US3699655A - Power driven hand tool - Google Patents

Power driven hand tool Download PDF

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Publication number
US3699655A
US3699655A US107355A US3699655DA US3699655A US 3699655 A US3699655 A US 3699655A US 107355 A US107355 A US 107355A US 3699655D A US3699655D A US 3699655DA US 3699655 A US3699655 A US 3699655A
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United States
Prior art keywords
housing
cutter blade
cutter
blades
support bar
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US107355A
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English (en)
Inventor
Robert W Taylor
Jerry W Sellers
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Porter Cable Corp
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Rockwell Manufacturing Co
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Assigned to PORTER-CABLE CORPORATION reassignment PORTER-CABLE CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: ROCKWELL INTERNATIONAL CORPORATIN
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    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G3/00—Cutting implements specially adapted for horticultural purposes; Delimbing standing trees
    • A01G3/04—Apparatus for trimming hedges, e.g. hedge shears
    • A01G3/047—Apparatus for trimming hedges, e.g. hedge shears portable
    • A01G3/053—Apparatus for trimming hedges, e.g. hedge shears portable motor-driven

Definitions

  • Another feature disclosed herein pertains to a pair of axially spaced bearing plates for journalling a motor armature shaft and gear-mounting shafts.
  • the bearing plates are trapped in position between the halves of the split clam shell housing and are constructed in such a manner that forces tending to turn or twist the bearing plates will be about an axis aligning with the rotational axis of the armature shaft.
  • SHEET 1 [IF 7 FIE] INVENTORS ROBERT W. TAYLOR JERRY W. SELLERS PATENTEDnm 24 1912 SHEET 2 BF 7 w wt INVENTORS ROBERT W. TAYLOR JERRY W. SELLERS An lin I PATENTEDUBI 24 1972 SHEET 3 OF 7 INVENTORS ROBERT W. TAYLOR JERRY W. SE LLERS ATTORNEYS PATENTEDMT 24 1972 3 599 55 has ' INVENTORS ROBERT w TAYLOR JERRY W. SELLERS ATTORNEY S PATENTEDIJBT 24 I972 SHEEI 6 0F 7.
  • the hedge trimmer of this invention provides a cutter blade support bar which is mounted by being trapped in position between mating a first shaft, and the intermediate gearing is mounted on a second shaft, with these first and second shafts being parallel to the motor armature shaft.
  • the first and second shafts and the inboard end of the armature shaft are journalled only by means of axially spaced apart intermediate and bottom bearing plates.
  • the intermediate bearing plate journals the inboard armature shaft end and corresponding ends of the above-menhalves of a split clam shell type housing.
  • the cutter blade support bar which supports two mutually reciprocable cutter blades in the preferred embodiment of this invention, is fixed in place solelyby separable seating engagement with opposing surfaces in the split clam shell housing.
  • Another important object of this invention is to provide a novel, compact, simplified drive train and bearing assembly for transmitting reciprocating motion to one or more cutter blades in a hedge trimmer.
  • the foregoing object is attained by providing for dual crank assembly having a motor driven gear and a pair of connecting rods having crank ends which interfitting snap over raised eccentrics on opposite side faces of the motor driven gear.
  • the opposite ends of the connecting rods are pin-connected respectively to two overlapping cutter blades in such a manner that-the cutter blades are reciprocated in opposite directions.
  • the motor driven crank assembly gear lies axially between the crank ends of the connecting rods, and the connecting rods extend in parallel planes that are parallel with the cutter blades.
  • the pin-connected ends of the cutter blades lie between the adjacent ends of the connecting rods, and the above-mentioned support bar,
  • the hedge trimmer has an electric motor in the hedge trimmer housing, and the armature shaft of the motor is drive connected to the above-mentioned motor driven a crank assembly gear by a gear on the inboard end of the tioned first and second shafts, while the bottom bearing plate journals the opposite ends of the first and second gear shafts.
  • the bottom bearing plate is seated on the bottom wall of the hedge trimmer housing to thus underlie the crank assembly mentioned above, while the intermediate bearing plate is disposed between the motor'and the housed end of the cutter blade support bar.
  • Another major object of this invention is to provide a novel electric motor driven power tool wherein the armature shaft and gear-mounting shafts are joumalled by bearing plates of the type mentioned above and wherein the bearing plates are arranged, constructed and supported in such a manner that forces tending to tumor twist at least that bearing plate which journals the armature shaft are not applied about an axis that is eccentric to the armature shaft to cause objectionable rocking or swinging motion of the armature shaft.
  • the two bearing plates in this invention are effectively self-centering about the armature shaft axis.
  • each bearing plate of this invention has a pair of angularly spaced apart ears or wings extending radially from a central. portion, and a gear reduction shaft bores are formed in these ears in such a manner that-lines extending radially of these bores and medially intersecting their'associated ears intersect at a point on the armature shaft axis. Furthermore; the fit of the bearing plate ears with the entrapping halves of the split clam shell housing is relatively loose as compared with the relative tight fit that is provided for between the central portion of each bearing plate and the entrapping halves of the split clam shell housing.
  • each bearing plate is slightly floating about an axis that is coincident with the armature shaft
  • each bearing plate will not be twisted or turned about an axis eccentric to thearmature shaft axis when the bearing plates are trapped in position by securing the mating halves of the bottom blade in the dual cutter bladeassembly.
