US2367941A - Drawbench dog - Google Patents

Description

jan. 23, E945. Gt 'HACKETT 2,367,941

DRAW BENCH DOG Filed Oct. 19, 1943 2 Sheets-Sheet l Zin/U crol GHa/cjeb jan. 23%, E945. Q HACKETT 2,367,941

DRAW BENCH DOG Filed Oct. 19, 1943 2 Sheets-Sheet 2 Fig.4

Patented Jan. 23, 1945 DRAWBENCH DOG George Hackett, West Bromwich, England, assignor to T. I. ham, England (Group Services) Limited, Birming- Application ctober 19, 1943, Serial No. 506,915 In Great Britain December 8, 1942 3 Claims. (C1. 305-24) This invention relates to the dogs used on draw benches for pulling a tube, rod or other work piece through a die.

The object of the invention is to provide iinproved means for effecting automatic engagement of such a dog with the end of the work piece previously inserted through the die.

In the accompanying sheets of explanatory drawings- Figures 1 and 2 are respectively a sectional side elevation and a plan of a draw bench dog constructed in accordance with the invention, and situated on the end of a draw bench adjacent to the die through which the work piece is to be drawn.

the arm is pivoted on the carriage adjacent to the grippers the toggle links are arranged adjacent to the hook pivot. One -of the toggle links m is pivoted on the carriage a, and the other is Pivoted on the arm 9', and nin combination with the pivotally interconnected ends of the links is arranged a roller n adapted to -co-operate Iwith a cam or ramp o (Figures 3 and 4) secured in any convenient position on the draw bench b. If desired the arm j may be provided with a weight l at the end adjacent to the toggle links m.

To elucidate the mode of operation of the mechanism above described let it be supposed that the Figures 3 and 4 are respectively a side eleva` tion and a plan of the other end of the draw bench, the dog being shown in chain-dotted lines in Figure 3.

In carrying the invention into effect as shown I employ a carriage a of any convenient fo adapted to be moved along the draw bench IJ. At one end of the carriage a is pivotally mounted a hook c adapted to engage an endless chain d in the usual manner. At the other end of the carriage is formed a recess e having mutually inclined sidesy and in this recess are arranged a pair of wedge-like grippers as f adapted to engage the tagged end of a tube, or 'a pull-pin attached to the tube, or the end of any other form of `work piece, previously inserted through a staf tionary die g on the draw bench b. At any convenient position adjacent to the grippers f there is pivoted on the lcarriage a a lever h having its lower end located in a transverse notch z' in the upper sides of the grippers, the purpose of this lever being to actuate the grippers under the action of pressure applied to the upper end of the lever. Preferably and as shown the lever h is loaded by a spring h1 which tends to retain it in the position in which the grippers f are in their open position.

