The invention relates to a strip brush assembly typically for use with a cylindrical mandrel and the method of making. In particular, the improved strip brush assembly has both metal and polymer bristles.
Street sweepers are vehicles that have a plurality of brush assemblies mounted thereon to clean streets. Typically a street sweeper has a cylindrical mandrel driven to rotate around its central axis mounted on the underside of the vehicle. Such central axis is generally perpendicular to the direction of movement of the street sweeper. Radially extending from the mandrel are a plurality of elongated bristles that, when the mandrel is rotated, result in a sweeping motion. A street sweeper may also have a pair of gutter brooms each having a disk shaped plate with tufts of metal wires extending from the planar surface towards the ground. The disk is mounted on each side of the street sweeper and is rotated to clean the street.
Due to the strong force that the bristles endure with repeated contact with the street, the bristles need to be replaced often. To facilitate the replacement of bristles, on the surface of existing mandrel are a plurality of channels that extend axially (helically, straight, curved, etc.). Each channel receives a strip brush assembly that includes a base that correspondingly and slidably mates with the channel. Extending from the base are a plurality of bristles.
Existing strip brush assembly is typically made entirely of polypropylene, including the base and the bristles. While there are benefits to have a strip brush assembly completely made of polypropylene, such as allowing the recycling of the entire strip brush assembly when it is worn, it lacks the aggressive cleaning of metal bristles. However, the use of only metal bristles in a strip brush assembly would not work for a street sweeper. As mentioned above, when the bristles are in contact with the street, there is a strong force against the bristles. As polypropylene bristles are resilient, they bend as they come into contact with the street and would return to its original at rest position after contacting the street, providing an efficient sweeping motion with the flicking/whisking action of the polypropylene bristles. On the other hand, metal bristles would bend, and stay bent, rendering it useless to provide a sweeping motion.
There are a number of prior art methods of making a strip brush assembly using either polypropylene bristles only or metal bristles only. See, e.g., U.S. Pat. No. 5,819,357 to Frances Gould and U.S. Pat. No. 6,665,902 to Hinderikus Vegter. The prior art methods disclosed in the '357 and '902 patents cannot be easily adapted to make a strip brush assembly having both polymer and metal bristles. Any attempt to adapt the prior art methods would be costly, in both the need of manpower and required stocking of raw material, and requires additional steps. There is no known method of efficiently and effectively making a strip brush assembly having both metal and polymer bristles or strip brush assembly having both metal and polymer bristles that is structurally sound and can withstand the force associated with a street sweeper.
Therefore, there is a need for an improved method of efficiently and effectively making a strip brush assembly having both metal and polymer bristles and an improved resultant strip brush assembly.
The present invention is an improved strip brush assembly having both metal and polymer bristles. A plurality of metal bristles are supported by a plurality of polymer bristles and mounted to a base having a corresponding shape for fitting into a corresponding channel on the surface of a mandrel.
The metal bristles and polymer bristles of the strip brush assembly extend vertically from an extrusion formed base and may be interspersed among each other or form distinctive sections (such as upper layer section and lower layer section) so long as the metal bristles are supported by some polymer bristles. The metal bristles of the strip brush assembly are generally straight and elongated and may be a straight wire or a crimped wire. Each metal bristle may be crimped either in two-dimension or in three-dimension direction. The polymer bristles of the strip brush assembly are generally straight and elongated and have a generally uniform cross-sectional shape such as generally circular or oval. The polymer bristles may have a wavy profile either in two-dimension or in three-dimension direction.
The method of the present invention includes the following steps:
1. providing a plurality of polymer bristles having first ends, aligned on a horizontal surface with the first ends of the polymer bristles in a first generally linear alignment;
2. providing a plurality of wire bristles having first ends, placed on the horizontal surface on top of the polymer bristles, with the first ends of the metal bristles in the first generally linear alignment;
3. extruding a formed base directly onto and around the first ends of the polymer and metal bristles;
4. cooling the extrusion formed base; and
5. cutting the extrusion formed base to form a strip brush assembly of a desired length.
Step 1 and Step 2 may be interchanged such that the wire bristles are first placed on the horizontal surface, with the polymer bristles placed on top of the wire bristles. Alternatively, the polymer bristles may be placed interspersed among the metal bristles. For certain other applications, Step 1 can be deleted to produce an all metal bristles strip brush assembly.
The method of the present invention is easily performed on a conveyor belt with the extruder and cooler positioned adjacent and along the first generally linear alignment.
