US1898574A - Method for forging insulator caps - Google Patents

Description

Feb. 21, 1933. I c. s, CARD 4 METHOD FOR FORGING INSULA'I'OR CAPS Filed Ma 12, 19:50 -2 shuts-sheet 1 ll/A INVENTOR.

CHARLES 5.. (4P2.

A T-TORNEY.

Feb. 21, 1933. c, s, CARD 1,898,574

METHOD FOR FORGING TO S Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE CHARLES S. CARD, CORTLAND, NEW YORK, ASSIGNOR TO THE BREWER-TITOHENEB CORPORATION, OF CORTLAND, NEW YORK, A CORPORATION OF NEW YORK METHOD FOR FORGING INQULATOR CAPS Application filed May 12, 1930. serial No. 451,581.

This invention relates to the art of. hollowed metal forgings and more particularly to the production of a one-piece cap or bellshaped socket adapted to securely mount therein the neck of an insulator disk of the multiple suspension type as used in connection with high-tension electric transmission lines or the like. My invention in certain particulars represents a refinement in method of fabrication over the disclosure made in the Clinton W. Stover Patent 1,463,601 as granted July 13, 1923.

The primary object of my improved method is to effectively and economically fabricate a perfectly sound chambered product of this character, which will consistently be relatively flawless in metal structure especially as practiced by the drop-forged process where the action is impactive or percussive as distinguished for instance from a more sustained pressure as appliedin the case of a steam hammer or hydraulic press. The present method of making such insulator caps involves among other things, an improved blanking operation preferably by the dropforging method, that allows of working up a relatively large cup-shaped forging out of comparatively small bar-stock. Said operation also facilitates the shaping up of a uniform skirt wall thickness and of otherwise holding the cap to exacting specifications, notwithstanding that the exterior of the cap dome is provided with a heavy integral suspension forming lug means forged to a thickness considerably greater than that given the said skirt wall and which lug means preferably permits of completing the lug formation by machining surplus stock out of such solid dome metal.

The blank for making my cap is purposely carried through a series of different shapes prior to blocking out of the blank into a cupshape, and one of such supplemental re-shaping steps includes a flattening operation de-. signed to repeatedly work the blank central region and thus insure a more nearly flawless swaging for the aforesaid thickened solid domemetal.

A further object is to provide in a drop forging operation, means whereby the relonger life and to so carry out the stepsof my method, that the various integral sections of my gang die block may all be made to wear out at an approximately uniform rate rather than have any one such section of the needed costly dies, wear at a relative ly faster rate and thus require the premature discarding of the entire gang block.

Die charges represent a considerable item of expense in the forging of insulator caps, and I have found that because of the inherently limited intensity given to the series of rapidly repeated blows, the successful carrying out of the drop-forge process by the use of board-lift hammers or the like, may be materially improved by a significant change in method over that heretofore practiced in connection with hydraulic or steam hammers, or the like where high pressure of controllable intensity is gradually applied. An important advantage of the present adaptation to drop-forged purposes lies in greatly increasing the rate of fabrication obtainable from a given press and in correspondingly reducing the labor and other production costs to a level that will place the forged product upon a competitive price basis with the more conventional caps of the cast malleable iron type.

To this end and the accomplishment of other new and useful results, my invention also consists in novel features of'stock manipulation and die structure, all of which will hereinafter be more fully set forth.

Reference is had to the accompanying two sheets of drawings which are illustrative of a specific embodiment of my invention, particularly as applied to drop-forged insulator caps, in which drawings: I

Fig. l is a sectional elevational view of an insulator cap assembly of the ear-suspension type.

Fig. 2 shows a perspective view of the billet or square bar stock from which a cap may be forged.

Fig. 3 is a side elevation of a ram and die block members showing them brought into operative raised relationship.

Fig. 4 represents a top face view of the line 4-4 of Fig. 3, while Fig. 5 is a bottom face view of the companion top block as seen from the line 5-5 of Fig.3.-

Fig. 6 illustrates a sectional vertical view through the assembled blocks when brought into cooperative relationship as taken along the line 6-6 of Figs. 4 and 5.

Figs. 7, 8 and 9 are similar sectional block views as taken along line 7-7, 8-8, and 99 respectively.

F ig. 10 shows in perspective a roller type of impression that is initially shaped up in the first of my die compartments, while Fig. 11 is a perspective of the blank that is formed therefrom.

Fig. 12 represents a sectional perspective view of the forging as it comes from the blocker compartment of my die block, and Fig. 13 show said forging after it leaves the finishing compartment.

Fig. 14; illustrates a fragmental view of a modified or socketed dome type of cap which may be forged up in a substantially identical manner.

