US637120A - Manufacture of electrical fuses. - Google Patents

Description

Patented Nov. I4, I899. n. m. HUNTER.

2 Sheets-Sheet MANUFACTURE OF ELECTRICAL FUSES.

(Application filed Nov. 11, 1896. Renewed May 1, 1899.) (No Model.)

I'lll No. 637,120. Patented Nov. I4, 1899'.

R. m. HUNTER.

MANUFACTURE OF ELECTRICAL FUSES.

(Application filed Nov. 11, 1896. Renewed May 1, 1899.) (No Model.) 2 Sheets-Sheet 2.

FIG-.7.

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UNITED STATES PATENT OFFICE.

RUDOLPH M. HUNTER, OF PHILADELPHIA, PENNSYLVANIA.

MANUFACTURE OF ELECTRICAL FUSES.

SPECIFICATION forming part of Letters Patent No. 637,120, dated November 14, 1899. Application filed November 11, 1896- Renewed May 1, 1899. Serial No. 715,205. (No model.)

To 'LtZZ whom it may concern:

Be it known that I, RUDOLPH M. HUNTER, of the city and county of Philadelphia and State of Pennsylvania, have invented an Improvement in the Manufacture of Electrical Fuses, of which the following is a specification:

My invention has reference to the manufacture of electrical fuses; and it consists of certain improvements, which are fully set forth in the following specification and are shown in the accompanying drawings, which form a part thereof.

This application (Case No. 293) comprehends a certain method or process for the manufacture of fuses for electrical circuits and the machines or apparatus therefor.

Heretofore electrical fuses or fuse-wires have been made of a suitable fusible alloy containing lead and tin, with or without other metals, and the said alloy after being cast is rolled down to the requisite cross-section calculated to carry a given current in amperes without fusing, but adapted to melt or fuse upon an excess of current beyond said calculated amount being unintentionally caused to pass over the circuit. In some cases the fuses are rolled out into flat plates, which are sub sequently notched to reduce the width of the rolled plate at or near the middle and have their ends united to stamped sheetmetal clamps, this latter construction being the form commonly employed on large circuits. Large quantities of the smaller fuses are formed of short lengths of the rolled-alloy wire and the ends united by soldering to stamped slotted copper clamping terminals. This method of constructing fuses is not only expensive, but is unreliable, since it is impossible to roll a soft alloy and secure a uniform density, without which no reliability can be had as to the current-carrying capacity from a given cross-section. This defect often permits the passage of as high as forty per cent. more current than its rated capacity. The same continuous length of fuse-wire will vary in its current-carrying capacity almost with every foot of its length, and hence the fuses made from the same reel cannot be relied upon for carrying only a definite current before fusing. The difficulty ofdetecting these defects before actual use lies in the fact that to test the fuse means to destroy it before ascertaining its capacity, and, furthermore; the testing of one fuse is no evidence that the next one of the same batch will respond to the same test.

My invention is designed to overcome these defects in the fuses as heretofore made; and my object is to manufacture fuses in such a manner that every fuse will carry exactly the currentitis intended to carry and no more and all fuses of a given capacity will each have that capacity assured without test or experi-' ment.

In carrying out my invention I dispense entirely with rolling and cast the fuse in the predetermined shape under a given and uniform pressure. If a sufficient pressure he employed, blow-holes will be eliminated and the density of the alloy must of necessity be uniform. When these results are secured, every fuse of a given cross-section will carry exactly the same current before fusing.

In carrying out my invention I may employ either of two methods or modes of operation. The preferred method is to feed automatically into a moving mold the fusible alloy under a given or constant pressure and preferably secured by employinga column of molten alloy. Suitable devices are employed to maintain that column constant or uniform in height, so that irrespective of the amount of metal taken away in the mold the upper level of the column of metal is constant. The manufacture of fuses by this method is only limited by the speed with which the metal may be molded. I prefer to employ a rotating mold-wheel having its face formed with molds which are moved rapidly over a moldsection in the form of a curved casting, through an aperture in which the alloy is fed to the mold. As the mold-wheelsurface passes below the mold-section the fuses drop out of the molds by gravity.