Preferred embodiments of the present invention have been chosen for purposes of illustration and description and are shown in the accompanying drawings, which are not necessarily to scale, forming a part of the specification wherein:
With reference to the drawings, wherein the same reference number indicates the same element throughout, there is shown in
The polymer bristles dispenser 150 dispenses a plurality of predetermined length elongated polymer bristles 152 onto the conveyor belt 400. The plurality of polymer bristles 152 are dispensed to lay generally flat on the surface of the conveyor belt 400, abutting or closely adjacent each other. A positioning device (not shown) may be provided to ensure the first ends 154 of the polymer bristles 152 are in a general linear alignment with the direction of the movement of the conveyor belt 400. When the polymer bristles 152 are dispensed, one or multiple layers of polymer bristles 152 may lay on the surface of the conveyor belt 400, depending on the desired application of the finished strip brush assembly 10.
The raw material for the polymer bristles 152 typically comes in a continuous coil of elongated polymer strips. The polymer strip is unwound, then machine cut to an appropriate length to form the predetermined length polymer bristles 152. The raw material for the polymer bristles 152 may be automated from unwinding the polymer strips to machine cutting the polymer strips, and then feeding into the polymer bristles dispenser 150 or be incorporated as a unit with the polymer bristles dispenser 150. The polymer bristles 152 may be made of polypropylene, nylon, other thermoplastic material, or other polymer. The polymer bristle 152 has a generally uniform cross-sectional shape, such as generally circular, generally oval, or generally ellipse. Optionally, the polymer bristles may have a slightly wavy profile having a generally uniform amplitude. For a polymer bristle 152 with an ellipse cross-sectional shape, the major diameter can be in the range of 0.06 to 0.16 inch and the minor diameter can be in the range of 0.05 to 0.11 inch. The polymer bristles 152 may be cut to a predetermined length of between 7 to 15 inches. For a strip brush assembly 10 for use with a street sweeper, the polymer bristles 152 may have a minor diameter of 0.085 inch, a major diameter of 0.135 inch and length of 13 inches.
The metal bristles dispenser 200 dispenses a plurality of predetermined length elongated metal bristles 202 onto the conveyor belt 400. The plurality of metal bristles 202 are dispensed to lay generally flat on top of the plurality of polymer bristles 152, abutting or closely adjacent each other. A positioning device (not shown) may be provided to ensure the first ends 204 of the metal bristles 202 are in a general linear alignment with the first ends 154 of the polymer bristles 152, which are in a general linear alignment with the direction of the movement of the conveyor belt 400. When the metal bristles 202 are dispensed, one or multiple layers of metal bristles 202 may lay on top of the plurality of polymer bristles 152, depending on the desired application of the finished strip brush assembly 10.
The raw material for the metal bristles 202 typically comes in a continuous coil of elongated metal wire. The metal wire is unwound, crimped, then machine cut to form the predetermined length metal bristles 202. The crimping of the metal wire is performed by a crimping machine having two driven rotating, and opposing, dies. The crimped metal bristle 202 is generally straight and has a generally sinusoidal curve (in 2-dimensional or 3-dimensional direction) with a generally uniform amplitude, without any sharp corners or deformed area where breakage can occur. While use of a crimping machine with one die to form the crimped metal bristle 202 is possible, it would produce a crimped metal bristle 202 that is not as straight (and may have an overall arc) and in a non-uniform/uneven zig-zag configuration with possibly sharp corners or deformed area. The raw material for the metal bristles 202 may be automated from unwinding the metal wire, crimping the metal wire and machine cutting the metal wire, and then feeding into the metal bristles dispenser 200 or be incorporated as a unit with the metal bristles dispenser 200. The metal bristle 202 has a generally uniform cross-section shape, such as generally round, generally oval, or generally ellipse. The diameter of the metal bristle 202 can be in the range of 0.015 to 0.050 inch. The metal bristle 202 may have a tensile strength of 200,000 to 400,000 psi, and a crimped amplitude of 0.09 to 0.1 inch. Similar to the polymer bristles 152, the metal bristles 202 may be cut to a predetermined length of between 7 to 15 inches. For a strip brush assembly 10 for use with a street sweeper, the metal bristles 202 may have a round cross-sectional shape with a diameter of 0.028 inch and a tensile strength of 260,000 to 290,000 psi.
