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Патент USA US3094827

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June 25, 1963
J.‘ s. BARTHOLOMEW
3,094381'7
CENTERLESS GRINDING MACHINE
Filed Oct. 2, 1961
I
INVENTOR.
JERRY 6. BARTHOLOMEW
8%
l?iq'ORNEYs
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9 VIA/40w“.
’
Umkd ' 1ates Patent
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3,094,811
Patented June 25, 1963
1
2
3,094,817
tion the regulating wheel 16 is operative to hold the
workpiece in contact with the grinding wheel 10 which
CENTERLESS GRINDING MACHINE
Jerry S. Bartholomew, Milford, Ohio, assignor to The
Cincinnati Milling Machine Co., Cincinnati, Ohio, a
corporation of Ohio
Filed Oct. 2, 1961, Ser. No. 142,118
4 Claims. (Cl. 51-103)
is abrasive and rotated at a high rate of speed to re
move metal from the workpiece. The surface of the
regulating wheel 16 drives the workpiece and prevents
it from picking up the speed of the‘ grinding wheel 10
but does not remove metal from the workpiece.
The workrest blade 18 is a thin strip of hard metal
which extends through the grinding area between the
The present invention relates to a workrest for a cen
terless grinding machine and is particularly adapted for 10 wheels 10, 16. The blade 18 is supported at each end
between pairs of guide plates 20, 22 and 24, 26 which
supporting small diameter workpieces during a grinding
are rigidly held in the upright portions 28, 30, respec—
operation.
A demand has been created in recent years for ac
tively, of the frame 32 which is received on the machine
slide 15 and ?xed thereto during grinding operations.
for example, microliter syringe plungers. These parts 15 One of the upright portions 28, 30 is located at 'each
end of the grinding area defined between the wheels
are ground in the form of short lengths of Wire of small
10, 16. A pin 34 extends through the guide plates
diameter and the completed parts must be extremely
curate production of parts of very small dimensions,
20, 22 and an end of the blade 18 to secure that end of
round in the diametral section and very straight end to
the blade between the plates 20, 22. A pin 36 extends
end. In addition the surface ?nish must be smooth and
uniform. Precision centerless grinding is an accepted op 20 through a slotted stud 38 which embraces the other
end of the blade 18 in the notch 40 in the guide plates
eration to produce straight cylindrical work with a good
24, 26 and secures this other end to the stud 38. The
surface ?nish but the support of small diameter work
stud 38 extends loosely through a space between the
pieces presents many problems for which solutions have
plates 24, 26 in a direction axially away from the blade
been difficult to ?nd. Development of a relatively rigid
workrest which will extend through the grinding area in 25 18. A wing nut 42 is threadedly engaged with a por
tion of the stud 38 which extends from between the
the small space available between the grinding wheel and
plates 24, 26. The wing nut 42 is advanced on the stud
the regulating wheel of a centerless grinding machine
38 to engage the plates 24, 26. The combination of the
has been a major problem in small diameter grinding
pin 36, stud 38, and wing nut 42 holds the end of the
operations where ?nished workpiece diameters are in the
30 blade 18'between the plates 24, 26 and provides a mech
neighborhood of .020 inch or less.
anism by which a tensile stress may be created in the
7 It is therefore an object of this invention to pnovide
blade 18. The tensile stress holds the blade 18 rigid
a workrest blade and a blade support which is adapted
between the pairs of plates 20, 22 and 24, 26.
for use in the centerless grinding of extremely small diam
In FIG. 2, the guide plates 20, 22 and blade 18 are
eter workpieces.
Other objects and advantages of the present invention 35 shown in section. Each of the plates 20, 22 has a blade
aligning surface 44 and a work aligning surface 46 in
should be readily apparent by reference to the following
stepped relationship. The plates 20, 22 are held in the
speci?cation, considered in conjunction with the accom
upright portion 28 so that a blade slot is formed be
panying drawings forming a part thereof, and it is to be
tween the surfaces 44 in which the blade 18 is received.
understood that any modi?cations may be made in the
A work guide way is also formed between the surfaces
40
exact structural details there shown and described, with
46 and guides a workpiece 49 as it passes between the
in the scope of the appended claims, without departing
plates 20, 22 in a grinding operation. The plates 24, 26
from or exceeding the spirit of the invention.
have similar stepped surfaces which perform the same
A centerless grinder workrest blade constructed in
functions at the other end of the blade 18. Thus, the
accordance with the preferred form of this invention
utilizes a thin strip blade held under tension through the 45 plates 20, 22, 24, 26 not only align the blade 18, but also
provide convenient entry and exit guide surfaces for a
grinding area between the grinding wheel and the regulat
workpiece as it passes through the grinding area during
ing wheel. That portion of the blade which is in the
a throughfeed grinding operation.
