Oscillated head with bearing support and counterbalance, for floor stripping machine
BACKGROUND OF THE INVENTION 
     This application is a continuation-in-part of my prior application &#34;Oscillated Head With Bearing Support for Floor Stripping Machine&#34;, Ser. No. 443,327, filed Nov. 22, 1982, now U.S. Pat. No. 4,452,492 which is a continuation-in-part of my prior application &#34;Blade Holder In Oscillated Head for Floor Stripping Machine&#34;, Ser. No. 329,523, filed Dec. 10, 1981, now U.S. Pat. No. 4,365,843 which is a continuation-in-part of my prior application &#34;Connector For Floor Stripping Machine&#34;, Ser. No. 318,827, filed Nov. 6, 1981, now U.S. Pat. No. 4,365,842. 
    
    
     This invention relates generally to floor stripping devices, and more particularly concerns improvements in the driving and blade support means for same. 
     U.S. Pat. No. 3,376,021 discloses a floor stripping machine of the type in which the present invention is usable to great advantage. Such machine incorporates a cutting blade carried by a head pivotally mounted to a frame. Problems with machines as disclosed in that patent include failure of rapidly oscillating, head driving connecting rods and associated parts and bearings; insufficient lubricating of such rods, parts and bearings, undue wear of the oscillating head at its pivots; unwarranted high cost of repair and replacement of such elements; and difficulty with clamping a blade to the bottom side of the head. 
     SUMMARY OF THE INVENTION 
     It is a major object of the invention to provide a solution to the above described problems and disadvantages. Basically, the invention is embodied in: 
     (a) a connecting element having a first tubular part and a second tubular part, said parts having spaced, parallel axes, said second tubular part pivotally connected to the head, 
     (b) a drive shaft extending within said first tubular part, said shaft operatively connectible to the drive to be rotated thereby, 
     (c) said drive shaft carrying eccentric means to be rotated by the shaft, 
     (d) bearing means carried by and within said first tubular part, said bearing means receiving said eccentric means to oscillate said first tubular part, said head and said blade as said eccentric means is rotated by the shaft, 
     (e) and counterbalance means located on said drive shaft to rotate therewith and reduce vibration created by said oscillation. 
     As will appear, the eccentric means may include two axially spaced eccentrics between which lubricant is confined, and the counterbalance means may comprise two axially spaced weights carried on the shaft at locations between which the two eccentrics extend. The head oscillating eccentrics rotated by the drive shaft may have oppositely facing end faces which flare radially outwardly and axially to urge and guide lubricant toward bearings for the eccentrics. Also, the tubular parts may simply and inexpensively comprise pipe sections interconnected by a plate welded thereto. Further, the blade is easily attachable to the bottom side of the head by fastening means to be described. 
     Importantly, the weights may be located outside of frame members supporting the drive shaft, or between such frame members and the eccentrics, the weights protruding normal to the shaft axis to substantially greater extent than the eccentrics, as will be seen. 
     These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following description and drawings, in which: 
    
    
     DRAWING DESCRIPTION 
     FIG. 1 is a side elevation showing a floor stripping machine incorporating the invention; 
     FIG. 2 is a top plan view of the FIG. 1 machine; 
     FIG. 3 is an enlarged elevation taken on line 3--3 of FIG. 4; 
     FIG. 4 is a section taken on lines 4--4 of FIG. 3; 
     FIG. 5 is a section taken on lines 5--5 of FIG. 3; 
     FIG. 6 is an enlarged section taken through connecting structure seen in FIG. 4; 
     FIG. 7 is an end elevation view of the FIG. 6 connecting structure; 
     FIG. 8 is a side elevation; 
     FIG. 9 is a perspective view; 
     FIG. 10 is a fragmentary front elevation, showing the head of FIG. 8; 
     FIG. 11 is a fragmentary plan view on lines 11--11 of FIG. 8, and FIG. 11a is a view like FIG. 11; 
     FIG. 12 is a view like FIG. 10, but showing a modification; 
     FIG. 13 is a fragmentary view similar to FIG. 4, showing use of counterbalance weights; 
     FIG. 14 is an end view of the shaft, eccentric and weight; and 
     FIG. 15 is a fragmentary view like FIG. 6, showing use of counterbalance weights. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings and initially, to FIGS. 1 and 2, inclusive, for this purpose, it will be seen that one type of machine in which the invention may be incorporated has been designated in its entirety by reference number 10. Mounted on the machine 10 are a pair of rubber tires 12 which permit the machine 10 to be easily transported and maneuvered. The wheels 12 are carried by an axle 14 which in turn passes through the rear portions of the base frame 16. Mounted on the frame 16 is an electrical motor 18. The machine 10 may alternately be powered by an internal combustion engine. The motor 18 is held in place by four mounting bolts 19 which pass through slots 20 in the frame 16. When the bolts 19 are loosened the motor can be moved forward or backward on the frame 16 by reason of the slots 20 to adjust the tension in the drive belt 21. Covering the motor 18 and attached to the frame 16 is a cover shroud 22. The shroud 22 slides over the side walls 23 of the frame and is held in place by bolts 24 as can be seen in FIG. 1. Positioned on the front of the frame 16 is a nose weight 25. The weight is held in place by means of a releasable wire clip 26 which fastens the forward edge of the shroud 22 with the weight 25. The weight provides the necessary weight on the cutting edge 28 which will later be described. 
