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Патент USA US2131965

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Oct. 4, 1938.
F. NELL
2,131,965
THREAD FORMING MECHANISM
Filed June 16, 193 6
3 Sheets-Sheet 1
Oct. 4, 1938.
‘
F. NELL
2,131,965 '
THREAD FORMING ‘MECHANISM
Filed June 16, 1956
3543
'
3 Sheets-Sheet 2
Oct. 4, 1938.
F_ NELL
2,131,965
THREAD FORMING MECHANISM
Filed June 16, 1956
3 Sheets-Sheet 3
7
‘90 7
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BMW”
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Patented Oct. 4, 1938
2,131,965
UNITED STATES
PATENT OFFICE
2,131,965
' THREAD FORMING MECHANISM
Frederic Nell, Waynesboro, Pa., assignor to Lan
dis Machine Company, Waynesboro, Pa., a cor
poration of Pennsylvania
Application June 16, 1936, Serial No. 85,563
18 Claims.
(G1; 10—145) '
This invention relates to thread-forming mech~
,It is another object of this invention to improve
anism, and especially to taps of the type designed upon
thread-cutting mechanism of the
to cut tapered threads and to collapse at the end type- tapered
disclosed in the Newman Patent No.
of each thread-cutting operation.
1,811,802, in such manner as to facilitate‘ the
H5
The present application is in part a continua~ return
of the chaser-controlling cam to cutting. 5
tion of the subject matter of my co-pending ap
position after it has been operated to collapse
'plication, Serial No. 5,129, ?led February 5, 1935. vthe chasers.
I
'
'
.
Throughout this speci?cation the’ term
It is a further major object of the present in
“chaser” is used in its broad as well as its limited
v10 sense. That is, it may mean the actual cutting vention to devise ~improved adjustable means for
selecting the. desired length of thread to be cut. 10
tool and its carrier or holder, or the de?nition
may be con?ned to the cutting element alone. .
It is a primary object of the present invention
to devise a thread-cutting machine having a
15 series of slidable chasers detachably connected
with a cam element, in association with means
for accurately positioning all of the chasers si
multaneously so that during assembly a single
movement of the cam element will readily and
20 assuredly pick up all of the chasers for inter
connection therewith. More speci?cally, the
present invention contemplates carrying out the
preceding object where the cam element is cen
This object contemplates, both individually and '
in combination, a major adjustment of the thread
length and a minor or limited adjustment of the
thread length.
'
'
'
r . Still another major object is to provide, in a .15
collapsible thread-cutting machine, cushioning
means for preventing shock or damage upon axial
movement of the chaser controlling means, and
especially, to devise an improved cushioning
means that becomes eiiectivewhen the controlv
cam is shifted in a direction to place the chasers
in thread-cutting position.
It is a further and related important object of
trally disposed and designed, upon axial move
25 ment, to positively move the chasers radially in the present invention to provide a combined cush
,ioning'means‘ and an adjustable stop for yield
both directions.
ingly resisting the movement of the parts and
It is another major object of this invention to checking them during their return to operative
provide new and improved means for adjusting a
.30
chaser-controlling cam element relative to its
operating means. In this connection it is an
object to provide an adjustment feature which
permits the removal of the chasers for sharpen
ing without in any way dismantling the machine
proper.
35
~
»
It is another important object of the present
invention to devise a thread-cuttingmachine
having a set of removable chasers which may be
replaced accurately without disturbing the, origi
nal setting of the machine and therefore with
40 out requiring trial cuts to place the machine in
condition to cut the same size threads.
or thread-cutting position.
'
The foregoing and further objects of themes
ent invention- will clearly appear upon a consider
ation of the following detailed description when‘
taken in conjunction with the accompanying
drawings wherein:
.
‘
Figure 1 represents a longitudinal section taken
vertically through a collapsible tap comprising a
preferred form of the present invention. In thisv
‘view the manually operable lever that stands
- vertically is-shifted 90'’ out of its true position for
convenience of illustration. This and the remain
ing parts are so disposed as to extend thechasers
. to thread-cutting position.
.
It is a further object of my invention to devise
Figure 2 is an end view of the tap of Figure 1,
a thread-cutting machine comprising a_ main showing the face of the head which carries the
body and a detachable head designed to carry chasers; ‘
»,
'
45 chasers, with a chaser-positioning cam that is
Figure 3 is a face view of a chaser comprising a
fully retractible to permit very quick chaser re
cutter and the slidable holder upon which it is
moval and immediate substitution of heads of . mounted. thev cutter being shown in the form
different sizes.
that it takes after being sharpened a number of
A further object of the present invention re
50 sides in the provision of improved means for
collapsing the chasers of the thread-cutting ma
chine, and especially to devise improved collaps
times;
'
_
Figure 4 is fragmentary sectional view taken
substantially on the plane indicated by the line" ~
4-4 in Figure 2;
p' .
ing means for a tap which embodies a positively ‘ "Figure 5 is a sectional View similar to Figure 1
controlled receding action for cutting tapered . but showing the parts in the position that they
threads.
