US1900139A - Attachment plug cap and method of making the same - Google Patents

Description

March 7, 1933. w c TREGONlNG 1,900,139

ATTACHMENT PLUG CAP AND METHOD OF MAKING THE SAME Filed Oct. 19, 1929 Patented Mar. 7, 1933 UNITED WILL-mm c. rnneoiqme, or

me, or MILWAUKEE,

STATES ATTACHMENT. PLUG GAP wauwa'rosa, WISCONSIN,

wrsconsm,

ASSIGNOR TO CUTLER-HAMME A CORPORATION OF DELAWARE m manner on mxiNe rrm sum Applicatlon filed October 19, 1929. Serial No. 400,881.

to improvements in methods of mak- This invention relates attachment plug caps and ing the same.

An object of the invention is to provide a method of making plug caps wherein the use of molded in metal eyelets or inserts is eliminated,-thereby facilitating or speeding up production of the molded pieces.

Another object is to minimize the number of metal parts required for production of a plug cap.

Another object is to facilitate assembly of the metal parts with respect to the mold ca V Another object is to provide a stronger and more rigid connection between the meta parts and the insulating cap.

Another object is to provide a method of making plug caps wherein the shrinkage characteristics of the molded piece may be utilized as the sole means for effecting a rigid bond between the same andthe metal parts associated therewith.

Other objects and advantages tion will hereinafter appear.

The accompanying drawing illustrates certain embodiments of the invention which will now be described, it being understood that the invention is susceptible of modification in cerwithout departing from of the inventain details thereof the scope of the appended claims.

Referring to the drawing, Figure 1 is an enlarged bottom plan view of a plug cap constructed and assembled in accordance with my invention.

Fig. 2 is a vertical sectional view on the line 2-2 of Fig. 1. 7

Fig. 3 is a bottom plan view of the cold molded insulating piece prior to assembly of the combined contact and terminal members with respect thereto.

Fig. 4 is a plan view of one form of punched metal blank from which each of the combined contact and terminal members may be produced.

' Fig. 5 is a perspective view of one combined contact and terminal members, tlia binding screw attached thereto, and

Figs. 6 and 7 are plan and fragmentary secof the with d comminuted asbestos 1 molded in metal eyelets or tional views, respectively, of a modified form of blank.

Referring first to Figs. 1, 2 and 3, the numeral 10 designates the insulating body portion of a cap, and said body portion may comprise any suitable or preferred composition which is adapted for cold molding under relatively heavy pressure while plastic and to be thereafter subjected to the usual prolonged heat treatment for curing or hardening. Thus I may employ the well known cold molding composition which comprises a filler and a pitch binder.

Heretofore it has been customary to either provide within the insulating body a pair of inserts to which the contact and terminal members of the cap may be subsequently attached, or to mold in integral portions of the contacts or terminal members themselves. However, the necessity for providing molded in metal parts renders production of the molded pieces comparative-- 1y slow and tedious. By my improved method the necessity for use of molded in metal parts or inserts is eliminated, whereby the rate of production of the molded pieces by a single press may be greatly increased.

Thus as is well known the insulating material after cold molding thereof to the desired form is still somewhat plastic, or of a consistency known in the cold molding art as mud. Also as is well known the usual prolonged heat treatment to which these cold molded pieces are subjected for curing or hardening thereof inherently results 1n a considerable degree of shrinkage of the material of which the pieces are composed. I have discovered that it is possible to utilize this shrinkage characteristic of the cold molded material to provide for rigid and permanent securement of a metal element pressed or inserted therewithin after the moldlng operation and before the heat induration treatment.

Thus I preferably mold or otherwise form in the piece 10 a pair of diametrically opposed groups of recesses 11, 12 and 11", 12. The recesses 12, 12 as shown may be circular and of a size to freely accommodate the shank of the usual binding screw. Recesses 11, 11"

llo

" receptacle ed piece in more positive engagement with the usual permit passage of the wiring cord or conas shown may be of rectangular shape in cross section, and the cross sectional dimensions thereof are preferably slightly (say two thousandths of an inch) less than the corresponding dimensions of metal members or shanks 13, ltto be pressed or inserted thereinto.

