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Патент USA US2261899

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Nov. 4; 19.41.
F, J, BECHERPr
2,261,899
COLLET
Filed Api‘il 6, 19:59
INVEN‘ILOR
FRED d. BECHERT
ATTORNEY-5 .
Patented Nov. 4, 1941
I
2,261,899 '
UNITED STATES PATENTI OFFICE-‘l ~ '
COLLETV
Fred J. Bech'ert,’ Stamford, Conn.,'a'ssignor to The '
New Britain Machine Company, New Britain,
Conn, a corporation of Connecticut
'
"
Application April 6, 1939, Serial No. 266,259
2 Claims. (01. 279-46) 7’
My invention relates to a chucking means and
more particularly to an improved form of collet
and, pad.
‘
jaws or pads 9-9. In the form shown each jaw
has a cylindrical seating surface I0 extending
from front to rear, and each pad _9 has a‘ corre
. It is now common practice to insert false jaws
or pads in a collet and the commonest method
sponding cylindrical seating surface II, extending
for holding the pads in place is by means of
radial movement of the pads in the jaws. ‘Each
Jaw has a generally radially outwardly extending
abutment surface‘or shoulder I2 and each pad
screws extending radially through the collet jaws
and into the pads. In order to change pads when
from front to rear, so as to limit the outward
so held in place it is necessary to move the collet
at the rear has a corresponding surface or
outlof its seat in order to render the screws ac 10 shoulder I3 to abut the surface; I2. , These sur
cessible.
Other means for holding pads which
have been proposed involve the use of screws or
other holding means, accessible from the front of
the collet to avoid the necessity of backing the
collet out of its seat for pad changing. Devices
of that sort are subject to the objection that the
holding screws may be accidentally backed out
and lost or in some cases interfere with the tools
faces I2-—,I3 are preferably slightly inclined so
that when the pad, 9 is drawn toward, the right
the inclined surfaces ;I2-I3 tend to urge or cam
the pads radially outwardly into engagement
with
the
jaws»
'
,
,
‘
.
-
‘
The pads are secured in place by improved
means interposed between the jaws and pads ac
cessible from the front and held by the jaws and
pads themselves against loss or dislodgment when
It is an object of ,my invention to overcome the 20 the parts are assembled. In the form illustrated
above di?iculties and, in general, to provide an
each jaw has a generally radially outwardly ex
improved form of collet and pad.
,
tending ?ange or- part I4,v which may?t into a
working adjacent to the collet.
'
A more speci?c object is to provide a collet
counterbore I5 in the front of the jaws. There
and pad with means for holding the latter in
is a space I6 between the rear of the part I4 and
place and positively preventing the same from 25 the bottom of the counterbore I 5, so that the pad
working loose when the pads are assembled with
may be moved toward the left to disengage sur
the collet jaws.
faces I2—I3 so the pads may be dropped radially
Another object is' to provide an improved form
inwardly for removal. In the preferred form, one »
of collet and pads, relatively simple and cheap to
of the jaw and pad members carries means en
manufacture and effective in use.
' 30 gageable with the other and prevented from dis
Other objects and various features of inven
lodgment by engagement with one of the parts.
tion will be hereinafter pointed out or will be
As illustrated, each jaw is provided with one or
come apparent to those skilled in the art.
more threaded bores I'I, preferably extending
In the drawings which show, for illustrative
generally longitudinally inwardly.
A threaded
purposes only, a preferred form of the inven 35 member I8, preferably in theform of a so called
tion
headless set screw, is threaded into the bore I‘!
Fig. 1 is a side view of a collet, parts being
and extends outwardly into engagement with the
shown in central vertical section to illustrate fea
rear portion of the ?ange part I4. The latter
tures of the invention; and
preferably has a generally countersunk recess I9
Fig. 2 is a fragmentary front View of the collet 40 in the rear face thereof and the screw I8 is pref
and other parts shown in Fig. 1.
erably chamfered off for engagement with the
The invention will be described as embodied in
upper portion of the countersink I9, so that when
a draw-back type of collet, though in its broader
the screw I8 is backed out, that is, moved toward ‘
aspects the invention is not so limited. The collet
the right, the entire pad will be urged toward
45
may be carried by means such as a rotating
the right and the chamfered end of the set screw
spindle 5, having a spindle nose 6 with a rear
will also urge the pad radially outward at the
wardly inclined or conical collet seat 1.‘ The col
front end. The member not carrying the set
let includes a plurality of jaws 8-8, three being
screw, in this case the pad, is provided with an
shown, which jaws have outer surfaces to ?t the
opening, say in the form of a hole 20, in general
seat ‘I, so that when the collet is drawn axially 50 alignment with the set screw I8, and the latter
rearwardly or to the left as viewed in Fig. 1 the
is provided with a depressed wrench socket 2I
jaws will move in radially, to grip the bar stock
for receiving a wrench inserted through the hole
or other work, all as is now common practice and
20, whereby the screw may be actuated.
will be understood.