Fuses formed as above may have the de sired shape and cross-section and definite current carrying capacity. I form. the fuses preferably of arch form, with the smallest sectional area in the center of the crown to facilitate the blowing at that point and also with slotted feet for clamping to the fuse blocks. To give good contact and durability in use, I subject the feet of the fuses so formed ICO to an electrolytic bath of copper and deposit electrically a coating of copper upon these parts ofsufficientthiclmess toimpartstrength and reduce the resistance. By plating these feet with a heavy layer of copper the soft fuse metal or alloy is incased in copper and cannot be squeezed out of shape very readily, thereby insuring a good electrical connection in the circuit. This secures all of the advantages of the solid stamped copper terminals, while avoiding their expense. Moreover, by casting my fuses I can secure the desired cross-section at every part, so that the fusing-section is decidedly of the least resistance, thus insuring the rupture or blowing occurring at a definite place.

My invention will be better understood by reference to the accompanying drawings, in which- Figure l is a sectional elevation of a machine for carrying out my preferred process of making fuses. Fig. 2 is a cross-section of same on line :0 (c. Fig. 3 is a perspective View of one of my improved fuses. Fig. 4 is a perspective view of a portion of the mold- Wheel. Fig. 5 is aside elevation of one of my fuses. Fig. 6 is a cross-section of a portion of the mold, showing a modified crosssection of the fuse-mold; and Fig. 7 is a sectional elevation of a galvanizing-bath.

A is the main frame of the machine and has jonrnaled in it near the bottom a transverse shaft C, upon which is secured the mold-wheel B. The shaft 0 may be rotated by a worm and worm-wheel D and a bandwheel E or otherwise. The cross-section of the rim of the mold-wheel B is best shown in Figs. 2 and 4, the same being with a higher central rim B intermediate of the two lateral or flange surfaces B. The mold b is formed or cut into the outer surfaces of the rim of the mold-wheel, as clearly shown in Figs. 1, 2, and 4:. The rim of the mold-wheel moves in contact with a curved mold-section F, constituting the outer part of the mold. This part F is stationary and carried by the main frame A in any suitable manner. The part F has its upper portion formed with a metal chamber to receive the molten alloy and is furnished with a casting-aperture f, through which the fluid metal finds ready access to the molds in the mold-wheel as they pass the aperture. The front of the metal-chamber may have a removable plug or stopper g to permit access to the chamber for cleaning purposes and for allowing a portion of the metal to flow off at starting to insure all air being ejected from the fluid alloy. This latter precaution would hardly be necessary in practice, because of the great weight of the column of metal under which the casting takes place.

The lower portion of the mold-section F acts as a curved guide-surface over which the castings are moved while cooling, and the solidifying may be quickened by the employment of a water-jacket F, through which cold water may be passed by pipes G. As the mold-wheel passes on in its revolution the castings are ultimately carried beyond the mold-section F, and thereby permitted to drop by gravity from the molds. The molds are preferably formed with sufficient taper in all directions and flaring toward the outer surface of the mold-wheel to insure the ready liberation of the castings. This is furthermore increased by the shrinkage of the castings in hardening.

Fitted to the top of the chamber F in the mold-section F is the hollow column, tube, or stand-pipe I, which may be of any height desired. In practice I prefer to make it about five feet, and upon the top of it I arrange a metal-pot I. To one side of this pot I movably support or hinge at 'i a pan 1 adapted to contain a large quantity of molten alloy S. By tilting the pan 1 it is evident that the level of the alloy in the pot I may be raised or lowered or maintained at a definite level. This pan or reservoir may be adjusted by any suitable means, that shown being excellently adapted to the purpose. This means consists of vertical screw J, connected with the pan by a link and working through a rotating nut having a worm-wheel J, which is driven by a worm and an electric motor K. By making the pitch of the screw J and the worm small the parts are locked against running down, that latter action being secured only by reversing the electric motor in the usual way. The motor K is in an electric circuit M, leading from a battery L or other source of electric energy. A switch N opens or closes the motorcircuit M automatically and is controlled bya magnet O of high resistance in a circuit Q, also including the battery L, and put into or out of energized condition by a circuit-controlling switch operated by the fluid alloy. This latter switch consists of a float 29, having a platinum contact and resting upon the molten metal in the pot I, and a contact-screw P,

carried by but insulated from the pot and making contact with the floating contact 19. The circuit Q of the magnet 0 includes the parts P and p of this controller or switch. The smallest variation in height of the level of the molten metal will break the contact between P and p, and thus open the circuit Q. and allow the armature-switch N to move away from the magnet under the action of a spring. This closes the motor-circuit and causes the motor K to rotate the worm-wheel and its nut, with the result of raising the pan I slightly, and therefore the level of the metal. This result once more raises the float p and closes the circuit 0, and thereby induces the opening of the motor-circuit. By employing speed-reducing gearing, such as shown between the motor K and screw J, the motor may make a number of revolutions to raise the pan to a very small extent. Any

other automatic mechanism may be employed to maintain the fixed height of the column of fluid alloyin lieu of that above described,

terially affect the fusing-point of the fuse.