  • the top and bottom cutter blades of the dual cutter blade assembly are the mirror image of each other. Furthermore, each cutter blade has two rows of laterally oppositely extending shearing teeth, and the teeth in the two rows are uniformly staggered relative to each other by an offsetting distance thatis equal to the throw imparted to each cutter blade by the crank assembly.
  • the throw for each cutter blade is made equal to one-half of the pitch between adjacent cutter blade teeth.
  • the teeth on the top cutter blade will align with the teeth on the bottom cutter blade when the cutter blades are at opposite limits of their linear strokes. As a consequence, the maximum available width between the coacting teeth on the top and bottom cutter blades is provided for to achieve optimum cutting action.
  • the above-described interchangeable. mirror image pair of top and bottom cutter blades are manufactured in a novel manner by first blanking out the staggered, uniformly pitched teeth throughout an appropriate length of a strip of stock.
  • the blanked stock is significantly longer than the longest blade that is excepted to be made. For example, it may be feet long.
  • the blanking dies are normally not this long.
  • the stock is blanked in end-to-end segments or sections, the lengths of which correspond to the size of the die.
  • the die may be of such a size as to blank out 5 inch lengths.
  • the thusly blanked elongated strip of stock then may be stored until such time that a supply of cutter blades of one length or another may be needed.
  • Typical cutter blade lengths are inches, inches and inches and are preferably integered multiples of the blanking die length.
  • the partially stamped stock is subjected to a second operation wherein the crankconnecting shank of the blade is formed by removing a number of the previously formed teeth at a region corresponding to the desired length of the blade.
  • FIG. 1 is a perspective view of a double-edged hedge trimmer constructed according to the principles of this invention.
  • FIG. 2 is a fragmentary side elevation showing the trimmer of FIG. 1 with one of the halves ofthe longitudinally split clam shell housing removed to illustrate the internal parts of the trimmer;
  • FIG. 3 is a section taken substantially along lines 3- v 3 of FIG. 2; I
  • FIG. 4 is a section taken substantially along lines 4 4 of FIG 2;
  • FIG. 5 is a section taken substantially along lines 5 5 of FIG. 2; r I
  • FIG. 6 is a section taken substantially along lines 6- 6 of FIG. 2;
  • FIG. 7 is a section taken substantially along lines 7 7 of FIG. 2;
  • FIG. 8 is an interior side elevation of the left-hand half of the split clam shell housing shown in FIG. 1;
  • FIG. 9 is an interior side elevation of the right-hand half of the split clam shell housing shown in FIG. 1;
  • FIG. 10 is a plan view of the intermediate bearing plate shown in FIG. 2;
  • FIG. 11 is a fragmentary top plan view of the dual double edged cutter blade assembly shown in FIG. 1, with the top blade being in the forward limit of its cutting stroke and the bottom blade being in the rearward limit of its cutting stroke;
  • FIG. 12 is a fragmentary top plan view similar to FIG. 11, but showing the top cutter blade in the rearward limit of its cutting stroke and the bottom blade in its forward limit of its cutting stroke;
  • FIG. 13 is a fragmentary bottom plan view of the bottom cutter blade shown in FIGS. 1, 1 1, and 12;
  • FIG. 14 is a partially schematic, sectioned fragmentary, top plan view showing a first step for forming the cutter blades shown in FIG. 1;
  • FIG. 15 is a sectioned, partially schematic, fragmentary, top plan showing subsequent operations which follows the forming step illustrated in FIG. 14;
  • FIG. 16 is a section taken substantially along lines 16--16 of FIG. 2;
  • FIG. 17 is an enlarged fragmentary section of the drive gear and crank eccentrics shown in FIG. 2.
  • the portable, hand manipulatable, power driven hedge trimmer incorporating the principles of the invention is shown to comprise a hollow, longitudinally split, clam shell type housing or casing 20.
  • Housing 20 contains the cutter drive mechanism which include an electric motor 22 (FIG. 2) for transmitting motion to reciprocate a pair of double edged cutter blades 26 and 28.
  • Motor 22 may be of conventional construction and, as best shown in FIG. 2, comprises a stator 30 having field windings peripherally surrounding an armature 32. Armature 32 is mounted on an armature shaft 34 which extends coaxially through stator 30 and which is drive connected by a gear reduction drive train to cutter blades 26 and 28 in a detail later on. t
  • housing 20 has a hollow body portion 38 and a rearwardly extending griptype handle 40.
  • Body portion 38 receives motor 22 and the above-mentioned drive train.
  • Handle 40 houses an electrical on-off switch 42 having a manually manipulatable switch actuator or trigger 44 for controlling operation of motor 22. Power is supplied to operate motor '22 through ,a conventional power cord 46 having conductors for supplying current to stator 30 under the control of switch 42.
  • a commutator 50 forming a part of motor 22, is carried by shaft 34 and is electrically connected to armature 32 in the usual manner.
  • Brush elements 52 which are spring biased intoelectrical contact with the commutator periphery, are mounted in electrical non-conductive brush holders'54. Armature 32 and commutator 50 are preferably electrically insulated from-shaft 34 by any suitable means.
