US2120842A - Feed mechanism for screw and similar machines - Google Patents

Description

June 14, 1938. A, R H 2,120,842

FEED MECHANISM FOR SCREW AND SIMILAR MACHINES Filed Aug. 21, 1936 2 Sheets-Sheet 1 Fig.1 16 34 .26 27 ig 74 30 a2 C.'A. RICH J ne 14, 1938.

FEED MECHANISM FOR SCREW AND SIMILAR MACHINES Filed Aug. 21, 1936 2 Sheets-Sheet 2 Fig. 5

Witness Mififlm Fly 6 Invgzior Patented June 14, 1938 UNITED STATES FEED MECHANISM FOR SCREW AND SIMILAR MACHINES Charles A. Rich, Providence, R. 1., assignor to Brown and SharpeManuf-acturing Company, a corporation of Rhode Island Application August 21, 1936, Serial No. 97,183

14 Claims.

The present invention relatesto improvements in feed mechanism for screw and similar machines for fashioning articles successively from bar stock.

In machines of this general description, the Work is fed through a rotary feed tube preferably provided at its forward end with feed fingers which are arranged to frictionally engage with and feed the Work into position against a stop which operates to position the work for the operation of the forming and cutting-off tools. Positively operating connections are usually provided for imparting to the feed tube a reciprocatory feeding and return stroke which is adjusted in accordance with the requirements of the work, so that it is always a little longer than that required to insure the advance of the feeding bar by the frictionally engaging feed fingers into operating position against the feed stop. With this construction and arrangement of the feed mechanism, it has been found necessary to chamfer the rear end of each piece of stock to prevent the engagement of the feed finger behind the waste end of the bar after the completion of the last article therefrom, with consequent injury to the machine as the positive advance of the feed tube brings the waste end into engagement with the stock stop.

It is a principal object of the present invention to provide a yielding connection in the feed mech anism above described, which will operate as a safety cushion against excessive resistanceto the advance of the feed tube, while at the same time retaining the advantages of an accurately determined feed stroke of the feed tube under normal operating conditions.

More broadly stated, it is also an object of the invention to provide-a feed mechanism for a screw or similar machine having certain elements of novel construction and mode of operation, to provide for the accurate and-certain feed of the bar into operating position, and having embodied therein a safety cushion to prevent possible injury to the machine through interference with the I, feed stroke-of the feed tube and bar engaging mechanism associated therewith.

With these and other objects in view, as may hereinafter appear, the several features of the invention consist in the devices, combinations and arrangement of parts hereinafter described and claimed, which together with the advantages to be obtained thereby will be readily understood by one skilled in the artfrom the following description takenin connection with theaccompanying drawings, in which Fig. 1 is a view in rear elevation of an automatic screw machine"; Fig; 2 is a somewhat fragmentary sectional View vtaken on the line 2-2 of Fig. 1, to illustrate particularly the stock stop and mechanism for actuating the same; Fig. 3 is an end View taken on the line 3-3 of Fig. 1, to illustrate particularly the feed slide and associated parts for actuating the feed tube; Fig. l is a sectional view taken on the line 44 of Fig. 3; Fig. 5 is a sectional plan view taken on the line 5-5 of Fig. 3; and Fig. 6 is a detail plan View of the latch.

The automatic screw machine disclosed in the drawings as embodying in a preferred form the several features of the present invention, comprises a base In, turret tool support l2, turret slide l4, stock stop It and a spindle assembly for rotating and. feeding the work to the operating tools including a feed tube "3 provided at its forward end with feed fingers 20 and a chuck mechanism generally indicated at 22 for positively gripping and rotating the work.

The spindle assembly including the feed tube i8 and chuck 22 is continuously rotated at a high rate of speed from either of two oppositely driven driving pulleys 24 or 26 through a clutch mechanism generally indicated at 21. The machine is also provided with a main driving pulley 28, amain clutch 30 and drive shaft 32, as generally indicated in Fig. 1, which is connected to drive the several operating mechanisms of the machine including the turret l2, slide l4, the stock stop E6, the chuck 22 andthe stock feeding mechanism. The connections through which these mechanisms are driven from the clutch 30 and shaft 32 are well known .in the art, and will be described only so far as necessary to show the connection of the present invention therewith.