It Will be essential to maintain the alloy in a fused or fluid condition, and to do this I may employ a gas-jet H under the chamber F where the alloy enters the mold, and a spiral burner H, arranged around the stand pipe or tube I. A lateral burner-tube h may be ar ranged under the pan I and moved with it.

* Any other means of supplying heat may be employed.

The preferred form offuse is shown in Figs. 3 and 5, and consists of the arched center T, having the smallest cross-section at t in the crown, and the slotted feet T at each end. The feet T of the fuse are suspended in an electroplating-bath U, Fig. 7,' and coated with a layer of copper. A sufficient coating of the copper will completely confine the fusible metal at the feet and provide a perfect contact and also reduce the resistance. The hard copper envelop will confine the soft metal, and thus permit it to withstand the clamping action in the fuse-block. While I prefer this shape of fuse, it is to be understood that it may be made in any other shape.

In the general method as above set forth the fuse is cast of the requisite shape under a uniform pressure, and it is immaterial to my invention, broadly considered, how this uniform pressure may be secured. The height of the column of alloy in Fig. 1 may be increased to vary the density of the casting in the same mold by adjusting the contact P to give to the given-sized fuse a different capacity; but in all cases the machines will make every fuse under like conditions and with the same capacity once the machines are set to perform their work.

The details of construction may be modified in various Ways without departing from the principles of my invention. Hence I do not limit myself to the details shown.

What I claim as new, and desire to secure by Letters Patent, is

1. In a machine for making electrical fuses, the combination of a mold, a pressure device for introducing into the mold a fusible alloy under a predetermined pressure, and an automatic pressure-regulating device constructed and arranged to be actuated by said pressure device.

2. In a machine for making electricalfuses, the combination of a mold, a pressure device for introducing into the mold a fusible alloy under a predetermined pressure consisting of a column of the fusible alloy, and an automatic pressure-regulating device constructed and arranged to be actuated by the varying levels of the surface of the column of alloy forming said pressure device.

3. In a machine for making electrical fuses, the combination of a mold, means for continuously supplying to the mold a fusible al- 10y under a substantially predetermined pressure, and automatic pressure-regulating devices to increase the said pressure whenever the same falls below the predetermined pressure.

4. In a machine for making electrical fuses, the combination of a mold, a stand-pipe for holding fusible alloy and feeding it to the mold under uniform pressure, an auxiliary reservoir or receptacle for containing an excess of the fusible alloy, and means for moving the auxiliary reservoir for transferring fusible alloy from the auxiliary reservoir or receptacle to the stand-pipe.

5. In a machine for making electrical fuses, the combination of a mold, a stand-pipe for holding fusible alloy and feeding it to the mold under uniform pressure, an auxiliary reservoir or receptacle for containing an excess of the fusible alloy, and automatic means under the control of the metal level in the stand-pipe for transferring in small quantities and at intervals fusible alloy from the auxiliary reservoir or receptacle to the standp In a machine for making electrical fuses, the combination of two or more molds, apressure device for introducing the alloy to the mold successively under a predetermined pressure, and means for automatically regulating and controlling the pressure arranged and constructed to be actuated by said pressure device, whereby all of the molds are supplied with the fusible alloy bythe same pressure and regulating devices and all castings are of exactly the same density.

7. In a machine for making electrical fuses, the combination of a mold, a pressure device for introducing into the mold a fusible alloy under a predetermined pressure, an automatic pressure-regulating device constructed and arranged to be actuated by said pressure device, a reservoir or receptacle for containing an excess of the fusible alloy, and means for transferring fusible alloy from the reservoir or receptacle to the pressure device, whereby the pressure device is constantly supplied with the proper quantity of fusible alloy for the casting operations.

8. In a fuse-making machine, the combination of a tubular column for fusible alloy, a moving mold adapted to receive fusible alloy from the lower part of the column, a separate reservoir of fusible alloy, means for transferring fusible alloy from the separate reservoir to the tubular column, and automatic controlling devices under the control of the fusible alloy in the tubular column for controlling the means for transferring the fusible alloy from the separate reservoir to the tubular column.

