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Патент USA US2405961

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Aug- 20, 1946-
I
F. J. LAPOINTE
2,405,961
‘ PULL HEAD FOR BROACHING MACHINESl
_
Filed Dec.
18, 1943
’
INVEN TOR.
Wg@ .fg/'manie
Patented Aug. 20,1946
2,405,961
UNITED STATES PATENT OFFICE
n
2,405,961
PULL HEAD FOR BROACHING MACHINES
Francis J. Lapointe, Ann Arbor, Mich., assignor
to American Broach & Machine Co., Ann Arbor,
Mich., a corporation of Michigan
Application December 18, 1943, Serial No. 514,733
5 Claims. (Cl. 279-79)
1
2
This invention relates to breaching machines
2, but showing` the locking member retracted to
and is concerned with the pull head of such a
machine in which the shank of the broach is rc
release position and the broach shank removed
from the bore of the tool head.
movably secured. It is customary to make the
smaller broaches with a round shank having a
transversely extending notch, usually arcuate in
While there is illustrated in the drawing and
hereinafter described, a preferred form of the
invention, it is contemplated that various modi
fications may be made by those skilled in the art
without departing from the spirit and scope of the
cross section, and to provide a pull head with a
bore to receive the shank and a cross bore inter
secting it in position to register with the notch so
appended claims.
that a locking Din may be inserted for holdingV the 10
broach in the pull head. Thisarrangement, how
'
As shown in the drawing, the pull head is
formed from a solid block of metal providing a
ever, is not entirely satisfactory, in that it re
body portion I of rectangular cross section and a
quires the notch in the broach shank to be care
shank 2 which is threaded at 3 for securement in
fully registered with the cross bore before the pin
the cross head of a broaching machine indicated
can be inserted, and also requires extreme ac 15 in dotted outline at 4. A circular lock nut 5 is
curacy in the construction of all of the parts to in
shown on the threaded shank 3 in accordance
sure that they shall fit properly.
with standard construction,
One object of the present invention is to pro
The block I is: provided with a bore 6 dimen
vide a new and improved pull head designed to re
sioned to receive the shank 'I of a broach 8, and,
ceive this type of broach shank, and provided with 20 as shown in Figs. 2 and 4, this shank 'l is formed
locking mechanism which shall be substantially
with a transverse notch 9 which is preferably ar
automatic in its engagement with the broach and
cuate in cross section. The locking member of
which shall be readily disengageable therefrom.
the tool head is round in cross section and of such
Another object of the invention is to provide a
a radius that it will ñt in the arcuate notch or
pull head having a locking member to cooperate 25 groove 9 of the shank 1. In the construction
with a notch in the broach shank and yielding
shown this round locking member is a cylindrical
means urging the locking member into position
pin I0 which is carried in a guideway II eXtendffor such engagement and permitting it to be
ing obliquely in the block I with respect to the axis
forced aside as the broach shank is entered in the
of the bore 6. This guideway is in the form of a
pull head.
slot cut transversely through the block I and
A further object of the invention is to provide
a pull head having a locking member designed to
opening through both side walls thereof, and, as
shown in Fig. 3, the end portions I (la of the pin I0
engage a notch in a broach shank and movable
project beyond the side Walls so as to be externally
along a path oblique to the axis of the shank so
accessible for moving. the pin manually, if de
arranged that the working strain on the broach ;, sired. The pin is held in place Iby a pair of snap
tends to tighten the locking member in its en
rings I2, I2 ñtted into grooves in the pin adjacent
gagement.
It is also an object of the invention to provide
a pull head with a spring-pressed locking mem
ber for engaging a broach shank and with means
externally accessible on the pull head for releas
ing the locking member at will or automatically at
the end of the stroke of the broaching machine.
Other objects and advantages of the invention
will appear from the following description taken
in connection with the drawing in which:
Fig. 1 is a side elevation showing a pull head
embodying this invention, with a broach inserted
therein.
'
Fig. 2 isa vertical section of the pull head taken
on a larger scale and showing the locking mem
ber engaged with the shank portion of a broach.