  • housing 20 is longitu- I dinally divided into two complementary shells 60 and 62 to provide a clam shell type enclosure for the internal parts of the hedge trimmer.
  • Shells '60 and 62 are separately molded from a suitable, electrically nonconductive plastic and have oppositely dished curvatures to define the interior, mechanism-receiving cavities as hereinafter described.
  • Shells 60 and 62 are respectively formed with mating longitudinal edge surfaces 64' and 66 which seat against each other along a planar interface that longitudinally and medially intersects body portion 38, handle and the cutter assembly.
  • the rotationalaxis of shaft 34 lies substantially in a plane containing this interface.
  • Machine screws 68 (see FIG. 2)extending through bores in shell 62 are threaded into tapped bores in shell to firmly and rigidly secure shells 60 and 62 together.
  • shells 60 and 62 are respectively formed with ribbed, complementary cavities 70 and 72 which mate to form a motor compartment that interfittingly receives and confines stator 30. End ribs 74 and 76 respectively forrned in tegrally with shells 60 and 62 confine stator 30 against axial movement.
  • Shell 60 is also formed with cavities 78 (FIG. 8) which interfittingly receive brush holders.
  • Resilient pads 80 ,(FIG. 9) made of rubber or other suitable material are mounted in shell 62 and engage brush holders 54 to confine them in cavities 78.
  • bearing 82 which preferably comprises a spherically contoured knuckle, is interfittingly seated for limited universal rocking movement in opposed complimentary cavities 84 (FIG. 8) and 86 (FIG.
  • Cavities 84 and 86 are respectively formed in shells 60 and 62, and bearing 82 trapped and thus confined in position between shells 60 and 62 solely by separable seating engagement with the wall surfaces of cavities 84 and 86.
  • plate 90 is formed with a central hub portion 92 and a pair of angularly spaced apart flat-sided ear portions 94 and 96 which extend radially from hub portion 92.
  • Portion 92 as shown inFIG. 2, is centrally formed with a raised boss 98, and sleeve bearing 88 is coaxially pressed into the upper end of a cylindrically smooth walledbore 100 which is formed coaxially through boss 98 and the bearing plate.
  • armature shaft 34 extends coaxially through and beyond bore 100, and the inboard end of shaft 34 projecting beyond bearing plate 90 is formed with a spiral gear 104.
  • Gear 104 meshes with a large diametered gear 106 which is journalled coaxially fixed on a shaft 108.
  • One end of shaft 108 is journalled in a bore 110 that is formed through ear portion 96.
  • the other end of shaft 108 iS. journalled in a bore 112.
  • Bore 112 is formed through an ear portion 114 (see FIG. 7) of a bottom bearing plate'l16.
  • gear 120 Coaxially fixed on shaft 108 in a second gear 118 (see FIG. 5) which constantly meshes with a crank arm drive gear 120.
  • the diameter of gear 120 is considerably greater than that of gears 106 and 118, and
  • gear 106 is greater than that of gear 1 18.
  • gear 120 is fixed on a shaft 122.
  • One end of shaft 122 is journalled in a bore 124 that is formed through ear portion 94 of bearing plate 90.
  • the other end of shaft 122 is journalled in bore 126.
  • Bore 126 is formed through a second ear portion 128 (see FIG. 7) of bearing plate 1 l6.
  • the axes of bores 124 and 126 are axially aligned and parallel with the axis of bore 100 and the rotational axis of armature shaft 34.
  • the axes of bores 110 and 112 are axially aligned and parallel with the axis of bore 100 and the rotational axis of shaft 34.
  • the rotational axis of shafts 34, 108, and 122 are in parallel spaced apart relation with respect to each other.
  • gear 120 is integrally formed with a raised, circular'eccentric 130.
  • Eccentric I 130 is in the form of a solid, uniformly diametered cylindrical boss which projects upwardly from the fiat upwardly facing side face of gear 120.
  • Eccentric 130 serves as a crank pin for a flat-sided connecting rod assembly 142 (FIG. for translating the rotary motion of gear 120 to linearly reciprocate cutter blade 26.
  • gear 120 is integrally formed with a second raised, circular crank eccentric 144.
  • Eccentric 144 is' in the form of a solid cylindrical boss which projects from the flat downwardly facing side of gear 120.
  • Eccentric 144 serves as a crank pin for a second flat-sided connecting rod 146.
  • connecting rod 146 is the mirror image of rod 132 and has an annular crank end portion 148 and an elongated arm portion 150. End portion 148 lnterfittingly snaps over eccentric 144. A connecting pin 152, which is rigidly fixed to the end of arm portion 150 remote from end portion 148, is interfittingly snapped into an aperture 139a formed through a flatsided end shank portion 154 of cutter blade 28.
  • eccentric 144, connecting rod 146 and pin 152 form a second crank assembly 156 for translating the rotary motion of gear 120 to linearly reciprocate cutter blade 28.
  • cavity 160 is defined by two spaced part, substantially parallel, inwardly extending wall portions 164 and 166 and a longitudinal end wall portion 168 that integrally joins wall portions 164 and 166 together.
  • Cavity 162 is formed with similar wall portions, and like reference numerals suffixed by the letter a have been applied to designate the corresponsing wall portions of cavity 162.
