Abrading – Abrading process
Reexamination Certificate
1999-09-14
2001-01-09
Scherbel, David A. (Department: 3723)
Abrading
Abrading process
C451S053000, C451S128000, C451S182000, C451S188000, C451S449000, C451S450000
Reexamination Certificate
active
06171176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a surface-shaping method, and more particularly to a method of forming a series of hills and valleys alternately arranged at a predetermined pitch on the surface of a given workpiece.
2. Related Arts
Referring to
FIG.7
, a solar cell
50
has minute hills
51
and valleys
52
alternately formed on its surface, thereby increasing the solar absorption rate and accordingly the rate at which electric power can be produced from sunlight.
A drum-like grindstone
55
having pulverized diamond deposited on its surface is fixed to a rotary spindle
56
. The drum
55
has a series of hills
51
and valleys
52
alternately arranged at the same pitches P of peak
54
-to-peak
54
intervals (or bottom
53
-to-bottom
53
intervals) as the solar cell
50
, which is to be provided. The height H measured from the bottom
53
of the valley
52
to the peak
54
of the hill
51
in the drum
55
is equal to the corresponding height measured in the solar cell. In short, the drum
55
has the same saw-toothed pattern as the solar cell, so that the saw-toothed pattern may be transferred from the grindstone
55
to the workpiece W.
In making the saw-toothed grooves on the workpiece W the hill-and-valley arrangement of the grindstone
55
is pushed against the surface of the workpiece. The machining gap remaining therebetween, therefore, decreases gradually toward the tight fit. Accordingly the grinding resistance increases with increase of the bite amount. Also, it is increasingly difficult that the cooling water flows into the ever decreasing gap. Finally, no cooling water is permitted to reach the blade-and-workpiece contact. The solar cell thus produced is of lower quality.
In transferring the valleys from the grindstone to the workpiece to form the corresponding hills therein the exactness of the hill shape thus formed in the workpiece is lowered, compared with the original shape.
There has been, therefore, a demand for decreasing the grinding resistance, and for supplying the machining gap with sufficient amount of cooling water, thereby improving the quality of products.
SUMMARY OF THE INVENTION
To meet such demand a method of forming a series of hills and valleys alternately arranged at a predetermined pitch (one pitch being equal to a peak-to-peak interval at which hills are arranged) on the surface of a given workpiece, is improved according to the present invention in that it comprises the steps of: carrying out a first grinding on the workpiece with a saw-toothed grindstone having a series of hills and valleys alternately arranged at “N” pitches (“N” being equal two or more integer or whole number), the height measured from the bottom of the valley to the peak of the hill in the saw-toothed grindstone being taller than the corresponding height measured in the workpiece, the grinding being effected while the surface of the workpiece is being supplied with cooling water; moving the saw-toothed grindstone and/or the workpiece one pitch relative to each other to carry out a second grinding on the workpiece with the saw-toothed grindstone, the grinding being effected while the surface of the workpiece is being supplied with cooling water; and repeating the relative movement of one-pitch long-distance and subsequent grinding until the final “N”th cutting has been finished in case of “N” being three or more integer or whole number.
Said method may be carried out by using a machine which comprises at least means for holding the workpiece, means for rotating the saw-toothed grindstone against the workpiece, means for indenting or moving the saw-toothed grindstone and/or the workpiece one pitch relative to each other, and means for supplying the workpiece with cooling water. The workpiece may be a solar cell wafer.
In making saw-toothed grooves in the workpiece according to the present invention the whole of the hill-and-valley pattern of the grindstone cannot be pushed against the workpiece to full extent, thus leaving a relatively wide machining gap therebetween to permit a sufficient amount of cooling water to flow into the machining gap. Thus, the efficient cooling effect is assured.
Also, as many hills as required can be formed in the workpiece after repeating the groove-grinding “N” times, permitting hills of exact shape to be formed each time in the workpiece. The so formed hills have an apex as sharp as the original shape.
Other objects and advantages of the present invention will be understood from the following description of the saw-toothed grooving according to the present invention, which are illustrated in the accompanying drawings.
REFERENCES:
patent: 5214881 (1993-06-01), Borchardt
patent: 6084175 (2000-07-01), Perry et al.
Kajiyama Keiichi
Sekiya Kazuma
Arent Fox Kintner & Plotkin & Kahn, PLLC
Disco Corporation
McDonald Shantese
Scherbel David A.
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