US2471250A - Self-opening die head - Google Patents

Description

May 249 394g, R. M. STRICKLAND 473%25@ SELF-OPENNG DIE HEAD Filed May ll, 1945 3 Sheets-Sheet l Flo.

3g l /fvvL-wroe 39 RoYcE Pl. STRICKLAND May 24, 94@ R. M. STRICKLAND SELF-OPENING DIE HEAD 3 Sheets-Sheet 2 Filed May 11, 1945 /lmm M on D N A w mmf T ma@ mm n E S n RO .M mm

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MSW 24, w49- R. M. STRBCKLAND ZyZ@ SELF-OPENING DIE HEAD Filed May l1, 1945 s sheets-sheet s l /Nyffv me Roma M. 5T mamma Patented May 24, 1949 UNITED STATES OFFICE SELF-OPENING DIE HEAD Application May 11, 1945, Serial No. 593,209

(Cl. 1li-95) 4 Claims. l.

The present invention relates to improvements in self-opening die-heads, i. e., die-heads which are provided with a plurality of thread-cutting chasers which latter, upon the completion of the threading operation, are retirable out of engagement with the threaded workpiece in order to permit the direct axial separation of the diehead and the work-piece without requiring the reverse relative rotation thereof.

The present invention involves improvements upon the self-opening die-head disclosed in United States Patent No. 2,135,067 granted November l, 1938, on the application of A. F. Breitenstein, and has for one of its main objects the overcoming of certain objections inherent in the structure of the said Breitenstein patent.

More particularly and like the structure of the said Breitenstein patent, the present invention relates to self-opening die-heads of the character which may be employed for cutting pipethreads or other tapered threads and which rely upon the inclination of the series of thread-cutting teeth of the normally-stationary thread-cutting chasers, in order to thread the work-piece at the desired angle of taper in contradstinction to thread-cutting tools which progressively retire their chasers during the normal thread-cutting operation in order to effect the desired taper.

It may here be noted that one of the main objections which has been found to the selfopening die-head disclosed in the aforesaid Breitenstein patent, has been that after a relatively-brief period of use the latch-member has failed to remain in its latching position, ,apparently due to vibration coupled with an inherent tendency for the said latch-member to retire inwardly under the force exerted by the Chaser-operating sleeve. It is another object of the present invention to provide a superior selfopening die-head which will overcome the objections just referred to in a simple, reliable and effective manner.

A further object of the present invention is to provide a superior self-opening die-head of the character referred to which will produce tapered threads free from abrupt shoulders extending longitudinally of the work-piece.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all fea- 2 tures in the said disclosure which are novel over the prior art.

In the accompanying drawings, in which certain modes of carrying out the present inven- 'tion are shown for illustrative purposes:

Fig. l is a View in side elevation of one form of self-opening die-head embodying the present invention, with the parts shown in the positions which they assume when in readiness to cut a taper-thread upon a work-piece;

Fig. 2 is a View thereof in front elevation;

Fig. 3 is a View thereof in rear elevation;

Fig. 4 is a broken longitudinal sectional View taken on the line li-d of Fig. 2;

Fig. 5 is a similar view but taken on the line 5 5 of Fig. 2;

Fig. 6 is a transverse sectional View taken on the line of Fig. l but on a larger scale;

Fig. '7 is a broken central-longitudinal sectional View with the forward part in section on the line l-la of Fig. 2, and the part to the rear of the head-portion of the body-member taken on the line 'l-lb of Fig. 2, but on a, larger scale than the latter figure;

Fig. 8 is a View similar to Fig. '7 but showing the parts in the positions which they assume at the instant that the latch-member has reached the point at which the full retirement of the chasers is about to take place;

Fig. 9 is a perspective View of the latch-carrying ring, detached;

Fig. l0 is a similar view of the latch-member, detached; and

Fig. 1i is a broken transverse sectional View of a threaded work-piece on a greatly-enlarged scale.

