US2037121A - Power-driven reciprocating hand tool - Google Patents

Description

UST/'Lim pril H4, i935. W H, DEAN POWER DRIVEN RECIPROCATING HANDv rFOOL Filed NOV. 20, 1954 2 Sheets-Sheet l Jn/vm WILLIAM HENRYDEAN,

pyi M, ma, w. H. DEAN 03am POWER DRT-VEN RECIPROCATING HAND TOOL Filed Nov. 2o, 1954 `2 sheets-sheet 2 FIGA( i n I JWM/wv WILLIAM HENRY DEAN,

Patented Apr. 14, 1936 iJiTED STATES PATENT OFFICE POWER-DRIVEN RECIPRQCATING- HAND TOOL William Henry Dean, Darlington, England Application November 20, 1934, serial, No.. 753,895 In Great Britain December 1,1933- Claims.

This invention relates to improvements in power-driven` reciprocating hand tools, and has for its primary object the provision of a power-driven i the tool whereby it can be guided through the work without risk of injury to the operator.

Other objects and certain advantages of the invention will become apparent from the follow.

ing description when taken in conjunction with the accompanying drawings, the invention consisting in the novel features of co-nstruction, combination and arrangement of parts hereinafter fully described and pointed out in the appended claims.

The drawings herewith illustrate, by way of example, two power-reciprocated hand tools in accordance with my invention. In the drawings,

Figure 1 is a perspective view of a two-handled saw reciprocated by llexible cables and mechanism driven by an electric motor;

Figure 2 is an elevation of the casing containing the reciprocating mechanism, partly in section;

Figure 3 is a central section at right angles to Figure 2; and

Figure 4 is a central longitudinal section of the two handles showing the connection of the ends of the saw blade to the flexible cables.

Figures 5 and 6 are an elevation and a plan respectively of an electric motor fitted with mechanism for reciprocating a single-handled saw;

Figure 'l is a central longitudinal section of the handle of the single-handled saw;

Figure 8 is a plan of said handle, partly in section;

Figure 9 is an elevation looking onv the lefthand end of the handle; and

Figure 10 is as section on the line Ill-l0 in- Figure 'l Similar reference letters are used in both constructions to indicate similar parts.

Referring to the said drawings, inthe example illustrated in Figs. 1 to fl, the ends of a short saw blade w are received in clamps comprising split bolts b tted with holdingnuts bi1 rigdlymounted onfthe outer endsof piston-like blocks c in ai. pairA of cylindrical handles d, said, blocks` being normallyY pressed towards the, forward ends ofv said'- handles by spiral springs e within the handles and adapted to be retracted against said springs 5 by flexible steelcables f attachedat q to thegjlnfner endsof' said blocks. The other ends; of the;4 operating cables are-oppositely attached by spherical-headedv nipples h to collars i on an eccentric pin`r lc projecting from the face of a flywheel 10l boss m screwed' onto the; end oftheshaft 11, oran; electric motor o and lockedthereongby. asetscrew m1. The rim m2 of the flywheel` is ofaluminium. shrunk onto the boss m. 'I'he'` cablesf are; en.

closed in flexible nonfreciprocatlng sheaths p the endsl ofv which abut, against, adjustable stops T1 at the rear ends of -thehandles dv and iixedstops` r2 at the ends of a casing q` enclosing the reciprocating mechanismV and' supported bybracketsv oi1 from the housing of the motor o. v

The motor-driven mechanism in thev casing qy rapidly reciprocates the saw blade-,a between thev handles elv whichv areA held by the operator and used to apply the blade to the work and guide it therethrough. 251

