Method and apparatus for improving operation of masonry saws and drills

Abstract

An improved method and apparatus for sawing or drilling concrete or like material comprises use of a fluid flow device for transmitting a stream of water from a pressurized water supply to the cutting elements of a masonry saw or core drill and for injecting a speed-enhancing compound into the stream of water, with the compound being injected under the influence of a venturi-induced suction force created by the stream of water as it flows through the device. Preferably the device includes means for varying the rate at which the speed-enhancing compound is sucked into the water stream.

Description

[0002] This invention relates to provision and use of means coupled to a masonry saw or core drill for facilitating the cutting or drilling of concrete or other hard masonry materials.

BACKGROUND OF THE INVENTION

[0003] As used herein the term “masonry material” means and includes concrete, steel-reinforced concrete, various kinds of rock including but not limited to granite, sandstone, fired brick, and tile. Special saws and drills are used for cutting and drilling those materials. Masonry saws take various forms, including rotary blade saws, ring saws, chain saws and wire saws. The drilling of lengthy holes, e.g., holes 10-20 inches long, in structures or structural components made of a hard masonry material is commonly accomplished with a core drill (also called “core drill bit”) attached to a manually operated driver. A core drill commonly comprises an elongate hollow tubular member, one end of which is adapted to be releasably secured to the rotatable output shaft of a driver that typically is an electrically powered or pneumatically powered device. The opposite end of the tubular member is in the form of or carries a tubular cutting head that may comprise diamond or carbide particles embedded in a metal matrix. The core drill derives its name from the fact that as it drills into concrete or other dense material the interior of the drill fills with a discrete cylinder, called a “core”, composed of particles of the material that is being drilled.

[0004] A common practice is to apply water to masonry saws and core drills to enhance cutting and drilling. When water is applied to saws, the sawing process is identified as “wet sawing”. The water is applied as a spray or jet(s) so as to flow over at least the cutting edge portion(s) of the saw device, e.g., the teeth of a chain saw, rotary saw blade or a wire saw. In the case of wet core drilling, the water is injected into the core drill. Injection of water into a core drill is accomplished by means of a coupling device that either is a component of the driver or is a separate component that may be detached when it is desired to perform dry core drilling.

[0005] Applying water aids the sawing process by cooling the cutting portion(s) of the saw device and removing saw residue from the work area. Similarly, injecting water into the core drill aids the drilling process by (1) cooling the drill, (2) facilitating movement away from the cutting head of the particles produced by the drilling operation so as to avoid unnecessary regrinding of those particles, and (3) reducing masonry dust in the work area. Consequently wet coring is preferred for renovation work in inhabited buildings where it is necessary to maintain a dust free environment. In such case it is common to surround the core drill with a water collector that serves to collect water, including suspended masonry particles, that escapes from the hole being drilled in the masonry. In core drilling of concrete, water may need to be supplied at a rate of as much as about 1 gallon per minute to achieve the desired cooling, whereas in wet sawing of concrete the water may need to be supplied at a rate as high as about 4-10 gallons per minute.

[0006] The speed at which cutting and drilling proceeds in concrete and other hard masonry materials is a function of the hardness of the material being cut or drilled. The harder the material, the lower the cutting or drilling speed, i.e., the rate of penetration of the material by the saw or drill head. As used herein, the term “cutting speed” identifies the rate, in terms of units of depth per unit of time, at which a saw cuts through, or a core drill penetrates, a masonry material. It is recognized that increasing the cutting and drilling rates in concrete and other like structural materials is desirable, if it can accomplished at reasonable cost. It is known that the cutting of concrete may be enhanced by applying an aqueous solution of one or more selected compounds to the cutting tool as it was cutting. See, for example, U.S. Pat. No. 5,196,401. However, there has existed a need for a practical, dependable and relatively inexpensive way of supplying masonry saw or core drill with cooling water containing a measured amount of a cutting speed-enhancing compound.

