US2797798A - Tractor-type stock feed - Google Patents

Description

July 2, 1957 K. w. HALLDEN TRACTOR-TYPE STOCK FEED 5 Sheets-Sheet 1 Original Filed July '7, 1952 LL JI I156 M5 I60 286 i INVENTOR a; Mala/71 Hallaezz 1412 ring/- July 2, 1957 K. w. HALLDEN TRACTOR-TYPE STOCK FEED 5 Sheets-Sheet 2 Origmal FiledJuly 7, 1952 July 2, 1957 K. w. HALLDEN 2,797,798

TRACTOR-TYPE STOCK FEED Original Filed July 7, 1952 5 sheets'sheet 3 I N V EN TOR.

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July 2, 1957 K. w. HALLDEN 2,797,798

TRACTOR-TYPE STOCK FEED Origmal Filed July 7, 1952 5 Sheets-Sheet 4 Elan:

July 2, 1957 K. w. HALLDEN TRACTOR-TYPE STOCK FEED 5 Sheets-Sheet 5 INVIENTOR. MZka/WHaZZde/Y ONW Original Filed July 7, B52

2,797,798 Patented July 2, 1957 TRACTOR-TYPE STOCK FEED Karl William Haliden, Thomaston, Cnn., assignor to The Hallden Machine Company, Thomaston, Conn., a corporation of Connecticut Original application July 7, 1952, Serial No. 297,504, new Patent No. 2,767,829, dated October 23, 1956. Divided and this application August 19, 1955, Serial No. 529,511

3 Claims. (Cl. 203-305) This invention relates generally to stock-feeding de vices, and more particularly to a tractor-type feed for rod stock.

This application is a division of my copending application, entitled Apparatus for and Method of Drawing Rod tock, Serial No. 297,504, filed July 7, 1952, and now Patent No. 2,767,829.

In order to draw continuous rod stock through a die, previous apparatus of this type rely on reciprocating grippers which alternately draw or pull the stock much in the fashion of hand-over-hand hauling. To achieve uniformity of the size, texture and temper, of drawn rod stock, it is imperative that the stock be passed through the die at uniform. speed, or at least substantially uniform speed. Due to the periodically alternating gripping and drawing action of the aforementioned grippers, they will meet the imperative requirement of substantially uniform passage of the stock through the die only when drawing the stock at a comparatively low rate of speed. Any attempt at increasing the stock-drawing speed of these grippers, especially to the high speed demanded by modern industry, is doomed to failure. This is due to the fact that any considerable increase in the operating speed of these grippers beyond their maximum permissible speed would, on each resumption of their alternate drawing action on the stock, result in uncontrollable slippage of the same on the stock, and accordingly in frequent variation in the speed of the stock. Furthermore, any considerable increase in the operating speed of these grippers beyond their maximum permissible speed would result in periodic engagement of the same with the stock with a prohibitive impact force which would mar the drawn stock and also lead to rapid wear of the grippers. Moreover, stock-drawing apparatus of this type used heretofore are, by virtue of their low operating speed, incapable of efiicient combined performance with modern high-speed stock-cutting shears of the flying type to elimiirate any handling of continuous rod stock between the drawing of the stock and its cutting into desired lengths.

It is an important object of the present invention to provide, especially, though by no means exclusively, for the passage of continuous rod stock through a die, a tractor feed which is not only capable of pulling the stock through the die at a much higher and more uniform speed than the previous grippers, but has also such a low specific pressure on the stock that marl-ing of the same is unlikely even at exceptionally high operating speed of the tractor feed.

It is (another object of the present invention to have the aforementioned tractor feed accurately set, and adapted solely, for gripping rod stock of the desired drawn size and pulling the stock through the die with such a force that the stock will neither be marred by, nor slip in, the tractor feed even at exceptionally high operating speeds of the latter.

It is a further object of the present invention to have the aforementioned tractor feed self-compensating so that rod stock will be securely gripped thereby for drawing purposes even if the die aperture should through wear have become enlarged.