     The handle bar 29 comprises a pair of elongated tubular members 30 which are attached at their lower ends to the shroud 22, and at their upper end are joined by tubular cross members 31 and 32. Hand grips 33 are used to handle and maneuver the machine 10. 
     FIGS. 3 through 5 show the cutter head subassembly 36 in detail. The frame 16 previously mentioned is substantially U-shaped with a horizontal web portion 34 and a pair of vertical flanges 35 as can best be seen in FIG. 5. At the forward end of the frame 16 positioned between the webs 35 is the cutting head 38. The head 38 is formed with a web 40 and a pair of flanges 42. The cutting head is pivotally mounted at the upper end to the frame 16 by a pin 44 which passes through both pairs of flanges 35 and 42. Passing through the pair of flanges 35 and journalled thereto is a rotatably mounted drive shaft 46 which is shown in FIGS. 4 and 6. The shaft 46 is journaled at its outer ends in a pair of roller bearings 48 which are in turn bolted to the frame flanges 35 by means of bolts 50. Retaining the cam shaft in the bearings 48 are a pair of locking sleeves 52 which are mounted on the shaft 46 immediately outward of the bearing 48. Keyed to one end of the shaft 46 is a sheave 54 adapted to carry a V-belt. Mounted on the shaft 56 of the motor 18 is a similar sheave 58 which lies in the same plane of rotation as sheave 54. The two sheaves 54 and 58 are connected by means of a rubber V-belt 21. The tension in the V-belt 21 may be adjusted as previously discussed. 
     The shaft 46 extends within a first tubular part 90 of a connecting element 91, the latter also incorporating a second and smaller diameter tubular part 92. Those tubular parts may advantageously and inexpensively comprise steel pipe sections, interconnected by a steel plate 93 which is simply welded to outer side portions of the sections, as at 94 and 95. See FIG. 7. Accordingly, the cost of element 91 is minimized. 
     Shaft 46 carries two axially spaced eccentrics 96 and 97. See in FIG. 7 the axis 96a of eccentric 96 offset from the axis 46a of shaft 46. Each eccentric is cylindrical, to rotate within a bearing, such as a bushing, the two bushings indicated at 98 and 99 and received in counterbore 98a and 99a in the pipe section, and against step shoulders 98b and 99b. The large space 100 thus provided between the eccentrics provides a lubricant (grease) reservoir, for long lasting lubrication of the two bearings, as the shaft rotates and as the eccentrics oscillate the shaft section 90, and the element 91 back and forth, as will be described. Shaft section 46b extends between and interconnects the two eccentrics. 
     Note that the eccentrics have oppositely facing end portions or faces 96a and 97a, which, due to their flaring eccentricity, tend to positively displace the grease as the eccentrics rotate. This serves to urge grease radially outwardly, and axially toward the bushings and the bearing surfaces of the eccentrics and bushings, for enhancement of lubrication. Note that faces 96a and 97a intersect the outer surface of the eccentrics in places 96b and 97b that are at angles α relative to the shaft axis, angles α being less than 90°. Grease is introduced to space 100 via a grease fitting 101 in shaft 90, as shown. 
     Annular elastomeric seals 102 and 103 are located at opposite ends of the bushings, and pressed into the shaft counterbores 102a and 103a, as shown. Those seals exert pressure on the shaft eccentrics to prevent escape of grease. 
     At the opposite end of element 91 is a bearing shaft 68 journaled via bushings 66 to the pipe section 92. Shaft 68 is in turn mounted to cutting head 38. When shaft 56 is rotated, element 91 is oscillated back and forth to cause head 38 to move back and forth about the axis of pipe 44, as indicated by arrows A in FIG. 3. 
     At the lower extremities of the cutting head 38 the flanges 42 become wider to accommodate the cutting blade shoe 70. The shoe 70 is adjustably held against the cutting head by two pairs of bolts 72 and 74. The bolts 72 pass through openings 75 in the rear of the blade shoe 70 and are threaded into the ends of the connecting rod shaft 58. The bolts 74 pass through openings 76 and are threaded into the ends of shaft 77. The purpose of the blade shoe 70 is to rigidly hold the cutting blade 78 in its cutting position. Located on the back edge of the blade shoe 70 are a pair of adjusting bolts 80 and locking nuts 81 which allow for adjustment of the position of the blade stop 82 which in turn adjusts the amount of blade edge exposure. The front edge 83 of the blade shoe 70 is tapered to provide a maximum amount of rigidity to the cutting blade and yet permit a shallow angle of slope between the cutting blade 78 and the flooring surface being stripped. 