I
-
.
.
‘assume when the chasers are collapsed;
_ m 55
2
V
- 2,131,965
Figure
6
is
a fragmentary sectional view
through only the tap body and a portion of the
mechanism which surrounds the same, taken sub
stantially on the line 6—5 in Figure 2;
Figure 7 is a view corresponding to Figure 6
but showing the mechanism surrounding the body
in a position corresponding to the collapsed posi
tion of the chasers;
>
Figure 8 is a fragmentary sectional view'taken
10 longitudinally of only the body of the device and
a surrounding cushioning and stop‘ means, as.
seen when looking substantially upon the plane
of line 8-3 in Figure 2. In this view the parts
surrounding the body are so disposed as to cor
15 respond with thread-cutting position of the
chasers;
Figure 9 is a view similar to Figure 8 showing
the mechanism surrounding the ‘body in the
position that it assumes upon collapse of the
20 chasers;
Figure 10 represents an enlarged fragmentary
ers will be positively drawn radially inwardly.
The cam member 24 has a rearward cylindrical
extension 21 which rather snugly ?ts the bores
of the body and head of the machine to guide the
cam member and lend support to the latter dur- 5
ing threading operation, and the cam member
is internally threaded to receive the externally
‘threaded end of a coupling rod 28. As will be
seen later the cam member is‘ axially*adjust—
able relative» to this rod and may be locked with 10
respect thereto in any desired position of adjust
ment. The rearward end of the rod 28 is periph
erally grooved and detachably coupled to an in
tegral forked forward extension 29 of a plunger
30. The plunger 33 is disposed within the bore 15
of the body 15 and is designed for reciprocation
therein.
The plunger 30 has a central slot 32 formed
sectional view taken through‘ the check valve as
transversely therethrough, .and to the opposite
walls of said slot are secured shoes 33. These 20
shoes are slightly inclined from the vertical
and are designed to ?t complementally within
sembly in one end of the pistonof Figures 8
and 9;
V
Figure 11 is a fragmentary section correspond
ing to the left-hand ends of Figures 1 and 5 but
with the’ chaser-controllingv cam so adjusted
as to be completely retracted to permit ready
removal of the chasers; and
I
Figure 12 is an enlarged sectional view' similar
to Figure 11 but showing a slightly modi?ed
type of cam-adjusting means.
_
'
The improvements and additions illustrated
similarly inclined grooves 34 that are formed on
opposite sidesvof a vertical bar 35, which is
mounted for vertical reciprocation between a 5'7‘25
pair of substantially semi-cylindrical gibs 36.
These gibs prevent movementof-the bar 35 lon-'
gitudinally of the tap'body l5 while permitting
it to reciprocate radially‘ through [the body, I
‘and they are so designed as to have no inter- ‘5'30
ference with longitudinal movement of the
plunger .and'its shoes 33. ‘All of this and some
of the further structure yet to‘ be described is
1,811,802,
more fullyanddisclosed
thereforein only
Newman‘Patent
sufficient descripNo. ‘s35
disclosed in association with collapsible taps
tion and explanation‘will be here given to pro.
of the type shown in Newman Patent 1,811,802 . vide a general understanding of the arrange
and my co-pending application Serial No. 5,129, ' ment and mode of operation of the old parts ‘of
in the drawings and about to be described are
35
J40
aforementioned; and although these are desir
able forms it will be appreciated that my im
provements and additions may be used on many
other thread forming machines within the
knowledge of those skilled in the'art and within
the scope of the appended claims.
With further reference to the drawings where
in
like numerals are employed to designate like
:45 parts
and'with particular reference for the mo
ment to Figures 1 and 2, the foundation or the
main body structure of the preferred embodi
ment of this invention comprises an elongated
hollow body l5 to which is secured a chaser car
50 rying head I6 by‘ means of detachable studs I'I.
At one end the body has an integral tail stock
I8, and at the other end the head l6 carries a
plurality ‘of cutting elements in- the form of
circular chasers l9 secured to radially slidable
chaser holders 20. The holders 20 are insertable
through and radially slidable within a corre
sponding series of slots 22 in the front face of
' head l6, and at their inner ends are provided
to with ?ngers 23 which form with the’bodies of
» the holders a series of cam slots 23a.