The stock stop I6 is moved downwardly into operating position to engage with and position the leading end of the feeding bar, and is thereafter retracted during the subsequent forming and cutting-off operations, through connections which include a rock shaft 34 to which the stock stop I6 is secured, a pinion 36 on the shaft 34, a rack bar 38 engaging therewith and connected at its lower end to a cam lever 48 supported on a stationary pivot 42 and provided intermediate its length with a cam roll 44 which rides against the periphery of an actuating cam 46 on the cam shaft 48 of the machine. A spring-pressed plunger 50 slidably supported in a bracket 52 in the machine base, engages against the under side of the cam lever 40 to maintain the roll 44 in operative engagement with the cam 46.

For advancing thesuccessive portions of the work into operating position against the stock stop, a feed mechanism is provided which operates to advance and retract the feed tube IS in timed relation to the operation of the operating tools, the stock stop l6 and chuck 22. This mechanism includes a feed slide 56 having guiding surfaces 58 which engage with a corresponding guideway carried on an extension 59 of the machine frame.

The operation of the feed slide is controlled from a feed lever 68 supported intermediate its length on a, stationary pivot 82 and provided at its lower end with a cam roll which rides in a spiral cam groove 84 formed in the face of a cam cylinder 66 on the cam shaft 48. per end of the feed lever 68 is grooved to receive a sliding block 68 pivotally mounted on a slide which is in turn adjustably supported in a sloping guideway 18 formed on the feed slide 58. The position of the block 58 and slide support therefor in the guideway 78 is adjustably determined to vary the length of the feeding and return stroke of the feed slide by means of a screw 12 threaded into the slide and supported at its upper end against axial movement in a bearing l4 carried on the upper end of the guideway 18. r

The feeding mechanism as thus far described, comprising the constant throw feed lever 68 and the adjustable connection with the feed slide 58, issubstantially identical with mechanism well known in the art, and is arranged to impart a positive advancing and retracting movement of the feed slide 58 which is always slightly in excess of that required to advance the leading end of the feeding bar, frictionally engaged by the fingers 28, into operating position against the stop l6.

The present machine is provided with the usual mechanism for actuating the chuck 22 to engage with and rotate the work during the operation of the forming and cutting-off tools. This mechanism includes the chuck actuating levers I5 fulcrumed in a ring 18 and controlled by a sleeve member I? and cam lever 18 which is actuated in timed relation to the feed mechanism from a cam on the cylinder 88. Inasmuch as this mechanism is well known in the art, and 7 does not form directly any part ofthe. present invention, no further description or illustration thereof is believed necessary. I

With the usual construction of the feed mechanism above described, in which the feed tube is positively connected for -movement through a predetermined stroke, it has been found that any excessive resistance or obstructionto the advance of the feed tube is likely to result in serious damage'to the machine. Such an obstruction to the advance of the feed tube is likely to occur, for instance, where the fingers 28 become caught behind the waste end of a feeding bar, and are therefore prevented from slipping with relation thereto as the waste end is advanced against the stop l6. 7

