US 3486796 A
Description (OCR text may contain errors)
Dec. 30. 1969 L. LECH ENE METHOD OF MAKINGv A BROOM 2 Sheets-Sheet 1 Filed March 6. 1968 FIG. I
WINDER DIE SLITTER STRETCI-E omemen EXTRUDER INVENTOR LEO L. LECHENE ATTORNEYS United States Patent Office 3,486,796 Patented Dec. 30, 1969 Int. Cl. A46d 3/00 US. Cl. 30021 1 Claim ABSTRACT OF THE DISCLOSURE A power-driven street sweeping broom is fabricated of a plastic cylindrical core onto which is tightly wound a continuous plastic channel-shaped strip of bristles. A first embodiment comprises a single flat sheet which is slit from both lateral edges and bent into a'channel shape to form the bristle strip. A second embodiment utilizes a channel shaped extrusion to which are transversely fused individual oval or round bristle elements, the assembly being then bent into a channel-shaped section. A third embodiment starts with an oval tubular extrusion which is split to form two channel shaped segments, each of which is then partially slit to form the individual bristles of the continuous bristle strip.
BACKGROUND OF INVENTION This invention relates to an improved power driven broom of the type used to sweep paved streets, and for an improved method of making such brooms.
In the past, brooms of this type have been assembled by laying channel or V-shaped bristle assemblies over a steel winding cable which was then wound onto the broom core, the core being provided with a helical groove to receive the winding cable. The object of the present invention was to eliminate the need of configuring the core surface and the use of the heavy winding cable for assembly and fastening, and to achieve an economical and rapid method of fabricating the bristles and assembling them to the core.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary sectional elevation showing the broom of this invention.
FIG. 2 is a fragmented perspective view of the bristle strip of this invention.
FIG. 3 is a block diagram showing the steps of fabricating the bristle strip and broom of FIGS. 1 and 2.
FIG. 4 is a fragmented perspective view of the bristle strip as it would appear following slitting but prior to the bending operation of the process of FIG. 3.
FIG. 5 is a block diagram showing the steps of fabricating a modified form of bristle strip and broom.
FIG. 6 is a fragmented perspective view showing the bristle strip as it would appear following joining but prior to the bending operation of the process of FIG. 5.
FIG. 7 is a fragmented perspective view showing the completed bristle strip following forming according to the process of FIG. 5 and ready for winding.
FIG. 8 is a block diagram showing the steps for fabricating a third embodiment of the bristle strip.
FIG. 9 is a fragmented perspective view showing the form of the extruded bristle strip prior to the stretching operation of the process of FIG. 8.
FIG. 10 is a fragmented perspective view showing the completed bristle strip made by the process of FIG. 8 and ready for winding.
broom assembly 10 of this invention is adapted to be connected to a power driven shaft 12 on the sweeping vehicle by means of pin 14. The broom assembly more particularly comprises a cylindrical sleeve or core 16 having hubs 18 inserted in each open end. The core is preferably fabricated of plastic and has a diameter of about ten inches. An adapter sleeve 20 may also be provided to complete the assembly of the broom core to the driven shaft.
Bristle strip 22 is spirally wound about the outer periphery of broom core sleeve 16 and may be secured thereto by riveting at each end of the strip or by adhesive along the entire contacting surface. As can be seen in FIG. 2, bristle strip 22 comprises a plastic channel-shaped base 24, preferably polypropylene, from which extend a plurality of integral individual bristles 26 which are formed by slitting the strip.
The fabricating method is schematically illustrated in the block diagram of FIG. 3. The first two steps comprise an extrusion and stretching operation which produces a continuous thin plastic sheet which is preferably approximately twenty-six inches wide and .075 inch thick. Commonly available extrusion and biaxial stretcher-orienter equipment may be employed for this purpose, the equipment itself not forming a part of the invention. As this sheet exists from the stretcher-orienter stage, it passes on to a slitting operation where a plurality of parallel transverse slits are made from each edge inward toward the center portion 24 (see FIG. 4). The individual bristles 26 formed by the slits are preferably .10 inch Wide, and the unslitted central channel 24 may be approximately 1% inches wide. A conventional guillotine type punch press may be used for this operation.