  • bearing plate 90 is axially confined with a relatively tight fit between wall portions 164 and 1640 on one side and wall portions 166 and 1660 on the other side.
  • Wall portions 164 and 164a are essentially contained in a common plane that substantially perpendicularly inportions 166 and 166a are essentially contained in a common plane that also substantially perpendicularly intersects the rotational axis of shaft 34. Plate is confine against movement transversely of shaft 34 by seating engagement with wall portions 168 and 168a.
  • any tendency of bearing plate-90 to twist or rotate during or after assembly will be about the centrally located axis of bore 100 which aligns with the rotational axis of shaft.
  • Such twisting or turning of plate 90 may occur as a result of torque applied by shaft 34 and/or accumulative tolerances of housing 20 and the parts contained therein.
  • any twisting, turning or rotation that may be imparted to plate 90 will be about an axis substantially aligning with shaft 34 and will therefore not rock or swing shaft 34 out of alignment. It will be appreciated that if plate 90 twisted or turned about an axis eccentric to the rotational axis of shaft 34, it would objectionably cause rocking or swinging motion of shaft 34.
  • Plate 90 is effectively self-centering about-the axis of shaft 34. More specifically, a line radially intersecting the axis of bore and medially intersecting ear portion 96 and a line radially intersecting the axis of bore 124 and medially intersecting ear portion 94 intersect at a point on the rotational axis of shaft 34, and since ear portions 94 and 96 are slightly floating as described above, plate 90 will not be twisted or turned about an axis eccentric to the rotational axis of shaft 34 when plate 90 is trapped in position by securing shells 60 and 62 together.
  • a fan compartment is formed in housing 20 axially between the previously described motor compartment and the bearing plate enclosure defined by cavities and 162.
  • the fan compartment is defined by opposed, complementary cavities (FIG. 8) and 172 (FIG. 9) that are respectively formed in shells 60 and 62.
  • a fan 174 is freely received in the compartment defined by cavities 170 and 172 and is fixed on shaft 34 adjacent to the inboard end thereof. By rotating fan 174 with shaft 34, air is drawn through openings 176 in housing 20, is directed through motor 22 to cool the motor parts, and is exhausted through openings 178 which are also formed in housing 20.
  • the boss portion 98 of bearing plate 90 extends upwardly beyond wall portions 164 and 164a and has a flat end face that may provide a thrust bearing seating surface for the assembly of shaft 34 and fan 174.
  • cavitiesv 160 and 162 shells .60 and 62 are respectively formed with two enlarged, opposed, essentially complementary cavities 180 (FIG. ,8) and 182 (FIG. 9) which cooperate to define a single compartment for receiving gears 106, 118, and 120, bearing plate 116, shanks 140 and 154 of cutter blade 26 and 28 respectively, the inner end of a stationary, flat-sided cutter blade support bar 184, and crank assemblies 142 and 156.
  • the compartment defined by cavities 180 and 182 may be filled with grease or the like.
  • Bearing plate 116 is transversely (i.e. transversely of shafts 108 and 122) trapped. and confined against movement between the upstanding wall portions that delimit seat 194.
  • Bearing plate 116 is fiat-sided and is seated on the flat, ribbed, interior bottom surfaces of walls 186 and 188.
  • Connecting rod 146 overlies and seats on bearing plate 116.
  • Gear 120 isdisposed axially between the crank ends of rods 146 and 132.
  • the cutter blade shanks 140 and 154 which slidable seat against each other extend between the pin-connected ends of connecting rods 132 and 146 and are spaced from gear 120.
  • connecting rod 146 underlies gear 120 and shank 154, and connecting rod 132 overlies gear 120 and shank 140.
  • Bearing plate 116 is thus confined against axial displacement between bottom walls 186 and 188 on one side and connecting rod 146 on the other side.
  • Connecting rod 146 is confined against axial displacement (relative to shaft 122) between gear 120 andbearing plate 116.
  • Connecting rod 132 is confined against axial movement (relative to shaft 122) between gear.l20 and the inner end portion of support bar 184.
  • This support bar end portion is indicated at 200 In FIG. 2 and is upwardly offset from the remainder of the bar so as to be vertically spaced by a relatively small distance above shank 140 and gear 120.
  • Connecting rod 132 is disposed in this space. End portion 200 thus overlies shank 140, connecting rod 132 and gear 120.
  • connecting rods 132 and 146 extend along parallel planes that normally intersect the rotational axis of shaft 122.
  • ear portion 96 is disposed at an obtuse angle relative to ear portion 94, and radial lines extending from the axes of bores 1 10 and 124 intersect each other at anobtuse angle.
  • Bearing plate 116 is similarly constructed in that an equal obtuse angle is provided between ears 114 and 128 and between intersecting lines extending radially of bores 112 and 126.
  • Gear 106 partially overlies end portion 200 as best shown in FIG. 4.
  • gear is coaxially formed with a through bore 204 for coaxially receiving shaft 122.
  • Bore 204 is disposed eccentrically of but parallel to the axes of eccentrics and 144.
  • Shaft extends upwardly through bore 204 and freely through an enlarged aperture 206 in end portion 200.
  • the free end of gear 104 is freely received in an enlarged aperture 208 which is also formed through end portion 200.