In accordance'with'the present invention, a yieldable driving connection is provided between the feed slide 56 and feed'tubel8 which is arranged normally to providea stationary relationship between these elements, but is capable of yielding against excessive resistance to the advance of the feed tube, and thereby prevent possible injury to the machine. This connection, as best shown in Figs. 3 to 6 inclusive, comprises a latch 88 which is carried on two supporting members 82 and 84 on the feed slide 56, and is provided intermediate its length with a flanged cover portion 88 which is arranged for locking engagement with a ball bearing 88 carried on the feed tube I8 and supported against axial movement with relation thereto between two collars 83 and 85. The members 1823and 84 take the form of cylindrical tubes which are slidably supported respectively in bores 81 and 89 formed in the feed slide 56. Each of the members 82 and The up- 84 has formed thereon a peripheral step 98 which serves as a support for the latch 88, and also provides a shoulder for engagement with the adjacent face of the feed slide 56 to limit the forward movement of the members with relation thereto. A shoulder 92 formed adjacent to the step 98 on each of the members 82 and 84 is arranged for engagement with adjacent side por- 'tions of the latch 88, so that any movement of the latch and. feed tube l8 rearwardly or to the left of the feed slide 56, as shown in Fig. 4, must carry with it the slidable supporting members 82 and 84. For convenience of assembly, the latch 88 is pivotally mounted on the step 98 of the supporting member 82, and is provided at its other end with a semi-circular slot 93 which is arranged to fit tightly over the peripheral step 98 of the member 84 between the sh0u1- der 92 and the adjacent face of the feed slide 56. With this constructionand arrangement of the parts, it will readily be seen that the movement of the latch 88 downwardly to the full line position shown in Fig. 3, operates to move the cover portion 86 thereofinto locking engagement with thebearing 88, and at the same time to position the slotted portion 93 thereof in engagement with the step 98 of the member 84, so that the members 82 and 84, latch 88 and feed tube I8 are connected-to move as a single operating unit. To assist in locking the parts in operating position, there is formed in the feed slide 56, a segmental supporting surface 95 for the bearing 88 which extends slightly more than half way around the periphery of the bearing, and serves to prevent the bearing 88 and feed tube I8 from moving out of position independently of the latch.

The assembly including the slidable members 82 and 84, the latch 88and feed tube l8 are normally maintained in a fully advanced position to the right with relation to the feed slide 56 as shown in Fig. 4 and as indicated by the dot-and-dash position of the latch 88 in Fig. 5, by means of identical spring connections acting respectively onthe slidable members 82 and 84. The spring connection acting upon the member 84 is fully illustrated in Fig. 5. A compression spring 94 housed within the member 84, engages at one end against a shoulder 96 of the member 84, and at its other end against a collar 98 of .a pin I88 which extends through the coils of the spring, and is connectedat its right hand or forward end to the feed slide 58. ,For clarity of illustration, the parts of the spring connection for the member 82, being exact duplicates of the spring connection for the member 84, have been given the same reference characters so far as they appearin Figs. 3 and 5 ofthe drawings. It will be noted that the two spring-pressed units including members 82 and 84 are located .on the feed slide 58 on opposite sides of the feed tube I8, so that a balanced condition is obtained, in which an equal pressure is exerted .by each of the spring-pressed members 82 and 84 to maintain the latch 88 and feed tube I8 in a relatively advanced position on the feed slide 56. l

The springs 94 of the illustratedconstruction are of suificient strength to maintain the members 82 and 84 and feed tube l8 connected thereto under'normal operating conditions of the machine at all times in their fully advanced position with relation to the feed slide 56, so that a normally stationary connection is provided between the feed slide and feed tube, thus retaining the advantages. of the usual construction in which a positively operating feed mechanism is employed having no lost motion or play in the parts to secure an accurate feed of the work. The full line position illustrated in Fig. 5, shows a relative position of the feed tube I8, latch and members 82 and 8.4 with relation to the feed slide 56 which is obtained when the advance of the feed tube is obstructed as for example by the engagement of the feed fingers behind the waste end of an old bar which is fed against the stock stop I6. Under these conditions the yield provided by the springs 94 will permit the feed tube and associated parts to move rearwardly away from the feed slide 56, thus preventing any possible injury to the parts of the feed mechanism.

With the construction as thus far described, it will readily be seen that the extent of the relative movement which may take place between the feed tube I8 and feed slide 56 is limited by the capacity of the springs 94, and that once the springs have been fully compressed, the feed tube will be again positively advanced with the feed mechanism. While the relative movement thus provided for is amply-sumcient to allow the feed slide to continue to the forward limit of its feeding stroke in the usual case in which the feed tube I8 and fingers are blocked from further movement behind the waste end of a feeding bar, it has been found desirable to make a further provision for an extreme case in which the feed tube I8 might become jammed at a relatively early stage in its forward movement. In order to prevent possible serious damage to the machine in the extreme case above supposed, shear pins are provided in the feed connections which will be sheared off by the imposition of an excessively heavy load on the feed connections to wholly disconnect the feed tube from its driving mechanism. To this end the pins I00 are connected to the feed slide 56 by means of shear pins I02 which extend through the pins I00 and engage at each side thereof against disks I04 recessed respectively into the ends of the bores 81 and 89 in the feed slide 56. The shearing off of the pins I02 operates to wholly disconnect the feed tube I8, latch 80 and members 82 and 84 from the feed slide 56 which can continue its movement independently of these parts to the limit of its feeding stroke.