Fig. 3 is a transverse vsection taken as indi
cated at the line 3-3 on Fig. 2.
Fig. 4 is a vertical sectional view similar to Fig.
the side walls of the block I, as shown in Fig. 3.
The guideway II provides a path for movement
of the locking member Ill into and out of locking
position, this path extending divergently with
respect to the inner end of the bore 6 so that when
the pin is pushed inwardly along the path it is
automatically carried out of the bore’ 6. Spring
means is provided for holding the pin normally in
, its locking position, but whether such means is
included in the construction, or gravity is relied
upon` to carry the pin to locking position, it will
be easily forced back along the divergent guide
way I I when the end of the shank 'I is entered in
the bore S, and this action is somewhat facilitated
by reason of the fact that the locking member I0
is circular in cross section so that it can either
slide or roll along the slot II when pressure is
applied in the direction of the axis of the bore 6
by the entry of the shank 'I therein.
2,405,961
3
The spring means for controlling the locking
together with a spring pocketed in the second
bore and reacting against the plunger to urge
member I0 comprises a coil spring I3 and a
plunger I4 which is slidably mounted in a bore
I5 extending parallel to the bore B in the block I.
The plunger is formed with a notch IE which
embraces the locking pin IB, as seen in Figs. 2
the pin yieldingly into position for engaging the
notch in the broach shank.
2. A pull head to receive a broach shank in
which there is a transverse notch of arcuate cross
and 4, and the spring I3 is pocketed in the inner
end of the bore I-5 so as to urge the plunger I4
outwardly and thus carry the pin It)> toward its
locking position, in which it will engage in the 10
notch 9 of the broach shank 'I. When the bore
6 is empty, the spring-pressed movement of the
locking member l0 is arrestedby encounter of
the pin I0 with the lower end Ha of the guide
slot I I; but in locking engagement with the notch 15
9 the pin I0 may not reach this end surface -I Ia
of the slot I I, since it will tend to be. wedged
'between the inclined top wall IIb of the slot II
and the surface of the notch Siv in the shank 'I.
Preferably, the pin will stop just short of the end 20
of the slot so as to insure its ñrm engagement
in the notch 9 of the broach shank. Then, dur
ing the working stroke, a pull on the broach will
tend to wedge the pin I Il more tightly between
the wall of the notch 9 and the inclined wall IIb 25
of the guide slot and will press the opposite side
of the broach shank 'l ñrmly against the boreY
6, thus holding it positively and steadily in work
ing position in the pull head.
’
When it is desired to remove the broach from
the pull head the operator will place his thumb
and first finger against opposite end portions IIJa
of the locking pin Ill and push the pin upwardly
along the inclined guideway I I out of engagement
section, said head having a bore to ñt the shank,
a slot extending transversely through the head
and obliquely with respect to the axis of said bore,
said slot intersecting the bore at the portion
thereof which is occupied by the notch of the
broach shank when said shank is inserted in
working position therein and extending from said
intersection divergently with respect to the inner
end portion of the bore, a round locking pin in
said slot dimensioned to ñt the notch in the shank
and movable in the slot into said intersecting
portion thereof for such engagement, a second
boreA in the pull head parallel to the first with a
plunger slidable in said second bore and formed
with a notch in which said locking pin is captive,
together with a spring pocketed in the second
bore and reacting against the plunger to normal
ly move the plunger outwardly and'urge the pin
yieldingly into position for engaging the notch
and in said broach shank.
