Glass manufacturing – Processes – Fusion bonding of glass to a formed part
Reexamination Certificate
1998-02-25
2001-04-03
Silverman, Stanley S. (Department: 1731)
Glass manufacturing
Processes
Fusion bonding of glass to a formed part
C065S057000, C065S059300, C065S059330, C065S059340, C065S108000, C065S109000, C065S120000, C065S152000, C065S276000, C065S278000, C065S279000, C065S292000, C065SDIG008, C065SDIG009, C264S248000, C156S172000, C156S187000, C156S082000, C138S109000, C138S142000
Reexamination Certificate
active
06209353
ABSTRACT:
INDUSTRIAL FIELD OF APPLICATION
The present invention relates to a method for producing an object having a flanged tubular portion at the outer periphery, by supplying a continuously extended, cylindrical body made of the flange material to a welding zone at the tubular portion of the object and welding the flange material to the welding zone by heating and winding the cylindrical body around the object, and it relates to an apparatus for producing an object having a flange which comprises feeding a continuously extended, cylindrical body made of flange material having a molten front end to a welding zone of the object.
PRIOR ART
Heat treatment of a semiconductor wafer has been performed conventionally by an operation comprising mounting the wafer on an airtight sealed reaction vessel, applying heat treatment, and taking out the heat treated wafer. Accordingly, it was necessary to provide the reaction vessel detachable from the mounting table, while also joining an aperture portion in an airtight manner on the mounting table. Thus, in general, a flange portion is provided on the outer periphery of the reaction vessel, so that the reaction vessel may be brought tightly into contact with or separated from the mounting table by the flange portion.
On forming the flange portion on the aperture portion of the reaction vessel, a plate material is perforated in such a manner that the hole may match the inner diameter of the aperture portion, cut into a donut-like plate having the desired outer dimension, and the resulting donut-like flange portion is welded to the aperture end of the reaction vessel. The resulting structure is subjected to mechanical processing thereafter to realize a smooth connection state on the inner diameter plane and the outer diameter plane by shaving them to remove irregularities that are formed previously by welding.
In the conventional technique above, a large portion of the plate material had to be wasted in forming the flange portion therefrom, and, moreover, the process required mechanical shaving to form a continuous smooth surface on the portion connecting the flange portion to the reaction vessel. This required a use of the material at a large quantity, as well as an incorporation of additional process steps which involves consumption of tools and an uneconomical increase of process steps.
In order to overcome the above mentionend problems another technique is suggested in JP-A-Hei8-178169. The known technique, which is shematically shown in FIG.
8
. comprises winding a ribbon of a quartz glass plate
103
around the surface of the ends of a transparent quartz glass tube
101
having a uniform cross section along the longitudinal direction thereof, and then heating and welding by heating the entire structure by means of a first burner
106
and a second burner
107
.
Problems the Invention is to Solve
However, in the technique above, the quartz glass member
103
is heated by the first burner
106
until it becomes soft enough that it may be easily bent, then, is wound up around the outer periphery of the quartz glass tube
101
while the quartz glass tube
101
is rotated in the direction of the outer plane, and, at the same time, the lower plane of the quartz glass member
103
is heated by the second burner
107
in such a manner that both planes to be joined may be melt. Thus, the quartz glass member
103
is welded to the surface of the quartz glass tube
101
.
It can be seen therefore that this method requires a welding operation while manually controlling the burners, the rotation speed, and the like depending on the welding state that is influenced by the thickness of the quartz glass member
103
, burner temperature, rotation speed of the quartz glass tube
101
, etc. Such a welding operation requires sophisticated manual technique or a manual skill of a well trained expert.
In the light of the aforementioned circumstances, an object of the present invention is to provide a method and an apparatus for producing an object having a flanged portion at the outer periphery without requiring sophisticated manual technique or a manual skill of a well trained expert.
Another object of the present invention is to provide a method and apparatus for producing tubes or vessels having flanged portion on the outer periphery of the tubular portion, which are economical and require use of less material and process steps.
Means for Solving the Problems
Concerning the method the above mentioned objects are achieved by a method comprising the following steps:
supplying the cylindrical body to the welding zone in a predefined feeding direction and with a adjustable feeding rate,
heating a front end portion of the cylindrical body and melting it to the welding zone,
continuously rotating of the object with a adjustable rotation speed, whereby the welding zone is moved in a direction parallel to the feeding direction,
observing at least one boundary of the cylindrical body in order to detect a lateral displacement of the boundary in a direction vertical to the feeding direction; and
providing an automatic control mechanism, whereby the detected displacement is used as a regulating variable.
The end plane of a cylindrical body (e.g., a quartz glass plate) is brought into contact with the outer periphery of the tubular portion of a quartz glass tube
1
as shown in
FIGS. 1 and 2
, and the front end portion of the cylindrical body inclusive of said end plane is heated and fused.
It was found that if the quantity of the front end portion to be heated and molten is equal to the quantity received by the tubular portion in the welding zone while rotating, that is, if the rotation speed of the tubular portion is set properly in accordance with the quantity that is heated and molten, no displacement occurs on the cylindrical body in the direction (indicated by arrows
40
and
41
) that crosses the feeding direction. If however the rotation speed of the tubular portion of the quartz glass tube
1
is too high, the quartz glass plate
3
is pulled by the tubular portion of the quartz glass tube
1
at a quantity exceeding the amount that is heated and molten. Thus, the cylindrical body (quartz glass plate
3
) undergoes deformation in the direction shown by the arrow
40
, because of the viscosity of the molten quartz glass, resulting in a lateral displacement of the boundary of the cylindrical body. If, on the other hand, the rotation speed of the tubular portion is too low, then the force pulling the quartz lass plate
3
becomes weak as to cause a lateral displacement in the direction indicated by the arrow
41
. The displacement of the cylindrical body can be observed within the welding as well as before the welding zone.
So, according to the invention the lateral displacement vertical to the feeding direction of the boundary of the cylindrical body is continuously observed. The observed values are used in an automatic control mechanism for the process. When detecting a displacement a correcting variable of the process is changed in such a way that the displacement disappears again.
In an preferred embodiment of the invention the feeding rate of the cylindrical body is used the correcting variable. In an other preferred embodiment the rotation speed of the tubular portion is used the correcting variable. Thus the displacement is detected in the direction crossing the direction of feeding the cylindrical body, and the feeding rate of the cylindrical body is varied in accordance to the quantity of displacement. Accordingly, no high manual technique or a well trained expert is required in feeding the cylindrical body in a molten state.
Alternatively the rotation speed of the tubular portion as well as the feeding rate of the cylindrical body simultaneously may be used as correcting variables in the automatic control mechanism. Accordingly if one of the feeding rate and the rotation speed may exceed the control range, adjustment can be made by the other. Thus, even in case it is impossible to control the rotation speed, the other variable can be used for the control. Hen
Ise Yoshiaki
Matsuya Toshikatsu
Takahashi Shoji
Colaianni Michael P.
Heraeus Quarzglas GmbH & Co. KG
Silverman Stanley S.
Tiajoloff Andrew L.
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