LOW-MAINTENANCE, WALK-BEHIND WET/DRY CONCRETE GRINDER/POLISHER

Abstract

A walk-behind, wet/dry grinder/polisher adapted for concrete floors does not use of pulleys, belts or chains. Maintenance is significantly enhanced, as such components are typically the first to wear out and cause replacement issues. A frame with forward and rear portions pivots about a single set of right and left wheels. A planetary grinding head, powered by a propane engine, is coupled to the forward portion of the frame. In contrast to all known designs, the engine is directly, mechanically coupled to the grinding head without the use of pulleys, belts or chains. The direct, mechanical coupling to the grinding head preferably uses a centrifugal clutch. A water tank and water feed line from the water tank to the grinding head facilitate wet floor grinding and polishing. The grinding head is also encased in a shroud coupled to a tube for dust collection associated with dry floor grinding and polishing.

Description

REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S. Provisional Patent Application Ser. No. 63/238,018, filed Aug. 27, 2021, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to hard floor resurfacing and, in particular, to a low-maintenance, walk-behind concrete grinder/polisher.

BACKGROUND OF THE INVENTION

Polished concrete floors are becoming increasingly popular for retailers, big-box stores, educational and medical facilities, and even residential applications. Common uses include warehouses and warehouse outlets, hotels and restaurants, office buildings and showrooms. Benefits include low cost, resistance to wear, low maintenance, and aesthetic appeal in many situations. Polished concrete floors are easy to clean, and the glossy surface of polished concrete resists the marks of forklift truck tires and staining from oil and chemical spills. The glossy appearance of polished concrete is desirable for office building, hotels, restaurants, and other public facilities that want to project a bright, clean, professional image.

Various different types of machines are used to achieve a polished concrete floor, including riding and walk-behind coarse and fine grinders and polishers using wet and dry techniques. Machines are also available for stripping and removing old floors, filling in cracks, applying concrete overlays, as well as slurry and dust collection.

The polishing process itself proceeds through a series of mechanical and grinding stages utilizing professional equipment designed for these purposes. The process may also include the use of a concrete “densifier” which penetrates into the concrete to harden and dustproof the surface. The concrete surface is processed through a series of steps with grinding and polishing disks having progressively finer grits. The disks are typically fabricated with industrial diamonds in a bonded material such as metal, resin or a combination thereof, often referred to as “diamond polishing pads.”

Typically the concrete goes through a process of grinding and polishing using aggressive equipment and abrasive elements or tooling, including pads of varying grit from 30 to 3,000. Concrete is considered “polished” until grits of 800 or finer are used, followed by finishing to 1500 3000-grit levels. The concrete may be ground without entering aggregate layers, or different sizes of aggregate may be exposed and polished to achieve different appearances. Dyes designed for concrete polishing are often applied to add color to polished concrete for borders, logos and decorative patterns. Such options provide a wide range of surface finish and color variations.

Concrete grinding and polishing begins with grinding pads or tools that have grits of 30, 70, and 120, which are used successively. These abrasive elements are rotated at a relatively slow speed during the grinding steps, e.g., at rotating speeds in the range of about 500 to 800 rpm. After grinding with the diamond pads, honing steps follow using grits of 50, 100, and 200, rotated at, for example, a speed of about 800 rpm. After about 200-grit honing step, dies or stains may be applied and, if necessary, a concrete densifier may be applied to the floor.

Polishing continues using a 400 grit or finer pad, with rotational speeds of the spindles and abrasive elements being in the range of about 800 to 1,100 rpm. The concrete will begin to develop a sheen, with the grit choice of the final polishing steps being dependent upon the reflection and shine desired. If the polishing process is continued through use of a 3000-grit pad, the concrete will assume a mirror-like finish. Burnishing may further promote a specular appearance. A topical sealer may be optionally applied to the finished floor.

The grinding and polishing steps may be dry or wet. With the latter, a water tank on-board the grinding/polishing machine delivers water to the diamond pads or resin pads through channels to the polishing head. With wet polishing, the generated slurry is collected with a squeegee, and with dry polishing the dust is collected with a vacuum. Typically, the polishing head is enclosed with a shroud that surrounds the rotating pads. A vacuum port is connected with a hose to an externally-provided vacuum, which may be nearby or wheeled alongside the grinding and polishing machine.

Although wet and dry techniques both have advantages and disadvantages, dry polishing tends to be faster, more convenient, and environmentally friendly. Wet polishing uses water to cool the diamond abrasives and eliminate grinding dust. The water acts as a lubricant to reduce friction, but cleanup is more involved. Wet polishing creates a tremendous amount of slurry that crews must collect and dispose of in an environmentally sound manner. With dry polishing, no water is required. Instead, the floor polisher is hooked up to a dust-containment system that vacuums up the mess.