.
grinding area is supported from its ends and it not backed
It will be appreciated that a thin strip of materia
up by other structure in the grinding area. The rigidity
of the blade is provided by the tensile stress therein which 50 may be used for the blade 18. In one application of the
invention, a blade of the dimensions .5 x .010 x 12
opposes de?ection and tends to reduce the magnitude of
inches and supported in the described manner was found
the vibrations of the blade.
to be eifective for grinding a workpiece of 5 inches in
A clear understanding of the operation and construc
length and .018 inch in diameter. The blade used was
tion of the workrest blade and support of this inven
tion may be obtained from the following detailed descrip 55 a strip of hardened and ground steel of the type com
mercially available for use as shim stock and feeler
tion and the attached drawings wherein:
gauges and found as a stock item in most machine
FIG. 1 is a perspective view of a centerless grinder
shops.
Prior to use an angle of 30 degrees was ground
workrest blade and support.
on the upper surface 48 (FIG. 2) of the blade 18 on
FIG. 2 is a section through the blade and support of
which a workpiece is supported. When supported and
FIG. 1.
60
constructed in the described manner, such a blade 18 and
iFIG. 3 is a partial plan View of the workrest blade.
supporting structure 32 do not interfere with the wheels
As shown in FIG. 1, the grinding wheel 10 is rotatably
10, 16 when they are closed together to the proper spac
supported in a wheelhead 12 on the machine base 14.
ing for producing the required small diameter. The
The regulating wheel 16 (shown retracted away from the
grinding wheel 10 to expose the workrest blade 18) is 65 blades of this type workrest are relatively inexpensive
and are easily replaced in the event of an accident which
supported on a slide 15 which is movably received on
might destroy or damage a blade and tooling costs are
the base 14. The regulating wheel 16 is supported in
appreciably reduced.
the housing '17 ?xed on the slide 15 and is adapted to
What is claimed is:
be rotated at a rate slower than the grinding wheel 10
1. In a centerless grinding machine having a base, a
to control the rate of rotation of a workpiece lying on 70
grinding wheel rotatably supported on the base, and a
the blade 18 and held thereon by the action of the grind
ing and regulating wheels 10, 16. In the grinding opera
regulating wheel rotatably supported adjacent the grind
3,094,817
ing wheel, the space between the grinding and regulating
wheels de?ning a grinding area, a device for supporting
workpieces in the grinding area comprising a thin strip
workrest blade non-rigid when tensilely unstressed, and
means at each end of the grinding area to hold an end
of said blade for support thereof through the grinding
area, said means operable to apply a longitudinal tensile
stress to said blade whereby said blade is maintained
rigid through the grinding area.
4
guide plates ‘in one upright portion having means to
secure one end of said blade therebetween, the guide
plates in the other of said upright portions having a mech
anism operable to hold the other end of said blade and
to apply a tensile stress thereto whereby said blade is
maintained taut through the grinding area to provide
rigidity of said blade.
4. In a centerless grinding machine having a base, a
grinding wheel rotatably supported on the base, and a
‘2. In a centerless grinding machine having a base, a 10 regulating wheel rotatably supported adjacent the grinding
grinding wheel rotatably supported on the base, and a
Wheel on the base, the space between the grinding and
regulating wheel rotatably supported adjacent the grind
regulating wheels de?ning a grinding ‘area, a device for
ing Wheel on the base, the space between the grinding
supporting workpieces in the grinding area comprising,
and regulating wheels de?ning a grinding area, a device
a support frame received on the base between the grind
for supporting workpieces in the grinding area compris
ing, a support frame received on the base between the
grinding and regulating wheels and having an upright
portion at each end of the grinding area, a thin ‘strip
workrest blade non-rigid when tensilely unstressed, means
to secure one end of said blade to one of said upright
portions, and means in the other upright portion to hold
the other end of said blade and to apply longitudinal
tension thereto, said means to secure and means to hold
ing and regulating wheels and having an upright portion
at each end of the grinding area, a thin strip workrest
blade non-rigid when tensilely unstressed, and a pair of
guide plates in each of said upright portions, each plate
of said pairs having a blade aligning surface and a work
aligning surface on one side thereof in stepped relation
ship, the plates of each pair held together in each of
said upright portions to form a blade slot and a guide
way respectively between said blade and work aligning
maintaining said blade taut through the grinding area to
surfaces adapted to receive said blade and to guide a
provide rigidity of said blade.
25 workpiece thereon, one of said pairs having means to
3. In a centerless grinding machine having a base, a
grinding wheel rotatably supported on the base, and a
secure one end of said blade in said slot thereof and the
other of said pair having means to hold the other end
regulating wheel rotatably supported adjacent the grind
of said blade in said slot thereof and to apply a tensile
ing wheel on the base, the space between the grinding
stress thereto whereby said blade is maintained taut
and regulating wheels de?ning a grinding area, a device 30 through the grinding area to provide rigidity in said blade.
for supporting workpieces in the grinding area corn-v
prising, a support frame received on the base between
References Cited in the ?le of this patent
the grinding and regulating wheels and having an upright
UNITED STATES PATENTS
portion at each end of the grinding area, a thin strip
workrest blade non-rigid when tensilely unstressed, and a 35 1,483,748
,Sanford _____________ __ Feb. 12, 1924
pair of guide plates in each of said upright portions, the
2,791,870
Horton ______________ __ May 14, 1957
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