US2882776A - Automatic thread-cutting arrangement for a lathe - Google Patents

Description

April 21, 1959 J. L. JEANNERET AUTOMATIC THREAD-CUTTING ARRANGEMENT FOR A LATHE Filed bee. 5, 1956 4 Sheets-Sheet-l 8 PIN I Y (/0455 [ow/5 t/sqw/vzefr AprilZl, 1959 J. L. JEANNERET AUTOMATIC THREAD-CUTTING ARRANGEMENT FOR A LATHE 4 Sheets-Sheet 2 Filed Dec. 5, 1956 April 21', 3959 J. ,L. JEANNERET AUTOMATIC THREAD-CUTTING ARRANGEMENT FOR A LATHE Filed Dec. 5, 1956 4 Sheets-Sheet S Avuavrae April 21, 1959 J. L. JEANNERET AUTOMATIC THREAD-CUTTING ARRANGEMENT FOR A LATHE Filed Dec. 5, 1956 4 Sheets-Sheet 4 United States Patent AUTOMATIC THREAD-CUTTIN G ARRANGEMENT FOR A LATHE Jules Louis Jeanneret, Niort, France Application December 5, 1956, Serial No. 626,403

Claims priority, application France March 21, 1956 4 Claims. (Cl. 82--5) In the case of conventional slide and thread-cutting lathes, the workman who has to cut a thread must define the successive cuts by means of the dividing means onthe worm of the transverse carriage. Furthermore, when the thread-cutting tool arrives at the end of its stroke, it is necessary to make it recede in an accurate and speedy manner. It is therefore necessary forthe workman executing these different operations to display some consider'able manual skill which should be based on a long experience.

My invention has for its object an arrangement to be fitted removably or permanently on a lathe or machinetool provided with a feedscrew, said arrangement allowing the automatic execution of the above mentioned operations. I obtain thus in succession a predetermined number of cuts over the desired succession of depths by means of a tool-holder including two parts adapted to be shifted transversely with reference to each other in a direction perpendicular to the axis of the thread to be executed, upon operation of a manually controlled lever. This lever, for a predetermined position given to it, shifts the two parts of the tool-holder apart to a maximum extent through a toggle link action so that the tool-carrier constitutes thus immediately a unitary member adjusted as to position by a suitable stop so that the tool may lie in the operative position corresponding to the desired depth of cut; the release of the tool before the return movement is ensured automatically by a ,stop acting at the end of the stroke on a mechanism releasing the two parts of the tool carrier with reference to each other so as to allow a spring to urge them towards each other and to return consequently the tool into its inoperative position.

Thus, it is possible for the workman to act at the beginning of each cut on his control lever with a view to providing for the positioning of the tool in its machining position and its automatic disconnection at the end of the cut.

According to a preferred embodiment of my invention, the depth of cut is defined before operation for a number of successive cuts by means of a star-shaped member mounted on the same carriage as the tool-holder and revolving at each end of a cut so as to set a peripheral abutment element arranged at a predetermined distance from the rotary axis of said star-shaped member in registry with the front of the tool-holder or more accurately of that part of the latter which does not actually carry the tool. The different peripheral elements on said starshaped member form abutments the increasing distances of which with reference to said axis define corresponding increasing depths of cut in a corresponding manner.

Obviously, it is possible to resort to different starshaped members for the different successions of cuts corresponding to the number and the depths of cuts required for executing a series of thread-cuttings. The intermittent rotation of the star-shaped member before each cut 2,882,776 Patented Apr. 21, 1959 may be obtained advantageously by a shifting of the control lever under manual control in a direction opposed to the direction ensuring the toggle link action.

The two-part tool-holder includes on the one hand a slide carrying the tool and on the other hand a slider adapted to engage the stop; the control lever which may be pivotally secured to said slider provides for the positioning of the tool and defines the depth of cut through contact between the slider and the corresponding peripheral element of the star-shaped member, said slider also carrying pivotally a tool-disconnecting lever operat ing at the end of the stroke.