The head
I6 is hollow and shaped internally to 'slidably
but non-rotatably receive a tapered chaser-con
trolling cam member 24, which has on its periph
ery a set of integral ?ngers or wings 26 that
65
cooperate with the cam body to provide a series
of cam grooves 25. The ?ngers 23 of the chaser
‘holders are received within the cam grooves 25
of the cam member, and the wings 26 of the cam
member are received in the cam grooves 23a- of
the chaser holders. Therefore, as the cam mem
thevillustrated' machine.
-
It will be perceived that any downward move-‘7210
ment of the bar 35 will cause the grooves 34 to
exert a camming action on the shoes 33 to force
the shoes 33, and with them the‘plunger 30,
rearwardly.
After a predetermined downward '
movement of the bar, it will come to a position§45
where its horizontal platforms 3!, which open
rearwardly from the grooves 34, are brought into
horizontal alignment with horizontal bottom
faces 38 on the shoes 33.
At this moment as
shown in Figure 5, shoes 33 are permitted to ride?
rearwardly over the faces 38 and thus permit
the plunger 30 to be retracted further rearward
ly at any desired speed as they are no longer
under control of the cam grooves 34 of the verti
cal bar 35.
*55
The purpose of the mechanism just described
is to ?rst impart a gradual receding motion to
the chaser-controlling cam 24 to thus cut a
tapered internal thread within a piece of work,
(such, for example, as a valve housing or pipef‘m
which rotates relative to the tap), and thereafter
upon completion of the taperedthread to permit
spring means ' (yet to be described) to quickly
shift the plunger 30 rearwardly and collapse the
chasers. The mechanism for causing vertical? 65
downward movement of the bar 35 gradually to
produce a tapered thread is as follows.
Theupper end of the bar 35 has an integral
cam element 39' in the form of a shoe which is
slidably. received in a cam groove 43 of an in-iwm
clined longitudinally arranged barv 42. At its
rear end the bar 42 is fastened at 43 (and may
ber is moved forwardly or to the left in Figure 1, . be fastened at 43a. to’ obtain a different degree
the chaser. holders will be positively cammed
radially outwardly; and Vice versa, as the cam
member is moved rearwardly, the chaser hold
of inclination of the groove 40-) ion abracket 44
which forms an integral part of a controlling-L75
collar 45 that is slidably mounted on the'tap
body I5. At its forward end the bar‘42 is piv
oted at 46 to the control collar 45. Upon mov
ing the ‘control collar 45 with its attached bar
42 rearwardly, the inclined groove 40 will cause
the coacting shoe-39 to move downwardly along
the groove and thus vertically shift the bar 35
downwardly.
’
' '
1
'
Rearward movement of the collar 45 is brought
housing a'spring assembly. comprising a small
cylindrical shell 64, which at its closed endis
constantly in'abutment withthe collapsing ring 63
‘and which contains a long relatively light spring
forward
65 ‘extending
end offorwardly
the control
into
collar
contact
45. with
A pinthe
65
‘is secured to the collar 45 and projects into the
spring 65 a sufficient distance to insure that the
'10 about by interconnecting it with the vpiece of latterv will . be maintained in proper position.
Spring 65, for a purpose later to be explained, is
work being threaded so that as the cutters enter always under some compression with a tendency 510
the piece of work the latter will push the collar
to urge the control collar 45 and the collapsing
45 axially of the tap in a direction away from J ring
53in opposite directions.
the work. This interconnecting mechanism is
‘A second and heavier spring 68 is disposed with
'
_
15 as follows:
in a cylindrical bore 67. of the control collar. This £15
The control collar 45 has a series ‘of integral
radially extending eyes 47 through which freely spring reacts against vthe forward end of the con
trol collar and is normally held in either neutral
pass a corresponding series of threaded rods 48. ‘or
but very' slightly compressed position by a
Nuts 49 are threaded upon the rods 48 so that
sleeve
59, which telescopingly receives the shell
upon relative adjustment of the eyes 41 with re
64 and which is held against removal by a plate?-20
spect to the rods 48 the adjustment may be main
tained by locking the nuts against the eyes 41 (see ‘l?. The latter is secured to'the control collar 45
and extends downwardly as‘far as a cut-away
also Figure 4).
1
surface 12 on the outer end of thesleeve 69-.