  • Bearing plate 116 is also effectively self-centering about the rotational axis of shaft 34 so that it does objectionably apply forces to plate 90 to act about an axis eccentric to the armature shaft axis to cause the armature shaft'to be deflected from-a properlyoriented position. More specifically, the fit between central portion 198 and the opposing upstanding wall portions of cavities and 192 is relatively tight, whereas the fit between each of the ear portions 114 and 128 and the opposing upstanding wall portions of cavities 190 and 192 is somewhat Iooser..As a result, ear portions 114 and 128 are slightly floating similar to the ear portions of plate 90.
  • the annular crank end portion 134 of rod 132 is seated on the flat face of a slightly raised uniformly diametered land 209 which is formed on the upwardly facing side of gear 120 in peripherally surrounding relation to eccentric 130.
  • Land 209 is raised slightly above the side face of gear 120 by about fourto six-thousands of an inch.
  • the remainder of connecting rod 132 will be spaced slightly from gear 120, thus reducing the area of contact between gear 120 and rod 132 and thereby reducing the amount of friction that is produced by contact of rod 132 with gear 120.
  • An annular land similar to land 209 and indicated at 209a in FIG. 17 is formed peripherally around eccentric 144 in the same manner as just described for land 209. Connecting rod end portion 148 seats on land 209a so that the remainder of rod 146 is spaced from gear 120 to reduce the contact area between rod 146 and gear 120.
  • shells 60 and 62 are formed with complementary notches 214 (FIG. 8) and 216 (FIG. 9) which define a slot 220 (FIG. 16') through which the assembly of cutter blades 26 and 28 and support bar 184 extend.
  • End portion 200 of support bar 184 is securely trapped between shells 60 and 62 when the shells are secured together. In a transverse direction, end portion 200 is confined between upstanding wall portions 210 and 212 (see FIGS. 8, 9 and 16) of cavities 180 and 182.
  • the assembly of support bar 184 and cutter blades 26 and 28, in the region where it extends through slot 220, is vertically confined between overlying and un derlying wall surfaces indicated at 222 in FIG. 16. Wall surfaces 222 delimit an inward extension of slot 220 which provides an entrance to cavities 180 and 182.
  • End portion 200 of support bar 184 extends through the compartment defined by cavities 180 and 182 and terminates at its rearward end in an upturned tab 224.
  • Tab 224 is received and trapped in complementary cavities 226 (FIG. 8) and 228 (FIG. 9) which are respectively formed in shells 60 and 62 at the juncture between handle 40 and body portion 38'. Abutment of tab 224 with opposing wall surfaces of cavities 226 and 228 provide an anchor to confine support bar 184 against longitudinal movement. It will be appreciated that the assembly of support bar 184 and cutter blades 26 and 28 are trapped in position between shells 60 and 62 only by separable seating engagement with interior cavity-defining surfaces of shells 60 and 62.
  • each assembly 230 comprises a bolt 232, a nut 234 and a washer 236.
  • Bolt 232 extends through an interfitting aperture in support bar 184 and slidably through longitudinally elongated, overlapping apertures 238 in cutter blades 26 and 28.
  • Washer 236 is confined between nut 234 and the underside of cutter blade 28 so that the assembly of cutter blades 26 and 28 and support bar 184 are confined between the head of bolt 232 and washer 236.
  • the elongation of apertures 238 enables each of the cutter blades to linearly reciprocate relative to bar 184 while being guided and confined to longitudinal motion by engagement of the side edges of apertures 238 with the peripheries of bolts
  • cutter blade 26 comprises an elongated, flat-sided, straight plate or bar which is formed along both side edges with separate, oppositely laterally extending sets of substantially flatside, parallel, equidistantly spaced apart shearing teeth 240 and 242.
  • each of the teeth in sets 240 and 242 are equidistantly staggered with respect to each other. More specifically, each tooth in set 240 is so staggered with respect to the teeth in set 242 that a line medially intersecting each tooth in set Y 240and perpendicularly intersecting the longitudinal
  • the number'of teeth in row 240 is equal to the number of teeth in row 242.
  • the cutter bar section which is indicated at 250 and which extends between teeth sets 240 and 242, has a uniform width which is substantially equal to the uniform width of support bar 184.
  • Support bar 184 is flat-sided and straight except for the previously described offset at end portion 200.
  • Cutter blade 28 (see FIGS. 11-13) is the mirror image of cutter blade 26. Accordingly, like reference numerals suffixed by the letter a have been applied to designated the corresponding portions of cutter blade 28. With this construction it will be appreciated that cutter blades 26 and 28 are interchangeable simply by turning one of the cutters over through an angle of In other words, either of the cutter blades 26 and 28 may be used as either the top or bottom cutter blade in the hedge trimmer assembly. This eliminates the necessity of manufacturing and stocking separate top and bottom cutter blades.
  • crank assemblies 142 and 156 are equal to each other and equal to or at least closely approaching one-half the pitch between adjacent teeth in each of the teeth sets on cutter blades 26 and 28. Since blades 26 and 28 are concomitantly reciprocated in opposite directions then the total throw of one cutter blade relative to the other will be substantially equal to the pitch between adjacent teeth.
  • the pitch between teeth in sets 240, 242, 240a, and 242a is uniform.
