US2613241A - Electric hammer with rectifier in handle - Google Patents

Description

Oct. 7, 1952 c s WEYANDT I 2,613,241

ELECTRIC HAMMER WITH RECTIFIER IN HANDLE Filed Sept. 19, 1949 2 SHEETS -SHEET 1 25 2 J4 MI I 39 O J5 35. J7 55 0 J6 56 /l\ 5'2 0 w u w Q 41 Q5 42 Q4 41 Z1 "f; \ii\ 26 V J 2J- 0 O H 15 IN V EN TOR. Cor/6. h/eyandzfi Oct. 7, 1952 c s, WEYANDT 2,613,241

ELECTRIC HAMMER WITH RECTIFIER IN HANDLE Filed Sept. 19, 1949 2 SHEETSSHEET 2 gig-h1g2 INVENTOR. COr/Jh/gano.

56 Y Azrm/f/ Patented Oct. 7, 1952 ELECTRIC HAMMER WITH mammal;

HANDLE:

Carl s. Weya'ndt, Homer city-P Application September 19, 1949, Serial No. 116,509

This invention relates generally to electromagnetic reciprocating hammers and more particularly to an electric hammer having spaced electromagnetic coils energized by alternate electricimpulses usually obtained from a rectified half wave alternating current circuit.

Electric hammers have been constructed to operate from various types of rectifiers such as vacuum tube diodes or dry disc rectifiers. These rectifiers, heretofore, have been mounted in a separate housin spaced some distance from the hammer itself, generally to feet. One disadvantage of such construction is that a separate unit for the rectifier is required, making it awkward to handle in many operations such for instance as drilling in ceilings overhead and drilling high on side walls of buildings Another disadvantage is that in 'groundingff's'uch devicesit is necessary to run a ground wire from the hammer to the case of the rectifier and from the case of the rectifier to the ground connection; 'This requires the use of four wires from therec'tifier to the hammer and four point recep'tacles and plugs. It also requires three wires fromthe rectifier to the source of supply and the ground. The requirement of four wires from the rectifier to the hammer ismore expensive than the ordinary three-wire or two-wire cable and does not give as good service as the lesser wired cables since there is more danger of breakage internally in the cable, due to twisting and bending in normal use. Another disadvantage is that in order to break all live connections to the hammer coils, it is necessary to have a threepo'le switch. This is rather an expensive device and means that the handle to contain the switch must be larger, making the device more clumsy and heavier and more difiicultto handle as a portable tool.

These objections have been eliminated in the present invention by placing the rectifier within a portion of the hammer itself. This makes possible the use of a two-pole switch to completely disconnect any live conductors from the hammer. It makes possible the use of a standard threeconductor cable from the source of supply directly tothe hammer for both supplying power and grounding of the hammer.

One object of this invention is the provision of an electro'magnetically operated reciprocating hammer having its rectifier built within the handle to provide a three-conductor cable with two" conductors for the supply circuit and one independent conductor for grounding the casing of the hammer.-

eating hammer with the plane of the discs paral- 4 Claims. (01.172-126) lel; with the vibratory action of the hammer {to avoidv mechanicaifixture of the discs. Another objectis the provision of'an electro: magnetic reciprocating'hammer havingan 1minterruptedfground connection to the casing and a doublepole switch in'the operating circuit of the hammer... I a

Another object is the provision of a dry disc rectifier built within the-handle of an electromagnetic hammer and requiring less,v discs per volt owing to the proximity and the'inductive reactance of the hammer operating coils. I Another object is theprovision of a rectifier mounting that supports one end of the cable and forms a portion of the handle. a a I Other objects and advantages appear in the following description and claims' The accompanying drawings show, for.the purpose ofexemplification without limiting the in: vention or claims theretog certaincpracticalflem bodiments of theinvention wherein: a

Fig. 1 is a sectional view of the electromagnetic reciprocating hammer; Fig. 2 is a circuit diagram of the amme'r shown i'nEFig. 1; and Fig. 3 is a view in side elevation electric hammer. Y v

Referring principally to the drawings, the electric hammercomprises the cylindricalfhou'sing I having a nose casting 2fitted to the bottom thereof and a'handle casting 3 fitted to thetopthereof. An electromagnetic core 4 is constructedonjthe tube '5 made of nonmagnetic material such as brass, bronze or other suitable alloy. The bore of the barrel 5 is cylindrical andits outer surface is octagonal to receive the eight sides of the electromagnetic core 4 which is brazed thereto to form an integral structure with annular winding recesses to receive the coils 6 and 1. A piston 8 of electromagnetic material is substantially the same diameter as the bore of the cylinder Sand reciprocatestherein and is arranged to strike; the tool shank 9 adjacentthe lower endyof the hammer and the resilient stop l0 withthe'upperen'd ofthe handle; a

-' The resilient stop l0 comprises an'elastomer member I I having a cylindrical portion 12 fitting within-the bore? l3 of the handle castings and a smallercylindrical portion l4 extending into the upper bore of the tubular barrel 5. The elastomer "member H has an opening there- -through to exhaust the air from the bore'of the barrel 5 ahead of the piston 8 which strikeslthe elastomermember l0. 'A pair of tierod bolts" l5 pass through theleaf spring l6 adjacent the ends thereof and are secured by means of'thenuts and spring washers as shown." The lower end of the tierods l5 are attached to the nose casting-Z showingthe to connect it with the handle casting 3 and hold them both in assembled relation on the cylindrical housing I of the hammer.