Fig. 15 is a cross-sectional view of the aforesaid impression as taken along line 1515 of Fig. 10, while Fig. 16 is a similar view after such impression is flattened, as taken along line 16-16 of Fig. 11. 7

Referring now to Fig. 1, this shows one member adapted to make up a chain of petticoat insulator discs such as 10, of which the uppermost is ordinarily suspended in any suitable manner from a transmission tower or the like. The respective discs may be connected together in tandem by means of the interposed metal insulator caps such as 11, which cooperate with oppositely disposed link-members such as 12, to constitute a built-up composite suspension insulator in the conventional fashion and of which the lowermost unit may be provided with a conductor clamp that carries the high tension transmission wire (not shown).

My invention seeks to promote quality and uniformity of product and is more largely concerned with forging up said cap 11, which essentially comprises a flared tubular skirt portion 13 formed integrally with the dome portion 14. The dome shown in Fig. 1 is of the common clevis type affording a pair of spaced ears or straps such as 15 arranged to pivotally receive a clevis type of adapter link 12, although the particular mode of suspension is immaterial as far as the present purarticle. Figs. 3 to 9 inclusive illustrate a' compartmental bottom die block 18 and a cooperating matrix or top die block 19 that is sunk in counter-part fashion. The respective die-blocks are here shown as equipped with four different compartments or heated recesses, of which the first may comprise a roller-like planchet forming chamber 20. The center region of this particular recess as measured from the die parting face preferably provides for a semi-cylindrical cavity with a cross-sectionally oval stem depression disposed at either end thereof as indicated. This die element is adapted to press up a distorted egg-shaped impression or planchet 21 (see Fig. 10) which may be formed up from the rectangular metal bar stock 22 that is shown in Fig. 2. The purpose of this initial step is to neck-in one end portion of the bar and gather suflicient stock in the overhanging bar extension to impart a transverse -cross sectional area to the body of said planchet (see Fig. 15) that shall become enlarged rel ative to the original bar stock, to the end that the body portion of the planchet 21 may be carried through a series of appropriate steps that admit of finally blocking out my blank into a flared skirted shape whose rim region shall be free from incipient flaws, cold-shuts in the ultimate product and without requiring the metal to be unduly strained during any one of the successive forging steps. The

operative end of each die recess may be dished to provide for the usual sprue by which the hot forging is shifted into a different compartment.

As a second step, said planchet is subjected tour. As represented in Figs. 11 and 16, the

opposite side faces of this blank may be hollowed out somewhat between the pairs of marginal stifi'ning ridges such as 25. The described blank contour induces the forged metal to uniformly fill out the more distant die interspaces. The use of such ridge means is not however essential since the cited flattening'action alone serves to more thoroughly work and thereby locally refine the metal lying in the centrally disposed body region of the initial impression or planchet 21; this metal portion ultimately forms up the thick dome wall element together with the supporting ears of my cap structure and all of which must be made capable of withstanding a heavy line load without rupture or incipient failure.

As a third step, said blank 24 after being flattened as described, is passed through the blocker compartment. The bottom die 18 thereof is preferably bored out at 27 for the snug insertion of a replaceable plug which affords a rather blunt frustrum-like protuberance 28 adapted to initially shape up the cap interior in cooperation with the corresponding top die recess 29. It will be observed that the diametral dimension D given to my blank 24 is preferably kept somewhat larger than the top face of the cone frustrum 28 and that the flattened surface of such blank is preferably made to wholly overlap the perimeter of said top face. After the blank 24 has been blocked up, it assumes the impression designated as 30 in Fig. 12, from the dome exterior of which impression, there is extruded a potential ear forming lug whose shape includes a relatively narrow projecting boundary face having a trapezoidal profile.

Said impression is now passed through the finishing die compartment 31 which may also comprise a replaceable plug entered into the lower die-block 18 having a cone frustrum I tip 32. This tip is shown as not so bluntly shaped and adapted to cooperate withthe corresponding depression in the top die 16 for the purpose of reforming the cap impression 30 into the semi-finished bell shape generally represented in Fig. 13 by the numeral'33 and in which shape, the potential ear lug perimeter may now be rooved or partially slotted in order to reduce the heft of the metal where a milling cut is to be made by subsequently slotting the suspension lug into spaced complementary ears of the kind depicted in Fig. 1, it being preferred to forge a pair of rounded upstanding beads (see Fig. 13) between which to confine the said indented groove and thus avoid the need for grinding 01f burrs or otherwise finishing any sharp strap edges after said lug has been machine slotted. Up to this point, all of the described forging operations are intended to be carried out in a single heat and it will be observed that the dome portion 14 is forged rather heavy in comparison to the relatively thin and flared skirt walls 13.

It now remains to trim the flash and cause the rim region of the open mouth skirt to be crimped inwardly by any suitable die means. In addition, the thickened crown portion may be machined or otherwise shaped up to provide for a pair of finished ears such as 15. Instead of the described clevis type of support, my cap may likewise be forged up and suitably machined to constitute a cap 34 of undercut socketed dome type such as illustrated in Fig. 14.