Another object of the present invention is to provide for adjustment of the aforementioned tractor feed so that rod stock drawn to different sizes in dilferent dies will be gripped evenly by the tractor feed and subjected thereby to equal tensile stresses throughout and no other stresses, with the result that drawn rod stock of any size will emerge straight, or substantially straight, from the tractor feed.

It is a further object of the present invention to provide the aforementioned tractor feed with two endless conveyor chains which pass over sprockets, and have adjacent rod-gripping or operating runs of which one run rides on a non-yielding track that is adjustable toward and away from the other run, and the latter is yieldingly urged toward its companion run and accordingly self-compensating, so that rod stock of any drawn size between these operating runs of the chains may readily be held thereby in exact axial alignment with the aperture of the die in which the stock is drawn to size.

Another object of the present invention is to provide for the aforementioned self-compensating chain run a yielding track on which the same rides when both operating runs of the chain draw rod. stock, so that this selfcompensating chain run will have as uniform a grip on the stock (as the adjacent companion chain run.

A further object of the present invention is to make arrangements for the power drive of those sprockets of the chains which are at the exit end of the tractor feed, so that the operating runs of the chains will have maximum traction on the rod stock for assuredly overcoming the high resistance encountered by the stock in the drawing die, and to provide for adjustment of these powerdriven sprockets toward and away from each other so that they may, on any adjustment of the non-yielding chain track for any given drawn size of rod stock, draw the operating chain runs in rectilinear paths over and beyond their respective tracks, with the result that the pull of these sprockets on the operating chain runs will not compel the latter into pressing engagement with their tracks and will not cause them to bend abruptly at the run-off ends of the latter.

It is another object of the present invention to provide each of the. aforementioned chain tracks with a multiplicity of antifriction rollers on which the respective operating runs of the chains ride, thereby to reduce to a minimum the friction between these tracks and chain runs when the latter :draw rod stock and, accordingly, save the operating parts of the tractor feed from undue wear and keep the power requirements of the latter at a minimum.

Another object of the present invention is to have the yielding chain track formed by a battery of side-by-side arranged track sections each of which carries a few rollers and is independently yieldable,-so that the rod stock will be gripped most evenly substantially by all the rollers on both chain tracks.

A further object of the present invention is to provide for each of the aforementioned sections of the yielding ehain track a pneumatic cylinder and a piston therein which is connected with the track section for normally yieldingly forcing the rollers thereon into firm gripping engagement with the stock in the tractor feed.

It is another object of the present invention to have each 'of the aforementioned pistons double-acting to permit also relief of the corresponding chain of the tractor feed of any strain from the yielding chain track when no stock passes through the tractor feed.

Another object of the present invention is to arrange the cylinders for the Sections of the yielding chain track wholly between the opposite runs of the associated tractor chain, and so that the axes of the pistons intersect the rod stock passing through the tractor feed in order that the full force of the pistons may directly be applied to the fed rod stock without setting up harmful bending stresses either in the pistons or in the track sections.

A further object of the present invention is to provide a control over the stock-gripping strokes of the pistons in the aforementioned cylinders, so that these pistons will, at the end of their stock-gripping strokes, be stopped while the operating runs of the chains are still sufficiently separated to grip and draw rod stock which may be introduced into the tractor feed while the latter is running.

It is another object of the present invention to provide for variation in the aforementioned control over the stock-gripping strokes of the pistons in the cylinders, so that stock of different drawn sizes maybe introduced into the running tractor feed and be gripped and drawn there- It is a further object of the present invention to facilitate the task of adjusting the tractor feed to rod stock of different drawn sizes, by having on the tractor feed provisions for simultaneously adjusting the aforementioned power-driven sprockets and the non-yielding chain track on manipulation of a single actuator.

Another object of the present invention is to expedite the accurate adjustment of the tractor feed to rod stock of different drawn sizes, by providing an indicator or pointer which is operatively connected with the aforementioned actuator so as to move over a scale or dial, which is graduated in different drawn rod sizes, and indicate thereon the adjustment of the tractor feed at any given moment as a guide to an operator undertaking an adjustment of the tractor feed to a given drawn stock size.