[0007] My copending U.S. patent application Ser. No. 09/834,314, cited supra, discloses an improved apparatus and method whereby a stream of cooling water applied to a drill or saw is dosed with a cutting speed-enhancing composition using a water-powered injector pump apparatus that comprises a reciprocating injection pump driven by a water motor. The cooling water is supplied under pressure to the water motor from a suitable water supply, e.g., a municipal water supply or a pressurized tank.

[0008] The apparatus disclosed in my copending patent application is easy to use, works dependably and provides adequate control of the rate at which the stream of cooling water is dosed with the selected speed-enhancing composition. However, water-powered injector pumps are relatively expensive and, because they have moving parts, are handicapped by the potential of breakdown and the cost and loss of time involved in repair. Care also must be taken to avoid accidental damage to the pumps by personnel or mechanical equipment operating at the same work site.

OBJECTS AND SUMMARY OF THE INVENTION

[0009] The invention stems from the desire to improve upon the invention disclosed in my copending U.S. patent application Ser. No. 09/834,314.

[0010] The primary object of this invention is to provide a method and apparatus for introducing a speed-enhancing composition into a stream of water applied to a saw or drill for cooling or rinsing purposes that avoids the use of a water-powered injection pump.

[0011] A more specific object is to provide a method and apparatus for dosing a stream of water applied to a masonry saw or drill that does not require a pump for accomplishing the dosing function.

[0012] The foregoing objects are achieved by using a venturi-effect chemical injector device to introduce a speed-enhancing compound into a stream of water as it is being applied to a masonry saw or core drill. In a first embodiment of the invention, a venturi-type injector device is installed in a pipe or hose line connecting a water supply to a masonry saw, and a speed-enhancing composition is injected into the water line by the injector device. In a second embodiment of the invention, a venturi type injection device is connected in a pipe or hose line connecting a water supply to a core drill that is attached to an electrically or pneumatically powered driver, and a liquid speed-enhancing surfactant-containing composition is injected into the water line by the via the injector device. In both embodiments the speed-enhancing composition is injected into the water line at a controlled rate as a function of the flow in the water line. In both embodiments the speed-enhancing composition is delivered only on a demand basis.

[0013] Other objects, features and advantages of the invention are described or rendered obvious by the following detailed description that is to be considered together with the drawings identified below.

THE DRAWINGS

[0014] FIG. 1 is a schematic view of a saw system embodying the present invention;

[0015] FIG. 2 is an exploded sectional view of one form of injector device; and

[0016] FIG. 3 is a schematic view of a core drill system embodying the present invention;

[0017] Like components are identified by like numerals in the drawings.

DETAILED DESCRIPTION OF THE INVENTION

[0018] FIG. 1 relates to a preferred embodiment of the invention and illustrates a conventional electrically powered saw 2 having a rotary blade 4 that is powered by an electric motor 6 controlled by a manually actuated switch 8. The blade 4 is provided with a protective blade guard or shroud 10 that covers a portion of the blade and has a port 12 therein through which cooling water may be injected onto the blade when the latter is being used to cut concrete or other masonry. The illustrated system also comprises a dosing device in the form of an injector 16 that comprises a housing 18 characterized by an inlet port 20, an outlet port 22, and a side injection port 24. Preferably the injector is of the venturi suction type that requires no moving parts for operation and permits adjustment of the rate at which liquid is injected via side injection port 24. Inlet port 20 is connected by a flexible or rigid conduit, e.g. a hose or pipeline, to a suitable supply of water 26 under pressure via a strainer 28 and a backflow preventer 30. The latter is for the purpose of preventing backflow of water to the water supply. The strainer 28 is to intercept any particulate matter in the water flowing to injector 16, e.g., dirt particles, that might adversely affect operation of the injector device. Preferably, but not necessarily, a main flow valve (“MV”) 31 may be provided in the water supply line on the inlet side of the injector to function as a shut-off valve when the same is not in use. Outlet port 22 is connected to the saw shroud port 12 via a check valve 32. Side injection port 24 is connected to a tank or other vessel 34 connecting a supply of a selected chemical additive via a flow control valve 36 and a strainer 38.