The self-opening die-head shown in the accom- .panying drawings for purposes of making clear one form of the present invention, includes a body-member generally designated by the reference character l5, a Chaser-operating sleeve I8, a tripping-sleeve il, a latch-carrying ring I8, and an adjusting-nut 2li. Y

The body-member i5 above referred to includes a, relatively-large-diametered forward head-portion 2l from which rearwardly extends a rela- .tively-small-diametered shank 22 formed integral with the said head-portion. Extending axially through both the head-portion 2 l-and the shank 22 of the body-member l5, is a clearancepassage 23 which is increased in diameter toward its forward end in two steps, as is particularly well shown in Figs. 7 and 8.

The head-portion 2| of the body-member I5 is formed in its forward face with four (more or less) circumferentially-equidistant radial slots 24, in each of which is slidably mounted one of four similar thread-cutting chasers 25. The inner edge of each of the said chasers is formed with a series of thread-cutting teeth 2S tapering forwardly and outwardly at an angle substantially corresponding to the desired angle of the threads to be cut upon a work-piece. The chasers 25 above referred to are retained in place in the slots 24 by four segmental plates 2l which are secured to the forward face of the said head-portion 2| by means of screws 28, as is shown in Fig. l.

Each thread-cutting chaser 25 is provided adjacent its outer end with a rearwardly-projecting pin 29. Thrusting radially outwardly against fthe said pin 29 and hence also against the chaser 25 from which it extends, is a cup-shaped chaserretracting plunger 3|] (one for each chaser) mounted for axial reciprocation in a radial spring-pocket 3|, one of which latter is formed in the head-portion 2| of the body-member I5 back of each of the slots 24 therein. Each of the plungers 30 is urged outwardly by a helical chaserretracting spring 32 and is limited in its outward movement by a stop-pin 33A which projects forwardly from the head-portion 2| into the outerportion of the `adjacent spring-pocket 3|, as is shown in Figs. 7 and 8.

Each of the thread-cutting chasers 25 is formed at its outer end with an inwardly-and-rearwardly-sloping cam-surface 34 which is engaged by one of four similarly-sloping cam-surfaces 35 formed respectively at circumferentially-equidistant points on the forward inner edge-portion. of the .Chaser-operating sleeve I6 .before referred t0, and which has axial sliding movement on the body-member I5. Y

The forward-portion of the: chaser-operating sleeve I5 is relatively-large and has its inner surface bearing upon the periphery of the head-portion 2| of the body-member I5. The rear-portion of the said chaser-operating sleeve is smaller in diameter and has its interior proportioned to slide upon the outer periphery of the latch-carrying ring I8 before referred to, as is especially well shown in Figs. 7 and 8.

The latch-carrying ring I8 is mounted upon the outer periphery of the shank 22 of the bodymember I5 at a, point immediately to the rear of the head-portion 2|. The said latch-carrying ring has limited axial movement upon the shank 22 for purposes of effecting certain adjustments, but under operating conditions is stationary thereon and may be said to constitute a bodyunit jointly with the said body-member I5.

The latch-carrying ring IS is urged rearwardly so as to seat its rear face against the forward face of the adjusting-nut 20 by means of two helical springs SI5- 36. Each of the said springs 36-35 is mainly accommodated in one of two spring-pockets 31-31 opening through the forward face of the latch-carrying ring I8 respectively at diametrically-opposite points thereon. The said springs 36-36 thrust at their rear ends against the respective bottoms of the spring-pockets 31-31 and thrust at their forward ends against the rear face of the head-portion 2| of the body-member I5, to thus rmly seat 4 the latch-carrying ring I8 against the adjustingnut 20.

The latch-carrying ring 8 is held against turning movement with respect to the Chaser-operating sleeve I6 (and hence also with respect to the body-member I5) by means of a key 38 which is seated in the periphery of the said ring I8 and which extends with a sliding t into a longitudinal keyway 39 formed in the interior of the rearportion of the Chaser-operating sleeve 5.