I will now describe by way of example a lathe with which is incorporated a preferred embodiment of an automatic device according to my invention. In the accompanying drawings:

Fig. 1 is an elevational view of the entire lathe.

Fig. 2 is a view from above.

Fig. 3 is an endwise view of the same lathe.

Fig. 4 shows the arrangement of the automatic device for two positions corresponding to the beginning and to the end of the cut executed by the thread-cutting tool said figure showing also the receding movement of the tool obtained at the end of the cut through the automatic release provided by a stationary abutment.

Fig. 5 is a cross-section of the same arrangement through line V-V of Fig. 4.

Fig. 6 is an endwise view of the arrangement of Fig. 4, said view being taken in the direction of the arrow VI of the latter figure.

Fig. 7 is a view from above of the tool-holder according to my invention in its operative position at beginning of the cut, i.e. the slide and the slider forming the toolholder being'illustrated as spaced to a maximum for machining.

Fig. 8 is a partly sectional view from above of the same tool-holder shown when the stationary abutment has released the slide of the tool-holder and allowed it to returnv towards the slider and to move the tool away from the part to be machined.

Fig. 9 is a sectional view of the tool-holder along the broken line IX-IX of Fig. 7. h

Fig. 10 is a partial cross-section of the same tool-holder through line XX of Fig. 6, said cross-section showing. the mechanism controlling the star-shaped member.

Figs. 11, 12 and 13 are diagrammatic views illustrating. the successive operative stages of the control lever associated with the tool-holder.

Fig. 14 shows the star-shaped member which allows defining thenumber and depth of the successive cuts.

Fig. 15 is a side view partly in section showing the tail-piece rigidly attached to the carriage.

In Figs. 1, 2 and 3, the lathe as a whole has been illustrated with my improved tool-holder the detail of which will be better understood, by referring to Fig. 4.j Said tool-holder includes a slide I mounted on the lathe carriage, carrying the tool ,2 and associated with the slider 5 moving transversely with reference to the lathe carriage as also does the slide 1, said slide moving towards the part to be threaded 3 starting from the tailpiece 12 (Figs. 11 to 13) rigid with the carriage C while the slider 5 moves in the opposite direction starting from the remote side of the same tail-piece 12. As will be disclosed hereinafter, the slide 1 and the slider 5" are adapted to form in their operative position a unitary block engaging through the projection 17 rigid with the slider an adjustable abutment mounted on the carriage so as to make the tool 2 enter the desired machiningposition. 1 Considering the-machining-stroke executed inthe direction of the arrow 4 under the action of the feed screw of the lathe, the tool starting from the'position 2 illustrated on the right hand side of Fig. 4 arrives at the end of its stroke into the position 2 illustrated on the left hand side of Fig. 4 corresponding to the end of the thread-cuttingstroke; at this moment, the slidel begins receding with the toolso as to bring the latter into its inoperative position 2" in which it executes itsreturn stroke and enters its starting position with a view to executing the following cut; said automatic receding movement is ensured by a lever 9 (Figs. 8 and 9) pivoting with reference to the slider and the tip of which abuts at the end of the cutting stroke against a stationary stop 10. The lever 9 thus shifted disengages as willalso be explained hereinafter the slide 1 with reference to-the slider 5 and these two parts 1 and 5 return each into contact with the tail piece 12under the action of the corresponding springs 13 and 15.

The maximum spacing of the slide with reference to the slider adapted to constrain said two parts to form a unitary block through a toggle actionis ensured at the beginning of each thread-cutting strokethrough the-operation by the workman of a control handle or lever 8, the action of which will be understood more readily by referring to Figs. l1, l2 and 13.

In Fig. 11, the tool-holder is illustrated in its starting position before the thread-cutting. The slide 1 carrying the tool 2 is urged against the tail-piece 12 by itsspring 13 which is comparatively powerful and acts in the direction of the arrow 14. The slider 5 is also urged on the other hand against the tail-piece 12 through its spring 15 acting in the direction of the arrow 16, i.e. in adirec tion opposed to the arrow '14, said spring 15 being substantially less powerful than the spring 13. For this position wherein the slide and slider forming the two component parts of the tool-holder are the nearest each other, the tool 2 is in its inoperative receded position and the tail-piece or projection 17 on the slider 5 has also receded in a manner such that there exists a certaintclearance 18 between said tail-piece and the start-shaped member 6 described hereinafter and forming an abutment for the tool-holder.

