Patent Publication Number: US-9840027-B2

Title: Reversible blade guard assemblies

Description:
BACKGROUND 
     The present disclosure relates generally to blade guard assemblies. In particular, blade guard assemblies for concrete saws that are designed to be reversibly mounted on either side of the saw are described. 
     The preparation of concrete pads is a common practice in the construction industry. Concrete pads are used in parking lots, roadways, as foundation slabs, in parks, patios, and any number of other building applications. Owing to its water-based nature, concrete naturally shrinks as it cures, due to the loss of water. This shrinking occurs first at the surface of the concrete, which is the location of water evaporation. Consequently, left to cure untended, concrete pads of sufficiently large size will develop cracks as they dry, which can compromise the concrete&#39;s integrity and mar an otherwise smooth surface. 
     One solution to prevent cracking during the curing process is to cut expansion gaps into the concrete surface early in the curing process, known as early entry cutting. These expansion gaps provide a space for surface tension to be relieved as the concrete further shrinks, thereby preventing cracks from developing in the slab. The concrete is typically cut from ¼ to ⅓rd of its depth. The timing of the cutting is critical; the concrete must cure sufficiently to withstand the weight of the concrete saw without marring its surface, but not have dried to the point where a saw requires water for cutting, or has begun to crack. Concrete at this point is known as green. Although a diamond masonry blade is used, due to the concrete still having relatively high water content, a saw cutting green concrete does not need water. As the concrete lacks the strength of fully cured concrete, the concrete saw must provide pressure against the concrete work surface immediately adjacent to the blade kerf to prevent spalling of the sides of the crack. 
     This pressure is supplied by a blade guard assembly attached to the concrete saw that houses the saw blade. The blade guard assembly also serves a safety function by substantially enclosing the rotating saw blade, and by channeling dust from the cutting action to keep the surrounding work area clear from the potential formation of dust clouds. The blade guard is typically immovably affixed to the concrete saw at the end of a drive shaft, to which is attached an arbor, to which the saw blade is further attached. 
     Known blade guard assemblies are not entirely satisfactory for the range of applications in which they are employed. For example, existing blade guard assemblies used on concrete saws employed in early entry applications are typically capable of being mounted on only one side of the saw. As concrete saws are bulky, walk-behind machines, having the blade assembly able to mount on only one side of a machine can pose problems on certain projects, such as when surrounding obstacles may prevent saw movement or not provide proper support for a clean cut. Often, being able to relocate the blade assembly to the opposite side of the machine will easily remedy these situations. The design of known blade guard assemblies tends to be unidirectional; mounting the blade guard on the opposite side of a machine may result in improper work surface contact and potential damage to the saw blade and green concrete. Consequently, operators of a saw that can accept a blade assembly on either side typically must carry a separate blade guard specific for each side of the machine, which increases costs. 
     A crucial part of the blade guard assembly is the blade shoe, through which the saw blade passes. The blade shoe serves as the contact point between the blade guard assembly and the work surface, and is the means by which pressure is applied to the work surface surrounding the blade kerf during cutting. The typical blade shoe configuration is substantially an elongated rectangular plate, with a centrally located slot through which the blade passes. Pressure supplied via the weight of the concrete saw and associated pressure devices is transmitted through the blade shoe to the work surface immediately surrounding the blade kerf. 
     In operation of the concrete saw, the blade shoe is subject to wear over time, which degrades both cut quality and blade life. As the concrete saw is moved forward in operation, the blade shoe slides upon the surface to maintain appropriate pressure. The blade cutting action generates dust, which is cleared from the cut primarily at the point where the blade rotates up out of the kerf. Depending on blade rotation, this point will be at either of the ends of the centrally located slot. This generated dust is abrasive in nature and, consequently, results in end of the centrally located slot wearing substantially faster than other portions of the slot, this wear being expressed as a noticeable widening of the slot. The widened slot, in turn, reduces the amount of pressure placed on the work surface immediately around the point where the blade is retreating from the work surface. Due to the retreating blade and dust ejection, this point is where opposing forces from the cutting action are at a maximum, and a slot that is widened due to wear is unable to effectively oppose these forces where they are immediately experienced. As a result, spalling of the work surface occurs, and due to the rougher cut, blade wear is increased with a commensurate decrease in blade life. Because the blade shoe is typically a single piece of cast or forged metal, a worn blade shoe must be replaced as a single piece, often at an elevated cost. Costs are further elevated by the fact that the blade and the shoe typically are replaced as a set; if the blade shoe wears, the blade must also be replaced, even if the blade would otherwise still have useful life. 