To provide for the adjustment of the adjustingnut 2U, it is formed internally with threads 40 interitting with threads 4I formed upon the periphery of the shank 22 of the body-member I5. For purposes of locking the adjusting-nut 20 in a chosen position of adjustment on the shank 22, an internally-threaded clamping-shoe 42 is employed. The said clamping-shoe is mounted in -a recess in the inner periphery of the adjusting-nut 20 and may be forced into tight engagement with the threads 4| on the shank 22 by means of a set-screw 23 threaded radially into the said adjusting-nut, as is especially well shown in Figs. 7 and 8.

The Chaser-operating sleeve I6 is yieldingly urged rearwardly, for purposes as will hereinafter appear, by two helical retracting-springs 411-41. The said retracting-springs extend in parallelism with the axis of the die-head and are respectively located at diametricaIly-opposite points. The forward-portion of each of the retracting-springs 44-44 is accommodated in one of two rearwardlyopening spring-pockets l5-45 formed in the rear of the head-portion 2l of the body-member I5, as is especially well shown in Fig. 4. The rear end of each of the retracting-springs lll-44 is accommodated in one of two forwardly-opening spring-pockets 46-46 formed in the small-diametered rear-portion of the chaser-operating sleeve I6. Extending lengthwise in each of the retracting-spring 44h44 is one of two guide-pins I1-41 rigidly mounted in and projecting rearwardly from the head-portion 2| in axial relationship respectively with respect to the adjacent one of the spring-pockets I5-45.

For the purpose of holding the Chaser-operating sleeve I6 against turning movement with respect to the body-member I5, while still permitting its relative axial movement with respect thereto, two coupling-pins 48-48 are employed. Each of the said coupling-pins is rigidly mounted at its rear end in the adjacent portion of the small-diametered rear part of the Chaser-operating sleeve I I5, as is shown in Fig. 5. The forward-portion of a given one of the said coupling-pins 48-48 is adapted to reciprocate in one of two couplingpassages IS-45 in the head-portion 2| of the body-member I5.

In the inner periphery of its small-diametered rear-portion, the Chaser-operating sleeve I6 is formed with a substantially-semicircular eccentric groove 5D, the forward wall of which stands substantially perpendicularly with respect to the longitudinal axis of the die-head and constitutes a rearwardly-facing latching-abutment 5|. The said groove 50 is adapted to receive a substantially-semicircular latching-rib 52 formed upon the outer periphery of a substantially-semicircular latch-member 53. The forward face of the rib 52 just referred to also extends perpendicularly with respect to the longitudinal axis of the die-head and constitutes a forwardly-facing latching-abutment 54 which is adapted to engage with the rearwardly-facing latching-abutment 5| in the Chaser-operating sleeve I6.

The substantially-send-circular latching-abutment 54 on the latch-member 53 extends at an acute angle with respect to the forward face of the said latch-member. The rear face of the said latch-member extends in parallelism with the said front face, as is especially well shown in Figs. 7 and 8. Both the iront and rear faces of the latch-member 53 are inclined slightly rearwardly with respect to the periphery of the latchmember, as the said faces progress inwardly toward the longitudinal axis of the body-member l5.

The latch-member 53 above referred to, is mounted for movement toward and away from the groove 50 in the Chaser-operating sleeve l5, in a rearwardly-and-inwardly-inclined latchguiding notch 55 formed in and extending transversely of the latch-carrying ring I8. The respective front and rear walls of the guide-notch 55 extend in parallelism with each other and are spaced apart just enough to receive the latchmember 53 between them with a smooth sliding t.

The latch-member 53 is urged outwardly by two helical latch-springs 543-56, each of which is seated in one of two spring-pockets l-5'i respectively formed in the opposite side walls of the latch-carrying ring I8 at the bottom of the notch 55, as is especially well shown in Fig. 6. The upper end of each of the latch-springs 5t- 56 bears against the adjacent under-face portion of the segmental latch-member 53.

Returning now to the tripping-sleeve il, it will be noted by reference to Fig. 6 that a key 58 is installed between the said tripping-sleeve and the Chaser-operating sleeve I6. The connection provided by the key 58 is such as to hold the Chaser-operating tripping-sleeve I1 against turning-movement on the outer periphery of the chaser-operating sleeve I6, while permitting relative axial movement between the two said sleeves.