To minimize friction, ample lubrication of the; flexible drive is necessary,and.-I utilize the casing q of the reciprocating mechanism as. a reservoir for oil, said casing being normally closed; by a cover q1. The sheathed operating cables fare enclosed4 in flexibletubes?` attached at onei endi of the sockets r4 ofthe xed stops 1'2 which form oil-tight joints and are, provided withaperturesy r3 (Fig. 2)k through which the cablesf enter the interior of the casing. The other ends of the tubes 'r are attachedv to the stops r1 at the rear ends ofthe handles, d. Oil, supplied to th-e cas,- ing q is fed therefrom through the apertures r3 into the sheaths paround the cables f and percolates through said: sheaths into the tubes r 40 thusensuringthat the tubes 'r are continuously supplied withoil and that the cables f, run in oilf in their sheaths. p. Moreover the oil travels` through the flexible drive into the handles andv lubricates the blocks c therein. The. oil,.which is introduced into` the casing q. through an aperture q2 when the screw plug q3therein isiremoved, is preferably of medium and clinging,v body and of a heat-resisting nature. The aperture c4 in the bottom of the casing. qallows-.the oil to ,bedrained from the casing, when desired, byremoving the screw plug qw5. The sheaths p comprise closelywound steel spirals ther turns of which ope-n-M slightly when the cables andi sheaths. are bent. The passage offoil' through thegsheaths is thus 55.

facilitated Where the cables are bent, which coincides with the positions Where the friction is greatest. A further advantage of the surrounding flexible tubes 1 is that they prevent the sheaths p and cables f being bent too acutely. The flexible drive may be of any suitable length.

The ywheel m, m2 acts as an oil impeller and throws oil towards the ends of the casing q which ensures the entrance of the oil into the flexible drives f, p, 1*. The casing q is maintained fully charged with oil. u

With adequate lubrication, little or no vibration is imparted to the handles, and accurate cuts can be readily and rapidly made by means of the reciprocating blade.

The handles each comprise a base portion d closed at its rear end to form an abutment against which the spring e bears. The ends of the saw a; and the ends of the operating cables ,f are rigidly clamped to the blocks c in the two handles, the cables passing through the centres of the Vsprings e and out through the stops r1 which are screwed into threaded apertures provided in the rear ends of 4said handles. a

The Vbase portion of the right-hand handle has at its forward end a reduced portion d1 provided with an axial slot d2 to receive a projection s` on the block c within said handle. Over the reduced forward portion d1 is loosely slipped a sleeve t held in position by a ring u screwed onto the forward end of said reduced portion, said sleeve serving to cover the slot d2. 'I'he block c in the left-hand handle is not provided with a projection s and is free to rotate therein. This arrangement allows the operator to control the cutting angle of the saw by the right hand alone by turning the right-hand handle and so varying the cutting angle of the blade.

lThe base portion dof the left-hand handle is fitted with a lining d5 which is attached to said cylinder by a screw d4 engaging a slot d6 in said lining which allows the latter to be slidden into the cylinder to uncover the block c when required. 'I'he rear end of the slot d6 has a right-angled extension so that, by turning the lining slightly, it can be locked against rearward movement. Over said lining is slipped a tube d'7 which is externally threaded and is held between a ring da screwed on the forward end of the lining d5 and the forward end of the base portion d, said tube being fitted with an internally-threaded sleeve t1 terminating in a cone t2 which acts as a guard while permitting the line of cut to be watched through the apertures t3 provided in said cone. The sleeve t1 can be adjusted axially to tension the blade against the face of the work which is indicated at v. The tube d'7 and sleeve t1 are preferably provided with left-hand threads.

To insert the blade a in the handles, the ring d8 of the left-hand handle is unscrewed from the lining d5, and the sleeve t1 and tube d? can then be removed together. The lining d5 is slightly turned and pushed into the base portion d to expose the left-hand block c and allow one end of the blade to be engaged with the split clamp b thereof and the holding nut thereon tightened up. The lining d5 is then pulled out to its full extent and turned to lock it against inward movement, and the sleeve t1 and tube d'1 are replaced and secured by the ring d8.' To secure the other end of the blade to the block c in the righthand handle, the flywheel m, m2 on the motor shaft n is rotated to cause the flexible drive to move the clamp b of said block opposite to apertures t4 and d3 provided in the sleeve t and the portion d1 respectively, the sleeve t being revolved, if necessary, to bring the aperture t4 into register with the aperture d3. The holding nut b1 of the clamp can then be turned by a small box spanner inserted through said apertures to secure the right-hand end of the blade therein. The flywheel m, m2 may, if desired, be biassed so that it tends to come to a standstill in such a position that the clamp b is opposite to the apertures t4 and d3.

