US2100619A - Method for making pawl or detent means - Google Patents

Description

F'Ipenno 0R mmmelq v ---n I v Nov. 30, 1937. 1 i F. D. WENN 2,100,619

METHOD FOR MAKING PAWL OR DETENT MEANS Filed March 1, 1935 2 2 23 FIG- Z 24 F/G. 3- FIG- 5. 3o l L Y w T2 T1 T3 m 1 25 T- 1 l FIG. 4. FIG- 6- F16. 8. 22 33 l.\ VENTOR.

ATTORNEY.

rch R\N Sea "c Patented Not. 3o, 1937 METHOD FOR MAKING PAWL R DETENT MEANS Floyd D. Wenn, Binghamton, N. Y., assigner to The Brewer-Ttchener Corporation, Cortland, N. Y., a corporation oi' New York Application March 1, 1935, Serial No. 8,930

4 claims. c1. 29-148) This invention relates to certain novel process steps that facilitate the economical fabrication on a rapid productive scale of a retractible pawl or the like article, such as are commonly utilized in Reference is had to the accompanying one sheet of drawings which are illustrative of a preferred mode of carrying out my method, and in which:

Fig. 1 represents a fragmental elevational side connection with a ratchet Wheel or to engage a view of an automotive emergency brake lever asnotched sector of an automobile emergency brake sembly having my pawl operatively embodied lever;V my improvements are also applicable to therein, while Fig. 2 shows a transverse View of a wide variety of analogous products of manu- Fig. 1. facture. Fig. 3 outlines the stamped blank contour from In smaller sizes, such pivotally mounted pawls which such pawl may be nished; and Fig. 4 is a 10 or detent levers are usually stamped up in large toe end view thereof. quantities from sheet metal stock to form a toe Figs. 5 and 6 are similar to the last named blank. A sharply formed acute angle is needed gures and depict the change in toe contour imin the pointed toe region of such spring actuated parted by a further processing of such blank. pawl in order to effectively drop between closely Fig. 7 is illustrative of companion dies by the 15 spaced ratchet teeth. As an initial step, a subuse of which such pawl may be shaped up to prostantially flat pawl blank may be pierced out of vide for a sharp toe, and Fig. 8 shows a crossrelatively heavy sheet metal stock of which the section of such die blank taken along line 8-8 perimeter includes a relatively blunt nose region 0f Fig. 7. that is perimetrically shaped to protect the dies In order to present a more comprehensive unagainst excessive Wear and tear in the lleted derstanding regarding the purpose of my pawl nose shearing region thereof. The accompanying devices, it is pointed out that the tubular body rather severe stamping blow is found to cause a of a brake lever may be stamped up from sheet localized nose region of such blank to become metal to include a hollow shank portion I0 that compressed to some extent so as to impart an commonly terminates in bifurcated fork arms arcuate deformation to a contiguous side face such as II and I2 adapted to be mounted upon thereof. Unless a corresponding amount of stock the rotatable fulcrum shaft I3. The swinging is subsequently restored, such supercial deforend of such lever may be provided with a suitmation reduces the potential width margin available handle portion and a manipulative grip able for a sharpened transverse toe edge when member (not shown). Such grip serves to actunished in the conventional manner by grinders ate the latch rod I4 which may be slidably enor equivalent metal working tools. cased within the tubular lever shank and carried As an improvement thereon, designed to corinto operative engagement with the latchable rect such inherent deciencies, I preferably repawl I5 in the inverted manner indicated in Fig. 1. sort to a modified coining operation that may vThe free fork ends of said lever may have a be performed in a c old state in order to attain rivet pin I 5 mounted therebetween. The flat a smoothly sharpened toe edge. Such use of sided pawl I5 herein depicted is of the balanced forming dies, not only upsets to restore such or medially supported lever type including a ceninitially reduced toe width, but the same opera.- trally located pivot aperture arranged to receive tion may be carried out to enlarge the finished said rivet pin. One end of such pawl has a hole toe width beyond the original stock thickness and 2| therethrough into which the latch rod I4 may impress thereon a sharply formed edge without be hooked, while the opposite pawl end is proneed of any grinding or milling agency. As a vided with an acute toe edge I5A that succesresult, I am enabled in one operation to economisively interlocks with the closely spaced ratchet cally complete a high grade product of this kind teeth I1 of the sector I8. When loosely mounted 45 while coining said initial blunt toe and at the about the fulcrum shaft, this sector may be resame time shipping oli' a small surplus stock portained by a stop pin such as I9. l return spring tion to render the sharpened toe free from any 20 usually carried by the lever, serves to thrust jutting tip or other iinlike appendage. the pawl toe into operative engagement with said The object of my invention is to devise an teeth upon release of the lever grip. improved processing method of the character in- The present invention is primarily concerned dicated and by the use of simple press operations, with the economical fabrication of the pawl ele; to shape up a finished pawl or the like article ment or the like detent means I5. Referring now of manufacture from sheet metal stock at a rapid to Figs. 3 and 4, they show the contour shape of a at blank 22 as sheared from sheet metal stock 55 productive rate with the minimum of labor cost.