The forward ends of the rods 48 are secured to ' ‘ As shown in Figure 6, the parts are in the posi
25 a corresponding set of links 50 which ‘in turn are
tion that they assume at the beginning. of 2.5.25
rigidly secured to a set of forwardly extending threading
operation. However, as rearward move
pins 52 that are threaded into and locked with ment of the collar’ 45 is brought about in the
respect to a work engaging ring 53. The ring 53
manner before explained, the long spring 65 im
surrounds the tap head adjacent the chasers and
30 is peripherally grooved to receive a channeled oil mediately begins to be further compressed and,
ring 54 provided with a socket 55 adapting it for when the rear end of the sleeve 69 comes intoi?30
the reception of a pipe (not shown) that supplies contact with the collapsing ring 63 the heavier
spring 68 begins to become compressed. This
a cutting lubricant. The lubricant passes to the
compression occurs because the ring 63
several chasers individually through small ports 5! spring
under pressure from the channel of ring 54. As cannot move rearwardly until the plunger 30 is
the ring 53 is in abutting contact with the work, released by the vertical bar 35. This release isi'i85
it is moved gradually rearwardly relative to the timed to ?rst permit adequate spring compres
tap body upon relative rotation of the work and‘ sion-that is, the bar surfaces 38 reach the level
of the shoe surfaces 31 at a point where the de
, the tap; or, otherwise stated, the tap body gradu
sired spring compression is obtained. There
ally moves forwardly in accordance with the pitch
after, upon releaseof the shoes 33 the springs areii?o
of the thread being cut because its cutting ele
permitted to react and kick the collapsing ring 53
ments l9 are entering the piece of work, with the rearwardly, thus withdrawing the chaser-oper
result that the control collar 45 is forced rear
wardly. Preferably the work is rotated in ?xed ating cam to the position illustrated in Figure 5.
" 45 axial position and the tap, while non-rotatable, is At this time the spring assembly will be in the
position illustrated in Figure '7.
{.45
positively advanced in ‘well known manner by
"At or just after the release of shoes 33 from the
means of a lead screw.
'
I
bar ‘grooves,'the control ring 45 engages the col
At the rear end of the body l5 there is disposed
a manually operable lever 56 which is projected vlapsing ring so that the shoes and the plunger 35
I Will be carried rearwardly in positive manner at
" 50 into the body and pivoted thereto at 57 and
i
the same rate as the collar (instead of at the much-e50
which has a camming toe 58 ,slidably engageable slower
rate of the time interval prior to shoe re
with the forward end wall of a slot 59 formed in
lease), if for any reason the springs should fail
the body of the plunger 30. Upon rocking this to
kick the collapsing ring rearwardly.
lever the plunger may be shoved forwardly in a
After
the withdrawal of the chaser-operating
55 manner later to be explained in detail, and it will
be appreciated that various other arrangements cam to the position illustrated in Figure 5, therear55
is a/spring tendency to urge collar 45 forwardly;
known in the art may be utilized for this purpose.
but
this cannot vbe done without raising the bar
At the extreme rear end of the body {5 there is
provided a transverse pin 60 which passes through - 35 vertically, and'such' vertical movement is pre
60 ‘the plunger 30 and which is movable forwardly vented because the bar surfaces 38 will be pressed
and rearwardly in a longitudinal through-slot 62 against the lower shoe surfaces 31 to lock the-1; .60
bar 35 against vertical movement and in this way
formed in the body l5. The extremities of the
pin 60 are received in a collapsing and expanding lock the collar 45 against forward movement. It
ring 53 that is mounted for reciprocation on the therefore becomes necessary to start the forward
or return movement by manually operating the
‘body l5.
In a manner now to be set forth the
lever 56 to force the plunger 30 forwardly until its-2.65
springs previously referred to are designed to shoes
33 laterally enter the bar grooves 34 and
shove the collapsing ring 63 rearwardly upon com
permit upward travel of the bar 35.
pletion of a full tapered thread, thus acting
' Due to the inclination of the grooves 34, it would
through the pin 60, plunger 3!] and the chaser 'be
difficult to use the lever 55 alone to complete
v70 controlling cam 24 to quickly withdraw the chas ' the return or forward movement of the plunger;:
ers inwardly away from the completed thread and To eliminate this difficulty the elongated spring 70
thus permit the piece of work to be removed easily 65 serves a still further function by reacting di
and without damage to the threads.
'
' .
With reference now to Figures-6 and 7, the con
trol collar 45 has a segmental portion, thereof
. rectly against‘ the collar 45 to urge it forwardly
and thus lift the bar 35 vertically. The spring 65
thus serves the triple function of (11 augmentingg'ls
2,131,965
4
the kicking action of the spring 68, (2) assuring a
locking action of the mechanism in collapsed
position regardless of the length of the thread that
‘has been cut and (3) facilitating the completion
which will permit a slow escape of the air rear
wardly into the passage 81 when the collar 45 is'
shoved forwardly by the manually operable lever
55.
of a return movement of the mechanism to
thread-cutting position.
.
Preferably, another spring assembly, construct
ed, mounted, and arranged exactly like that just
described, will ‘be disposed at a diametrically op
'11) posite locus in the control ring for purpose of
balance and smooth action.