     Thus, there exists a need for blade guard assemblies and improved blade shoe designs that improve upon and advance the design of known blade guard assemblies and blade shoes. Examples of new and useful blade guard assemblies and blade shoes relevant to the needs existing in the field are discussed below. 
     Disclosure addressing one or more of the identified existing needs is provided in the detailed description below. Examples of references relevant to blade guard assemblies and blade shoes include U.S. Pat. No. 8,276,578. The complete disclosures of the above patents and patent applications are herein incorporated by reference for all purposes. 
     SUMMARY 
     The present disclosure is directed to a reversible blade guard for a concrete saw that can be mounted on either side of the saw, and is equipped to quickly be reconfigured depending upon the side of the saw upon which it is mounted. A mechanism for applying pressure to the work surface through a blade shoe is disclosed as part of the blade guard. In addition to allowing for truck reconfiguration of the blade guard as appropriate, the pivoting attachment points between the blade housing and the blade shoe aid in providing consistent pressure upon the work surface, even over minor surface irregularities. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of an example blade guard assembly, showing the blade shoe in place and the cover to one. 
         FIG. 1B  is a perspective view showing the back side of the blade guard assembly depicted in  FIG. 1A . 
         FIG. 2  is a perspective view of the blade housing and base plate of blade guard assembly depicted in  FIGS. 1A and 1B . 
         FIG. 3  is a perspective view showing the blade guard assembly depicted in  FIGS. 1A and 1B  attached to a concrete saw, with the cover in place. 
         FIG. 4  is a perspective view showing the blade guard assembly depicted in  FIG. 3  with the cover removed, showing the saw blade in place within the blade guard assembly. 
         FIG. 5  is a perspective view showing the cover for the blade guard assembly depicted in  FIGS. 1A and 1B . 
         FIG. 6A  is a perspective view showing the blade shoe assembly as it interfaces with the blade guard assembly depicted in  FIGS. 1A and 1B . 
         FIG. 6B  is an exploded view of the blade shoe assembly depicted in  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION 
     The disclosed reversible blade guard assemblies will become better understood through review of the following detailed description in conjunction with the figures. The detailed description and figures provide merely examples of the various inventions described herein. Those skilled in the art will understand that the disclosed examples may be varied, modified, and altered without departing from the scope of the inventions described herein. Many variations are contemplated for different applications and design considerations; however, for the sake of brevity, each and every contemplated variation is not individually described in the following detailed description. 
     Throughout the following detailed description, examples of various reversible blade guard assemblies are provided. Related features in the examples may be identical, similar, or dissimilar in different examples. For the sake of brevity, related features will not be redundantly explained each example. Instead, the use of related feature names will cue the reader that the feature with a related feature name may be similar to the related feature in an example explained previously. Features specific to a given example will be described in that particular example. The reader should understand that a given feature need not be the same or similar to the specific portrayal of a related feature in any given figure or example. 
     With reference to  FIGS. 1A -_, an example of a reversible blade guard assembly, blade guard  100 , will now be described. Blade guard  100  functions to provide a blade guard that can be reversibly mounted on either side of a concrete saw that is equipped to receive a guard on either side, requiring only minimal reconfiguration by reversing the direction of the blade shoe, if the blade shoe is not symmetrical. The reader will appreciate from the figures and description below that blade guard  100  addresses shortcomings of conventional blade guard assemblies. 
     For example and as can be seen in the figures, blade guard  100  can be mounted on either side of a concrete saw equipped with suitable mounting points. This is facilitated by the blade guard&#39;s substantially symmetrical configuration, with a tension mechanism on either end that maintains a downward pressure of the blade shoe. The blade shoe attaches to blade guard  100  by two detachable pivot points associated with each tension mechanism, thereby allowing the blade shoe, which may be unidirectional, to be mounted facing either direction, depending upon the side of concrete saw upon which blade guard  100  is attached. Thus, blade guard  100  can be swapped between sides of a concrete saw with a minimal amount of reconfiguration and no required additional side-specific parts, while suffering no diminishment of functionality. 