The lower ends 13, 14 of said shanks are preferably slightly rounded to assist in guiding the same into said recesses, said shanks eing integral with and bent downwardly at right angles from the portions 15 and 16 respectively, which form the terminal plates of the plug cap. Also integral with said portions 15 and 16 and bent upwardly at right angles therefrom are the portions 17 and 18, respectively, which form the jacks or blade contacts of the plug cap, said contacts being provided with the usual beveled upper ends and the usual perforations intermediate the ends thereof for detachable interlocking engagement with the cooperating contacts of a (not shown). .Also as shown at 13", 14" in Figs. 2, 4 and 5 the shanks 13, 14 are preferably provided with suitable notches .or indentations forming inwardly extending shoulders in the sides and edges thereof for by the material of the insulating cap after shrinkage of the latter.

As best illustrated in Fig. 2 the shanks 13 and 14 are pressed downwardly into the respective recesses 11 and 11 until the terminal plates 15 and 16 engage or rest upon the ledges 19 and 20 formed in the insulating cap. The binding screws 21 and 22 are preferably threaded into tapped openings in the terminal plates 15 and 16 prior to insertion of the shanks 13 and 14 into the aforementioned recesses, the shanks of said screws being upset or staked as indicated at 21 (Fig.

to prevent subsequent entire removal of said binding screws.

' The molded insulating cap 10 is provided central perforation 23 to ductors (not shown),the recesses 23, 23 being arranged to communicate therewith for reception of the knot or other type of strain relieving means, and to permit attachment of the wires by leading the samedirectly to the respective binding screws or by snubbing said wires around the respective contact jacks. The ledges 24 and 25 provide a seat for the usual thin fiber enclosing disk (not shown). The exterior surface of the molded cap may be of any desired contour, but the cap is preferably of slightly tapered form and milled or otherwise roughened, as indicated at 26 (Figs. 2 and 3) to facilitate gripping thereof by hand.

Withthe combined wcontact and terminal members assembled with respect to the moldthe manner aforedescribed, the latter is subjected to the usual prolonged heat treatment for curing or hardening,

usual strain relieving.

whereupon it is found that the shrinkage effect aforementioned results in rigid and permanent securement of said metal parts with respect to the insulating cap.

In the modified form .of blank shown in Figs. 6 and 7 the shank 27 of the combined contact and terminal member is provided with a pair of spaced angular depressions or pockets 28 having horizontal or right angular shoulders at the lower ends thereof, into which pockets the insulating material is adapted to project upon insertion of the shank into its corresponding recess, or as a result of the shrinkage of the insulating material as aforestated.

By my improved method of making plug caps it will be noted that the contact and terminal members may be formed of a single piece of metal and that the binding screw may be assembled and staked to the terminal member in the first instance. The contact and terminal members are rigidly and permanently secured to the molded cap without the use of molded in eyelets or inserts and without the necessity for the usual riveting or upsetting operations incident to use of such additional parts.

After the completely assembled caps have been heat treated for hardening of the insulating material the same may be dipped or momentarily immersed in a suitable acid bath to clean the surfaces of the metal parts, including removal of any oxide which may have formed upon such surfaces as a result of the heat treatment.

While I prefer to provide notches or depressions of the character illustratled for positive and cooperative engagement by the shrunken walls of the recesses, I have nevertheless demonstrated in practice that the slightly rough and irregular edges formed on the shanks by the punching or shearing of the blanks will be sufliciently tightly interlocked with the shrunken walls of the recesses to resist or withstand all pulling strains to which the parts of the cap will ordinarily be subjected when in use.

Similarly, while I have shown but one form of molded insulating cap, it will be understood that the form of the molded piece may be modified as in from the scope of the appended claims.

TVhat I claim as new and desire to secure by Letters Patent is:

1. The methodof making an attachment plug cap, which comprises cold molding a mass of insulating material to form an article of the desired shape, then pressing into the molded article an integral portion of a combined contact and terminal member, and

article to the usual shrinkage of the insulating material.