  • cutter blade 26 when cutter blade 26 is at the forward limit of its stroke, cutter'blade 28 is at the rearward limit of its stroke and the teeth in sets 240 and 242 will align with corresponding teeth in sets 240a and 242a respectively, thereby providing the full unobstructed blade opening width between adjacent teeth for receiving theshrubbery or other matter being trimmed.
  • cutter blade 26 is moved rearwardly and cutter blade 28 is moved forward to the positions shown in FIG. 12 where cutter blade 26 is at the rearward limit of its cutting stroke and where cutter blade 28 is at the forward limit of its cutting stroke.
  • each tooth will relatively be moved through a distance substantially equal to the pitch between adjacent teeth so that in the positions of cutter blades 26 and 28 shown in FIGS. 11 and 12, the teeth in sets 240 and 242 will align with corresponding teeth in sets 240a and 242a respectively. For example, in FIG.
  • tooth indicated at 252 in set 240 will align with the tooth 254 in set 240a, and when cutter blades 26 and 28 are reciprocation to their positions shown in FIG. 12, tooth 252 will align with the preceding tooth in set 240a as indicated at 256.
  • the full unobstructed blade opening width between adjacent teeth is again provided for receiving the shrubbery or other matter being cut.
  • the cutter blade teeth on opposite sides of each blade are required to be staggered in the manner previously described to accommodate the offset that occurs between the top and bottom cutter blades by virtue of the oppositely directed throws of the crank assemblies.
  • the full width between teeth will be unobstructed at opposite limits of blade reciprocation even when blade 28 is used as the top blade and blade .26 is used as the bottom blade.
  • the dual cutter blade construction of this invention lends itself to anovel method of manufacturing the blades.
  • a suitable strip of stock is provided for in the form of an elongated flat-sided bar or plate.
  • Annealed steel may be used to make the strip of stock.
  • the strip of stock in unblanked form may be of any desired length from which a multiplicity of cutter blades can be fabricated.
  • the strip of stock may be feet long.
  • teeth in one row will be staggered relatively to the teeth in the other row in the manner previously described. That is, a line medially intersecting each of the teeth in one row and normally intersecting the longitudinal axis of the stock will extend medially between adjacent teeth in the other row.
  • These two rows of relatively staggered teeth are formed through the entire usable length of the stock that is intended to be used in fabricating the cutter blades. Preferably, to avoid waste the two rows of teeth are formed throughout the entire length of the stock.
  • Formation of the cutter blade teeth may be effected by stamping them out of the strip of stock in a blanking die of suitable form.
  • the length of the blanking die and the desired lengths of differently sized cutter blades are so selected that the desired lengths of the blades are integered multiples of the length of the die.
  • it may be desired to fabricate different length of cutter blades such as 15 inches, inches and inches inch lengths.
  • a suitable die length would therefore be 5 inches.
  • the unblanked strip of stock is fed into the blanking die which is indicated at 300 in FIG. 14.
  • die 300 a section or segment of the unblanked strip of stock corresponding to the length of the die is blanked to form the cutter blade teeth on opposite sides of the strip as shown.
  • the strip of stock is advanced in the die by a distance equal to the dies length, and the next section is stamped or blanked. This operation is continued, thus blanking out end-to-end sections of the strip of stock until the full usable length of the strip of stock has beenstamped with teeth on both side edges.
  • the pitch of the teeth in both rows will be uniformly equal throughout the entire blanked out length of the strip of stock.
  • the strip of stock is indicated at 302 and is partially blanked out as shown.
  • the blank portion of strip 302 is indicated at 304, and the unblanked portion is indicated at 306.
  • apertures 238 are also blanked out.
  • the number of these apertures to be blanked out in each blanked section of strip 302 is determined by the length of the blanked section.
  • strip 302 is blanked out in 5 inch linear sections, and for this length there will be one aperture (238) per blanked section as shown.
  • the spacing between apertures 238 in the blanked out strip of stock will be uniform.
  • each blanked-out 5 inch section will have four cutter blade teeth on each side and one aperture 238.
  • the blanked strip of stock may be stored or stocked if a supply of cutter blades is not needed at the time.
  • the blanked strip of stock is removed from storage and subjected to a combination cutting and punching operation to form the cutter blade shank (140, 154) and the crank pin-receiving aperture (139, 139a) and also to cut the cutter blade off from the remainder of the strip of stock at its desired length.
  • the cutoff line is located as determined by the selected cutter blade length. This may be done by counting off the necessary number of blanked sections from one end of the blanked strip of stock to locate the last section that will complete the desired length of the cutter blade. For example, assume that it is desired to make a' 20 inch cutter blade from the blanked strip of stock in which the blanked end-to-end sections are each 5 inches long. To locate the last or shank end section and the cutoff line, the fourth blanked section is located from one end of the blanked strip of stock. This located section of the blanked strip of stock is placed in a cutoff die as shown in FIG. 15 wherein the cutoff die is indicated at 310. I
  • the desired length of the cutter blade is cut off from the remainder of the blanked stock as indicated at 312, and a predetermined number of cutter blade teeth are cut off as indicated at 316 to form the toothless shank of the cutter blade.
  • the cutter blade shank is formed by cutting off the last two cutter blade teeth on each side of the blade.