In order to prevent the springs 94 and pins I 00 from flying out of the machine when released by the shearing off of the pins Hi2, each of the members 82 and 84 have heavy metal caps indicated respectively at Hi6 and I08 screwthreaded into the rear ends thereof.

It will be understood that the invention is not limited to the specific embodiment shown, and that various deviations may be made therefrom without departing from the spirit and scope of the appended claims.

What is claimed is:-

1. In a feed mechanism for a screw machine, the combination with a stop against which the work is fed, of a feed tube having means for frictionally engaging the work, driving connections for reciprocating the feed tube constructed and arranged to advance the feed tube beyond a position in which the work is engaged against the stop, and a resilient connection in said driving connections of sufficient strength to cause slippage of said friction means on the work when engaged against the stop.

2. In a feed mechanism for a screw machine, the combination with a stop against which the work is fed, of a rotary feed tube including means for frictionally engaging and advancing the work against the stop, driving connections for advancing and retracting the feed tube between predetermined limits constructed and arranged to advance the feed tube beyond a position in which the work is engaged against the stop, a feed adjustment in said connections to vary the feed and return stroke of the feed tube, and a resilient connection in said drive independent of said feed adjustment to provide a safety cushion against excessive resistance to the advance of the feed tube, said resilient connection being of sufficient strength to cause slippage of said friction means on the work when engaged against the stop.

3. In a feed mechanism for a screw machine, the combination with a stop against which the work is fed, of a rotary feed tube including means for frictionally engaging and feeding the work against the stop, a feed member, driving connections for positively advancing and retracting the feed member between predetermined limits constructed and arranged to advance the feed tube beyond a position in which the work is engaged against the stop, a feed adjustment in said connections to vary the feed stroke of the feed member, and a resilient connection between the feed member and tube to provide a safety cushion against excessive resistance to the advance of the feed tube, said resilient connection being of sufiicient strength to cause slippage of said friction means on the work when engaged against the stop.

4. In a feed mechanism for a screw machine, the combination with a stop against which the work is fed, of a feed tube having means for frictionally engaging the work, driving connections for reciprocating the feed tube between predetermined limits constructed and arranged to advance the feed tube beyond a position in which the work is engaged against the stop, and a resilient connection having a limited yield and of sufficient strength to cause slippage of said friction means on the work when engaged against the stop, and a safety device rendered operative by relative movement of the feed tube and drive connections beyond the limit of said yield to operatively disconnect the feed tube from said driving connections.

5. In a feed mechanism for a screw machine, the combination with a stop against which the work is fed, of a rotary feed tube including means for frictionally engaging and feeding the work against the stop, a feed member, driving connections for advancing and retracting the feed member between predetermined limits constructed and arranged. to advance the feed tube beyond a position in which the work is engaged against the stop, a resilient connection between the feed member and tube having a limited yield and of sufficient strength to cause slippage of the friction means on the work when engaged against the stop, and a safety device including a shear pin rendered operative by relative movement of the feed tube and feed member beyond the limit of said yield to operatively disconnect the feed tube from the feed member. I

6. In a feed mechanism for a screw machine, the combination of a rotary feed tube, a feed slide, driving connections for advancing and retracting the feed slide to feed the work, and a resilient connection between the slide and the tube comprising a latch on the feed slide arranged for locking engagement with the feed tube to prevent axial movement of the latch and feed tube, and a spring connection between the latch and feed slide acting to maintain the latch in a relatively advanced position on the feed slide in the direction of feed.

7. Ina feed mechanism for a screw machine, the combination of a rotary feed tube, a feed slide, driving connections for advancing and retracting the feed slide to feed the work, and a resilient connection between the slide'and tube comprising a bearing supported on the tube against axial movement relatively thereto, a latch on the feed slide arranged for locking engagement with the bearing to prevent relative axial movement of the latch and feed tube, and a spring connection between the latch and the feed slide acting to maintain the latch in a relatively advanced position on the feed slide in the direction of feed.

