Developing an Assembly Method to Fix the Glass to the Body with High Precision
Another difficult problem was figuring out how to fix the glass to the pillars. In particular, there was an extremely minute gap between the glass on the body side and door side outside the pillar, and the roof panel, and even a slight misalignment in the position of the glass would make it difficult to open the doors. To make matters worse, the manufacturing process resulted in a +/-1 mm error in external dimensions. In order to ensure a smooth outer surface and smooth opening and closing of doors, we had to allow for the error in the external dimensions of the glass while also coming up with a precise method for fixing the glass to the body.
The conventional method involved securing the glass to the body, and then covering the surrounding area with rubber strips. This method would require the use of wide strips of rubber in order to allow for the dimensional error in the glass. Since we had put so much effort into the design of the SVX, we were not willing to use this method.
A new method was proposed, using encapsulated strips. This method involved setting the glass into a mold and then injecting a urethane resin around the glass, in order to integrate it with the glass. As long as the glass was positioned accurately in the mold, this method allowed the problems of dimensional error and appearance to be overcome. In addition to finishing the glass with extremely high precision, quality was also dramatically improved.
A variety of other efforts were made to improve precision, including the technology for fixing the windshield and rear window to the body. One such improvement was the use of guide pins to determine positioning. The alignment of pins installed in windows with holes created in the roof allowed precise positioning. However, this precision positioning affected the precision in the body manufacturing.
In order to monitor the pinholes in the body, a method was devised to install television cameras. With this system, images from cameras monitoring the positions of holes were processed by computer, so that the robots performed welding only when the holes were in the correct positions. If the holes were misaligned, the work was stopped so that the parts would not continue on to other lines.
Shigeo Nomura, project manager of the Body Design Department, said,
“The SVX is a completely new model that overcomes design challenges unprecedented in various fields. Our team succeeded in part due to strong support from developers at cooperating manufacturers. In particular, the round canopy was achieved through the efforts of our team working closely together with glass manufacturers and rubber manufacturers.”