At this moment and as illustrated in Fig. 12, the workman causes the handle 8 to pivot round its axis 40 (Fig. 7) carried by the slider 5 so as to bring it through rotation in the direction of the arrow 19 (Fig. 12) into the position 8'. This pivotal movement acts on the starshaped member 6 in the direction of the arrow20 so as to bring into position the desired peripheral element of the star-shaped member 6 as will be disclosed hereinafter.

This being done, the workman causes the handle 8 to pivot in the opposite-direction, i.e. in the direction of the'arrow 24 up to the position 8" and the roller 25 mountedon a lever 26 rigid withthe operative handle 8 passes through its position 25', the lever 26 entering its position 26. In-this position (Fig. 13), the roller 25 is just about to arrive into contact with the wedge 27 rigid with the slide 1 so that the subsequent movement of the handle 8 in the direction of the arrow 24 urges the slider Ssubjected to the action of the weaker spring 15 through a'toggle action having its bearing point constituted-by the slide 1 until the tail-piece or projection 17 has-enteredits position 17' for which it is in contact with the abutment constituted by the-star-shaped member 6. This being done, the toggle action continues and the lever 26 engaging the slider 5 which is now held fast urges the slide 1 towards the part tobecut, i.e. in the direction of the arrow 29 (Fig. 13). At the moment at which the roller 25 enters its final position 25", a locking-system to be described hereinafter holds it fast. It is thus apparent that the slider 5 which is first held fast'againstthe tail-piece 12 through itslightspring 15 moves beforethe slide-1 subjected to the action of a-stronger spring:13.

The device locking the lever 26 and the tool-holde'r dn its operative position is I illustrated more ,particularlyin Fig. 7. This locking device includes a lever 30 rocking in unison with the releasing lever 9 round the spindle 36 carried by the slider 5, said lever 30 engaging a nose 31 provided on the lever 26 under the action of the spring 32. On the other hand, the-lever 26 carries in an oblique recess a piston 33 urged by a spring 34 against an abutment 42 so that the reaction on the piston produces a rocking of the lever 26 in the direction of the arrow 35 and a shifting thereof away from the surface of the slider S'Which lies in contact with said piston 33. By reason of this arrangement, when the tool 2 lying in its operative position has executed a thread-cutting stroke in the direction of the arrow 4 (Fig. 4), the tip 37 of the releasing lever 9 arriving in contact with the stationary abutment 10 providesfor a rocking round its axis 36 of said lever 9 together with the lever 30 rigid therewith in the direction of the arrow 38. This provides for the release of the control lever 26, the nose 31 of which no longer engages the lever 30 which has rocked and has allowed the spring 34 engaging the piston 33 to urge the lever 26 back, said lever being thus released, and being urged by the spring 34in the direction of the above mentioned arrow 35. The slide 1 urged by the spring 13'is then free to rapidly'move in the direction of the arrow 14 until its transverse surface 39 has returned into contact withthe tail-piece 12 while the slider 5 carrying the spindle 40 for the control lever 26 and the spindle 36'for the double lever 30-9 is similarly moved in the direction of the arrow 16 as soon as the roller 25 is no longer incontact with'the wedge 27 as provided by its pivotal movement so that said slider 5 has its surface 42 again in contact with the tail-piece 12 rigid with the carriage.