9. In a fuse-making machine, the combination of a tubular column for containing fusible alloy, a moving mold adapted to receive fusible alloy from the lower part of the column, means for supplying fusible alloy to the top of the column to compensate for that run off from the bottom, and automatic devices for controlling the supply of fusible alloy to the column constructed and arranged to be operated by the height of the column of alloy.

10. Inafuse-makingmachine,thecombination of an upright tube for feeding an alloy under pressure, a mold adapted to receive al- 10y from the bottom of the tube, a reservoir of molten alloy movably supported so as to change the level of the column of alloy formed by the tube, an electric motor to move the reservoir, a switch to control the motor, an electromagnetic device to control the switch to arrest the operation of the motor, and means controlled by the height of the column of molten alloy to control the electromagnetic device, whereby the motor is automatically operated to increase the level of the molten alloy upon any appreciable lowering of the column of alloy.

11. In a fuse-making machine,the combination of a rotating mold-wheel having its surface formed with m0lds,a mold-section against which the mold-wheel operates and provided with a casting-aperture, a tubular column or stand-pipe opening from the mold-section to secure a constant and uniform pressure, and a reservoir for molten alloy at the upper part of the column or stand-pipe having a movable bottom.

12. In a fuse-making machine,the combination of a rotating mold-wheel having its surface formed with molds,a mold-section against which the mold-wheel operates and provided with a casting-aperture, a tubular column or stand-pipe opening from the mold-section, a reservoir for molten alloy at the upper part of the column or stand-pipe, means to raise or lower the reservoir to adjust the level of the molten alloy in the stand-pipe, and means to heat the column or stand-pipe and reservoir.

13. In afuse-making machine,the combination of a moving mold having its surface formed with mold-recesses, a tubular column or stand-pipe of metal for supplying alloy to the mold under pressure, a reservoir for molten alloy to one side of the upper part of the column or stand-pipe, and a gas-pipe having a portion spirally encircling the metal stand-pipe to heat the column or stand-pipe and formed with a lateral branch to heat the reservoir.

14:. In a fuse-making machine the combination of a moving mold having a continuous smooth surface throughout its length and having formed in its surface a series of shallow depressions the walls of which are fixed and flaring outwardly for receiving molten alloy whereby the surface surrounding and intermediate of said depressions is continuous and adapted to act as a seal or valve to the alloy-supplying means with a smooth moldsection against which the moving mold travels to form a close joint, means for supplying sci-.1526

intermediate of said mold and mold-section a fusible alloy under pressure, and automatic pressure-regulating devices constructed and arranged to be actuated by the alloy when varied as to its pressure whereby it is fed under constant and uniform pressure to the moving mold.

15. In a fuse-making machine,the combination of mold-wheel having its circumference formed with an annular raised center and provided with molds formed into the metal of the center and extending down its sides and upon the circular lateral surfaces of the periphery, with a mold-section having internal curved surfaces corresponding in shape to the surface of the mold-wheel, and means for supplying a fusible metal through the mold-section into the molds.

16. In a fuse-making machine,the combination of mold-wheel having its circumference formed with an annular raised center and provided with molds formed into the metal of the center and extending down its sides and upon the circular lateral surfaces of the periphery, with a mold-section having internal curved surfaces corresponding in shape to the surface of the mold-wheel, means for supplying a fusible metal through the moldsection into the molds, and means for maintaining the pressure of the fusible metal when casting always the same.

17. In a fuse-making machine,the combination of mold-wheel having its circumference formed with an annular raised center and provided with molds formed into the metal of the center and extending down its sides and upon the circular lateral surfaces of the periphery, with a mold-section having internal curved surfaces corresponding in shape to the surface of the mold-wheel, means for supplying a fusible metal through the moldsection into the molds, and means for cooling the mold-section to solidify and cool the castings before being discharged.

18. In a fuse-making machine, a mold for a fuse consisting of a movable mold-piece having a continuous surface furnished with a raised portion B intermediate of two side portions 13 formed with their longitudinal surfaces parallel and in which said portions 13 B and the two upright side walls between them are provided with transverse moldgrooves, a stationary mold-section fitted to the grooved surface of the movable moldpiece to close the grooves in the surface of the mold, means to move the movable mold-piece of the mold relatively to the stationary moldsection, and means to supply a fusible metal to the grooves of the mold under pressure.