The extruder 250 takes raw material 252 and heats it to a molten state and extrudes it through a die to form a predetermined shaped base 254 onto and over the first ends 154 and 202 of the polymer and metal bristles 152 and 202 being carried on the conveyor belt 400. The first ends 154 of the polymer bristles 152 may be pre-heated/warmed before the extruder 250 to improve bonding of the extruded base 254 with the polymer bristles 152. When the extruder 250 extrudes the molten raw material 252 over the first ends 154 and 204 of the polymer and metal bristles 152 and 202, it flows in between and permeates the first ends 154 and 204 to bond and encapsulate the first ends 154 and 204 in a formed base 254 and provides a secure anchor of the polymer and metal bristles 152 and 202 in the formed base 254 in one step.
The die of the extruder 250 may have a predetermined cross-sectional profile shape as shown in
The cooling device 300 cools the formed base 254 with the polymer and metal bristles 152 and 202 extending therefrom that are moved on the conveyor belt 400 after being extruded from the extruder 250. The cooling device 300 aids in retaining the shape of the formed base 254 as it exits from the die of the extruder 250.
The cutter 350 cuts the formed base 254 as it moves on the conveyor belt 400 to form strip brush assembly 10 of a desired length. Optionally, either before or after the cutter 350, the second ends 156 and 206 of the polymer and metal bristles 152 and 202 may further be trimmed to ensure all have the same length. Optionally, either before or after the cutter 350, the base 254 may also be trimmed or grinded to provide a more polished base 254 to improve tolerance such that the strip brush assembly 10 can easily be inserted into and retained within corresponding channels 502a or 502b of mandrel 500 according to specification.
The steps in carrying out the process of the present invention to manufacture a strip brush assembly 10 of the present invention with the polymer bristles dispenser 150, metal bristles dispenser 200, extruder 250, cooling device 300, cutter 350, and conveyor belt 400 as shown in
1. Dispensing with the polymer bristles dispenser 150 a plurality of polymer bristles 152 of a predetermined length in at least one layer abutting and in general alignment with each other onto the surface of a conveyor belt 400.
2. Dispensing with the metal bristles dispenser 200 a plurality of metal bristles 202 of the predetermined length in at least one layer abutting and in general alignment with each other on top of and in general alignment with the layer of polymer bristles 152 on the surface of the conveyor belt 400.
3. Extruding with the extruder 250, having a predetermined shaped die, a formed base 254 onto the first ends 154 and 204 of the polymer and metal bristles 152 and 202 as they move on the conveyor belt 400 to bond and encapsulate the first ends 154 and 204 within the formed base 254.
4. Cooling with the cooling device 300 the formed base 254 as it moves on the conveyor belt 400.
5. Cutting with the cutter 350 the formed base 254 as it moves on the conveyor belt 400 at a predetermined length to form a strip brush assembly 10 of a desired length.
The order of Steps 1 and 2 can be reversed such that the layer(s) of a plurality of metal bristles 202 is first dispensed onto the surface of the conveyor belt 400 with the layer(s) of a plurality of polymer bristles 152 dispensed on top of the layer(s) of metal bristles 202 in a stacked manner as shown in
The specification above and the drawings show a layer of polymer bristles 152 forming a section and a layer of metal bristles 202 forming another section above it, additional alternating of sections with layers of either polymer bristles 152 or metal bristles 202 may be dispensed to form a strip brush assembly 10 with more than two layers of bristles. For example, a strip brush assembly 10 may have two sections of polymer bristles 152 sandwiching a section of metal bristles 202 therebetween, or vice versa. Further, an additional section of other type of bristle layer or material layer (such as felt, micro fiber, baffle strip, etc.) can also be added to the two sections of bristle layers.
While
Optionally, between Steps 2 and 3, an additional step of pre-heating or warming the first ends 154 and 204 of the polymer and metal bristles 152 and 202 would improve bonding with the extruded formed base 254. Optionally, between Steps 4 and 5 or after Step 5, an additional step of trimming the second ends 156 and 206 of the polymer and metal bristles 152 and 202 would ensure all bristles 152 and 202 have the same length. Optionally, between Steps 4 and 5 or after Step 5, an additional step of trimming or grinding the formed base 254 would provide a more polished base 254 to improve tolerance such that the strip brush assembly 10 can easily be inserted into and retained within corresponding channels 502a or 502b of mandrel 500.