'The stationary abutment entering into contact with the tail-piece or projection 17 is constituted as described by a removable cam or star-shaped member 6 provided peripherally with a series of flat elements 21 the distances of which to the center increase stepwise from the first to the last as apparent at 21, 22, 23 in Fig. 12 so as to hold the tail-piece or projection 17 in corresponding positions with reference to said center. In its inoperative position, the slider 5 engages the tail-piece 12 and the tail-piece 17 allows a free rotation of the star-shaped member 6 with reference to which it is spaced. In order that the star-shaped member may be set in front of the tail-piece 17 before each cut in a manner such that the successive abutments may be constituted by the successiveflat elements 21, the workman provides'as disclosed fora movement of the handle 8 bringing it into its position 8' (Fig. 12). The axis or spindle 40 of this handle 8 rigid with the control lever 26 carries as shown in Figs. 9 audit) an auxiliary lever 43 which is also rigid with the handle 8. The end 44 of said auxiliary lever 43 produces during its pivotal movement in the direction of the arrow 19 (Fig. 12) the rocking of a pivoting member 45 in the direction of the arrow 20 in Figs. .10 and 12. This pivoting member 45'carries in its turna catch 46 whichactuates then through one tooth interval the ratchet wheel 47 rigid with the same spindle 48 as the star-shaped member 6. It is thus apparent'that the progression of the starshaped member is obtained by the intermittent rotation of the ratchet wheel 47 as obtained through the agency of the handle 8 in the direction referred to.

The star-shaped member 6 is held in position on its spindle 48 by a key 49 (Fig. 9) and by a knurled. knob 50-screwed over the upper end .of the spindle 48. It is thus easy to dismantle the star-shaped member 6 after removal of the knob .50 and of the key v49. Theinterchangeable star-shaped member 6 carries furthermore as apparent from inspection of Fig. .14 two studs 51 and 52 defining through abutment against a stationary pin 53 thebeginning and the end of the thread-cutting stroke; in other words, the. intermittent rotation of the star-shaped member 6 is limited by radial planespassing through said-studs 51'and 52 and between which are located'the flatgperipheralelements 21 forming the abutments for the successive -cuts to be provided. When a threadcutting stroke is at an end, the stud 52 arrives into contact with the stationary pin 53 and it is suflicient for the workman to depress a spring-urged push button 54 (Fig. so as to release through the agency of the rocker 57 the catch 46 with reference to its ratchet wheel, after which the workman acts on the knurled knob 50 so as to turn the system 4850 carrying the star-shaped member 6. This turning in the direction of the arrow 55 in Fig. 10 returns the other stud 51 into contact with the stationary pin 53, i.e. it returns the star-shaped member 6 into its starting position. Since the star-shaped member 6 is removable and interchangeable, it is possible to define before hand the number and the depth of cuts required in accordance with the diameter of the piece of work, the pitch of the thread and the material forming the piece of work to be threaded.

Generally speaking, it is apparent that the automatic device described allows selecting as required the number and the depth of the successive cuts without any further step being necessary during the machining and furthermore the speedy and accurate receding movement of the tool is obtained automatically in a very simple manner. The workman has simply to act on the handle 8 after each return of the tool.

The arrangement according to my invention may be fitted on various tool-carrying turrets of extant lathes. It may be angularly set in a horizontal plane in a manner such that the thread-cutting tool may thus engage the piece of work to be machined perpendicularly to its axis or again along the generating line of the flank of the thread to be cut. The arrangement described may be fitted at any desired height either at the level of the lathe centres or at a level vertically shifted with reference to the latter as required by the method of thread-cutting adopted. Furthermore the arrangement including the slides and associated parts as described hereinabove may be fitted not only on the carriage of a machine tool, but on any suitable moveable carrier to form a trip lock mechanism.

What I claim is:

1. In a thread-cutting machine including a longitudinally shiftable carriage, the combination of a tool-holder including two sections adapted to be shifted with reference to each other over the carriage along alined paths perpendicular to the direction of movement of the latter, a stop rigid with the carriage extending between the alined paths followed by the tool-holder sections, a cutting-tool rigid with one section, springs urging the tool-holder sections towards each other into engagement with the corresponding sides of the stop, a cam-shaped member carried by the carriage and revoluble round an axis perpendicular to the directions of movement of the carriage and of the tool-holder sections, said cam-shaped member being provided with peripheral flat surfaces parallel with its axis, lying at different stepwise increasing distances from said axis and adapted to form selectively when facing the second section of the tool-holder an abutment for the latter, a hand-operable control lever pivotally secured to the said second section round an axis perpendicular to the directions of movement of the carriage and of the toolholder sections and adapted when shifted out of an inoperative position into an operative position against the action of the springs to space said sections apart through a toggle link action and thereby urge the second section of the tool-holder into engagement with the abutment formed by the peripheral flat surface facing said section, and a mechanical connection operatively interconnecting the control lever and the cam-shaped member and adapted upon actuation of said control lever out of its inoperative position into a further operative position to shift said cam-shaped member by the amount required for substituting one of its fiat surfaces by the next abutment surface to define increasing depths of cut for the tool.