19. In a fuse-making machine, a mold for a fuse consisting of a movable mold-piece having a continuous surface furnished with a raised portion B intermediate of two side portions B formed with their longitudinal surfaces parallel and in which said portions B B and the two upright side walls between them are provided with transverse mold IIO grooves and in which the side walls of the mold-grooves flare outward at all points so that the castings automatically drop out of the grooves by gravity, a stationary mold-section fitted to the grooved surface of the movable mold-piece to close the grooves in the surface of the mold, means to move the movable mold-piece of the mold relatively to the stationary mold-section, and means to supply a fusible metal to the grooves of the mold under pressure.

20. In a fuse-making machine, the combination of a mold, a stand-pipe or tubular column for supplying fusible metal to the mold under pressure, a metal pot at the top of the stand-pipe or column, and amolten-metal reservoir hinged or flexibly connected to or relatively to the pot for supplying it with molten metal.

21. In a fuse-making machine, the combi- A nation of a mold, astand-pipe or tubular column for supplying fusible metal to the mold under pressure, a metal-pot at the top of the stand-pipe or column, a molten-metal reservoir hinged or flexibly connected to or relatively to the pot for supplying it with molten metal, and automatic devices under the control of the fusible alloy in the stand-pipe for operating the reservoir to supply molten metal to the pot for maintaining the level of the molten metal therein uniform.

22. The combination of a mold, a metal stand-pipe for delivering molten alloy to the mold under pressure, and a spirally-arranged gas-pipe havingburner-openin gs surrounding the stand-pipe for heating it.

23. The combination of a mold, means for supplying a fusible alloy to the mold under pressure, an auxiliary reservoir or receptacle for the fusible alloy, and automatic devices controlled by the pressure-creating means constructed and operating to transfer the fusible alloy from the reservoir to the means for supplying it to the mold under pressure.

24. The combination of a mold, means for supplying a fusible alloy to the mold under continuous and uniform pressure, an auxiliary reservoir or receptacle for the fusible alloy, devices constructed and operating to transfer the fusible alloy from the reservoir to the means for supplying it to the mold to maintain it at the same level, and automatic means controlled by the level of the alloy to govern the action of the transferring devices.

25. The combination of a mold, an alloypot, means for conveying the alloy from the pot to the mold, movable auxiliary reservoir or vessel for holding an excess of fusible al- 10y, means to move the auxiliary reservoir for transferring the fusible alloy from the reservoir to the pot, and means to heat both the pot and reservoir.

26. The combination of a mold, an alloypot, means for conveying the alloy from the pot to the mold, an auxiliary reservoir or vessel for holding an excess of fusible alloy, means constructed and controlled by the movement of an arm or lever for transferring the fusible alloy from the reservoir to the pot, a float resting upon the alloy and rising and falling with its change of level, an electric contact controlled by said float, an electric circuit including said contact, and an electromagnetic device in the electric circuit and controlled by the contact to operate the arm or lever of the transferring means.

27. The combination of a mold, means for supplying a fusible alloy to the mold under uniform pressure, an auxiliary reservoir for fusible alloy, devices constructed and operating to transfer the fusible alloy from the reservoir to the means for supplying it to the mold, and means operated by the level of the fusible alloy to electrically control the oper ation of the devices for transferring the fusible alloy.

28. In a machine for casting the combina-- tion of a mold, a stand-pipe for holding fusi ble alloy and feeding it to the mold under uniform pressure, an auxiliary reservoir independent of the' stand-pipe adapted to contain much alloy and sustain it independently of the alloy in the stand-pipe, and means controlled by the pressure-creating alloy in the stand-pipe for transferring said alloy from the reservoir to the stand-pipe in a gradual manner so that it shall become active in creating a pressure in the stand-pipe and maintain said pressure constant and uniform.

29. In a machine for casting the combination of a mold, a stand-pipe for holding fusible alloy and feeding it to the mold under uniform pressure, an auxiliary reservoir independent of the stand-pipe adapted to contain much alloy and sustain it independently of the alloyin the stand-pipe, means for transferring said alloy from the reservoir to the stand-pipe in a gradual manner so as to become activein creating a pressure in the standpipe and maintain said pressure constant and uniform, and electrically-controlled means governed by the level of the alloy in the standpipe to control the transferring means.

In testimony of which invention I have hereunto set my hand.

R. M. HUNTER.

Witnesses:

J. W. KENWORTHY, R. M. KELLY.

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