To provide for the disengagement of the latching-abutment 54 of the latch-member 53 from the latching-abutment 5I in the Chaser-operating sleeve I6, the said Chaser-operating sleeve is formed in its rear portion with a substantiallyradial guide-passage 59 in which is mounted a ball 60, or other suitable transmitting-member. The inner-portion of the ball 60 presses against the outer periphery of the latching-rib 52 of the latch-member 53, while the outer-portion of the said ball rests against a forwardly-and-inwardlyinclined cam-surface 6l constituting the sloping forward wall of an arcuate recess 52 fon-med in the interior of the rear-portion of the trippingsleeve l1.

In the outer surface of its rear-portion, the axially-movable tripping-sleeve Il is formed with a circumferential groove 63 into which a suitable stop-member may extend, in a manner well known in the art.

For the purpose of limiting the rearward movement of the Chaser-operating sleeve I6 from the position in which i t is shown by full lines in Figs. '7 and 8 into its retired position in which it is indicated by the broken lines 16a in Fig. 8, the adjusting-nut 2D is formed with a transverse groove 64 in which is located an arcuate stopmember 65. The said stop-member is pivotally mounted at one end upon a pivot-pin 66 mounted in the adjusting-nut. The opposite end of said stop-member is pressed outwardly by a plunger 61 mounted for axial reciprocation in a pocket 58 extending perpendicularly with respect to and vopening through the portion of the bottom wall of the groove 64 opposite the pivot-pin G6. 'Inte-i'- posed between the inner end of the plunger 51 Operation For purposes oi description, let it be assumed that the self-opening die-head above described is mounted by means of its shank 22 in the rotating chuck of a thread-cutting machine, and that the said die-head is advanced axially toward a work-piece arranged coaxially with respect to the die-head. The said advancement of the die-head will take place after the chaseroperating sleeve l5 has been locked in its forward position, to thereby hold the group of threadcutting chasers `25 inwardly in position in readiness for cutting the threads as is shown in the drawings.

As the die-head, including its tripping-sleeve l'i, is advanced axially toward the work-piece, or vice versa, the teeth 26 of the thread-cutting chasers 25 will engage with the work-piece and will cut a tapering thread thereon as the said axial movement continues.

Just before the desired length of tapered thread has been cut upon the work-piece, the trippingsleeve il may have its forward axial movement checked while the remainder of the die-head continues to advance axially. The checking referred to may be effected by means of any suitable stop such, for instance, as a stop-member entered into the annular groove 63 in the said tripping-sleeve.

After the forward axial movement of the tripping-sleeve H has been checked as just described, the remaining elements of the die-head will still continue their forward axial movement, with the result that :the ball 6U will be forced radially inwardly by the cam-surface 6| in the tripping-sleeve. The inward movement of the ball 6] will, in turn, force the latch-member 53 inwardly until it reaches the position shown in Fig. 8.

Now, inasmuch as the above-described inward movement of the latch-member 53 is along a slightly-rearwardly-inclined path, the latchingabutment 54 of the said latch-member will move slightly rearwardly during the described inward movement of the said latch-member of which it forms a part. This slight rearward movement of the latching-abutment 54 will permit a corresponding slight rearward movement of the Chaser-operating sleeve I6 under the urge of its retracting-springs I4-M, and hence will permit the slight outward movement of the chasers 25 under the urge of their respective Chaser-retracting springs 32, all while relative rotation is taking place between the die-head and the work-piece being threaded. Y

For a better understanding of the effect produced by the slight preliminary or let-off movement of the chasers 25 as just above described, attention may be called to the fact that were the said chasers permitted to retire abruptly while still engaged in a thread-cutting operation, a shoulder such as is indicated by the broken line 1l, would be produced upon a work-piece 12 as is illustrated in Fig. 11. However, inasmuch as ythe retirement of the chasers is eiected gradually as a preliminary step to their complete release (to be presently described), the shoulder Il will be erased and a substantially perfect tapered thread will be produced upon a workpiece such as 12.