Although
Although the polymer and metal bristles 152 & 202 of strip brush assembly 10 are shown to be extending substantially perpendicular from the base 254 in
In summary, the strip brush assembly 10 of the present invention utilizes a section of polymer bristles section 158 to support a section of metal bristles section 208 to prevent the metal bristles from bending out of shape. The presence of metal bristles 206 advantageously provides a better, more thorough, and deeper, cleaning and digging of the street surface, and lasts longer than a strip brush assembly that only has polymer bristles. The smaller cross-sectional shape of the metal bristles 202 allows each metal bristle 202 to reach into crevices or cracks on the street surface that cannot be reached by polymer bristles 152 that have a wider cross-sectional shape, which is particularly helpful in completely removing weeds or for weed control. The wavy profile of the polymer bristles 152 along with the sinusoidal curve of the metal bristles 202 provide additional cleaning capability with their ability to intertwine to efficiently deflect and move debris encountered during the sweeping motion. For example, two metal bristles 202 that cross each other (such as forming an “X”), can trap debris (such as weeds) at the juncture and pull it away from the street surface S. When the polymer and metal bristles 152 and 202 are intertwined in various areas, the strip brush assembly 10 essentially resembles a net that captures or pushes different size debris that it encounters to provide efficient street cleaning.
The strip brush assembly 10 and its method of making has many advantageous over the prior art, other than those mentioned above, including but not limited to the following:
1. Customization of the strip brush assembly 10 is easily implemented to produce strip brush assembly 10 with different characteristics to meet certain specification and for different purposes or applications. For example, the number of polymer and metal bristles 152 & 202 used in a strip brush assembly 10 can vary, the cross-sectional width and size of the polymer bristles 152 can vary, the gauge of the metal bristles 202 can vary, and the proportional amount of metal bristles 202 to polymer bristles 152 can vary.
2. Single processing line that starts with raw material (i.e. a continuous coil of elongated polymer strips, a continuous coil of elongated metal wire, and raw material for extrusion) and ends with a finished strip brush assembly 10 ready to be used.
3. Continuous processing through a conveyor belt assembly line that can be fully automated and requires minimal manpower to keep the processing going continuously and requires minimal disruption of the process, which saves time and money.
4. No need to stock or use pre-formed base, which is voluminous and more expensive, that the prior art method requires to be fused to the bristles.
5. No need to stock multiple shapes of pre-formed bases to produce different strip brush assemblies. Only need to stock different shaped dies for the extruder 250, which can be easily interchanged.
6. No need to pre-heat a pre-formed base or pressure mold the base as in the prior art to securely anchor the bristles to the base.
7. Overall process is faster and simpler than prior art.
8. Uses only minimal raw material as necessary to produce the strip brush assembly 10 with less waste than the prior art.
9. Uses less heating elements than the prior art; thereby saving energy, costs and the environment.
10. Strip brush assembly 10 of the present invention on a mandrel 500 can withstand a higher revolution per minute speed due to the efficient and effective bonding and anchoring of the polymer and metal bristles 152 & 202 to the formed base 254.
11. Strip brush assembly 10 of the present invention can be used in hot environment as the metal bristles 202 provide support to the polymer bristles 152 that are softened in such environment.
While the strip brush assembly and method of making is mentioned for use with street sweepers, it is not so limited and can be applied to other uses and applications. It is anticipated that the method of the present invention encompasses use of any fusible material or combination of fusible material. For examples, using metal bristles and extruding a formed metal base directly onto the ends of the metal bristles, and using polymer and metal bristles and extruding a formed metal base. It is understood that aside from metal and polymers, ceramics and concrete can also be extruded. Therefore, any current and future material that can be extruded is anticipated to fall within the scope of the present invention.
The features of the invention illustrated and described herein are the preferred embodiments. Therefore, it is understood that the specification is intended to cover unforeseeable embodiments with insubstantial differences that are within the spirit of the specification.
This application is a divisional of pending patent application Ser. No. 15/689,954 filed on Aug. 29, 2017, which claims benefit of provisional patent application Ser. No. 62/381,502 filed on Aug. 30, 2016, and both are hereby incorporated by reference.
Number | Date | Country |
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102009043167 | May 2011 | DE |
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Translation of DE-102009043167 retrieved from Espacenet on Jan. 24, 2023 (Year: 2011). |
Number | Date | Country | |
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20210244169 A1 | Aug 2021 | US |
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62381502 | Aug 2016 | US |
Number | Date | Country | |
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Parent | 15689954 | Aug 2017 | US |
Child | 17243090 | US |