     FIGS. 8, 10 and 11 show a modified head 138 consisting of lightweight metal such as aluminum, or aluminum alloys, or magnesium, or magnesium alloys. The head has two elongated flanges 142 interconnected by a web 140. The flanges are locally thickened near upper ends of the flanges to define two widened lugs 242 that form widened bearing openings 150 for a pivot shaft 144. The latter is connected to the frame flanges 135 (corresponding to flanges 35 in FIG. 5). The bearing openings (and the lugs) have lengths &#34;l&#34; in excess of 3/4 inch, and preferably are between 3/4 and 11/2 inches in length. As a result, destructive wear of the head metal surrounding the openings 150 is eliminated, and in particular for heavy duty operation where stripping forces are extensive. 
     The openings are sized to closely receive the pivot shaft 144, and define a common axis 144a. FIG. 11a shows a modification, with a steel tube 344 received in openings 150, and in turn receiving the shaft 144. Tube 344 helps distribute loading to insure against destructive wear of the lightweight metal lugs 242. 
     FIGS. 8 and 9 also show the use of the modified blade holder plate 170 attached to the head 138 at its bottom side 138a. Blade 178 is clamped against that side, by the plate. Two shafts, 177 and 168 extend parallel to the web 140 and through flanges 142 to provide shaft projections 177a and 168a at the exterior side of each flange. Two pairs of fasteners 200 and 201 extend in parallel relation through suitable openings in the holder plate and in the blade, at opposite ends of the shafts, respectively. The fasteners have heads 200a and 201a that clamp split washers 202 and 203 against the bottom of the holder plate. Also, the fasteners have threaded shanks 200b and 201b received in threaded engagement with threaded openings 177b and 168b in the shaft projections 177a and 168a. Accordingly, tightening of the blade in position as shown in FIG. 9 may be accomplished using one hand 210 only i.e. by manipulation of the wrench 204 in grip engagement with the fastener heads, and the blade may be held and positioned by the other hand 211. 
     The operation of the stripping machine 10 varies with the type of floor being removed. The steeper the angle of the blade 78 with the floor the deeper the blade will dig. The angle can be varied by lifting the wheels 12 off the floor. The angle can also be varied by extending the blade 78 further past the edge of the shoe 70. When removing a plywood or particle board floor an extra long blade which extends an additional four inches or more past the edge of the shoe 70 has proven very useful. The longer the blade 78 is extended out of the shoe the less the angle between the cutting blade and floor. The amount of weight applied to the cutting edge 28 is also variable depending upon the flooring being removed. The weight can be varied by the amount of pressure applied by the hands to the handle bar 29. Generally, the machine best operates when the handle bar 29 is lifted up until the wheels are one-half inch off the floor. When an exceptionally tough flooring is being removed, a blade with teeth formed on the cutting edge has been found to be very effective. 
     FIG. 12 is a view like FIG. 10, with corresponding elements having the same identifying numbers. It differs from FIG. 10 in the provision of bushings 280 and 281 fitted and retained in bores 282 and 283 in lugs 242. The bushings may endwise fit against stop shoulders 284 and 285 in the lugs. the bushings may advantageously be self-lubricated, as provided by annular material 280a and 281a carried in metallic (as for example bronze) sleeves 280b and 281b press-filled in bores 282 and 283. Material 280a and 281a may for example consist of molybdenum disulfide. One example of such bushings are known &#34;OILITE&#34; bushings. 
     Pivot shaft 144 (typically steel) is received in, and has low friction running fit in, the bores of the annuli 280a and 281a, for long lasting, low wear operation. 
     FIG. 13 is a fragmentary view like FIG. 4, with corresponding elements having the same numbers. It differs from FIG. 4 in the provision of counterbalance means so located on the drive shaft 46 as to rotate therewith and reduce vibrations created by the eccentrics oscillating the head and blade. As shown, the counterbalance means comprise two axially spaced weights 300 and 301 carried on the shaft 46 at locations between which the two eccentrics 96 and 97 extend. Thus, weight 300 is located at the outer side of frame part 35a and shaft bearing 48a, and is protectively confined by a shield 303 attached at 304 to the frame 35a; and weight 301 is located at the outer side of frame part 35b and shaft bearing 48b, and is protectively confined by the sheave 54. The weights may be attached to the shaft as by keys or pins (see pins 305 in FIG. 15 to be described). 
     In FIG. 15, the weights 300a and 301a are protectively located at the inner sides of the frame members 35a and 35b and between the latter and the other ends 96a and 97a of the eccentrics 96 and 97. The metallic (typically steel) weights are similar in size and shape, and are narrow in thickness &#34;t&#34; (typically less than 3/8 inch). Referring to FIG. 14, the eccentrics, represented by eccentric 97, protrude in one direction (see arrow 310) normal to axis 46a defined by the shaft; and the weights, represented by weight 300, protrude in a second and substantially opposite direction (see arrow 311) normal to axis 46a. Further, the weights protrude as described to substantially greater extent than the extent to which the dual eccentrics protrude. Such extents appear at &#34;p 1  &#34; for the eccentrics and &#34;p 2  &#34; for the weights. The center of mass &#34;C&#34; of weight 300 is outside the cross sectioned areas of the shaft and of the eccentrics. The weight may advantageously have bell outside shape, as shown. The two weights are substantially equally spaced from the two like eccentrics, for best balancing results.