[0019] Venturi suction injectors are well known and may take various forms, but essentially they are characterized by a through bore that has a constriction and a side injection bore that intersects the through bore at the constriction. When liquid flow under pressure occurs in the main bore, a negative pressure is created at the constriction, with the result that liquid in the side injection bore is drawn into the through bore and mixes with the liquid flowing in the through bore. The control valve may be separate from the injector as shown in FIG. 1 or be attached directly to the injector housing.

[0020] FIG. 2 illustrates one form of injector device that is suitable for practicing the present invention. In this case the injector housing 18 has a through bore identified generally by numeral 42 that is characterized by inlet and outlet ports 20 and 22 at opposite ends of a constricted section 44. Housing 18 also has a side injection bore 46 that connects with side port 24 and intersects the constricted section 44 of through bore 42. The diameter of side bore 46 is smaller than that of constriction 44. The inlet and outlet ends of housing 18 have a reduced outer diameter as shown at 47 and 48 that are adapted for connection, e.g., by external screw threads (not shown), to other components of the system shown in FIG. 1. The side port 24 is provided with an internal screw thread 50 for attachment of an injection flow control valve assembly 36A shown in FIG. 2.

[0021] The latter comprises a tubular housing 62 having a first external thread 64 at its inner end and a second external thread 66 at its outer end. The external thread 64 permits the inner end of housing 62 to be screwed into the side port 24 of housing 18. Housing 62 has an internal flange 68 intermediate its opposite ends, with the flange defining a fixed diameter orifice 70. Mounted within housing 62 is a combination valve element/flow connector unit 72 that consists of an inner valve section 74 having an outer diameter that is substantially the same as or slightly larger than that of orifice 70, an outer connector section 76 that is adapted, e.g., by a ribbed outer surface or an external screw thread (not shown), for facilitating a friction grip or screw thread connection of the conduit (flexible hose or pipeline) that leads to additive supply 34 as described above, and a large diameter intermediate section 80 that is sized to make a close sliding fit with the inner cylindrical surface of housing 62.

[0022] The unit 72 has an axial bore 82 that terminates in an end wall 84 at its inner end and communicates with a diametrically-extending discharge bore 86 that provides two opposite side discharge ports whereby additive in bore 82 will flow into housing 62 and then into orifice 70. A hollow knob 88 surrounds housing 62 and has an internal screw thread that makes a screw thread connection with screw thread 66. The outer end of the knob has an end wall 90 with a center opening that is slightly larger than the maximum diameter of outer connector section 76, and the latter extends through that center opening. The end wall 90 overlies and engages the annular outer end surface of intermediate section 80. A compression coil spring 92 surrounds valve section 74, with one end of the spring engaged with the outer surface of flange 68 and the other end engaged with the annular inner end surface of intermediate section 80. The effect of spring 92 is to urge the unit 72 outwardly away from housing 18 so as to maintain a gap between the inner end of valve section 74 and orifice 70, whereby liquid additive in axial bore 82 can be sucked into the through bore 42 of housing 18 via bore 82, diametric bore 86, orifice 70 and side bore 46.

[0023] Rotation of knob 88 functions to vary the gap between the inner end of valve section 74 and orifice 70, with rotation of the knob in one direction allowing the spring 92 to move the unit 72 move away from orifice 70, thus increasing the gap between the valve section 74 and orifice 70, and rotation of the knob in the opposite direction causing its end wall 90 to force the unit 72 toward orifice 70 so as to decrease the gap. Varying the size of the gap between valve section 74 and orifice 70 has the effect of varying the flow of liquid through orifice 70 into port 24. The combination of valve section 74 and orifice 70 functions essentially as a needle-type valve.

[0024] By way of example but not limitation, a venturi injector of the type represented in FIG. 2 is available commercially in the form of the Model YSSAINJ23 adjustable injector produced by General Pump of 1174 Northland Drive, Mendota Heights, Minn. 55120. Other forms of commercially available venturi type injectors also may be use in practicing the invention, e.g., an injector as shown in U.S. Pat. No. 6,453,926, issued Sep. 24, 2002 to G. A. Baker.