Other objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illus trative purposes:

Fig. 1 is a side elevational view of a tractor feed embodying the present invention;

Fig. 2 is a top view of the tractor feed;

Fig. 3 is an enlarged side view of the tractor feed similar to Fig. 1, but with certain parts removed and other parts shown in section; 7

Figs. 4, and 6 are cross-sections through the tractor feed, taken substantially on the lines 44, 55 and 6-6, respectively, of Fig. 3;

Fig. 7 is a longitudinal section through the tractor feed taken substantially on the line 7-7 of Fig. 5;

Fig. 8 is another elevational view, partly in section, of the tractor feed as seen from the side opposite to that from which the same is viewed in Figs. 1 and 3;

Fig. 9 shows a part of a certain detail element of the tractor feed; and

Fig. 10 is a fragmentary section taken on the line 1010 of Fig. 4.

Referring to the drawings, the reference numeral 10 designates a tractor feed which comprises two chains 12 and 14 which pass over spaced pairs of sprockets 1618 and 20-22, respectively. The sprocket pairs 16-18 and 2022 are so arranged that two adjacent straight feed runs 24 and 26 of the chains 12 and 14 are substantially parallel and closely adjacent each other. The chains 12 and 14 are of the double-roller type (Figs. 4, 5 and 6) and carry between their inner links 28 feed blocks 30 which are grooved on the outside as at 32 to grip rod stock s between the feed runs 24 and 26 and guide the same through the latter. The sprockets 16 to 22 for the chains 12 and 14 are journalled, in a manner to be described, in an upright feed frame 34, so that these sprockets and the chains thereon are located and '4 accessible on the side of the feed frame. In the present example, the rod stock s passes through the tractor feed in the direction of the arrows 36 in Fig. 3, and the sprockets 18 and 22 at the exit end of the tractor feed are power-driven so that the feed runs 24 and 26 of the chains have traction on the rod stock throughout its extent through the tractor feed.

As shown in Fig. 6, the sprockets 16 and 20 at the stock-entry end of the tractor feed are journalled on antifriction bearings 38 and 40 on stub extensions 42 and 44 of shafts 46 and 48, respectively, which are turnably mounted in bushed apertures 50 and 52, respectively, in the feed frame 34. The driven sprockets 18 and 22 at the exit end of the tractor feed are keyed at 54 and 56 to stub extensions 58 and 60 of shafts 62 and 64, respectively (Fig. 4). Of these, shaft 62 is journalled in spaced antifriction bearings 66 and 68 in a journal box 70 which is turnably mounted in a cylindrical aperture 72 in the feed frame 34. The sprocket shaft 64 is journalled in spaced antifriction bearings 74 and 76 in a journal box 78 which is turnably mounted in a cylindrical aperture 80 in the feed frame 34. The ends of the sprocket shafts 62 and 64 extend in 'back of the feed frame 34 and have keyed thereto at 82 and 84 sections 86 and 88 of two flexible couplings 90, respectively, the other sections 92 of which (Fig. 2) are connected by shafts 94 with any suitable power-operated variable-speed mechanism (not shown) for the drive of the sprockets 18 and 22 for stock-feeding purposes.

The feed runs 24 and 26 of the tractor chains 12 and 14 ride on tracks 96 and 98, respectively, which hold these feed runs in position to grip the rod stock uniformly throughout and with suflicient over-all pressure to prevent slippage of the stock (Figs. 3 and 7). The tracks 96 and 98 are in this instance roller tracks so as to keep the friction between them and the chain runs 24 and 26 thereon at a minimum.

The track 98 for the feed run 26 of the lower chain 14 comprises a support 100 for a series of rollers 102. For convenience of manufacture and assembly, the support 100 is in this instance divided into complementary sections 104 and 106 (Fig. 7) which have oppositely inclined bottom surfaces 108 and 110, respectively, with which to rest on wedge-blocks 112 and 114, respectively. The complementary support sections 104 and 106 are in end-to-end engagement with each other and are guided for movement toward and away from the adjacent chain run 26 between machined surfaces 116 and 118 of laterally projecting lugs 120 and 122, respectively, on the feed frame 34. The supportsections 104 and 106 are provided in their top surfaces with grooves 124, respectively, which combine to form a continuous groove throughout the longitudinal extent of the support 100. Carried by each support section 104 and 106 are a plurality of equally spaced pins 126 which extend across the top groove 124 therein and rotatably support the rollers 102, respectively, so that the peripheries of the latter project above the tops of the support sections and are solely engaged by the inner links 28 of the feed run 26 of the chain 14 (see also Fig. 5).

