US2121979A

US2121979A - Staybolt and method of manufacturing the same

Info

Publication number: US2121979A
Application number: US79026A
Authority: US
Inventors: William B Peirce; Nicholas J Kouche
Original assignee: Flannery Bolt Co
Current assignee: Flannery Bolt Co
Priority date: 1936-05-11
Filing date: 1936-05-11
Publication date: 1938-06-28
Anticipated expiration: 1955-06-28

Description

Patented .lune 1938 STYBOLT AND METHOD oF MANUFACTUR- ING THEv SAME,

William` B. Peirce, Pittsburgh, and Nicholas J. Kouche, Bridgeville, Pa., assignors to Flannery Bolt Companyridgeville, Ea., a corporation of Delaware .Y Application May 11, 1936, SerialmNo."79,026

5 claims. (c1. 111-275 invention relates' to staybolts and their `manufacture, and more particularly to the form and manufacture of what is known as a rigid `staybolt with a square head.

l Theusual form of a'finished rigid staybolt is a round bar or blank with a square head being used to hold the bolt during the threading operation and also used to screw the finished bolt in the boiler during the installation' operation. As the object of a staybolt is to support the outer and kinner sheets ofa boiler or to keep them from A spreading under pressure it is obvious that it must be tightly screwed and riveted in the boiler sheets to prevent leakage and to have the necesl5 sary sustaining strength.

In order to make a staybolt fit neatly in the tapped holes of a boiler the threads .must be ac- `curately cut and perfect in shape, especially the tops of the rthreads must be fully formed. If, in

zo the process vof threading, a rigid Astaybolt is not held perfectly concentric with the threading dies, thenthe dies will cut too much off on oneside and not leave enough material on the opposite side to make a full thread.

In theathreading of a rigid staybolt where the thread must be perfect in shape right upto the Isquare head it is necessary in commercial thread- .ing to hold the bolt on the square head. If the head is not concentric with the body then the -body willnot be concentric with the die and the thread will not be perfect in form. A head that is non-concentricwith thenished body of a rigid .bolt has a. tendency to wobble the bolt when it is being screwed in the boiler plates with a motor driven square socket. This wobbling sometimes keeps the bolt from entering the second boiler sheet after screwing through the first sheet.

` Heretofore in the manufacture of rigid staybolts it has beenzthe usual practice to out the commercial bar of staybolt iron into lengths and then either hot forge or cold press the square on one end, and then thread the bolt its entire length by holding it by the square while the die cuts the thread. It is almost impossibley to commercially make a hot forged square on a bolt blank that is exactly concentric with the body, and the cold pressing of the square doesnot always make the squares concentric even if the dies are in perfect shape. In either hot forged 4or cold pressed squaring a rough shoulder lis left between the "5A '.Squaredportion and' the' rest of the bolt which varies in length according to diameter of the bolt "being squared. :This rough lshoulder is neither square nor. round and is` therefore a lost nl `length as the thread. cut. on it is not fully formed.

venough'stock` to make a good square.

Usually the size of the squares on all rigid staybolts are of the same size'regardless of the diameter of the bolt. To make a good square of a standard dimension by the cold press process required a certain diameter of iron regardless of 5 what diameter the bolt happens to be, then the end'of all rigid bolts requiring a standard square should be the same or standard diameter regardrless ofthe diameter of the body of the bolt. It is obvious that if this standard diameter to make a-m standard square is maintained for all diameters of bolts, the body diameter of large bolts must` be reduced tof this standard diameter for a length long enough to make the square. This has been customarypractice, but usually is done by a sepy 15 arate operation. j l,

According to the present invention, an annular kerf is vcut into the blank stock at the time the blank stock is parted from the commercial bar on a parting machine. This-kerf is a distancezo from the end of the blank which allows just As the kerf is cut vduring the parting operation no extra time is required and when `a forming or shaving tool is used between the parting and kerfing tool thisz5 portion of the bolt body may be reduced to` ther proper diameter to make a good standard square Without any extra time over the parting operaftion. Both ends of the bolt blank may also be chamfered by using a chamfering tool in combi- 3.0

nation with the parting, kerfing and formingL tools without yany loss of time. The kerf is ordinarily cut to a depth making its diameter equal or slightly under the flats of thesquare to be put on. This kerf leaves a clean-cut shoulder on the 35 body of the bolt capable of receiving a clean-cut vthread of fullv size, and an accurate termination of the thread of the bolt, also an accurate termi. nation of the square end and itsv width is allowed to be computed as part of the square length, thus ,40 eliminating the lost length due to the rough shoulder made by the ordinary squaring process. When a bolt blank with a formed end of the proper size' and a kerf cut to the proper depth at a proper distance from the end of theblank is 415 subjected to the squaring dies it produces a good square, concentric with the body of the bolt.

`This then allows a perfect thread to `be cut on the blank clear up to the kerf shoulder. By reasonv of the cutting kerf the cold working does not o 50 extend back into the threaded section of the bolt.r

The invention may readily be understood by reference to the accompanying drawing, in which:

Figure 1 indicates moreor less diagrammatically, the. step in the process", of manufacturingv .the 5.5

bolt wherein one length of stock is being cut off or parted from a rod while the next adjoining length of stock is having a kerf formed therein and the portion for the square formed to size.

Figure 2 is a side elevation of a portion of the blank showing the head end thereof in its proper shape.

Figure 3 is a similar view showing the blank after the head end had been squared.

Figure 4 is an end View of the completed bolt.

Figure 5 is a side elevation of the completed bolt.

Figure 6 is a side elevation of the head end of a slightly modified form of bolt.

Figure 7 is a perspective view illustrating one of two dies which are used in forming the square on the boit.