[0025] Operation of the system shown in FIG. 1 is straightforward. When water under pressure flows from supply 26 through injector housing 18, the pressure drop produced by constricted section 44 (the venturi effect) creates a suction force that draws additive into the injector housing via the injector valve assembly 36A.

[0026] FIG. 3 shows an alternative embodiment of the invention comprising a conventional core drill bit 100 and a conventional electrically powered heavy-duty driver 102 for driving the drill bit. The latter is shown in exploded relation to the driver for convenience of illustration and description. The driver is shown as having a power cord 104 for coupling it to an electrical power source. The illustrated core drill bit 100 comprises an elongate hollow cylindrical barrel 106 having a hollow cylindrical drill head 108 at its forward end. Typically the drill head 108 comprises diamond or silicon carbide particles embedded in a strong metal matrix. Core drill bit 2 may take other forms without affecting the invention. Core drill bits are available commercially from a number of companies. One such company is Hilti, a corporation having a place of business at 12330 E. 60th Street South, Tulsa, Okla. 74121.

[0027] The output end of the driver includes a chuck 110, which is adapted to receive and releasably lock the core drill bit to the driver. The design and construction of the driver is not critical to this invention. Various forms of core drill drivers are available commercially from a number of companies, including Hilti (supra) and Flex Porter-Cable, a company having a place of business at 4825 Highway 45 North, Jackson, Tenn. 38305.

[0028] A water intake device 112 is interposed between core drill bit 102 and chuck 110. The water intake device 112 is designed to inject water into the interior of the core drill as it is rotated to execute a drilling operation. For this purpose water intake device 112 has an inlet port 114 whereby water can be delivered from a source of supply 116 into water intake device 112 and from there into the core drill bit during a drilling operation. As with the embodiment of FIG. 1, the water supply 116 may be a domestic water supply. As used herein, the term “domestic water supply” is intended to include municipal and non-municipal water sources, including commercially or privately owned wells, that are capable of providing a continuous flow of water under a suitable near constant or regulated pressure.

[0029] Water intake device 112 may be a separate component that can be removed when it is desired to perform dry core drilling; alternatively it may be built as an integral part of the chuck assembly. Thus, for example, the water intake device may take the form of the water swivel attachment sold by Hilti under the designation “Hilti DD 100 ⅝″ Water Swivel” which is adapted for use with the Hilti DD-100 Drill (i.e., driver). The Hilti water swivel functions to rotatively connect a core drill to the driver's chuck and also to inject water into the core drill bit. Alternatively, and further by way of example, the driver 104 and water intake device 112 may take the form of the Flex Porter-Cable Model BHW 812 V electrically-powered driver which has a built-in water intake. Whether the water intake device is a separate component or is an integral part of the driver is not critical to the invention, and the water intake device may take various forms so long as it satisfies the requirement of providing means for directing water into the core drill bit as the latter is driven by the driver into concrete or other masonry material.

[0030] The system of FIG. 3 further includes the use of a dosing device in the form of a venturi-type injector 16 as described above for introducing a selected chemical additive to the water that is supplied to water intake device 112. Port 114 is connected to the water supply 26 via a backflow preventer 120, a strainer or filter 122, a main valve (“MV”) 124, injector 16 and a check valve 126. The backflow preventer 120 and strainer 122 prevent backflow of water to the water supply and removal of any particulate matter that might adversely affect operation of the injector device. Check valve 126 prevents backflow of solid particle from the core drill to the injector.

[0031] Operation of the system shown in FIG. 3 is essentially the same as that of FIG. 1. Flow of water under pressure from water supply 116 causes additive to be injected into the water stream flowing to water intake device 114, according to the setting flow control valve 36. It is to be noted that valve 36 in both FIG. 1 and FIG. 3 the valve 35 may be set to a fully closed position, whereby no additive will be injected into the water stream flowing to the cutting tool.