The wedge-blocks 112 and 114, which are slidably supported on wear plates 128 on a lateral ledge 130 on the feed frame 34, are held against a machined surface 132 on the feed frame (Fig. 5) by a retainer plate 134 which is bolted at 136 to the ledge 130 and lugs 120 and 122 on the feed frame (see also Fig. 3). The wedgeblocks 112 and 114 have their adjacent ends partly cut away so that they may overlap each other in the fashion indicated in Fig. 7 and permit movement of the wedgeblocks toward and away from each other for upward or downward adjustment of the roller track 98.

In order to move the wedge-blocks 112 and 114 for the purpose of adjusting the roller track 98, the former are provided with vertical grooves 138 and 140, respectively, in which are slidably received blocks 142 and 144 on crank pins 146 and 148 on the ends of shafts 150 and 152 (Figs. 5, 7 and 8). Shaft 152 is journalled in a bushed bearing aperture 154 in the feed frame 34, and the other shaft 150 is similarly journalled in the feed frame. The ends of the shafts 150 and 152 which extend to the other side of the feed frame 34 carry identical worm gears 156 and 158, respectively, which are in permanent mesh with worms 160 and 162 on shafts 164 and 166, respectively (Fig. 8). The worm shafts 164 and 166, which are journalled in suitable bearing brackets 168 and 170 on the feed frame 34, are coupled to each other as at 172, and the worm shaft 166 is further coupled at 174 to another shaft 176 which is journalled in a suitable bearing bracket 178 on the feed frame. Carried by one end of the shaft 176 is a bevel gear 180 which is in permanent mesh with another bevel gear 182 on the lower end of a vertical shaft 184 which is journalled in spaced bearing brackets 186 and 188 on the feed frame 34 on the rear side thereof. The upper end of the vertical shaft 184 carries a bevel gear 190 which is in permanent mesh with another bevel gear 192 on the rear end of a horizontal shaft 194 which extends to the front of the feed frame 34 and is journalled in a suitable bearing bracket 196 on top of the feed frame. The other end of the horizontal shaft 194 carries a handwheel 198 which is readily accessible from the front side of the tractor feed (Figs. 1, 2 and 3). The crank pins 146 and 148 are so coordinated that manipulation of the handwheel 198 in either direction will, through intermediation of the bevel gears 192, 190, I82, 180 and the worm gearings 162, 158 and 160, 156, result in equal movement of the wedge-blocks 112 and 114 toward or away from each other and, accordingly, in upward or downward movement of the roller track 98 for the feed run 26 of the lower chain 14.

The track 96 for the feed run 24 of the upper chain 12 is made up of complementary track sections 200 (Figs. 3, and 7) which are arranged side-by-side to form a continuous support for a multiplicity of rollers 202 which are rotatably mounted, in this instance in series of 3 rollers, in grooves 204 in the individual track sections 200 in the manner best shown in Fig. 5. The sideby-side arranged track sections 200 are guided for upward and downward movement toward and away from the feed run 24 of the upper chain 12 between machined surfaces 206 and 208 of projecting lugs 210 and 212, respectively, on the feed frame 34 (Fig. 7). The track sections 208 are suspended on rods 214 of pistons 216 in cylinders 218 which are arranged battery-like between the opposite runs 24 and 24' of the upper chain, and

bolted at 220 to the feed frame 34 from the back side thereof (Figs. 7 and 8). More particularly, the track sections 200 are suspended on enlarged heads 222 on the piston rods 214 which are received in T-type slots 224 in the track sections, so that the latter may readily t be assembled with or dismounted from the piston rods 214. The track sections 200 are held against a machined surface 226 on the feed frame 34 by a retainer plate 228 (Figs. 3 and 5) which is bolted at 230 to the lugs 210 and 212 on the feed frame. Further bolts 232 and spacer sleeves 234 serve to hold the retainer plate 228 in properly spaced relation with the machined surface 226 of the feed frame between the lugs 210 and 212 thereon.