Immediately following the inward movement of the latch-member 53 into the position in which it s shown in Fig. 8, the outer edge of its latchingabutment 54 will clear the inner edge ci the latching-abutment l in the Chaser-operating sleeve I6, whereupon the retracting-springs lill-fill will assert themselves and snap the said Chaser-operating sleeve rearwardly into the position in which .it is represented by the broken line ita in Fig. 8. The described rapid rearward movement of the Chaser-operating sleeve I6 will be checked by the engagement of the rear face of the said sleeve with the forward face of the pivotal arcuate stop-member 65. The described rapid rearward movement of the Chaser-operating sleeve i@ will also retire its cam-surfaces 35, thereby permitting each of the chasers to be moved radially outwardly by their respective chaser-retracting springs 32. The die-head structure and the nowthreaded work-piece may be axially separated without requiring an unthreading operation.

When it is desired to remove the chasers 25 from the body-member i5, the pivotal stop-mem- L described, the forward end of the Chaser-operating `sleeve I6 will lie slightly to the rear of the rear faces of the chasers 25, whereby the said chasers may be removed radially from the bodymember l5.

By the construction and arrangement of parts exemplified in the accompanying drawings and described above, the gradual shoulder-erasing or let-off movement of the chasers may be accomplished without the liability that the chasers will be unintentionally fully retired by the failure of the latch-member to remain latched when it is intended that it should. This reliability of operation is secured despite severe shock and vibration to which the die-head may be subjected in operation.

The invention may be carried out in other specic ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the' present embodirnents are, therefore, to be considered in all respects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

l. A self-opening die-head, including .in combination: a body-unit having a front and provided with a latch-guiding recess having parallel front and rear walls both oi which inwardly from a lateral cuter surface of the bodyunit toward the longitudinal axis thereof but an angle 4which progresses away from the said front as it progresses inwardly toward the said axis; a plurality of thread-cutting chasers car- 8 ried by and movable with respect to the front oi the said body-unit toward and away from the longitudinal axis thereof; a Chaser-operatinember operatively-associated with the said s and provided with a rearwardly-facing latching abutment, the said member being movable in a direction longitudinally of the said bodyunit into and out of position to hold the said chasers in their advanced or thread-cutting position; spring-means yieldingly urging the said Chaser-operating member rearwardly into a position wherein the said chasers are retired into inoperative position; and a latch-member having parallel iront and rear walls respectively engaging with the inclined front and rear walls of the latch-guiding recess in the said body-unit, the said latch-member being provided with a forwardly-racing latching-abutment releasably engageable with the' rearwardly-facing latchingabutment oi the said Chaser-operating member and therefrom by an inward and rearward "novement of the latch-member in the cia-guiding recess of the body-unit, the latch- -gf-abutment of the latch-member extending 'in a plane more nearly perpendicular with respect e tudinal axis of the said body-unit than rear walls of the latch-guiding recess therein.

A seiicpening die-head, including in combination: a body-unit having a front and having a cyli initially-contoured portion formed in a directi i tr isverse of its longitudinal axis with a latci guiding recess intersecting the periphery thereof, the said latch-guiding recess having parallei front and rear walls both of which extend inwardly from the periphery of the said cylindrically-contoured portion toward the longitudinal axis ci the die-head but at an angle which progresses away from the said front as it progresses inwardly toward the said axis; a plurality i thread-cutting chasers carried by and movable with respect to the iront of the said body-.unit toward and away from the longitudinal axis thereof; a Chaser-operating sleeve encircling the cylindrically-contoured portion of the said bodyunit and provided with a rearwardly-facing latehing-abutment, the said sleeve being operativelyssociated with the said chasers and movable in a direction longitudinally of the said body-unit into and out of position to move the said chasers in their advanced or thread-cutting position; spring-means yieldingly urging the said Chaser-operating member rearwardly into a position wherein the said chasers are retired into inoperative position; and a latch-member having a cylindrically-contoured outer surface and having parallel front and rear walls respectively engaging with the inclined front and rear walls of the' latch-guiding recess in the cylindricallycontoured portion of the said body-unit, the said latcl'i-member being provided with a Vforwardlyfacing latching-abutrnent releasably engageable with the rearwardly-facing latching-abutment oi the said Chaser-operating member and disengageable therefrom by an inward and rearward movement oi the latch-member in the inclined latch-guiding recess of the body-unit, the latching-abutment of the latch-member extending in a plane more nearly perpendicular with respect to the longitudinal axis of the body-unit than the front and rear walls of the latch-guiding recess therein.