[0032] As has been noted in my copending application Ser. No. 09/834,314 (which is incorporated herein by reference) it has been determined that addition of a surfactant to the cooling water for a concrete saw or core drill can provide a substantial increase in the speed at which such tools penetrate concrete, and also in reduced wear of the cutting elements of the tool. Accordingly the liquid additive supplied by operation of the proportioning device comprises an aqueous solution of one or more surfactants. The invention is not limited to particular surfactants, and the surfactants may be anionic or cationic materials. Surfactants like those used in household and industrial detergent compositions may be used with the invention to improve drilling and cutting speeds. Examples of anionic surfactants that are useful with the invention are alkyl benzyl sulfonate, alkyl sulfates derivatives of coconut oil and tallow, sodium dodecyl sulfate, and alkyl ether sulfate. An example of a suitable cationic surfactant is trimethyldodecyl ammonium chloride. Still other cationic surfactants are known to persons skilled in the art. Preferably the surfactant is a non-ionic polymer capable of hydrogen bonding with water to produce charge-neutralizing positive charge dipoles, e.g., a polyalkylene oxide such as polyethylene oxide and a polyacrylamide-based non-ionic polymer is preferred. The use of such non-ionic polymers in relation to cutting or drilling rock or concrete, and the resultant benefits of increased cutting speed and reduced cutting element wear, is discussed in detail in U.S. Pat. No. 5,196,401, issued Mar. 23, 1993 to W. H. Engelmann et al. The minimum concentration of such polymer in the aqueous solution injected into core drill 2 should be about 1-3 parts per million. That concentration is easily accomplished with a proportioning pump of the type described. Still other surfactants that may be used in drilling or cutting concrete or like material according to the invention are disclosed by U.S. Pat. No. 5,807,810, issued Sep. 15, 1998 to M. Blezard et al. The teachings of U.S. Pat. Nos. 5,196,401 and 5,807,810 regarding use of surfactants for cutting materials like concrete and rock are incorporated herein by reference. Of course, the optimum concentration of surfactant in the aqueous solution may vary according to the specific surfactant used.

[0033] The advantage of using an injector-type dosing device of the character described is that it facilitates injection of small amounts of additive solution into a stream of water flowing under a high pressure, is rugged, has a long useful life since it has no moving parts, and is relatively inexpensive. By way of example, venturi-type injectors are available that an accommodate water flow in the range of 1-300 gallons per hour. This is important not only from the standpoint of enhancing the cutting speed, but also from an economical basis, since in using saws to cut concrete walls or floors, the consumption of water may vary substantially depending on various factors, including the hardness of the masonry material. Available injectors of the type described are capable of injecting an additive solution into the water stream flowing through the injector at a controlled rate so as to provide a selected ratio of additive flow to water stream flow. By appropriately diluting the additive solution it is possible to limit the concentration of speed-enhancing compound injected into the flowing water stream to within, for example, the range of 1-150 parts per million.

[0034] An additional advantage is that the presence of a flow control valve for injection of additive via the side injection port makes it possible to increase or decrease the rate of introduction of additive into the cooling water fed to the saw or core drill without changing the concentration of additive in the solution contained in supply vessel 34. This aspect is important since the rate of flow of water through the injector must be kept above a minimum level in order achieve the desired venturi-effect injection of additive. Additionally the invention provides a benefit of economy in that the additive is supplied to the sawing or drilling operation only when water is flowing to the saw or drill. Consequently, and particularly considering the relative high cost of certain surfactants, the use of the liquid surfactant additive is controlled. A further advantage is that use of an injector device of the type described in place of an injection pump reduces equipment cost.

[0035] Obviously the invention may be practiced otherwise than as described above and illustrated in FIGS. 1-3. Other forms of injection may be used. Also strainers 28 and 122, backflow preventers 30 and 120, and main control valves 31 and 124 may be omitted where there is no need for them. The injector also is applicable to pneumatically powered tools in place of electrically powered tools. Also the invention may be applied to different forms of drills and saws. For example, although saw 2 is represented as a rotary blade saw, it is to be understood that the invention may be practiced with other types of saws for cutting concrete, notably ring saws, chain saws and wire saws. The invention also is not limited in its application to saws employed at construction work sites, but extends as well to saws used in quarries and various stone work shops.