Reference will now be had to Figures 8 and v9,
wherein there is disclosed a‘ major adjustment for
thread length, and a device for cushioning the
<15 shiftable mechanism upon its return to thread
cutting position. As seen in these views the con
trol collar 45 has a segmental portion shaped to
receive between it and the body I5 a number of
cooperating parts. . This shaping includes the
provision of a longitudinal through-slot 13 within
the collar for reception of a rack bar 14 which
is slidable in the guideway or slot 13 and which
has a number of teeth forming interdental spaces
15 facing radially outward toward the‘ collar.
25 Fitting into any one of these spaces is a tongue '16
formed on a plate 11 which is detachably secured
to the forward end of the collar 45 by a cap screw
18. In this way the rack bar may be adjusted
forwardly or rearwardly and locked in any one
of a number of positions corresponding to the
number of interdental spaces for a purpose later
to be explained.
‘
The rack bar has a longitudinal slot 19 into
which projects a pin 89 formed as part of a
When the forward end of the piston comes into r
abutment with the end wall of the cylinder, for
ward motion of the collar 45 is stopped and at this
time the position of the collar 45 will of course
depend upon the position of the stop' lug 9i of
the rack barrelative to the collar 45. This‘ rela- >_
tive position is predetermined through selectionv
of any one of the interdental spaces 15 for en
gagement by the ?nger "I6 as previously pointed
out to determine the thread length. Variation of
the thread length follows from the fact‘ that this»; 15
adjustment varies the point at which the shoe 39
will be‘ located along the groove 40 at the start
of the tapping operation. If it is desired to vary
the thread length by an amount less than the dis
tance between a' pair of adjacent interdental‘ .240
spaces 15, this minor adjustment may be effected
by loosening 'thenuts 49 in Figure 4, sliding the
collar 45 slightly relative to the rod 48 and then
relocking the nuts 49.: The last mentioned ad
justable feature, however, is provided primarily; 25
to set the work-engaging structure in such posi
tion that a receding action will start simultane
ously with the ‘thread-cutting operation.
With particular reference now to Figures 1 and
11, as aforestated the chaser-controlling cam", 30
member 24 is adjustable longitudinally of the
threaded rod 28. The means for effecting this ad
.justment and for locking the parts in adjusted
‘position are as follows. The'forward end of the
rod 28 is tapped to receive an externally threaded; 85
threaded element 82 that is screwed into the ' sleeve 96 which extends, slidably through the
collar. Slot ‘[9 also receives a pin 83 formed on a
front end of» the cam member 24 and which is
square element 84 that is set into a small piston provided with a head 91, that can be rotated by
85 which reciprocates longitudinally in a barrel an actuating tool. The threaded portion of
or cylinder 86 that is longitudinally arranged and sleeve98 has a transverse slot therethrough which, 40
P40 attached to the tap body l5. Therefore, during . receives a pair of diametrically opposed . brake“
rearward travel of the collar 45 the pin 80 will shoes 98 that are slidable radially in ‘the slot and
engage the pin 83 and move the piston 85 rear
that may be forced‘ outwardly into locking en
wardly ‘in its cylinder. During‘ this movement gagement with diametrically opposite portions '
air is admitted to the working chamber of the "of the tapped bore of rod 28'by rearward motion.
piston cylinder by way of a longitudinal passage of a tapered stem 99~that ?ts between the shoes
81 in the piston, a passage 88 through the square and forms an integral part of a manually adjust
element 84, and a check valve assembly 89 at the ' able screw I99. ‘Screw I89 is threaded into the
forward end of the piston. ' Some air may also
sleeve 95 and may be manually‘operated by in
enter the chamber through a port 90 in the'for
serting a tool through the hollow head 91 of the, 50
ward end of the cylinder but the cross-sectional
'50 ‘ area of this port is such that it alone would not sleeve 96. ,
To effect an adjustment, screw I09 is loosened
permit the free and rapid retraction of the piston. ‘to unlock the brake shoes 98 and the sleeve 96
The purpose of the port 90 is to retard the return is rotated within the rod 28 to obtain the desired
stroke of the piston when the ‘check valve assem
relative disposition of each part, after which the,
‘screw 199 is ‘again locked to expand the brake“
89 is "closed.
'
.