The pistons 216 in the cylinders 218 are in this instance operated by compressed air, and are double-acting as evidenced by the provision of air ducts 236 and 238 in the cylinders 218 which lead to the opposite ends of the chambers therein (Fig. 7). For simultaneously distributing compressed air to either ends of the chambers in the cylinders 218 and venting the other ends of the latter, there is provided a single manifold 240 (Fig. 7) having two longitudinal grooves 242 and 244 as well as branch grooves 246 and 248 therefrom, respectively, which lead to transverse passages 250 and 252 that are in communication with the ducts 236 and 238, respectively, in the various cylinders (Fig. 5). The manifold 240' is interposed between the cylinders 218 and a machined surface 254 on the feed frame 34 (Fig. 5), and is held in place by the same bolts 220 which are used for mounting the cylinders 218. Preferably interposed between the surface 254 of the feed frame 34 and the manifold 240 is a gasket 256 (Fig. 5) which effectively seals the grooves 242, 244, 246 and 248 against leakage of air therefrom. The main-distributing grooves or channels 242 and 244 of the manifold 240 communicate with passages 258 and 260, respectively, in the feed frame 34 (Fig. 5), and these passages 258 and 260 are, in turn, connected through conduits 262 and 264 with a suitable valve 266 (Fig. 8) for controlling the admission of compressed air into either one of the main distributing channels 242 or 244 and permitting simultaneous exhaust of compressed air from the cylinders through the other main distributing channel in the manifold 240.

As shown in Fig. 5, the axes of the piston rods 214 intersect the stock-gripping grooves 32 in the feed blocks 30 in the chains 12 and 14, so that the full force of the pistons 216 is directly transmitted to the fed rod stock s and the track sections 200 are not subjected to harmful bending stresses.

The sprocket-carrying stub extensions 42 and 44 on the shafts 46 and 48, respectively, are disposed eccentrically thereon (Fig. 6), and these shafts are normally yieldingly urged in directions to move the respective sprockets 16 and 20 at the entry end of the tractor feed away from the driven sprockets 18 and 22 (Fig. 3) in order to take up all slack in the chains 12 and 14 and tension the same as desired. To this end, the shafts 46 and 48 carry in back of the feed frame 34 levers 268 and 270, respectively, which are connected at 272 and 274 with the rods 276 and 278 of pistons in cylinders 280 and 282, respectively (Figs. 6 and 8). The cylinders 280 and 282 are pivotally mounted at 284 and 286, respectively, on a bracket 288 on the back side of the feed frame 34. The pistons in the cylinders 280 and 282 are in this instance operated by compressed air, and are of the double-acting type as evidenced by the provision of conduits 290, 292 and 294, 296 (Fig. 8) that communicate with the opposite ends of the chambers in the cylinders 280 and 282, respectively. The conduits 290 and 296 may also be connected with a suitable valve (not shown) to admit compressed air to either one of the adjacent ends of the cylinders 280 and 282, and simultaneously vent the other adjacent ends of these cylinders.

Provisions are made to provide between the feed runs 24 and 26 of the chains 12 and 14 a minimum gap which will be retained even if no stock is between these feed runs and which, while narrow, is nevertheless sufficient to admit new stock into firm gripping engagement with the feed runs 24 and 26 without appreciably resisting the feed of the new stock into the tractor feed. To this end, there is provided ontop of each of the cylinders 218 a block 293 through which extends a rod extension 380 of the piston in the cylinder (Figs. 5 and 7). These rod extensions 300 have end collars 302 which rest against a spacer plate 304 on the blocks 298 on top of the cylinders 218 when compressed air in the upper ends of the latter forces the upper track 96 downwardly and no stock is between the feed runs 24 and 26 of the chains 12 and 14. When the end collars 302 on the rod extensions 300 thus rest on the spacer plate 304, the pistons 216 in the cylinders 218 are held some distance from their lowest possible stroke positions therein, and the aforementioned minimum gap between the feed runs 24 and 26 of the chains 12 and 14 is retained when no stock is between these feed runs. The pistons 216 in the cylinders 218 are in Figs. 5 and 7 shown in retracted position in which the upper track 96 is withdrawn from the adjacent feed run 24 of the upper chain 12 in order to relieve the same of the tension imparted thereto by this track when the apparatus is idle or the chain 12 is to be relaxed for any other purpose to the extent aiforded by the retraction of the track 96. The spacer plate 304 is removably seated in aligned machined grooves 386 in the blocks 298 on the cylinders 218 (Fig. and has notches 308 to clear the rod extensions 3%. On account of the considerable length of the tractor feed, the spacer plate 304 is preferably formed in complementary sections 304 (Fig. 9) each of which has handles 310 for its convenient mounting and removal.