[0036] It is to be noted also that the invention is not limited to supplying cooling water. Instead, for example, the cooling medium supplied to the proportioning pump 18 could be a light oil, with the proportion of speed-enhancing surfactant compound and the selection of speed-enhancing compound being adjusted according to whether oil or water is being used as the cooling medium.

[0037] As used herein, the term “conduit” herein shall mean and include, where the context so admits, a hose, tubing or pipe. Also the term “cutting device” as used in the claims in intended to embrace and include core drills and saws and, where the context so admits the drivers for such cutting devices. The cutting elements of a saw are its cutting teeth, and the cutting elements of a core drill are the teeth of and/or the diamond or silicon carbide particles carried by the cutting head of the drill.

[0038] Still other modifications and variations of the invention will be obvious to persons skilled in the art from the foregoing description and the FIGS. 1 and 2.

Claims

1. A method for improving the rate at which a driven cutting device penetrates a masonry material such as concrete, granite or other rock, sandstone, fired brick or a like material using a core drill, said method comprising: passing a cooling stream of water to said cutting device; and injecting a speed-enhancing composition into said stream of water by a venturi-induced suction force.

2. A method according to claim 1 wherein said driven cutting device is a saw.

3. A method according to claim 1 wherein said driven cutting device is a core drill.

4. A method according to claim 1 wherein said stream of water is passed to said cutting device by means of an injection device having a through passageway with a constriction therein, and said venturi-induced suction force is produced by said stream of water flowing through said constriction.

5. A method according to claim 1 herein said composition is introduced into said passageway via a side port in said device.

6. A method according to claim 5 wherein said composition flows into said side port from a supply vessel via a flow control valve.

7. A method according to claim 1 wherein said speed-enhancing composition is a solution of a surfactant.

8. A method according to claim 7 wherein said surfactant is an anionic compound.

9. A method according to claim 7 wherein said surfactant is cationic compound.

10. A method according to claim 7 wherein said surfactant is a non-ionic polymer capable of hydrogen bonding with water to produce charge-neutralizing positive charge dipoles.

11. A method according to claim 10 wherein said non-ionic polymer is a polyalkylene oxide or a polyacrylamide-based non-ionic polymer.

12. Apparatus for improving the rate at which a driven cutting device penetrates a masonry material such as concrete, granite or other rock, sandstone, fired brick or a like material using a core drill, said apparatus comprising: water-directing means for directing a flow of water to said cutting device; and a venturi liquid injection device having a water flow-through passageway, inlet and outlet ports communicating with said passageway, and an injection port communicating with said passageway, said outlet port being connected to said water-directing means, said inlet port being adapted to be connected to a water supply and said injection port being adapted to be connected to a supply of a liquid speed-enhancing composition; said injection device being designed so that a stream of water flowing under pressure in said passageway from said inlet port to said outlet port will produce a venturi-induced suction force in said injection port sufficient to cause injection of a liquid speed-enhancing composition into said passageway via said injection port when said injection port is connected to a supply of said composition.

13. Apparatus according to claim 12 wherein said injection passageway has a constriction and said suction force is produced by the flow of water under pressure through that constriction.

14. Apparatus according to claim 12 wherein said driven cutting device is a saw.

15. Apparatus according to claim 12 wherein said driven cutting device comprises a core drill.

16. Apparatus according to claim 12 further including flow control valve means associated with said injection port for varying the rate at which liquid is injected into said passageway by said venturi-induced suction force.

17. Apparatus according to claim 16 wherein said injection device comprises a housing having said through passageway and said injection port, and said flow control valve is attached directly to and supported by said housing.

18. Apparatus according to claim 17 wherein said flow control valve means comprises an injection orifice and means for varying the effective size of said injection orifice.