2. The method which comprises cold moldcombined conta an integral pro an article of the desired shape and providing said recess, said proj thin sai ing a mass of insulating materialto provide ing within said article a recess of predetermined ly secured W1 5 size and shape, then inserting within said reof the walls of th cess a metal shank the cross sectional dimenusual heat in-duration t sions of which are at least as great as the ed cap.

cross sectional dimensions of said recess, and 7 As an ar then subjecting said article to heat treatment tachment plug cap 10 for curing whereby said shank is permanentsulating materi ly secured within said recess by shrinkage of shape, said cap in by the molding ope termin tion inserted tion being per d recess by con sult of the usual the molded cap, f said member carryhaving a recess nce for the the walls of the latter.

3. The method which comprises cold moldbined contact and ing a mass of insulating material to provide an integral proje a plug cap having recesses therein, thereafter recess, said proj e inserting within said recesses the integral cured within sai projecting shanks of combined contact and the walls of terminal members, then subjecting said cap heat indurationt to curing treatment to permanently secure the terminal said shanks within said recesses through ing shrinkage of the walls of the latter.

rovide a plug cap having diametrically of cold molded insula spaced pairs of recesses therein, thereafter having a recess formed inserting within certain of the recesses of ing each pair the integral projecting shanks of tact and terminal a pair of one-piece combined contact and ing an integ terminal members, said shanks having insaid recess and per wardly extending shoulders formed in the by shrinkage of thei surfaces thereof, and simultaneously insert- 9. An attachment p ing within the other recesses of each pair the insulating bo shanks of binding screws carried by said terany kind, sai

minal members, then subjecting sa d cap to recesses forme the usual heat treatment for curing whereby eration, and

said first mentioned shanks are rigidly and bined contact an formed therein 4. The method which comprises cold moldshank of said screw. ing a mass of plastic insulatingmaterial to 8. In combination,

ct and terminal al co having a recess ration, a onethe latter as a re reatment of portion 0 and said cap to provide cleara on, and a one-piec member, sa projecti manen dy molde d body h d therein by the molding opof one-piece com- 1 members having d within said rea plurality d termina permanently secured within their respective integral projections recesses through contraction or distortion of cesses and shrinkage of th the walls of the latter.

inserting within certain of the recesses of tion, a 4 each pair the integral projecting shanks of to provi apair of one piece combined contact and terplate, minal members, said shanks having inwardbent npwar ly extending shoulders formed in the surprovide a cont faces thereof, simultaneously inserting withtegral with said plate a in the other recesses of each pair the shanks at right angles the of binding screws carried by said terminal tapped 0 members, then subjecting said cap to the ususcrew having t al heat treatment for curing whereby said opening,

first mentioned shanks are rigidly and perto-preven manently secured within their respective resaid plate,

cesses through contraction or distortion of and said secon the walls of the latter, and thereafter subtaneously inserted i jecting at least the metal portions of the asbase prior to heat-in sembled cap to the action of an acid bath to th latter,

- 11. An attachment 6. As an article of manufacture, an at-. h at-i duratabl insul tachment plug'cap comprising a body of ined free from inser sulating material cold molded to the desired having a p shape, said cap having a recess formed theremined cross-sec in by the molding operation, and a one-piece therein by the mo 60 clean the surfaces thereof.

permane ntly e materia 5. The method which comprises cold mold- 10. In combination, ing a mass of plastic insulating material to cold molded and heat (1 therein by d sheet me de a horizontally e an arm integr dly at r act blade, a se nd bent do reto, herethrough, hreaded engageme f said screw aration thereof t end of said screw d arm being simuld recesses in the duration treatment of t complete sep and the upse d mentione tso tional lding operation,

d recess by e latter as a member havd within being permanentcontraction t of the of the moldticle of manufacture, an atcomprising a ld molded to body of inthe desired formed therepiece comer having within said manently setraction of a pre-formed plug cap ting material, said cap therein by the mol e combined conid memberhavnserted within tly retained therein 'nsulating material.

lug cap comprising an d free from inserts of aving a plurality of d therein by l of said body.

-formed base of ble insulating having a plurality of rethe molding operatal member formed xtending terminal th said plate and es thereto to cond arm inwnwardly e having a a binding nt with said being upset from p comprising a body cold moldnd, said body of recesses of predeterdimensions formed a plurality scribed my name.

WILLIAM C. TREGONING.

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