Having described my process in detail, further advantages accruing therefrom may be more fully pointed out. In the use of drop hammers operating with intermittent blows rather than sustained pressure, an undue number of repeated blows would be required if attempt were made to forge'the bar stock directly into a thoroughly worked product described in connection with fabrieating the blank 24. Such practice leads to excessive wear on part of certain compartments with the result that the remaining die recesses would at the same time become useless and soon require resinking or replacement by entirely new die equipment. It is further found that the plug elements 28 and 32 are likely to suffer from surface checks or even fracture, while with my improved design, it becomes possible to individually replace such plug elements 28 and 32 at a moderate cost. Said insertable plugs also allow of more readily changing the tip contour in order to hold the close tolerances that must be met in a product of this kind. Finally, the life of dies which do not include passing said egg-shaped planchet 21 through the blanking die compartment 23 according to my invention, has heretofore proven inadequate under such heavy-duty service and hardly likely to produce more than half the perfect impressions that can be obtained by the sequence of steps embodied in my improved method. The inclusion of the novel flattening step also tends to prevent the hot forging from sticking in the relatively deep die-recesses and at the same time reduces die charges in the making of complicated forgings of this kind.

It is to be understood that in the structural details and mode of manipulation may be resorted to in carrying out my improved method of making insulator caps or like bell-shaped forgings, all without departing from the spirit and scope of my invention heretofore described and more particularly pointed out in the appended claims.-

I claim:

1. The method of forging from bar stock, a one-piece supportable insulator cap of the undercut socketed type or the like, which method consists in swaging said stock into a relatively fiat blank having an elongated contour provided with a depressed central face region flanked by spaced ridges, and thereupon blocking o'ut sald blank into a cup-shape comprising a skirt portion to which said ridges contribute stock, said skirt being provided with a mouthed rim end adapted to be subsequently cupped inwardly while the closed end of the cup is formed with a solid projection integral therewith.

2. The method of forging from bar stock, a onepiece supportable insulator cap of the undercut socketed type or the like, which method consists in gathering said stock into an egg-shaped planchet, then swaging said stock into a relatively flat blank having a spear-like contour, and thereupon blocking out said blank into a cup-shape comprising a relatively thick dome wall from which there is extruded an exteriorly disposed lug means for said cap.

3. The method of passing bar stock through compartmental die means and forging therevarious changes from a one-piece supportable insulator cap or the like, which method consists in swaging said stock into successively different shapes starting with an egg-like shape and of which the last shape forms a relatively flat blank whose center region has been worked in a plurality of die compartments, and there-' by the use of a plurality of such die compartments and of which shapes the first comprises an egg-like shape and the last a flattened blank, and thereupon passing said blank into still another compartment for the purpose of blocking out said blank into cup-shape, whereby to equalize the rate of die wear of all said die compartments.

5. The method of hot forging from barstock, in a' single heat, a one-piece insulator cap or the like, which method includes an initial step. of gathering stock to form a planchet of distorted egg-shape whose mid transverse cross-sectional area is enlarged over that of the original bar; thereupon, by the use of a separate supplementary swaging step, flattening a surface region of the aforesaid planchet; and by the use of still another step, blocking out such flattened planchet into a cup-shape comprising a supportable dome portion to which said supplementary swaged metal contributes stock.

6. The method of forging from bar-stock, a one-piece insulator cap or the like, which method includes an initial step of gathering stock to form a blank of distorted eg -like v shape, the mid-transverse cross-sectional area of said shape being enlarged over that, of

' sulator cap or the like from bar-stock by the use of mated die-blocks having a blocking compartment therebetween, which method consists in gathering said stock into a distorted egglike shape, the mid-transverse area of said'shape being enlarged over that of the original bar; and then by the use of a su lementary swaging step transformin said distorted shape to proviiie for a blan havin a flattened surface region; and thereupon orming said blank into cup shape by means of the blocking compartment provided with a chambered female block and a cooperating male block carrying a frustumlike projection that terminates in a blunt tip face, the aforesaid surface region being sufficiently flattened prior to blocking said blank that when superimposed upon the tip face, said surface region will lie contiguous to, and overlap the entire perimeter of, the aforesaid tip face.

8. The method of forging from bar-stock, a one-piece insulator cap or the like provided with machine slotted supporting ears,

which method includes an initial step of gathering stock to form an impression of distorted egg-like shape, the mid-transverse cross-sectional area of said shape being enlarged over that of the original bar; therev upon by a supplemental swaging step, transforming said distorted shape'to provide for a flattened blank surface region that is centrally depressed and blocking out said fiattened blank into cup-shape from the closed dome exterior of which there is extruded a solid, polyfaced ear-forming lug which includes a relatively narrow, projecting boundary-face of trapezoidal profile; and then by the use of still another step, finishing said cup-shape and simultaneously grooving a portion of the aforesaid boundary-face lengthwise thereof to facilitate the machine slotting" of said lug into spaced comple-.

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