Referring to Figure 1, A ldesignates a piece of stock of indefinite length which is in the process of being cut up into blanks. B indicates a blank which is almost cut off, the cutting tool for severing the blank B from the length of` stock A being designated C. D represents a cutting tool maintained in predetermined spaced relation to cutter C for cutting a kerf in the stock A, a predetermined distance back from cutter C. F represents the portion of the bolt to be made into a square. If the diameter of the stock is such that the portion F has to be reduced to bring the diameter down to a diameter necessary to make a square head of standard size, a third cutter for turning down the diameter o-f portion F may be provided between cutters C and D. In this cutting operation it may be assumed that the rod A is being turned by some suitable chuck not shown. After the blank B has been completely cut off the support E on which the cutters are carried is moved transversely away from the stock, the stock advanced the necessary length to form a blank, and the operation is again repeated, the length of stock A thus being successively out into blanks, each blank when it is completed having a portion for a head and a kerf formed therein a predetermined distance from one end thereof, such head portion also being reduced where necessary.

This is clearly illustrated in Figure 2 wherein the blank B has a kerf designated 2 therein, a head forming portion 3 between the kerf and the end of the blank. In this figure, as distinguished from Fig. 1, we have shown the head portion reduced in diameter to the extent necessary to form a good square head of standard dimension. The body of the blank is designated 4. The body 4 has the original diameter of the stock A while the portion 'is, as is usually the case, of smaller diameter. The kerf 2 is of such depth that the diameter of the neck portion 5 connecting the body Il with the portion 3 is substantially the same or slightly less than the ats of the square head which is subsequently formed.

If the blank shown in Figure 2 has the head forming portion 3 formed into a square by being pressed between two dies as shown in Figure 7, the body portion being laid in the semi-circular part of the die 'l and the head forming portion 3 in the square part of the die then the formed blank, as shown in Figure 3, will be produced. This die is of the type now generally used in the manufacture of staybolts, and forms no part of the present invention per se. The square head thus formed by being pressed between two dies as shown in Figure 7 is more perfectly formed on a blank with a kerf for the reason that the metal is allowed to flow longitudinally in both directions and as the portion that is to be squared is of the proper diameter regardless of the diameter of the body, the square made therefrom is as nearly perfect as can commercially be made, and as the squaring die does not have to shear the body diameter of the bolt'down to the square size, the concentrating and'alignment is more easily maintained.

Figure 3 clearly illustrates a blank that has been squared, showing the square shoulder made by the kerf, while Figure 4 shows an end View of the same bolt.

Figure 5 shows the side elevation of a finished bolt showing the clean-cut threads right up to the shoulder made by the kerf and also that the length of the square can be computed from this shoulder. To install a rigid staybolt in a boiler it first must be screwed through both boiler sheets and just enoughof the threaded portion left to project past the face of the sheet to rivet over. The riveting process upsets the bolt in its threaded hole and forms a slight button head that seals the joint between the bolt and the boiler sheet. It is obvious then that the square head must be removed after the bolt is screwed in place, the square then having served its full function. The removal of the square head is sometimes done by breaking it off, and in such cases it is sometimes desirable to facilitate the breaking by what is commonly known as necking in or nicking the head. This is illustrated in Figure 6 where the neck portion 8 is of less diameter than the thickness of the head portion 9 and the threaded body of the bolt lll. 'Ihis neck is sufficiently strong to withstand the torque of both threading the bolt and of screwing it into place, but facilitates the severing of the head after` the bolt has been screwed into place. This extra deep kerf can be cut in the same way as the standard depth of kerf and does not require any more time or expense.

By the practice of the present invention, bolts of better appearance and greater accuracy are produced. All of them are of uniform appearance and all have a full thread up to the kerf'. The head forming is effected with less distortion of the metal, and the effect of cold working is conned to the head and does not extend into the body of the bolt. Less work has to be performed by the dies, so that the operation is performed more easily and with less wear on the dies. The method, moreover, enables the blank to be initially a fraction of an inch shorter than with' methods heretofore employed, and this results in a further economy to the manufacturer.

We claim: l

1. The method of forming a staybolt which comprises forming a blank of round metal stock, producing an annular kerf in said stock adjacent one end thereof thereby dividing the blank into a body portion and a head portion connected by an intervening neck portion of reduced diameter, and subsequently forging the head portion to produce a square head having a diameter less than the diameter of the body portion and subsequently threading the body portion of the blank.

`2. The method of making staybolts which comprises producing a blank of round metal stock having a kerf therein adjacent one end thereof, said kerf dividing the blank into a body portion and a head-forming portion connected by a neck portion of reduced diameter, and subsequently pressing the head-forming portion of the blank to a square shape the transverse yus thickness of which is not substantially less than the diameter of the neck portion.l y

3. The method of making staybolts which comprises producing a blank of round metal stock having a kerf therein adjacent one end thereof, said kerf dividing the blank into a body portion and a head-forming portion connected by a neck portion of reduced diameter, and subsequently pressing the headfformingportion of the blank to a square shape the thickness of which is some what greater than the diameter of the neck portion. Y

4. In the manufacture of staybolts from a length of round stock, the steps Which comprise simultaneously cutting ,the stock into lengthsy and forming on each length an annular kerf near one end of the blank whereby the blank is ldivided into a body portion and a head-forming portion connected by a neck portion of smaller diameter than the body or head portion, pressing the headforming portion to a substantially square crosssection the thickness of Whichv is substantially less than the outside diameter of the body pore tion, and thereafter threading the body portion.`

5. A staybolt comprising a threaded body portion, a forged head portion and a circular neck portion connecting the head and body portions, said neck portion being of less diameter than the threaded body portion and having substantially the original grain of the metal blank from which the bolt is formed. WILLIAM B. PEIRCE.

NICHOLAS J. KOUCHE.