Abrading – Precision device or process - or with condition responsive... – Computer controlled
Reexamination Certificate
1999-12-06
2001-02-06
Banks, Derris H. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
Computer controlled
C451S041000, C451S043000, C451S011000
Reexamination Certificate
active
06183344
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for grinding the seal edge of a glass funnel and an apparatus therefor, in particular grinding method and apparatus for grinding the seal edge of a glass funnel for a cathode-ray tube.
2. Discussion of Background
Glass funnels, which form a cathode-ray tube for a TV set, a display and other devices, have a seal edge thereof ground by a grinding apparatus before having been assembled into the Cathode-ray tube since the seal edge is required to have proper surface roughness and good flatness.
An example of such a grinding apparatus, there is the grinding apparatus disclosed in JP-A-1034505, wherein a glass funnel is rotated with the seal edge thereof directed downward, and rotating grinding wheels are pressed against the seal edge to grind the seal edge. This grinding apparatus presses the grinding wheels against the seal edge by a weight to grind the seal edge at a constant pressure in order to improve the grinding precision of the seal edge.
On the other hand, the grinding apparatus disclosed in JP-B-533114 presses the seal edge of the glass funnel against grinding wheels by a weight to grind the seal edge at a constant pressure. This grinding apparatus includes a device for stopping the downward movement of the glass funnel when the glass funnel has lowered to a location corresponding to a set grinding removal.
However, the grinding apparatuses disclosed in JP-A-1034505 and JP-B-0533114 have created a problem in that it is impossible to improve grinding efficiency since the apparatuses grind the seal edge at a constant pressure all the time.
This problem may be eliminated by making the weight load heavier to increase the level of the constant pressure. However, if the pressure is increased too much, the flatness of a ground surface has been deteriorated because of variations in the behavior of the grinding wheels, and a defect, such as a chip, has been caused at the seal edge in some cases.
SUMMARY OF THE INVENTION
The present invention is proposed in consideration of the circumstances. It is an object of the present invention to provide a method for grinding the seal edge of a glass funnel and an apparatus therefor capable of grinding the seal edge in better and more effective fashion.
In order to achieve the object, the present invention provides a seal edge grinding method for a glass funnel, wherein a glass funnel seal edge and a grinding wheel are pressed against each other, and the seal edge is ground with the grinding wheel, comprising moving a glass funnel and a grinding wheel by a certain quantity in an relatively approaching direction by a mobile unit under numerical control to grind a seal edge of the glass funnel with the grinding wheel by the use of feed controlled grinding; and relatively pressing the seal edge and the grinding wheel at a certain pressure by a pressing force of a pressing unit to grind the seal edge with the grinding wheel by the use of pressure controlled grinding after completion of the feed controlled grinding.
In order to achieve the object, the present invention also provides a seal edge grinding apparatus for a glass funnel, wherein a glass funnel has a seal edge ground, comprising a supporting member for supporting a glass funnel at a yoke portion thereof; a grinding wheel for grinding a seal edge of the glass funnel; a mobile unit for moving the supporting member and the grinding wheel in a relatively approaching direction by a certain quantity; a controller for numerically controlling relative displacement of the supporting member and the grinding wheel by the mobile unit; and a pressing unit for pressing at least one of the supporting member and the grinding wheel at a certain pressure by a pressing force; wherein the seal edge of the glass funnel is ground by the use of pressure controlled grinding by the pressing unit after the seal edge has been ground with the grinding wheel by the use of feed controlled grinding, being numerically controlled.
In order to achieve the object, the present invention also provides a seal edge grinding apparatus for a glass funnel, wherein a glass funnel has a seal edge ground, comprising a supporting member for supporting a glass funnel from upwardly and pressing the glass funnel with the glass funnel having a seal edge directed downwardly; an elevating member for vertically moving the supporting member; a grinding wheel provided under the supporting member; a pressing unit for pressing the supporting member toward the grinding wheel at a certain pressure; a mobile unit for moving the supporting member by a certain quantity with respect to the grinding wheel; and a controller for numerically controlling vertical displacement of the supporting member by the mobile unit.
In the grinding method according to the present invention, the seal edge of a glass funnel and the grinding wheel are first contacted each other. Next, the glass funnel and the grinding wheel are moved by a certain quantity in the relatively approaching direction by the mobile unit under numerical control to grind the seal edge with the grinding wheel by the use of feed controlled grinding. Then, the seal edge and the grinding wheel are relatively pressed at a certain pressure by the pressing force of the pressing unit to grind the seal edge with the grinding wheel by the use of pressure controlled grinding after completion of the feed controlled grinding. In this case, the grinding removal in the feed controlled grinding may be preset, or be set whenever the seal edge is ground.
In other words, in accordance with the present invention, a large part of a set finishing allowance is removed by the use of the feed controlled grinding, and the remaining part of the finishing allowance, which is smaller, is removed by the use of the pressure controlled grinding. By combining the feed controlled grinding and the pressure controlled grinding in such fashion, the grinding removal per a unit time can be increased in comparison with the grinding removal only by the pressure controlled grinding to improve grinding efficiency. The pressure controlled grinding can be finally carried out to remove a deficiency of the seal edge caused during the feed controlled grinding, such as incorrect flatness and a chip, so as to make the seal edge better.
In accordance with the grinding apparatus of the present invention, the supporting member, which supports a glass funnel, or the grinding wheel is first moved in the relatively approaching direction by the mobile unit to contact the glass funnel seal edge and the grinding wheel each other. Next, the move of the glass funnel and the grinding wheel in the approaching direction can be continued by the mobile unit to grind the seal edge with the grinding wheel by the use of the feed controlled grinding. At that time, the grinding removal by the use of the feed controlled grinding can be finely controlled since the controller numerically controls the displacement by the mobile unit. Then, the seal edge and the grinding wheel are relatively pressed at a certain pressure by the pressing force of the pressing unit, and the seal edge of the glass funnel is ground with the grinding wheel by the use of the pressure controlled grinding after the seal edge has been ground with the grinding wheel by the use of the feed controlled grinding.
Thus, the seal edge can be ground in better and more efficient fashion.
In accordance with the present invention, a glass funnel is first supported by the supporting member provided on the elevating member, and the elevating member is lowered toward the grinding wheel by the mobile unit to press a seal edge of the glass funnel against the grinding wheel. Next, the downward move of the glass funnel can be continued by the mobile unit to grind the seal edge with the grinding wheel by the use of the feed controlled grinding. At that time, the controller numerically controls the displacement of the elevating member by the mobile unit. Then, the seal edge is pressed against the grinding wheel at a ce
Muramoto Shigeru
Tanaka Shinji
Tsuchimoto Yoshihiro
Asahi Glass Company Ltd.
Banks Derris H.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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