U.S. patent number 3,638,366 [Application Number 04/881,867] was granted by the patent office on 1972-02-01 for lapping method for metallic workpieces.
This patent grant is currently assigned to Norton Company. Invention is credited to Norman M. Gamache.
United States Patent |
3,638,366 |
Gamache |
February 1, 1972 |
LAPPING METHOD FOR METALLIC WORKPIECES
Abstract
A process for providing clean lapped surfaces on metallic
workpieces supported in operative relation to the working surface
of a bonded abrasive lap for sliding and rotary movement relative
to such working surface throughout a single continuous lapping
operation including a first predetermined time period during which
an abrasive slurry is supplied to the working surfaces of the lap
and a second predetermined time period during which the working
surface of the lap is flooded continuously with a nonabrasive
cleaning fluid effective to wash clean the working surface of the
lap and the lapped surfaces of the workpieces.
Inventors: |
Gamache; Norman M. (Worcester,
MA) |
Assignee: |
Norton Company (Worcester,
MA)
|
Family
ID: |
25379368 |
Appl.
No.: |
04/881,867 |
Filed: |
December 3, 1969 |
Current U.S.
Class: |
451/57; 451/446;
451/450 |
Current CPC
Class: |
B24B
37/042 (20130101) |
Current International
Class: |
B24B
37/04 (20060101); B24b 001/00 () |
Field of
Search: |
;51/281R,281P,281C,281SF,263,267,323,326,327 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Swingle; Lester M.
Claims
What is claimed is:
1. The method of producing a clean lapped surface on a workpiece
with at least one surface to be finished by lapping comprising
supporting a given workpiece with its surface to be lapped in
operative engagement with a working surface of a given lapping
element composed of bonded abrasive material,
producing relative sliding movement between the given workpiece and
the given lapping element,
supplying an abrasive slurry to the working surface of the given
lapping element only during a first predetermined period of time,
and then
flooding the working surface of the given lapping element with a
nonabrasive cleaning fluid during a second predetermined period of
time sufficient to produce a clean lapped surface on the given
workpiece.
Description
BACKGROUND OF THE INVENTION
There are two well-known lapping methods for providing lapped
surfaces on metallic workpieces of various different sizes and
shapes.
One of these methods applies to lapping machines equipped with a
bonded abrasive lap, made like a grinding wheel, effective first to
remove stock from workpieces and then to produce a clean lapped
surface, without the use of a loose abrasive on the working surface
of the lap.
The other method is applicable to lapping machines equipped with a
metal lap, usually either cast iron or steel, to which a loose
abrasive is applied. On such lapping machines, this loose abrasive
is usually either combined with a paste or with a liquid vehicle to
form a slurry.
SUMMARY OF THE INVENTION
The instant invention consists of a new lapping method combining
the use of a bonded abrasive lap characteristic of the first
well-known method described above with the use of loose abrasive in
a slurry or paste characteristic of the second well-known method
described above, and also introduces the use of a nonabrasive
cleaning fluid to flood the working surface of the lapping
element.
This new lapping method is most effective when it is applied to a
lapping machine equipped with a relatively hard-bonded abrasive
lap, in order to avoid producing excess quantities of loose
abrasives from the lap itself, particularly while the working
surface of the lap is flooded with a nonabrasive cleaning fluid
which may comprise a thin filtered mineral seal oil.
DRAWING
The single FIGURE of drawing shows schematically a bonded abrasive
lapping element ("lap") which is lapping the lower surface of
metallic workpiece MP.
The workpiece is held in a holder H, such as the planetary ring
holder shown in Norton U.S. Pat. No. 2,870,580. The lapping action
is accomplished by relative sliding motion between the surface to
be lapped and the lap in the presence of abrasive particles. A
first source of abrasive particles is the lap itself which is
selected as noted above, to be of the bonded abrasive rather than
of the metallic type. A second source of abrasive is a fluid
reservoir containing abrasive grains in a fluid AF. The reservoir
has a value V1 and nozzle N1 for selectively dispensing fluid to
the lap where the lap motion tends to distribute it to the
lap/workpiece butting surfaces. The relative sliding motion may be
of various directions but in accordance with conventional practice
is shown here as rotary/planetary with the lap being driven about a
major or central axis of rotation of the machine A1 and the
workpiece MP being driven about a second local axis A2. Details of
the necessary drives and other conventional elements necessary to
complete a lap machine are omitted and reference is made to said
Norton patent for a description of these.
A reservoir of clear fluid CF with a valve V2 and nozzle N2 for
selectively dispensing such clear fluid to the lapping region is
also provided. Lapping cycles are carried out with initial feed of
abrasive bearing fluid via valve V1, nozzle N1 and with valve V2
closed for a predetermined period of time and the cycles are then
finished off with continuous feed of nonabrasive cleaning fluid via
valve V2, nozzle N2 and valve V1 closed for a second predetermined
period of time to wash clean the working (upper) surface of the lap
and the lapped (bottom) surface of the metallic workpiece. While
this drawing illustrates a single workpiece, it will be understood
that multiple workpieces can be simultaneously lapped in a single
lapping cycle.
The usual requirement for interrupting the lapping operation to
true the bonded abrasive lap can be avoided by applying this new
lapping method to a lapping machine equipped with cast iron or
other metallic conditioning rings such as those shown and described
in U.S. Pat. Nos. 2,565,590 and 2,870,580, so that lap conditioning
is a continuous process during lapping operations according to this
new method.
While this new method has been described thus far as it applies to
lapping machines equipped with a single lap, it is also applicable
to lapping machines equipped with opposing upper and lower bonded
abrasive laps arranged in the manner already well known in the art
to finish workpieces on opposite sides at the same time in a single
lapping operation.
* * * * *