8. In a feed mechanism for a screw machine, the combination of a rotary feed tube, a feed slide, driving connections for advancing and retracting the feed slide to feed the work, and a resilient connection between the slide and tube comprising a bearing supported on the tube against axial movement relatively thereto, a latch on the feed slide arranged for locking engagement with the bearing to prevent relative axial movement of the latch and feed tube, a pivotal support on the feed slide on which the latch moves axially and turns in a plane normal to the axis of the feed tube, and a spring connection between the latch and the feed slide acting to maintain the latch axially in a relatively advanced position on the feed slide in the direction of feed.

9. In a'feed mechanism for a screw machine, the combination of a rotary feed tube, a feed slide, driving connections for advancing and retracting the feed slide to feed the work, and a resilient connection between the slide and tube comprising a latch on the feed slide arranged for locking engagement with the feed tube to prevent relative axial movement of the latch and tube with the feed slide.

10, In a feed mechanism for a screw machine, the combination of a rotary feed tube, a feed slide, driving connections for advancing and retracting the feed slide to feed the work, and a resilient connection between the slide and the tube comprising a bearing supported on the tube against axial movement relatively thereto, a latch arranged for locking engagement with the bearing to prevent relative movement of the latch axially of the feed tube, a pivotal support for the latch on the feed slide arranged to permit movement of the latch axially of its pivot, a second support for the latch on the feed slide located on the opposite side of the bearing from said pivotal support, and springs associated with each of said supports acting on the latch to maintain the latch in a relatively advanced position on the feed slide in the direction of feed.

11. In a feed mechanism for a screw machine, the combination with a stop against which the work is fed, of a rotary feed tube and a feed collet for frictionally engaging and advancing the work against the stop, a feed slide, driving connections for advancing and retracting the feed slide between predetermined limits" to feed the work frictionally against the stop, a latch on the feed slide arranged for locking engagement with the feed tube to prevent relative axial movement of the latch and feed tube, and a yielding connection between the latch and feed slide acting to maintain the latch in a relatively advanced position on the feed slide in the direction of feed including a compression spring, a spring supporting member and a shear pin.

12. In a feed mechanism for a screw machine, the combination with a stop against which the work is fed, of a rotary feed tube and 'a feed collet for frictionally engaging and advancing the work against the stop, a feed slide, driving connections for advancing and retracting the feed slide between predetermined limits to feed the work frictionally against the stop, a latch on the feed slide arranged forlocking engagement with the feed tube to prevent relative axial movement of the latch and feed tube, and a yielding connection between the latch and feed slide com prising a latch supporting member slidably mounted on the feed slide, and a spring connection between the latch supporting member and the feed slide acting to maintain said memher and latch engaged thereby in a relatively advanced position on the feed slide in the direction of feed.

work is fed, of a rotary feed tube and a feed collet for frictionally engaging and advancing the work against the stop, a feed slide, driving connections for advancing and retracting the feed slide between predetermined limits to feed the work frictionally against the stop, a latch on the feed slide arranged for locking engagement with the feed tube to prevent relative axial movement of the latch and feed tube, and a yielding connection between the latch-and feed slide comprising latch supports slidably mounted on the feed slide on opposite sides of the feed tube, and spring connections between each ofsaid supports and the feed slide'to maintain said supports and the latch engaged thereby in a relatively advanced position on the feed slide.

14. In a feed mechanism for a screw machine, the combination with a stop against which the work is fed, of a rotary feed tube and a feed collet for frictionally engaging and advancing the work against the stop, a feed slide, driving connections for advancing and retracting the vfeed slide between predetermined limits to feed the work frictionally against the stop, a latch on the feed slide arranged for locking engagement'with the feed tube to prevent relative axial movement of the latch and feed tube, and a yielding connection between the latch and feed slide comprising a hollow latch support slidably mounted on the feed slide and having the rear end thereof closed, a compression spring housed within said hollow support connected at its forward end to said support, and a c0nnection between the rear end of the spring and the feed slide including a shear pin acting on said spring to maintain the support and latch engaged thereby in a relatively advanced position on the feed slide.

CHARLES A. RICH.

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