     Blade guard  100  is attached to a concrete saw and enshrouds a concrete cutting saw blade  130 , which passes through a blade shoe. When mounted properly, blade guard  100  helps to contain and channel cutting dust and residue, apply appropriate pressure to the work surface so as to facilitate a clean cut, and extend the useable life of the saw blade. As will be described below, blade guard  100  in conjunction with the blade shoe includes a series of flanges that help to better contain dust and neatly channel it to the sides of the blade kerf. 
     In  FIGS. 1A-B  reversible blade guard  100  is comprised of a blade housing  102  that includes a plurality of attachment points  104  for mounting blade housing  102  to a concrete saw. A blade shoe  106  is attached to blade housing  102  via a plurality of connectors  108  attached to and extending from blade housing  102 . Connectors  108  allow blade shoe  106  to be removably affixed to blade housing  102 , wherein each of plurality of connectors  108  removably attaches to blade shoe  106  in a pivotable fashion such that blade shoe  106  can rotate within the plane of blade housing  102 . Each connector  108  allows blade shoe  106  to slide within the plane of blade housing  102  so as to increase or decrease distance from blade housing  102 , and applies pressure against blade shoe  106  as it slides towards blade housing  102 . Importantly, the attachment points  104  and plurality of connectors  108  allow the blade guard assembly to be reversibly mounted. Mating with blade housing  102  is cover  120 , which in conjunction with blade housing  102  encloses a substantial portion of saw blade  130 . 
     As can be seen in  FIG. 2 , blade housing  102  is comprised of a base plate  122  that is preferably semicircular in shape, with a perimeter edge  124 , and a flange  126  disposed upon at least part of perimeter edge  124 . Although perimeter edge  124  and associated flange  126  are depicted as semicircular in the figures, a person skilled in the relevant art will understand that any shape suitable for containing the saw blade can be utilized, such as a square or polygon. A notch  128  is provided in base plate  122  that extends inward from perimeter edge  124  and is positioned so as to allow a circular saw blade  130  to be mounted on an arbor within blade housing  102 . Alternatively and depending on the concrete saw being used, notch  128  can be instead implemented as a hole large enough to pass through the blade arbor, in which case the hole can be disposed in base plate  122  away from the perimeter edge. 
     In the preferred embodiment and as can be seen in  FIG. 2 , base plate  122  is shaped roughly like half of a saw blade  130 , so as to conform to the profile of a blade. Thus, as illustrated in the figures base plate  122  has a semicircular perimeter edge  124  that intersects with a straight perimeter edge  144 . As described in the foregoing paragraph, suitable shapes other than a semicircle could be utilized, and the shape of base plate  122  would be defined by the shape of perimeter edge  124 . Notch  128  preferably bisects and extends from the straight perimeter edge. Base plate  122 , along with flange  126 , can be manufactured from metal, plastic, wood, composites, or any other suitably rigid material now known or later developed. Base plate  122  and flange  126  can be manufactured from the same or differing materials. 
     Flange  126  is attached to semicircular perimeter edge  124  of base plate  122  on one side, and extends from base plate  122  perpendicularly in a direction away from the concrete saw. Flange  126  also may extend past the two points where semicircular perimeter edge  124  intersects with the straight perimeter edge  144 , so as to form two protrusions  136  that extend downward past base plate  122  towards blade shoe  106 . Flange  126  can either be molded as an integral part of base plate  122  during forming, be fabricated from an appropriate long rectangular strip that is attached on one long side to perimeter edge  124 , or in any other fashion known in the art or later developed. Flange  126  can be attached by welding, glue, or other mechanical fastening means such as rivets, screws, press-fitting, folding over of a second flange, or any other suitable means of attachment. Flange  126  can be manufactured from the same or a different material as base plate  122 . 