The front faces of the apertured cone t2 and the ring u lie in planes perpendicular to the direction in which the blade a reciprocates, and are accurately machined to allow them to be held flat against the surface of the work 'u on each side thereof as shown in Fig. 4 when the latter is of such a nature as to permit this. The forward faces of the apertured cone t2 and the ring u ensure that the blade a reciprocates in alignment with the axes of the handles d and that the plane of the cut is perpendicular to said faces. For beveling, the plane of the face of the right-hand handle may be 45 to the direction of reciprocation. Where the work consists of a thin board supported only at one point (as in a bench vise), the application of said faces to the work prevents the board vibrating during the sawing operation and assists in accurately guiding the saw blade.

A foot-operated press switch (not illustrated) is provided in a convenient position to control the supply of current to the moto-r While the hands of the operator are engaged in guiding the handles d between which'the blade a. reciprocates.

The positions of the blocks c on the ends of the voperating cables f in relation to the handles d may be adjusted, when necessary, by adjusting the stops r1 in the ends of the handles. The spherical-headed nipples h whereby the flexible cables f are attached to the collars j of the reciprocating mechanism allow the cables to rid themselves of any twist due to adjustment of the stops r1.

Instead of connecting each end of the saw blade a by a flexible cable f to the reciprocating mechanism and employing a pair of handles d as in the example illustrated in Figs. l to 4, I may, as illustrated in Figs. 5 to l0, employ a rigid blade al' projecting from a single handle d, the end of said blade within said handle being rigidly clamped at bl to a block cV coacting with a strong spring e and attached at g to one end of a flexible cable f whose other end is attached at h to a single collar :i on an eccentric pin lc projecting from the face of a flywheel m fixed on the end of the shaft n; of an electric motor o. handled saw, the operating cable f is enclosed in a flexible non-reciprocating sheath p abutting at one end against an adjustable stop r1 screwed into the rear end of the handle d and at the other end against a fixed stop r2 at one end of the casing q enclosing the reciprocating mechanism, said sheath being enclosed in a flexible tube r supplied with oil from the casing q in similar manner tothe flexible tubes enclosing the drive of the two-handled saw. Oil is supplied to the casing q through an aperture closed by a plug q3 fitted with a dipper rod qf'and a drainage plug q5 is also provided.

The tube r is protected near the casing q by a short length of flexible tubing w of heavier make than the tube r and is supported by a iiexible guard comprising a spring :c one end of which is rigidly heldin a socket x1 attached to the end of the casingq, said spring embracing the tube w As in the twoalmost to the outerend of the latter and then 'I'he stoppage of the block c does .not therefore -being disengagedfrom-said tube and bent at an angle at :1:2,fthe other end of the spring being attached by a bolt x3 to one of the feet o4 of the lmotor. I'he support given by the spring :c and outer tube i'Lo prevents the outer tube being too acutely bent and also prevents undesirable angular movement of the inner tube r and sheath p about the point where the former is attached to the casing q. A spring clip y is provided on the opposite end of the casing q to the socket w1 to receive the handle d when the tool is not in use, the flexible drive being loosely coiled around the motor.

The feet o4 of the motor are bolted to a frame comprising a pair of angularly-disposed tubular members o2 welded together at o3 to form a carrying handle whereby the motor and tool can be readily transported.

The single handle which is illustrated in Figs. 'l to 10 comprises a base portion d closed at its rear end and having at its forward end a cylindrical extension d1 formed with the axial slot d2 to receive the projection s on the block c which prevents relative rotation between the block and the handle. The end of the saw blade a1 and the end of the operating cable f are rigidly clamped to the block as in the two-handled arrangement. 'Ihe cylinder d1 is screwed into the forward end of the base portion d and terminates in a cone t2 provided with inspection apertures t3. The front edge of said cone lies in a plane perpendicular to the direction in which the blade reciprocates. Over the cylinder d1 is slipped a loose sleeve t in which is an aperture t4 which, by partially revolving the sleeve, can be moved into register with an aperture d3 in the cylinder d1 to permit the insertion of a small box`spanner whereby the holding nut b1 of the sp-lit clamp bv can be manipulated to release or secure the blade w1 to permit of its removal and replacement in case of breakage or when desired. Normally the sleeve t is clamped against rotation by screwing up the base portion d on the cylinder d1, but the sleeve can be readily released for rotation when desired by slightly slackening the joint.