755 blyClosing
movement of the piston is effected by a shoes 98; ,For preventing-rotation of the rod 23
lug 9| at the rear end of the rack bar which en
during this adjustment and for preventing unde
gages, the element 84 after a predetermined for
sired rotation of the rod at any other time rela
ward movement of the collar 45.‘
'
~
tive to cam member 724-, a yielding latch mecha-v
As seen in Figure 10, the check valve assembly nism is provided comprising. a- plug I92 longié
may comprise a hollow‘ sleeve 92 in communica
tudinally ‘slidable in the front end of the plunger
tion with the passage 81 and affording a seat-fora 30, but locked against rotation with respect there
ball valve 93 that is pressed toward said seat‘ by a to by a pin I593. A spring 194 urges the plug for
spring 94, carried by a hollow plug 95 that is wardly, and complemental latching serrations I 05
screwed into the forward end of the piston. are provided on the plug and on the rear end of
' Pulling the piston rearwardly causes the valve to
the rod 28. 'This latching ‘mechanism is substan
unseat and admit air freely to the working'cham
ber of the cylinder; Upon‘ movement'in' the op ' tially identical with. that shown in Newman
.
posite direction,‘ however, the valve will seat and Patent No. 1,912,298.
The'adjustment just described accurately de
the'only escape for air is through the small port
70
termines the thread diameter because it definitely
90, as a result of which the return or forward
locates the ‘head 91 longitudinally of the device,
movement of collar 45 is cushioned. Various and the head 91 in turn de?nitely locates the
equivalent porting means may be utilized For cam member 24, for in actual working positions
example, port 99 may be eliminated and the as illustrated in‘Figures 1 and 5 the forward end 75
valve seat provided with one or more small grooves
2,131,965
of the cam member is always tightly in contact
with the rear end of the head 91. This contact
is obtained, not through rotation of the cam
member which can only slide in the head I6,
but through bodily rotating as a unit all of the
screw-threaded elements which are housed within
the cam member 24. Upontightening the screw
IE9 to lock the brake shoes 98, the manipulation
of the head 91' with the proper tool will cause
10 the sleeve 96, the screw I00 and the rod 28 to
rotate as a unit within the cam member to ad
vance or retract the latter depending upon the
direction of rotation of the head 9'7. This man
ual operation is permitted by the yielding latch
1.5 mechanism I02 to I05 which, however, has suffi
cient resistance to rotation to prevent any inad
vertent bodily rotation of the screw-threaded
elements to get the cam member out of- adjust
ment.
20,
.
I
In Figure llgthe cam member 24 is shown su?i
ciently retracted, by the adjustment just de
scribed, to take the cam ?ngers or wings 26 out
of overlapping engagement with the complemen
tal ?ngers 23 of the chaser holders, thus permit
25 ting the chasers to be readily withdrawn radially
for sharpening, adjustment or repair. A chaser
is shown partly removed in Figure 11, and in
Figure 3 there is shown a removed chaser having
its cutting element resharpened. Due to the fact
that removed and replacement of the chasers
does not involve any alteration of the position
of the head 91 longitudinally relative to the
plunger 38, the chasers‘may be replaced and
the screw-threaded elements bodily rotated to
3.5. bring the cam 24 into engagement with the rear
end of. the head 91, thus assuredly bringing the
parts exactly in the same position that they
previously had prior to removal of the chasers.
Hence, operation of the machine may be resumed
40 to cut threads of exactly the same size, and this
is important because it eliminates any trial and
error adjustments and trial cuts with attendant
loss of time and possible slight inaccuracies.
A highly important feature of this invention
45 resides in the provision of means for facilitating
a quick coupling between the cam members and
the chaser holders upon insertion or replace
_ ment of the ‘latter. As seen in Figure 2 the body
of the cam member 24 has a plurality of ?at
50 inclined faces corresponding in number to the
number of chasers. The inclined faces termi
nate in forward extensions or ledges I06, as best
seen for example in Figure 11, which project for
wardly a slight distance beyond the forward ex
55 tremities of the cam wings 23. Therefore, when
the chasers are replaced the holders can be
simply pressed radiallyv inwardly until their cam
?ngers 23 engage ledges I65 in which position
every one of the cam ?ngers 23 is accurately
60 located for reception by a corresponding groove
25 of the, cam, and as the adjustment is performed
to move the cam member forwardly all of the
chaser holders are picked up and intercoupled,
simultaneously and without di?iculty, to the cam
6.5 member. This feature is shown but not claimed
in myv aforementioned co-pending application
Serial No. 5,129, the claims which are directed to
cam member adjusting and locking means of the
character above set forth..
.70
Figure 12 is carried forward from said co~pend~
ing application and discloses a tap head which
differs from the head of the form already de
scribed chie?y in the provision of a slightly mod
i?ed form of cam adjusting and locking means.
e In this modi?ed form a sleeve 28a is provided
which differs in no material respects from sleeve
28, and this sleeve receives an adjusting sleeve
26a having a head 91a differing only from the
corresponding elements of the form already de
scribed in the elimination of the locking shoes 5
98. In place of the locking shoes and the screw
I00, there is provided a screw-threaded ‘element
I01 having a manually operable head I08. To
look all of the screw-threaded elements together
for bodily rotation, the head I08 is rotated until 10
the rear end of the screw I 9'! is jammed into
abutment with. the internal end surface I 09 ‘of
the rod 28a. 'Ledges I 06 are provided in Figure
12 for facilitating the replacement and inter
coupling of the chasers as already set forth.