The elastomer member ll, having its small diameter portion l4 and its large diameter portion [2, is arranged to aid the spring 16 in stopping the upward travel of the free piston 8, striking and deforming the elastomer member ll,

both of which absorb energy from the blow and return it to the piston as it is energizedv by, the lower coil 1 on its downward stroke. tomer member H provides a novel mode for receiving the shock and retransmitting it to the free piston.

The handle casting 3 is provided with a hous- The elas-I ing which is enlarged, as shown at 2| in Figs. 1

inthehorizontal plane when the hammer is held in a vertical position, the rectifier discs are disposed parallel to the. axes of'the piston and any shocker vibration due to the axial movement of the free piston}; is not transmitted to the rectifier discs in the direction that would tend to flex them, but is parallel to-the discs. This aids in obtaining a long life-for the rectifier;

The housing 2| is provided with a series of openings through which air may; pass to cool the-discs of the rectifier.

As shown in Fig; 1, the three wire conductor 31 extends through thereinforcing member 32 to the interior of the handle, from whence the three wires33, 34 and 35'extend. The wire 33 will be noted to be fastened by a bolt to the interior of the lid 22 that is in turn secured to the housing ofthe hammer to ground the frame. I

1 The wires 34. and 35 are connected to'the ter- 'minal block 36jand. extend to the switch 3T'which isafdouble pole switch, thereby opening both sides of the circuit to the hammer. The wire 34,, which represents one side of the A. 0. line; extends through the switch3lv and is connected by..con-

(motor 38to the center. of the rectifie'ristack as indicated at 39. the switch 31; is connected by the conductor 40 topon'e end of .both .coil's 6 and], as shown in Fig. 2. The other end ofcoil 6 is connectedby the wire 4| to one end of the rectifier. stack, as indicated,atj42.' The. other end of. the coil 1 is connected bythefwire 43 to the other-lend ofthe rectifier stack,.as.indicated at 44.; Thus, the twopole. switch 31Ibr'e'aks both the lines/to; theoper- The wire 35 passing' through ating'mechanism of the hammer and the: ground wire 33-is maintained at all timesetdthe casing o f-the tool. 'Sucha simple circuit could not be obtained unless "the rectifier is formed'as .aunitary part of theelectrichammer as shown.

-, ;The impedance of "the hammer operating coils 6 and 7 is high due to the constantly varying reluctance uponthe reciprocation of the core:8. Ordinarily it would require. twelvev rectifier discs for 110 v. cycle current. However the high varying reluctance of the coils' reducesthe. discs to four per coil, thus permitting'such a small quantity to'be assembled asra unitformingan integral-part of the hammer-- I claim:

1. An electric hammer comprising a housing, a free piston of magnetic material reciprocable in said housing, spaced coils carried by said housing to.electromagnetically actuate the free piston and having their adjacent ends connected together, a unidirectionally assembled rectifier stack and switch means for opening the line current mounted on said housing, a tri-conductor current supply cable having one conductor for ground connected to said housing and the other two conductors to supply alternating current to said switch means, conductors from the two poles on the other side of said switch to the center of ,the rectifier stack and the common coil connection respectively; and conductors between the other ends of said coils and the ends of. the rectifier stack. respectively thereby eliminating external control and reducing the external connections to the primary power supply;

2. .An integral handle casting for an electromagnetic reciprocating hammer consisting of a transverse handgrip having spaced. therefromean annular reciprocating motor housing, an integral wall on one endof the handgrip extending to said housing and annularly shaped to form a chamber open on one end thereof, a disc rectifier having mounting means engageable with the wallof the chamber tosupport the rectifier in thelchamber with the discs lying parallelwith. theaxis of, the reciprocating motor housing, anda closuremember for said chamber.

3. An integral handle casting for an electromagnetic: reciprocating hammer consisting. of a transverse handgrip having spaced therefrom an annular reciprocating motor housing, an integral wallonone end of the handgrip extending to said housing and annularly shapedto form a chamber open on one end/thereof, a discrectifier have ing mounting means engageable with, the walls of the chamberto support the rectifierin the chamber with the discs lying parallel with the axis of, thereciprocating motor housing, a closure member for said chamber, and a flexible electric cable supported by. saidclosure member as supplying. electric current to said. hammer.

4.. .An. integral handle casting for. an. electromagnetic reciprocating hammer consisting of a transverse handgrip having spaced therefroma circular housing for receiving a reciprocating motorganintegralwall.on one end of thehandgrip extending: to said housing and annularly shaped to, form. a chamber open at one .end thereoiflja closure member for said chamber, a discrectifler having a mounting bolt engageable with s'aidcl'osure, member. of the chamber to support the rectifier in said chamber with its discs axially of the. cylindrica1 housing, and. parallel with the reciprocating. movement of the hammer.

CARL s. .WEYANDT;

REFERENCES CITED The following-references are of record in the file of this patentz UNIIEDTSTATES PATENTS Number Name Date-p 1,827,372 Riddel-l a :.'Oct.l3, 1931 1,899,741 1 Bauer; ;Eeb. 28, 1933 2,100,660 Greiner Nov; 30,193! 2,154,627 Knobel --Apr. 18, 1939 2,310,166 Way, Feb. 2, .1943 2,403,034 I Weyandt et al. July 2, 1946 2,497,141 Schultz Feb. 14.1950

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