'Ihe motor driving the reciprocating mechanism may be controlled by a switch or plug in any convenient position, and, to enable the saw blade to be stopped at will by the person holding the handle without affecting the running of the motor, I provide a set screw a in the rear end of the cone t2, said screw having a knurled head al for ready rotation. A locking ring z2 is mounted on a thread on the rear end of the cone, and can be adjusted to press against the screw e to hold it and prevent it working loose.

The screw e can be projected into the handle to coact with the inclined face c1 on the block c therein. When the screw is retracted, the block and saw reciprocate the full extent of the drive, but, on rotating the screw to project it into` the handle, it engages the face c1 and progressively curtails the forward stroke of the block until eventually the block is prevented from working from its most rearward position and is therefore held stationary. The connection of the end of the flexible cable ,f to the collar j on the eccentric pin lc of the reciprocating mechanism is by means of a spherical-headed nipple h as described in connection with the double-handled tool of Figs. 1 to 4, and allows the nipple at the end of the cable to revolve freely in its socket in said collar when the driving tension is released so that twists imparted to the cable are removed.

interfere with the running of the motor, and the screw z can be used to hold the block during removal and replacement of the blade a1.

While I have herein described reciprocating mechanism driven by an electric mo-tor, it will be understood that, if desired, a suitable internalcombustion engine or compressed air engine may be substituted for the electric motor, and while I have illustrated and described hand tools tted with saw blades, it will be understood that a le or other cutting tool may be substituted for the saw blade.

Changes of a minor character may be made in the construction and arrangement of the various parts of my improved hand tools without departing from the essential features and purposes of rmy invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I declare that what I claim and desire to secure by Letters Patent isz- 1. A power-driven reciprocating hand tool comprising, in combination, a power-driven flywheel, a pin eccentrically mounted on said ilywheel, an oiltight casing enclosing said flywheel land eccentric pin, a flexible cable connected to said eccentric pin to transmit the pull thereof in one direction, a sheath around said cable coacting therewith, means for attaching said sheath to said casing which allow oil therein under pressure due to the centrifugal action of s-aid flywheel to pass continuously from said casing into said sheath, a piston-like block attached at its rear end to the end of said cable remote from said eccentric pin, a cylindrical handle enclosing said block concentric with said cable, means for preventing rotation of said block in said handle whilst allowing it to slide therein, means for clamping a cutting tool to the forward end of said block, a spring interposed between the rear end of said handle and said block, and means for attaching the adjacent end of the sheath to the rear end of said handle which means allow the oil in said sheath to pass therefrom into said handle.

2. The combination with a power-driven reciprocating hand tool as claimed in claim 1, of an apertured conical guard support attached to the forward end of the cylindrical handle, said guard support having a frontal surface to engage the work when manipulating the tool.

3. The combination with a power-driven reciprocating hand tool as claimed in claim 1, of adjustable means for holding the piston-like block stationary in the cylindrical handle.

4. The combination with a power-driven reciprocating hand tool as claimed in claim 1, of an apertured conical guard support attached to the forward end of the cylindrical handle, said guard support having a frontal surface to engage the work when manipulating the tool, a set screw in said guard support, and an inclined face on the piston-11k@ mock in the handle with which said set screw coacts to hold said block stationary.

5. A power-driven reciprocating hand tool comprising, in combination, a power-driven flywheel, a pin eccentrically mounted on said flywheel, an oiltight casing enclosing said flywheel and eccentric pin, a pair of flexible cables oppositely connected to said eccentric pin, sheaths around said cables coacting therewith to trans'- mit the reciprocatory motion of said eccentric pin, means for attaching said sheaths to said casing which allow oil therein under pressure due vto the centrifugal action of said iiywheel to pass Continuously from said casing into said sheaths, a piston-like block attached at its rear end to the end of each of said cables remote from said eccentric pin, a cylindrical handle enclosing each block concentric with its cable, means for preventing rotation of the block in one of said handles whilst allowing it to side therein, means for clamping the ends of a cutting tool tol the forward ends of said blocks, springs interposed between the rear ends of said handles andthe blocks therewithin, and means for attaching the adjacent ends o-f the sheaths to the rear ends of said handles which means allow the oil in said sheaths to pass therefrom into said handles.

WILLIAM HENRY DEAN.

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