From the slitter, the strip passes to a bending or forming die, Where the strip is folded over under a combination of heat and pressure until it assumes the channel shape of FIG. 2. It will be noted from FIG. 2 that the preferred inch width of the channel is less than the 1% inch total width of the unslit central portion 24, so that the base of each of the two bristle-bearing legs of the channel is stiffened and reinforced by 9 4 inch of this unslit section.
The next stage of the operation comprises a helical winding of the now slit channel-shaped strip 24 onto the outer periphery of broom core sleeve 16. This step is preferably accomplished by orienting the axis of core 16 transversely to the direction of flow of strip 24 as it leaves the bending die. The end of strip 24 would be secured by rivet or adhesive to one end of core 16. Then the core would be slowly moved transversely and rotated as the bristle strip 24 was fed onto it, resulting in the desired helical winding. With the completion of the winding, the strip would be severed and the end secured to the core. Adjacent windings should be tightly butted together to give additional rigidity and to prevent slippage.
In the embodiment of FIGS. 5 through 7, the modified bristle strip 22A is fabricated of a channel-shaped base member 28 to which are separately secured a plurality of individual bristles. The channel-shaped base 28 is extruded from a first extruding machine, and a second such machine extrudes a generally oval or circular shaped section (about .075x.105 inch) which is then passed through a stretcher-orienter to further elongate and refine the shape. These latter two operations are preferably placed at a point adjacent the exit from the channel extruder and at right angles thereto, so that when the oval extrusion is cut to approximately 26 inch lengths, these individual bristles 30 can be automatically laid directly on and across the moving channel extrusion as it leaves the channel extruder.
FIG. 6 illustrates the condition at this stage of the operation. The channel and bristles next pass through a joiner which welds or fuses these members together at the zone of intersection. The now assembled elements pass through a bending die as in the first embodiment to form the channel-shaped final configuration illustrated in FIG. 7. Following this bending operation, the actual winding of the strip 22A onto the broom core is accomplished as in the first embodiment,
A third embodiment is illustrated in FIGS. 8 through 10. Here, an extruder is employed to form the oval tubular shape shown at 32 in FIG. 9. This extrusion then passes onto a stretcher which widens the oval from a three or four inches width to approximately 26 inches. 'From the stretcher, the extrusion passes on to a splitter which places a vertical cut down the center line of the extrusion to form two identical U-shaped extrusions as shown at'34 in FIG. 10. These severed sections are next each slit in such a way that unslit base portion 38 serves as a reinforcing channel base as in the case of the first embodiment of FIG. 2.
Following slitting, bristle strip 22B is wound onto the broom core as in the case of the first two embodiments.
The bristle strips made in accordance with this invention can be economically fabricated and rapidly and easily assembled. The need for a heavy winding cable has been eliminated, and the time-consuming process of placing bristles on the winding cable has also been eliminated.
Although not necessary, the full length of the bristle strips made in accordance with any of the three above described embodiments may be adhesively secured to the core surface.
This invention may be further developed within the scope of the following claim. Accordingly, the above specification is to be interpreted as illustrative of only three operative embodiments of this invention, rather than in a strictly limited sense.
I now claim:
1. The method of fabricating a generally cylindrical power-driven street sweeping broom which comprises the steps of:
extruding a hard stiff plastic material into a long thin channel-shaped strip; joining to said channel section a series of parallel bristles, said bristles being oriented transversely to said channel across the bight thereof and joined at their midpoints thereto to form a bristle strip;
bending said bristles over said channel section to form a channel-shaped assembly;
helically winding said strip onto a cylindrical broom core with the free ends of said bristles directed radially outwardly from said core axis; and
securing said bristle strip to said core.
References Cited UNITED STATES PATENTS 2,595,776 5/1952 Downey 300-21 XR 2,980,467 4/1961 Lechene 300-21 3,207,556 9/1965 Lechene 300-21 GRANVILLE Y. CUSTER, JR., Primary Examiner