For actuating the lever h automatically l. pivot at the end of the carriage a adjacent to the hook pivot lc an arm y' consisting of a pair of interconnected and conveniently spaced side members. Alternatively the anm may be pivoted on the hook arc at the end of the carriage adjacent to the grippers. At any convenient intermediate position on the arm y' is arranged a cross piece 9'1 (which may be a roller) adapted to bear on the upper end of the gripper-actuating lever h and at the end or the arm adjacent tothe grippers f is arranged a pair of toggle links m' for supporting the arm in its upper position. Alternatively when serted through the die g. Vallowed to engage the chain d and the dog comdog has completed a drawing action on a work piece and that it is being returned (by hand or mechanical means towards the die g. During this condition the arm 7' is in its upper position and is held there by the toggle links m which occupy a position slightly to one side of the dead centre as shown in Figure 1. Also the hook c is held in its upper position clear of the chain d in any convenient manner. When the dog reaches or approaches the die gthe toggle links m encounter an adjustable or other stop p on the draw bench b or die, so that' asmall continued movement of the dog moves the toggle llinks to the other side of the dead centre. The links m are now free to collapse under the Weight of the arm j, and the descent of the latter causes the gripper lever h to advance the grippers finto engagement with the end of the work piece previously in- The hook c is now mences its next forward travel along the bench b in the condition indicated by the chain-dotted lines in Figure 3. At any convenient position during the forward travel of the dog the roller n on the toggle links m encounters the cam or ramp o, and by the interaction of these parts the arm y' is raised to its upper position and the toggle links are returned to the first mentioned position at one side of the dead centre. When the dog reaches the end of its forward travel the gnppers f are released either automatically or by hand operation or the lever It. Also the chain d falls away from the hook c inthe usual manner and the dog is returned, the cycle of 'action being then repeated. When the dog is returned by a Weight acting through a rope, the latter is attached to the junction of the toggle links above mentioned. In this case the ramp or cam above mentioned may be dispensed with as the rope can then serve for holding the hook c in its upper position clear of the chain d during the return travel of the dog, consists of a catch lever q which is pivoted on the carriage a, and which is adapted at one end to engage a shoulder r on the rear end of the hook. For releasing the catch lever q from the hook c at the end of the return travel of the dog, a spring-loaded push rod s may be mounted on the carriage a, this rod having one end pivoted to the catch lever, and serving to release the catch lever when the other end ofv the rod comes into contact with a xed stop which may be formed by the adjacent side of the die g, Alternatively the catch lever maybe releasedby an abutment provided on or formed by another cross piece as t on the arm :i when the latter descends for actuating the grippers f. For re'- engaging the catch lever q with the hook c I make use in the known manner of the condition that when the chain d commences to exert lts pull on the hook, the portion ofV the lchain jengaged by the'hook'r'ises above the normalhorizontal line of the chain causing the forward end of the `hook to `rise withit. In Lthis movementthe catch lever'q engages the hook c'either by gravity or the `action of a spring-or otherwise. When at the'end of the'drawing 'operation the pull on `the hook c is relaxed the `chain d falls from the hook leaving the latter in Ithe elevated position. Rie-engagementof the hook c with thechain d -follows Withdrawal of the catch lever q under the -action'of the `puvshrod s or arm :i as above described, near'theendofthe return movement of the dog. u l

By my invention I am able to leffect 'automatic engagement of the g'rippers'with'the'work piece in a very simple and reliable manner. The invention is not, however, restrictedtovthe example described as subordinate details kmay be varied to suitdiierent requirements. p

Having thus described my invention what I claim as new'and desire to 'secure by'LetteisLPatent is:`

l. A draw bench doglcomprising the combination of a carriage movable along the draw'bench, wedge-like .grippers sldably mounted on', the carriage, a lever for actuating thegrippers, a movably mounted member adapted to actuate the lever in the direction for engaging the grippers with the work piece,'and` a toggle device for supporting thesaid member in anupper inoperative position to which it'can` be moved during the forward movement of the carriage l wedge-like grippers sldably mounted on the carriage, a lever for actuating the grip- `gers, a movably mounted member adapted to actuate the lever in the direction for engaging the gripper's with the work piece, means for l5 supporting the said member in an upper inoperative positon to which it can be moved during the `forward movement of the carriage on the draw bench, the said means being operable to release the lever-actuating member when the carriage 2o approaches the end of its return movement,

and thereby permit the said member to actuate the grippers through kthe leverfor effecting engagement of the grippers with the work piece, a hook pivotally mounted on the carriage and adapted to engage an endless chain, a catch member mounted on the carriage and adapted by engagement with the hook to hold the'latter in a position clear of the chain, and an abut ment on the lever-actuating member for releasi ing the catch member from the lhook when the gripper'sr are brought into action.

3. A draw bench dog comprising the combination ofy a carriagemovable along the draw'bench, la hook pivotally mounted'on the carriage and adapted to engage yan endless chain, wedge-like grppers sldably l'mounted on the carriage, a lever for actuating the grinpers, a movably mounted member independent of the said hook and adapted under the action of gravity to ac- I40 ltu'ate the lever in the direction for engaging the v grippers with the work piece, and interconnect- 'ying means arranged between the said member 'and carriage `for rele'asably supporting the said member in an upper inoperative position to whichit can be moved during the forward move- 'ment of the carriage on the draw bench, the said means being operable to release the said member ywhen the carriage approaches the end of its return movement, and thereby permit the said member to actuate the grippers through the lever for eiecting engagement of the gripper-s Awith the work piece.

GEORGE HACKETT.

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