plan view; fig. 4 is a schematic perspective view of a heating station included in the apparatus, illustrating the currents of heating air in an individual heating station; and fig. 5 depicts the coupling of a suction track with a suction ring at the edge of a glass sheet. The apparatus shown in figs. 1 - 3 includes a pre¬ heating station 1 , three heating stations 2 and a re¬ cooling station 3 set successively to define together a heating tunnel, through which the pairs of glass sheets to be laminated are carried in a substantially upright position by means of a conveyor 4. Conveyor 4 is provided with holding arms 5 for supporting the pairs of glass sheets in an upright position. Adjacent to conveyor 4 is a suction track 6, which is also extended through the heating tunnel and whose suc¬ tion tubes 16 (fig. 5) can be coupled with suction rings 15 surrounding the edges of laminated glass sheets. Fig. 4 shows in more detail an individual heating sta¬ tion 2. It includes air circulation ducts 14 which terminate in blasting ports or slots 12 on the ceiling of station 2 and in suction slots 13 on the floor. Thus, said blasting and suction slots 12, 13 are loca¬ ted on opposite sides of the heating tunnel for blast¬ ing the heating air through between glass sheets in vertical direction from top to bottom. For the circu¬ lation of heating air said duct 14 is fitted with a fan 10. In addition, duct 14 is provided downstream of fan' 10 with electric resistance heating elements 11 for heating the air typically to a temperature of 140 C. The temperature of pairs of glass sheets to be laminated in heating station 2 is typically raised to the range of 90 - 100°C. Preheating station 1 and recooling station 3 are linked with each other by at least two air circulation ducts 7 and 8, which by-pass heating stations 2 and whose blasting and suction slots are located in stations 1 and 3 on opposite sides of the heating tunnel. Ducts 7 and 8 are fitted with fans 9 for effecting the circu¬ lation of air from recooling station 3 to preheating station 1 and from preheating station 1 back to recool¬ ing station 3. Th s, the circulation air travels in both stations 1 and 3 in horizontal direction between the glass sheets. Thus, the heat energy delivered by glass sheets upon cooling can be used for preheating the glass sheets in station 1. Preheating is typically effected from an initial temperature of 25 C to a tem¬ perature of 34°C. The temperature of preheating air blasted from duct 7 is e.g. appr. 62 C. By virtue of preheating, the output of heating elements 11 in heating stations 2 can be reduced e.g. from 151 k to 132 kW for an energy saving of appr. 13 %. In addition to energy savings, another advantage gained is a more uniform heating and more rapid cooling. The external sides of stations 1 , 2 and 3 are provided with sufficient room for ducts 7 and 8. Ducts 7 and 8 as well as ducts 14 in individual heating stations 2 can be dimensioned in a manner that the volume flow rate of air is in the order of 2 m /s, the flow area 2 in the order of 0,7 m , resulting in a flow rate in the order of 3.1 m/s. Thus, in all stations 1, 2 and 3 is achieved an effective heat transfer between flowing air and glass sheets.

Claims: Claims 1. An air-exhausting and pre-pressing apparatus for laminated glass sheets, comprising - a conveyor (4), fitted with means (5) for supporting laminated glass sheets in a substantially upright po¬ sition on the conveyor, - a preheating station (1), a heating station (2) and a recooling station (3) set successively to define together a heating tunnel for carrying said conveyor (4, 5) therethrough, - a suction track (6) , mounted adjacent to the conveyor and also extending through the heating tunnel and pro¬ vided with suction tubes (16) that can be coupled with suction rings (15) surrounding the edges of laminated glass sheets, and - air circulation ducts (14), included in heating sta¬ tion (2) and having their ends fitted with blasting and suction slots (12, 13) on opposite sides of the heating tunnel for blasting the heating between glass sheets, as well as - fans (10) and heating elements (11) associated with air circulation ducts (14), c h a r a c t e r i z e d in that said preheating sta¬ tion (1) andrecooling station (3) are linked with each other by at least two air circulation ducts (7, 8) , which by-pass the heating station or stations and whose blasting and suction slots are located in both stations (1, 3) on opposite sides of the heating tunnel and which are fitted with fans (9) for the circulation of air from recooling station (3) to preheating station (1) and from preheating station (1) back to recooling sta¬ tion (3) , the circulation air travelling in both sta¬ tions between the glass sheets. 2. An apparatus as set forth in claim 1, c h a r a c - t e r i z e d in that said air circulation ducts (7, 8) between stations (1, 3) are located on the external sides of the stations and the blasting and suction slots of these ducts (7, 8) are located on the internal sides of the stations in a manner that the air currents in preheating station (1) and recooling station (3) pro¬ ceed in a substantially horizontal direction and in the opposite directions relative to each other. 3. An apparatus as set forth in claim 1 or 2, c h a r ¬ a c t e r i z e d in that said blasting and suction slots (12, 13) of heating station (2) are located on the ceiling and floor of station (2) in a manner that the flow of circulation air in the heating tunnel pro¬ ceeds in a substantially vertical direction.

Inventors: LEPONEN MAURI, LIND KALEVI, LEPONEN, MAURI, LIND, KALEVI
Applicants: TAMGLASS ENG OY, TAMGLASS ENGINEERING OY
Application year: 1992
Main classification: C03C27
IPC codes: B32B17, C03B29, C03C27