  • the cutoff line indicated at 312 preferably extends between one of the cutter blade teeth on one side and one of the two nearest cutter blade teeth on the other side. As shown, the cutoff line at 312 extends between tooth 315 on oneside and the next tooth 316 which is staggered form tooth 315 on the other side of the blanked strip of stock. Tooth 316 is one of the four teeth that are removed to form the cutter blade shank. By cutting off the selected length of the cutter blade in this manner, tooth 315 will therefore be usable in making up the next cutter blade that is to be cut from the blanked strip of stock.
  • crank pin-receiving aperture (139, 139a) may be punched out as indicated at 318 in FIG. 15.
  • the length of the cutter blade is not limited to an integered multiple of the length of each blanked section or segment of the blanked strip of stock. Instead, the blanked stock may be cut to provide a cutter blade of any selected length.
  • the thusly cut off cutter blade will consequently have its two rows of staggered teeth, the crank pinreceiving aperture (139, 139a) and the reciprocating guide aperture 238.
  • This blade may be used as either the top cutter blade or the bottom cutter in the dual cutter blade assembly as previously described.
  • a second cutter blade having a length substantially equal to that of the first cutoff cutter blade is cut off from the remainder of the blanked strip of stock, with the length of the second cutter blade being preferably taken from the cutoff line at 312 to the shank end of the second cutter blade.
  • the crank pin-receiving aperture (139, 139a) is punched out preferably in the same die or dies used for the first cutter blade so that when the second cutter blade is turned over relative to the first cutter blade, it will be the mirror image of the first cutter blade.
  • top and bottom cutter blades to be assembled as a pair in a hedge trimmer need only be the mirror image of each in the region extending from the crank pin-receiving apertures 139 and 139a to the end of the toothed, overlapping regions where cutter blade teeth on one of the cutter blades will be coacting with teeth on the other cutter blade to provide a shearing action.
  • one cutter blade, at its end remote from the shank or at its end extending beyond the crank pin-receiving aperture 139, 139a) may be longer than its mating cutter blade, but this would serve not remedial purpose as far as cutting action is concerned.
  • each cutter blade may be utilized as either the top cutter blade or the bottom cutter in an assembled pair.
  • cutter blades After the cutter blades are cut from the blanked strip of stock, they may be nickel penetrated by placing them in random order in a basket and dipping the basket in liquified nickel. It will be appreciated that it is unnecessary to pair off the cutter blades and to keep them paired off during this and subsequent finishing operations or during any storage or stocking periods between operations. For convenience, however, blades of like lengths may be segregated from blades of different lengths, but for a multiplicity of blades of a given length it is unnecessary to pair off the blades and to keep them paired off upon being cut from the blanked strip of stock.
  • the cutter blade teeth are shaved on one or both sides in a shaving die to form the previously described cutting edges 244 and 246. After shaving, the blades are fed to a sander for deburring.
  • At least one cutter blade supported from said support member for relative reciprocatory movement in overlapping relation with said member, and means in said housing for reciprocating said cutter blade, at least said body portion of said housing being divided longitudinally of said support member into a pair of separately formed shells, said support member being trapped in position at said one end between interior surfaces of said shells and being secured in place only by separable surface seating engagement with said interior surfaces of said shells.
  • an elongated cutter blade support member at least one cutter blade reciprocably supported from said support member, a housing receiving corresponding ends of said support member and said cutter blade, and means disposed in said housing and operatively connected to the end of said cutter blade received in said housing for reciprocating said cutter blade, and said support member overlying said cutter blade when said housing is in an upright position and being secured against movement relative to said housing at its end received in said housing only at a region that is disposed above said cutter blade when said housing is in an upright position.
  • an elongated cutter blade support bar a pair of relatively reciprocable cutter blades reciprocably supported from said support bar, coacting sets of cutting teeth along oppositely facing side edges of said cutter blades,-a housing receiving corresponding ends of said support bar and said cutter blades, and drive means in said housing and operatively connected to the corresponding ends of the cutter blades that are received in said housing for reciprocating said cutter blades in opposite'directions, said support bar (a) having a portion extending longitudinally of and overlying said pair of cutter blades when said housing is in an upright position and (b) being secured against movement relative to said housing at its end that is received in said housing, and said portion of said support bar lying entirely between the roots of the cutting teeth at opposite edges of said blades.
  • an elongated cutter blade support bar a pair of relatively. reciprocable cooperating cutter blades underlying and reciprocably supported from said support bar, a housing receiving corresponding ends of said support bar and said cutter blades, and drive means disposed in said housing and having a crank assembly operatively connected to said corresponding ends of said cutter blades for reciprocating said blades in opposite directions, said support bar being fixed against movement at its corresponding end in said housing, and said corresponding end of said support bar overlying said crank assembly and said corresponding ends of said blades when said housing is disposed in an upright position.
  • a pair of cooperating, overlapping, relatively reciprocable cutter blades a housing receiving corresponding ends of said cutter blades, and cutter blade drive means mounted in said housing and comprising an electric motor having a rotatable armature shaft, and means including a crank assembly drive connecting said shaft to said corresponding cutter blade ends for reciprocating said blades in opposite directions, said crank assembly comprising a pairof connecting. rods respectively connected to said corresponding cutter blade ends, with said corresponding cutter blade ends lying between said connecting rods, and said motor being vertically disposed above said crank assembly and said corresponding cutter blade ends when said housing is in an upright position.