In summary, the process of concrete floor polishing may include some or all of the following steps

• • Remove existing coating(s);
  • Deposit new layer of concrete onto uneven or damaged floor;
  • Seal cracks, joints or imperfections with an epoxy or other semi-rigid filler;
  • Progressively grind with a 30/40-, 80- and 150-grit metal-bonded diamond pads;
  • Optionally apply a chemical hardener to densify the concrete;
  • Progressively polish with a 100/200-, 400- and 800-grit resin or metal-bonded diamond pads;
  • Apply optional dye(s) for coloration;
  • Finish with a 1500- or 3000-grit resin-bonded diamond pads to achieve a desired sheen level; and
  • Optionally seal to help protect the polished surface and make it easier to maintain.

SUMMARY OF THE INVENTION

This invention improves upon the prior art by providing a walk-behind, wet/dry grinder/polisher adapted for concrete floors that does not use of pulleys, belts or chains. By eliminating the use of such “consumables,” maintenance is significantly enhanced, as such components are typically the first to wear out and cause replacement issues.

The grinder/polisher is constructed around a frame having forward and rear portions that pivots about a single set of right and left wheels. The rear portion of the frame includes a handle bar assembly. An engine is mounted on the frame, and a planetary grinding head, powered by the engine, is coupled to the forward portion of the frame. In contrast to all known designs, the engine is directly, mechanically coupled to the grinding head without the use of pulleys, belts or chains.

In the preferred embodiment the engine is a propane engine, and the direct, mechanical coupling to the grinding head uses a centrifugal clutch. A water tank and water feed line from the water tank to the grinding head facilitate wet floor grinding and polishing. The grinding head is also encased in a shroud coupled to a tube for dust collection associated with dry floor grinding and polishing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front, perspective view of a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

There are numerous walk-behind floor grinders and polishers, but they all use belts, pulleys or chains to couple the motor to the grinding head. This creates substantial maintenance issues, since these consumables are often the first components that need replacement, and if such replacement is required during a job and parts are not available, significant unwanted down time may be encountered.

This invention improves upon the existing art by providing a walk-behind floor grinder/polisher wherein the engine is directly, mechanically coupled to a planetary grinding head, thereby eliminating the need for belts, pulleys or chains.

FIG. 1 is a front, perspective view of a preferred embodiment of the invention, depicted generally at 100. The machine includes a frame 122 to which there is mounted an engine 114, which in this case happens to be a propane engine fed by a propane tank (not mounted). The engine includes an air intake 113 and catalytic exhaust 116 to reduce emissions.

The frame couples to a handle bar assembly 102 with right/left handles 103. The handle bar assembly 102 is hinged to the forward portion of the frame through a pivoting joint 104 with locking pins 105 enabling the handle bar assembly 102 to be adjusted and folded down for more compact transport. Various user controls are available on the handle bar assembly 102, including ignition switch 108, throttle 110, hour/tachometer 109 and emergency stop button 106,

The machine may be used for dry or wet grinding or polishing. For wet processing, water from tank 112, feeds the abrasives through water line 118. A floating shroud 120 (or rubber equivalent) covers the grinding head, and exhausts out tube 126 for dust collection if dry processing is used.

The unit pivots about right/left wheels 128, with gas springs 124 being used for weight distribution. While not visible in the photo, the engine 114 is directly coupled to the planetary grinding head through a centrifugal clutch. The clutch is between the engine and a middle gear box that acts as a speed reduce and torque increaser (2:1). Electric and manually engaged clutches may be implemented as alternatives to centrifugal. The middle gear box is bolted to the main planetary gearbox and, in turn, rotates the planetary heads. All rotational power is transmitted through shafts with keyways.

In contrast to all known designs, the engine is directly coupled to the grinding head without intervening belts, pulleys or chains. This substantially simplifies maintenance issues, since these consumables are often the first components that need replacement, and if such replacement is required during a job and parts are not available, significant unwanted down time may be encountered.

Claims

1. A walk-behind, wet/dry grinder/polisher adapted for concrete floors, comprising:

a frame having forward and rear portions that pivots about a single set of right and left wheels;

the rear portion of the frame including a handle bar assembly;

an engine mounted on the frame;

a planetary grinding head coupled to the forward portion of the frame and powered by the engine; and

wherein the engine is directly, mechanically coupled to the grinding head without the use of pulleys, belts or chains.

2. The grinder/polisher of claim 1, wherein the engine is a propane engine.

3. The grinder/polisher of claim 1, wherein the engine is directly coupled to the grinding head through a centrifugal clutch.

4. The grinder/polisher of claim 1, further including a water tank and water feed line from the water tank to the grinding head facilitating wet floor grinding and polishing.

5. The grinder/polisher of claim 1, wherein the grinding head is encased in a shroud coupled to a tube for dust collection associated with dry floor grinding and polishing.