'
i
'
3. A pull head to receive a broach shank in
which there is a transverse notch of arcuate cross
section, said head having a bore to ñt the shank,
so a slot extending transversely through the head
and obliquely withf respect to the axis of said
bore, said slot intersecting the bore at the por
tion thereof which is occupied by the notch of
the broach shank when said shank is inserted in
with the notch 9, so that he can grasp the broach 35 working position therein and extending from- said
intersection divergently with respect to the inner
shank with his other hand 'and withdraw'it from
the pull head. In some operations it is desirable
to have this release eiîected automatically, and
for that purpose the plunger'Ill is equipped with
end portion of the bore, a round locking pin in
said slot dimensioned to fit the notch in the shank
and movable in theslot into said intersecting
a tappet screw I ‘I threaded into its outer end and 40 portion thereof for vsuch engagement, and a sec
ond bore in the pull head parallel to the'ñrst
provided with> a lock nut I8 so that the screw
with a plunger slidable in said second bore and
can be adjusted to engage a part of the broach
ing machine at the proper instant in the return
formed with a notch in which said locking pin
stroke of the pull head and thus release the broach
is captive.
to permit its insertion in a new work-piece.
With the construction shown it is a compara
tively sirnple matter for the operator to insert
the broach in the pull head, becauseeven though
the shank '1. is inserted with the notch 9 turned
away from the locking pin I0, the operator can
easily rotate the shank in the bore 6 until the
notch 9 is brought into position to receive the
pin I Il, the latter being spring-pressed to its lock
ing position and thus entering the notch auto
matically when theparts are so registered.
4. A pull head to receive a broach shank in
which there is a transverse notch of arcuate
cross section, said head having a bore to nt theV
shank, a slot extending transversely in the head
I claim as my invention:
1. A> pull head to receive a broach shank in
which there is a transverse notch of arcuate cross
and obliquely with respect-to the axis of saidl
bore, said slot intersecting the bore at the por
tion thereof which is occupied by the notch of the
broach shank when said shank is inserted in
working position therein and extending from said
intersection divergently with respect to the inner
end of the bore,- a round locking pin in said slot‘
dimensioned to ñt the notch inthe shank and
movable in the slot into said intersecting portion
thereof for such engagement, and a second bore
in the pull head parallel to the first with a plunger
section, said head having a bore to iit the shank,
a slot extending transversely'through the head 60 slidable vin said second bore and formed with' a
transversely extending notch, the width of said
and obliquely with respect to the axis of said
last mentioned notch being substantially equalA
bore, said slot intersecting the bore at the por
to the diameter of said pin and said slot opening
tion thereof which is occupied by the notch of
through the pull head at one side thereof whereby
the broach shank when said shank is inserted
in working position therein and extending from 65 the pin may be inserted through the open end of
the slot and engaged in the notch of the plungersaid intersection divergently with respect to the
becoming captive therein and being movable along
inner end portion of the bore, a round locking
pin in said slot dimensioned to nt the notch in
the oblique slot by axial movement ofthe plunger
the shank and movable in the slot into said in
in said second bore, said pin comprising the sole
tersecting portion thereof for such engagement,
means retaining the plunger in said second bore.
the-ends of said pin projecting from said slot
5. A pull head to receive a_ broach’shank in
beyond the side walls of the pull head, a second
which there is a transverse notch, said head hav
bore in the pull head parallel to the iirst'with a
ing a bore to slidably receive the shank; a slot ex
plunger slidable in said second bore and formed
tending transversely in the'head and obliquely
with a notch in which said locking pin is captive, 75 with respect to the axis of the-bore, said slot
5
2,405,961
intersecting the bore at the portion thereof which
is occupied by the notch of the breach shank when
said shank is inserted in Working position therein,
said slot extending divergently from said inter
section with respect to the inner end of the bore,
being approximately that of the locking pin and
said slot opening through the pull head at one side
thereof whereby the pin may be inserted through
the open end of the slot and engaged in the notch
of the plunger, said pin being loosely mounted in
the notch in the plunger and bodily movable radi
a locking pin in said slot dimensioned to be seated
in the notch in the shank and movable in the
ally therein, longitudinal movement of the plung
slot into said intersecting portion thereof for such
er being simultaneously accompanied by radial
engagement, a second bore in the pull head par
movement of the locking pin in the plunger notch
allel to the first, a plunger slidable in Said second 10 and oblique movement of the locking pin in the
bore and formed with a transversely extending
divergent slot.
notch, the width of the last mentioned notch
FRANCIS J. LAPOINTE.
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