3. A self-opening die-head, including in .combination: 9, body-member having a front portion; a latch-carrying member carried by the said body-member and adjustable axially with respect thereto, the said latch-carrying member being provided with a latch-guiding recess having parallel front and rear walls both oi which extend inwardly from a lateral outer surface of the latch-carrying member toward the longitudinal axis thereof but at an angle which progresses away from the said front as it progresses inwardly toward the said axis; a plurality of threadcutting chasers carried by and movable with respect to the front portion of the said body-member toward and away from the longitudinal axis thereof; a Chaser-operating member operatively associated with the said chasers and provided with a rearwardly-facing latching-abutment, the said Chaser-operating member being movable in a direction longitudinally of the said body-member into and out of position to hold the said chasers in their advanced or thread-cutting position; spring-means yieldingly urging the said Chaser-operating member rearwardly into a position wherein the said chasers are retired into their inoperative position; and a latch-member having -parallel front and rear walls respectively engaging the inclined front and rear walls of the latch-guiding recess in the said latch-carrying member, the said latch-member being provided with a forwardly-facing latching-abutment releasably engageable with the rearwardly-iacing latching-abutrnent of the said Chaser-operating member and disengageable therefrom by an inward and rearward movement of the latchmember in the inclined latch-guiding recess of the latch-carrying member, the latching-abutment of the latch-member extending in a plane more nearly perpendicular with respect to the longitudinal axis of the body-member than the front and rear walls of the latch-guiding recess in the latch-carrying member.

4. A self-opening die-head, including in combination: a body-member having a front portion; a cylindrically-contoured latch-carrying member carried by the said body-memb-er and adjustable axially thereof, the said latch-carrying member being formed in a direction trans- 4 verse of its longitudinal axis with a latch-guiding recess intersecting the periphery thereof, the said latch-guiding recess having parallel front and rear walls both of which extend inwardly 10 from the periphery of the said latch-carrying member toward the longitudinal axis of the said die-head but at an angle which progresses away from the said front as it progresses inwardly toward the said axis; a plurality of thread-cutting chasers carried by and movable with respect to the front portion of the said body-member toward and away from the longitudinal axis thereof; a Chaser-operating sleeve encircling the cylindrically-contoured latch-carrying member and provided with a rearwardly-facing latchingabutment, the said sleeve being operatively associated with the said chasers and movable in a direction longitudinally of the said body-member into and out of position to move the said chasers into their advanced or thread-cuttingposition; spring-means urging the said chaseroperating sleeve rearwardly; anda latch-member having a cylindrically-contoured outer surface and having parallel front and rear walls respectively engaging with the inclined iront and rear walls of the latch-guiding recess in the cylindrically-contoured latch-carrying member, the said latch-member being provided with a forwardly-facing latching abutment releasably engageable with the rearwardly-facing latchingabutment of the said Chaser-operating member and disengageable therefrom by an inward and rearward movement of the said latch-member in the inclined latch-guiding recess of the latchcarrying member, the latching-abutment of the latch-member extending in a plane more nearly perpendicular 'with respect to the longitudinal axis of the body-member than the iront and rear walls of the latch-guiding recess in the latch-carrying member.

ROYCEy M. STRICKLAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,782,804 Breitenstein Nov. 25, 1930 1,867,192 Strickland July 12, 1932 1,872,059 Breitenstein Aug. 16, 1932 2,135,067 Breitenstein Nov. 1, 1938

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