In both forms the head I6 is readily removable
from body I5. Although the cam member 24 is
15
?rmly supported radially in the head I6, it can
readily slide out of the same rearwardly. Ac
cess to the studs I1 is had by performing the 20
adjustments above described to remove the chas
ers, and thereafter, upon removal of the studs
I‘! the head I6 can be replaced by a'larger or
smaller head which also ?ts the body I5 but
which is designed for use in cutting another range
.25.
of thread, diameters.
The particular means for mounting and ad
justing the cutting elements with respect to their
holders forms no part of the present invention,
but is fully set forth and claimed in my co-pend 30
ing application Serial No. 23,901, ?led May 28,
1935.
The invention may be embodied in other spe
ci?c forms without departing from the spirit or
essential characteristics thereof. The present 35
embodiments are therefore to be considered in
all respects as illustrative and not restrictive, the
scope of the invention being indicated by the
appended claims rather than by the foregoing
description, and all changes which come within
the meaning and range of equivalency of the 40
“
claims are therefore intended to be embraced
therein.
What is claimed and desired to be secured by
United States Letters Patent is:
1. A tap for cutting tapered threads compris- “115
ing a body structure carrying chasers, a chaser
controlling device movable axially of the body
structure, an external control member slidable
on said body structure longitudinally thereof, a
50
transverse bar operating through said device
and provided with a shoe, said external control
member having a longitudinally arranged in
clined cam groove complemental to said shoe,
and adjustable stop means for predetermining the 55
point along said groove at which said shoe is ‘
located at the start of the thread-cutting oper
ation.
'
2. In a thread-cutting machine, a body mem
ber carrying chasers at the forward end thereof, 60
a control member shiftable longitudinally of said
body members, and means for cushioning relative
movement of said members, said means com
prising a, cylinder and piston device forming a
Working chamber and mounted on one ,of the
members and a cooperating device on the other
member for causing relative reciprocation of the
cylinder and piston, and means forming a port
ing arrangement for said working chamber de
signed to permit free relative movement of the 70
control member in a rearward direction while
resisting rapid forward movement thereof.
3. In the combination de?ned in claim 2, one
of said devices being longitudinally adjustable to
govern the thread length.
75
2,131,965
6
4. In a thread-cutting machine, a body struc
retracting direction upon release of said operat
ture carrying slidable chasers, a shiftable device
arranged axially of said body structure to con
trol said chasers, an external member mounted
on said body structure for longitudinal sliding
ing device and to assist in the initial return move
ment thereof towards chaser extending position,
and one of said springs being continuously op
movement and operatively connected to said
shiftable device, a ?xed rearwardly opening cyl
inder provided longitudinally of said body struc
erable thereby assisting in the ?nal portion of
said return movement of said device against said
adjustable stop and cushioning device.
ture and containing a piston, a device detachably
secured to said external member for longitudinal
adjustment and designed to engage said piston
after predetermined forward movement ‘of said
. external member, whereby the piston and cylin
9. In a thread-cutting machine, a body mem
ber carrying extensible and retractable chasers,
operating means for said ‘chasers including a
15 forward movement, and means associated with
said piston and cylinder to produce a cushioning
action during said continued forward movement.
5. A collapsible tap comprising a body provided
limiting movement of said movable member in
chaser extending direction, said stop means be
ing adjustable and provided
a control member and a collapsing member
mounted in spaced relation on said body and
movable relatively toward each other in response
to thread-cutting action, the control member be
ing operatively associated with said device and
25 the collapsing member being connected to said
device, a spring engaged by one of said members
and designed to engage the other only after a
predetermined’amount of relative travel between
said members, and means for causing said spring
to separate said members after it has been de
formed a predetermined amount through con
tinued relative travel of said members toward
each other.
6. In the combination de?ned in claim 5, said
35 spring being a relatively heavy coil type spring,
and there being a lighter but longer coil spring
concentrically arranged with respect to the ?rst
mentioned spring and having its ends constantly
in engagement with the control and collapsing
members respectively.