and in which the several apertures may be pierced simultaneously therewith. The nose endv region of said blank is initially given a relatively blunt nose contour 23. 'Ihe stock thickness actually used for certain purposes measures around Tl=%. When such blank is pierced out in one operation in the Yusual manner, the cutting dies tend to form an arcuate surface deformation as at 24 upon one side face of the blank as indicated in exaggerated scale by Fig. 4 and in which the potential toe length T2 becomes less than the original stock thickness TI. In this same figure, the severed blank edge portion that is finally torn away in shear, is represented by shaded vertical lines designated as 25. The dotted contour 26 indicates the acute shape into which my finished toe is ultimately brought by a special coining operation that will presently be defined. The nished product 21 then assumes a sharpened toe shape corresponding to Figs. 5 and 6, the length of the toe edge T3 being thereby restored and even increased over the initial stock thickness Tl. It will be obvious that the preservation of a full toe thickness represents an important requisite in the maintenance of adequate pawl life under severe service conditions. If desired, such acute faces may be subjected to a hardening process.

Figs. 7 and 8 schematically portray a die block element 3U and a cooperating guided punch member 3l, which may respectively be provided with oppositely disposed coining jaws such as 32 and 33 respectively having a relatively blunt V- shaped face profile. My blank 22 may be snugly jigged into a suitable die recess with its nose tit interposed between the respective jaw apexes.

' Upon descent of the punch, the initially rounded pawl nose 23 will be reshaped by a combined upsetting and squeezing action that imparts a sharpened detent edge 26 extending transversely between the respective side faces of the iinished pwl without need of any toe grinding operation.

Said jaws at the same. time serve in the capacityof a double acting cold chisel or cutter that snips off a small surplus tip or other appended fin portion of the pawl, denoted as 28 in Fig. 3 which might otherwise jut beyond the toe edge 26. The cited pointing process serves to form a relatively long and sharply coined toe edge on a rapid productive scale and one that may be struck up reasonably smooth in a cold rather than a hot state so as to admirably iit my pawl for its intended purposes. While said dies are adapted to complete the described formations in a single operation, the same results may be had by a series of separately performed steps.

It is believed the present teachings have been suciently disclosed to make apparent the inherent advantages thereof to those skilled in this art. As will be obvious, such pawl improvements also find far wider application than to brake lever uses and that various changes in the structural details of my product or the manipulation thereof may be resorted to in likewise carrying' out the method herein disclosed, all without departing from the spirit and scope o1' my invention heretofore described and more particularly pointed out in the appended claims.

I claimzl 1. The method of producing a stamped article from sheet metal stock and reshaping the edges thereof, and which method consists in stamping up a blank from said stock of which the sheared perimeter includes an initially blunt nose region, then by a coining step flattening opposite perimetric edge regions" of such nose to initiate a wedge shaped toe having a jutting tip appendage, and finally by a continuation of said coining step, snipping to sever said appendage and thereby leaving a smoothly iinished wedge shaped toe that is rendered sharp at the severed extremity thereof.

2. 'I'he method of producing a stamped article from sheet metal stock and reshaping the edges thereof, and which method consists in stamping up a blank from said stock of which the sheared perimeter includes an initially blunt nose region, then by a coining step flattening opposite perimetric edge regions of such nose to initiate a wedge shaped toe having a jutting tip appendage, and nally by a continuation of said coining step, snipping to sever said appendage and which snipping is performed coincident with the completion of the sharpened wedge shaped toe.

3. The method of producing a stamped article from sheet metal stock and reshaping the edges thereof, and which method consists in piercing said stock to shape up a blank whose sheared perimeter includes an initially blunt nose region and the tip portion of which nose is reduced in thickness with respect to that of the original stock, then by a coining step restoring said reduced thickness by squeezing inwardly opposite perimetric edge portions of said nose region and thereby initiate a wedge shaped toe having a jutting tip appendage, and nally by a continuation of said coining step severing said appendage to leave a smoothly finished wedge shaped toe of which the flattened faces intersect to constitute a sharp edge.

4. 'I'he .method of fabricating pawl means on a rapid productive basis and which method consists in shaping up a substantially flat metal blank Who's''perimeter includes an initially blunt nose region and which blank is pierced with an aperture through the respective sides thereof, and thereupon by a combined coining and snipping step first flattening opposite perimetric edge portions of such nose to form a wedge shaped toe having a jutting tip appendage and finally coincident with'the completion of said toe, snipping to sever said appendage and thereby leaving a smoothly finished Wedge shape of which the faces intersect in a sharp edge extending transversely of the aforesaid sides.

v FLOYD D. WENN.

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