2. A trip lock mechanism comprising a carrier, a front and a rear section adapted to be shifted with reference to each other in a rear-to-front direction over said carrier and to be shifted bodily with said carrier over a path extending in a direction perpendicular to that of said rear-to-front shifting, a stop fitted on the carrier between the two sections, springs urging the sections towards each other into engagement with the corresponding sides of the stop, the spring acting on the front section being stronger than the spring acting on the rear section, an abutment fitted on the carrier to the rear of the rear section to define its rearmost position, a handoperable control lever pivotally secured to the rear section round an axis perpendicular to the two directions of shifting of said sections and adapted, when shifted out of an inoperative angular position into an operative angular position to space said sections apart against the action of the springs through a toggle link action and thereby urge the rear section of the carrier into engagement with the corresponding abutment, a bolt adapted to lock the control lever in its operative position, and a stop at one end of the path of the carrier adapted to impinge against the bolt and thereby release the control lever when the carrier reaches said end of its path.

3. A trip lock mechanism comprising a carrier, a front and a rear section adapted to be shifted with reference to each other in a rear-to-front direction over said carrier and to be shifted bodily with the said carrier over a path extending in a direction perpendicular to that of said rearto-front shifting, a stop fitted on the carrier between the two sections, springs urging the sections towards each other into engagement with the corresponding sides of the stop, the spring acting on the front section being stronger than the spring acting on the rear section, a camshaped member provided with a plurality of abutment surfaces adapted to be set selectively in registry with the rear section at corresponding diflferent distances therefrom, a hand-operable control lever pivotally secured to the rear section round an axis perpendicular to the two directions of shifting of said sections and adapted, when shifted out of an inoperative angular position into an operative angular position, to space said sections apart against the action of the springs through a toggle link action and to urge the rear section of the carrier into engagement with the cooperating abutment surface registering therewith, a mechanical connection operatively interconnecting the control lever and the cam-shaped member and adapted upon actuation of said control lever out of its inoperative position away from its first operative position into a further operative position to shift said cam-shaped member by the amount required for substituting one of its abutment surfaces by the next abutment surface, a bolt adapted to lock the control lever in its operative position, and a stop at one end of the path of the carrier adapted to impinge against the bolt and thereby release the control lever when the carrier reaches said end of its path.

4. A trip lock mechanism comprising a carrier, a front and a rear section adapted to be shifted with reference to each other in a rear-to-front direction over said carrier and to be shifted bodily with said carrier over a path extending in a direction perpendicular to that of said rear-to-front shifting, a stop fitted on the carrier between the two sections, springs urging the sections towards each other into engagement with the corresponding sides of the stop, the spring acting on the front section being stronger than the spring acting on the rear section, an abutment fitted on the carrier to the rear of the rear section to define its rearmost position, a hand-operable control lever pivotally secured to the rear section round an axis perpendicular to the two directions of shifting of said sections and adapted, when shifted out of an inoperative angular position into an operative angular position, to space said sections apart against the action of the springs through a toggle link action and to urge the rear section of the carrier into engagement with the corresponding abutment, a further lever revolubly mounted on the rear section round an axis parallel with the axis of the control lever and adapted toilock said 'control'lever during the movement of the sections alongsaid pathin .a predetermined 'directiomratstationary stop lying in the path of the looking lever moving with the carrierand adapted to shift .theulocking lever out of its operative position when subjected to the impact of the latter and to thus release the control lever, and elastic means returning the released control lever into its inoperative position.

References Cited in .the file of this patent

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