The feed runs 24 and 26 of the chains 12 and 14 are, by virtue of the described yieldability and adjustability of the tracks 96 and 98, respectively, adapted for feeding rod stock of different sizes. Accordingly, the shafts 46 and 48, which carry the sprockets 16 and 28 at the entry end of the tractor feed, are so spaced from each other that the gap between the adjacent ends of the feed runs 24 and 26 of the chains on these sprockets 16 and 20 is not less than the maximum rod size to be fed by the tractor feed. On the other hand, provisions are made for adjusting the power-driven sprockets 18 and 22 at the exit end of the tractor feed toward and away from each other so that they may, on any adjustment of the track 98 for any given rod size, draw the feed runs 24 and 26 of the chains in rectilinear paths over and beyond their respective tracks 96 and 98, with the result that the pull of these sprockets 18 and 22 on the respective feed runs 24 and 26 of the chains will not compel the same into pressing engagement with their tracks and will not cause them to bend abruptly at the run-off ends of the tracks. This is accomplished by mounting the bearings 66 and 68 for the sprocket shaft 62 eccentrically in the journal box 70 (Figs. 4 and 10) and providing on the journal box 70 on the back side of the feed frame 34 a worm gear 312 (Figs. 4 and 8) which is in mesh with a worm 314 on the previously described shaft 176. The bearings 74 and 76 for the sprocket shaft 64 (Fig. 4) are similarly eccentrically mounted in the journal box 78, and carried by the latter on the back side of the feed frame 34 is another worm gear 316 which is also in mesh with the worm 314 (Figs. 4 and 8). Thus, the driven sprockets 18 and 22 are adjusted toward and away from each other simultaneously with a like adjustment of the track 98 for the feed run 26 of the lower chain 14, all on manipulation of the handwheel 198, as will be readily understood.

in order to facilitate an operators task of adjusting the tractor feed to a given size rod stock and to expedite the accurate adjustment of the tractor feed, there is provided in front of the feed frame 34 within ready view of an operator at the handwheel 198 a dial 318 (Fig. 3) with which cooperates a turnable hand or pointer 320 that indicates on the graduations 322 on the dial the adjustment of the tractor feed at any instant. The dial 318 is preferably graduated in different rod stock sizes, and the pointer 320 is carried by a shaft 324 (Fig. 4) which is journalled in a suitable bearing bracket 326 on top of the feed frame 34, and carries in back of the latter a sprocket 328 which is drivingly connected by a chain 330 with a sprocket 332 on the journal box 70 (see also Fig. 8). Thus, if an operator is called upon to adjust the tractor feed for any given size rod stock, he manipulates the handwheel 198 and simply watches the hand 320 travel on the dial 318. When the hand 320 points to that graduation on the dial 318 which corresponds to the size of the rod stock to which the tractor feed is to be adjusted, the operator stops further manipulation of the handwheel 198 since the tractor feed is then accurately adjusted to the desired rod size. The adjustment of the tractor feed to odd sizes of rod stock not noted on the dial 318 is as facile as its adjustment to the standard rod sizes noted on the dial, the standard rod size graduations 322 on the dial then serving as approximate guides for the quick and accurate adjustment of the tractor feed.

Adjustably mounted at 334 at the front side of the feed frame 34 is a channel-shaped support 336 (Figs.