  • the power driven hedge trimmer defined in claim 10 comprising a support bar extending longitudinally of and overlying said cutter blades, and means carried by said support bar for supporting said blades for reciprocation from said support bar, and said support bar being supported in said housing at an end portion received in said housing, and said end portion overlying said connecting rods.
  • the power driven hedge trimmer defined in claim 10 comprising a support bar extending longitudinally of and overlying said cutter blades, said cutter blades being supported for reciprocating motion from said support bar, said support bar being supported in said housing at an end portion received in said housing,
  • said motor having an armatureand stator winding assembly, and sa1d end portion lying between said armature and stator winding assembly and said crank assembly-

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US107355A 1971-01-18 1971-01-18 Power driven hand tool Expired - Lifetime US3699655A (en)

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3805385A (en) * 1972-10-11 1974-04-23 Sunbeam Corp Housing for a portable grass shear
US3971132A (en) * 1971-09-17 1976-07-27 Rockwell International Corporation Saber saw
US5531027A (en) * 1994-07-21 1996-07-02 Mcculloch Corporation Hedge trimmer drive assembly
US5659958A (en) * 1995-06-15 1997-08-26 Goings; Walter W. Catcher for sicklebar mower hedge trimmer
US6598299B2 (en) * 2000-11-08 2003-07-29 Andreas Stihl & Co. Eccentric drive for a portable handheld work apparatus
EP2668840A1 (de) * 2012-05-30 2013-12-04 Makita Corporation Elektrisch gesteuertes Gartenwerkzeug
US20140007717A1 (en) * 2012-07-04 2014-01-09 Makita Corporation Electrically powered gardening tool
US20160023346A1 (en) * 2014-07-23 2016-01-28 Black & Decker Inc. Range of Power Tools
US20220210969A1 (en) * 2021-01-05 2022-07-07 Yamabiko Corporation Shearing Mechanism

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8419115U1 (de) * 1984-06-26 1984-09-27 Fa. Andreas Stihl, 7050 Waiblingen Heckenschere
DE4138625B4 (de) * 1991-11-25 2010-07-22 Robert Bosch Gmbh Elektromotorischer Stellantrieb
IT1267685B1 (it) * 1994-02-11 1997-02-07 Valex Spa Lama tagliasiepi perfezionata
DE19522971A1 (de) * 1995-06-28 1997-01-02 Bosch Gmbh Robert Heckenschere
DE19622594A1 (de) * 1996-06-05 1997-12-11 Gardena Kress & Kastner Gmbh Motorisch betriebenes Handgerät
CN103548590A (zh) * 2013-11-01 2014-02-05 苏州安必瑟斯机电技术有限公司 绿篱修枝机

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3083457A (en) * 1961-05-03 1963-04-02 Sunbeam Corp Hedge trimmer
US3212188A (en) * 1962-04-03 1965-10-19 Black & Decker Mfg Co Cordless electric hedge trimmer

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3083457A (en) * 1961-05-03 1963-04-02 Sunbeam Corp Hedge trimmer
US3212188A (en) * 1962-04-03 1965-10-19 Black & Decker Mfg Co Cordless electric hedge trimmer

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3971132A (en) * 1971-09-17 1976-07-27 Rockwell International Corporation Saber saw
US3805385A (en) * 1972-10-11 1974-04-23 Sunbeam Corp Housing for a portable grass shear
US5531027A (en) * 1994-07-21 1996-07-02 Mcculloch Corporation Hedge trimmer drive assembly
US5659958A (en) * 1995-06-15 1997-08-26 Goings; Walter W. Catcher for sicklebar mower hedge trimmer
US6598299B2 (en) * 2000-11-08 2003-07-29 Andreas Stihl & Co. Eccentric drive for a portable handheld work apparatus
US20130318799A1 (en) * 2012-05-30 2013-12-05 Makita Corporation Electrically powered garden tool
EP2668840A1 (de) * 2012-05-30 2013-12-04 Makita Corporation Elektrisch gesteuertes Gartenwerkzeug
US9101094B2 (en) * 2012-05-30 2015-08-11 Makita Corporation Electrically powered garden tool
US20140007717A1 (en) * 2012-07-04 2014-01-09 Makita Corporation Electrically powered gardening tool
US9357711B2 (en) * 2012-07-04 2016-06-07 Makita Corporation Electrically powered gardening tool
US20160023346A1 (en) * 2014-07-23 2016-01-28 Black & Decker Inc. Range of Power Tools
US10807226B2 (en) * 2014-07-23 2020-10-20 Black & Decker Inc. Range of power tools
US20220210969A1 (en) * 2021-01-05 2022-07-07 Yamabiko Corporation Shearing Mechanism
US11864489B2 (en) * 2021-01-05 2024-01-09 Yamabiko Corporation Shearing mechanism

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Publication number Publication date
FR2122473B1 (de) 1977-04-01
DE2201976A1 (de) 1972-08-10
CA966294A (en) 1975-04-22
CH549331A (de) 1974-05-31
FR2122473A1 (de) 1972-09-01
DE2201976B2 (de) 1977-09-15
GB1338949A (en) 1973-11-28

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Effective date: 19811019