When it is desired to remove the pad a wrench
The collet jaws 8-8 are provided with false
is inserted and the screw I8 turned into the
2,261,899
bore l1, after which the pad may be moved
it is to be understood that various changes may
toward the left to disengage the surfaces l2-l3
be made within the scope of the invention as
and permit the pad to drop radially inwardly
de?ned in the appended claims.
I claim:
for removal. A new pad may then be applied
by ?rst engaging the surfaces [2-43 and then
by means of a wrench backing the set screw [8
outwardly in its bore ll, so as to cause engage
ment of the forward end of the screw with the
rear portion of the ?ange part Hi. It will be
.1. A collet having a plurality of spring jaws
including tapered jaw members and spring legs
rearwardly of said jaws, removable pads for said
jaw members, said jaw members each having a
generally radially extending undercut abutment
seen that so long as the pads are in place on 10 surface toward the rear thereof, the inner diame
the jaws the screws l8 cannot become dislodged. 4 ter of each of said jaw members from said abut
' ment surface to the rear end of said jaw mem
and lost nor can they project axially outwardly
beyond the face of the jaws. Therefore, there’
lbers and the inner diameter of said spring legs
being at least as great as the inner diameter of
is no possibility of losing the screws nor pos
sibility of their interference with. tools-acting 15 the jawfmember at the base of said abutment,
said pads having abutments to fit said abutment
adjacent to the front of the collet. Instead of
surfaces on said jaws, and means for holding
employing the countersink IS the rear, part of
said pads in place on said jaws.
the flange may be inclined radially outwardly
2. A collet having a plurality of spring J'aws
and rearwardly and the screw [8 may be screwed
into a bore inclined to the axis of the collet, so 20 including tapered jaw members and spring legs
rearwardly? of~said jaws, removable pads'for-said
as to urge the pad toward ‘the right andiradially
jaw‘ members, said jaw members each having a
outwardly, as will be understood.
' ‘By reason of my invention the manufacture of
generally radially extending undercut abutment‘
the'jaws and pads is somewhat simpli?ed. The
only surfaces, with the possible exception of the
surfaces .|2—l3 and the stock gripping surfaces,
which‘ need grinding 'or other accurate ?nishing
are‘ the surfaces l0—-| l, and those'surfacesare
surface toward the-'rear‘thereof, the inner diame
ter of each of said jaw members from said abut-'
ment surface to the rear end of said jaw mem-‘
hers and the inner diameter of said ‘spring legs
being at least as great as the inner diameter of
the jaw ‘member at the, base of said abutment,
of a uniformdiameter and continuous from end
tofend, that is to say, ‘the ?nishing of the sur
25
30 each said'jaw member having a longitudinally
face III ‘is a simple bore grinding operation‘ and
the. ?nishing of the surface H is an equally
extending surface thereon forwardly of said un:
of each ‘jaw from' the surface l2 to the rear
face yon-said jaw member, each said pad having,
of the? jaw " member and the inside diameter
an outwardly directed‘ ?ange thereon at the
front,’ and a screw threaded in each jaw member
and engaging the rear of said ?ange to hold'the
dercut abutment surface,- each said pad having
an'abutment to engage said abutment‘surface
simple“ operation; The grinding or ?nishing of
one-said jaw member and‘ having a longitudinally
the surface 12 on each jaw is greatly facilitated
by reason of the fact that the inside diameter 35 extending surface to ?t the corresponding sur-'
of- the spring leg carrying the jaw are at least
as great as the inside diameter of the jaw mem
ber at the base of the abutment surface I2._ ' While the invention has been described in con
siderable detail and a preferred form'illustrated,
40 pad in place on the said jaw‘ member.
'
FRED J. BECHERT.
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