3, 5 and 7) on which the lower run 26 of the lower chain 14 may rest when the latter is slackened for replacement, repair or other purposes. A similar support 338 is mounted at the front side of the feed frame 34 for the upper run 24' of the upper chain 12. Mounted at 340 at the front side of the feed frame 34 at the entry end thereof is a bracket 342 which carries a guide 344 that leads rod stock into the entry end of the feed runs 24 and 26 of the chains 12 and 14 (Fig. 3). A similar rod stock guide 346 is carried by a bracket 348 on the feed frame 34 at the exit end of the tractor feed (Fig. 3). The sprockets 16 to 22 are preferably normally covered by removable protective guards 350 (Fig. 1).

Due to the considerable length of the tractor feed and its extensive contact area with the fed stock therein, the same exerts such a low specific gravity on the stock that the latter will assuredly not be marred even at exceptionally high operating speed of the tractor feed. Further advantageous is the provision of an adjustable track and a yielding companion track for the respective feed runs of the chains of the tractor feed, in that these feed runs may be brought into exact axial alignment with the aperture of a die through which the stock is drawn by the feed. Of further considerable advantage is the powerdrive of those sprockets of the tractor chains which are at the exit end of the tractor feed, so that the operating mns of these chains will have maximum traction on the rod stock for its pull through a reducing die, for instance. Also advantageous is the adjustability of the power-driven sprockets of the chains of the tractor feed, in that they may, on any adjustment of the non-yielding chain track for any given rod size, draw the feed runs of the tractor chains in rectilinear paths over and beyond their respective tracks, with the result that the pull of these sprockets on the feed runs of the chains will not compel the latter into pressing engagement with their tracks and will not cause them to bend abruptly at the run-off ends of these tracks. Of considerable advantage also is the formation of the yielding chain track of the tractor feed by a battery of side-by-side arranged track sections each of which is individually yieldable, so that rod stock will be gripped most evenly by the opposite chain tracks throughout their lengths. In this connection, it is a distinct feature to provide for each of the aforementioned track sections a cylinder and a piston therein for urging the track section against the adjacent feed run of the associated chain of the tractor feed, and to arrange these cylinders between the opposite runs of the associated chain, and so that the axes of the pistons therein intersect the rod stock passing through the tractor feed, with the result that the full force of the pistons is directly applied to the fed rod stock without setting up harmful bending stresses either in the pistons or in the track sections. Another distinct feature lies in the provision of the interchangeable spacer plates on top of the cylinders for the yielding chain track of the tractor feed, so that the pistons in these cylinders will be stopped short 'or" their full stock-gripping strokes and the feed runs of the tractor chains will remain sufiiciently separated to permit the introduction therebetween of new stock without encountering undue resistance. The task of adjusting the non-yielding chain track and the driven sprockets of the chains of the tractor feed to rod stock of different sizes is greatly facilitated in that these adjustments may be undertaken simultaneously on manipulation of a single handwheel.

The invention may be carried out in other specific ways than those herein set for hwithout departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes comingwithin the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is: 1. A tractor feed for rod stock, comprising two pairs of spaced rotary sprockets carrying endless chains, respectively, so that adjacent feed runs thereof extend substantially parallel to each other and are adapted to grip and feed rod stock therebetween; a fixed track on which the feed run of one of said chains rides; a battery of fixed cylinders arranged side-by-side between the opposite runs of the other chain; pistons in said cylinders, respectively; track sections connected with said pistons, respectively, and adapted to be urged thereby against the feed run of said other chain to form a yielding track therefor, said pistons having shouldered extensions beyond the cylinder ends most remote from the feed run of said other chain; and removable spacers interposed between said cylinder ends and shoulders on said piston extensions, respectively, to limit the stock gripping strokes of said pistons and allow between said feed runs of the chains a gap smaller than the size of the rod stock to be fed.

2. A tractor feed as set forth in claim 1, in which said spacers are formed by a single removable spacer plate on which said shoulders on the piston extensions are References Cited in the file of this patent UNITED STATES PATENTS 2,281,875 Gleissner May 5, 1942 2,288,612 DeWyk July 7, 1942 2,387,446 Herz Oct. 23, 1945 2,642,280 Fisk June 16, 1953 2,696,907 Fisk Dec. 14, 1954 2,736,425 Fisk Feb. 28, 1956

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