' '7. In a thread-cutting machine, a body mem
ber carrying chasers, control means movable lon
gitudinally of saidbody member in opposite di
rections to extend or retract said chasers, an
45 operating device for said control means also mov
able longitudinally of said body member, inter
connecting means between said control means
and said device adapted to be released at a pre
determined point in the movement of said con
50 trol means in chaser retracting direction, an ad
justable stop between said device and said body
member to limit relative movement thereof in
one direction, said adjustable stop including a
cushioning device, a spring mechanism compris
55 ing a plurality of springs interposed between said
control means and said device operable to rapidly
move said control means in chaser retracting
direction upon release of said interconnecting
means, means to move said control means in
60 chaser extending direction and against said stop,
said spring mechanism being arranged so that
the plurality of springs assists in the initial por
tion, and one spring assists in the ?nal portion,
‘
.8. In a thread-cutting machine, a body mem—
ber carrying chasers, control means for said
chasers, a longitudinally movable operating de
vice releasably interconnected with said control
means, an adjustable stop and cushioning device
70 arranged between said operating device and said
body member, spring means interposed between
said control member and said device comprising
two spring elements, said spring elements‘being
75 adapted to move said control means in chaser
15“
with a cushioning ‘
device, spring mechanism interposed between
with slidable chasers, a device mounted for axial
20 reciprocation in said body to position said chasers,
of said last named movement.
'
said body member and a control member re
leasably connected therewith, stop means for
, der determine the maximum extent of continued
40
10i
longitudinally movable member associated with
said movable member and said control member
comprising a plurality of spring elements oper
able upon release of said control member to 20V
move the same in chaser retracting direction,
means to return said movable member to chaser
extending position against said stop means, said
spring mechanismbeing arranged so that only
a single spring element is operative during the 25
?nal portion of said return movement.
10. The combination set forth in claim '7 where
in said cushioning device comprises a piston and
cylinder associated with said body member and
said adjustable stop.
11. The combination set forth in claim rI where
in said spring mechanism comprises a light spring
and a heavy spring coaxially' arranged within
said operating device, a tubular plunger element
associated with each of said springs adapted to
successively engage said control member when
said device is moved in chaser retracting direc
tion.
12. In a thread-forming machine; a Support,
an abutment on said support, a plurality of ra
40
dially movable chasers carried by said support;
means for controlling the radial positions of said
chasers, comprising a member movable axially of
said support; work engagingv means adjustably
mounted on said member; and stop means ad 45
justable longitudinally of said member and en
gageable with said abutment on said support for
limiting axial movement of said member in a‘
forward direction.
'
v
13. In a thread-forming machine, a support; a 50
plurality of radially movable chasers carriediby
said support; means for controlling the radial
positions of saidchasers, comprising an axially
movable member; and work engaging means on
said member; said work engaging means being 55
formed to receive a cooling medium and to direct
the same against said chasers.
'14. In a thread-cutting machine, a support; a
chaser controlling means mounted for axial
movement along said support; a work engaging 60
element carried by said means and adjustable
longitudinally thereof; a cushioning device car
ried by said support; and an abutment on said.
controlling means adjustable longitudinally
thereof and adapted to engage said cushioning 65
device and limit movement of said controlling
means in a forward direction.
‘15. In a thread-cutting machine, a body mem
ber, a control member shiftable longitudi
nally of said body member, a cylinder mounted 70
on said body member, a piston in said cylinder,
a lateral projection on said piston, an abutment
means ?xed to» said collar, a second abutment
means adjustably secured to said collar, said ?rst
abutment means being arranged to engage said 76
2,131,965
projection and withdraw said piston from said
cylinder when said control member is shifted in
one direction, said second abutment being ar
ranged to engage said projection and move said
piston into said cylinder when said control mem
ber is shifted in the opposite direction, means
associated with said piston and cylinder forming
a porting arrangement for permitting free ?ow
of air into said cylinder when said piston is with
10 drawn and a slow flow of air out of said cylinder
when said piston is moved into said cylinder,
whereby movement of said control member, in
said ?rst named direction is cushioned.
16. In a thread~cutting machine, the combina
tion set forth in claim 15, wherein said second
7
prises a bar member having external rack teeth
thereon and provided with an abutment portion,
together with means cooperating with said rack
teeth to hold said bar in any one of several posi
tions on said external member.
5
18. In a thread-forming machine, a support; a
plurality of chasers radially movable in said sup
port; means for controlling the radial positions
of said chasers during thread-forming operation,
comprising an axially movable member; and stop
means adjustable longitudinally of said movable
10V
member and adapted to engage with means on
said support to limit movement of said member
in a forward direction, said adjustable stop means
including a bar arranged for adjustment longi
named abutment comprises a slotted bar mem
tudinally of said movable member and having a
ber adjustably secured to said control member‘ series of recesses, and a device secured to the
with said ?rst named abutment and said piston movable member and projectable into any select
projection received in said slot.
ed one of said recesses to lock the bar against
17. In a thread-cutting machine, the combina
longitudinal movement relative to said movable 20
tion set forth in claim 4, wherein the device de
means.
tachably secured to said external member com
FREDERIC NELL.
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