     Although the figures depict protrusions  136  as being integral with flange  126 , protrusions  136  can also be implemented as separate mountable components that are secured to the ends of flange  126  by screws, welds, adhesives, clamps, or any other temporary or permanent method of affixation. 
     Attachment points  104  are typically located on base plate  122 , and may be as simple as a series of holes for passing through mounting bolts that attach into the underlying mounting structure on the receiving concrete saw. Alternatively, attachment points  104  may be hooks, notches, recesses, clamps, or any other appropriate mechanism that allows blade guard  100  to be removably attached to a receiving concrete saw. The number and type of attachment points  104  will vary depending on the saw model, or some blade guards  100  could be equipped with several types of attachment points  104  to allow them to be used with a number of different saw models. Attachment points  104  will preferably allow blade guard  100  to securely be attached to a stationary structure on the receiving concrete saw, such as the saw frame, although the structure of the concrete saw to which blade guard  100  is attached may vary depending on the saw model and intended use. Still further, attachment points  104  could mate with an intermediate adapter that would enable blade guard  100  to be mounted to any type of saw via an appropriately configured adapter. In such an arrangement, a single blade guard  100  could be made for a universal fit, with only different adapters needed depending on the selected saw model. Attachment points  104  may, as applications require, be located on components or blade guard  100  other than base plate  122 . 
     In the preferred embodiment, blade guard  100  has two connectors  108 , with each connector  108  attached on either end of blade housing  102 . Connectors  108  serve to hold blade shoe  106  in proper position relative to blade housing  102  and a saw blade mounted therein and, in conjunction with tensioning devices  118 , transmit force to keep blade shoe  106  under pressured contact with a work surface. Connectors  108  are designed to cooperate with corresponding mount points  202  on blade shoe  106  to provide a pivot point at each mount point  202 , thereby allowing blade shoe  106  to ride over possible work surface irregularities. While the preferred embodiment has two connectors, it will be appreciated by a person skilled in the relevant art that alternative configurations having more than two connectors, or potentially one connector, could be implemented depending on the specific application needs, without departing from the disclosed invention. 
     In the example shown in  FIG. 1A , each connector  108  is further comprised of a shaft  110  having a first end  112  that removably and pivotably attaches to blade shoe  106 , and a second end  114 . A corresponding keyway  116  is attached to blade housing  102  and receives second end  114  of shaft  110  such that shaft  110  is capable of sliding axially through keyway  116  and is substantially prevented from moving laterally with respect to keyway  116 . A tensioning device  118  is removably affixed to both shaft  110  and keyway  116  such that force is applied against shaft  110  as it moves within keyway  116 . Specifically, as shaft  110  moves inward through keyway  116  in the direction of blade housing  102 , tensioning device  118  applies force resistive of the movement, urging shaft  110  to move away from blade housing  102 , and thereby creating pressure between blade shoe  106  and the work surface to be cut. 
     In the figures, tensioning device  118  is depicted in its preferred implementation as a plurality of springs, with two springs per connector  108 . The type of spring should be selected with the goal of maintaining sufficient pressure by blade shoe  106  against the work surface so as to prevent spalling, but not so great a pressure that a green concrete surface is marred, or travel of the concrete saw is impeded. Furthermore, connector  108  could be configured so as to allow adjustable tension, to accommodate potential variations in work surface or job requirements. Such adjustment mechanisms could include provisions to remove or attach additional springs, or an adjustment knob for pretensioning the springs. 
     A person skilled in the relevant art will also appreciate that many possible implementations of tensioning device  118  are possible without departing from the disclosed invention. Possible variations include more or fewer springs, or different types of pressure or tension devices such as gas cylinders or struts, spring cartridges, or any other method of applying pressure in response to linear movement now known or later developed. Depending on how tensioning device  118  is implemented, it will be understood by a person skilled in the relevant art that connector  108  may lack a number of the various aforementioned components of connector  108 , as tensioning device  118  may implement the functionality of the various components in a different fashion. Such varying implementations do not depart from the disclosed invention. Any varying implementation will be expected to at least have some version of a first end  112  that offers a connection point to blade shoe  106 . 
       FIGS. 3 and 4  depict blade guard  100  as attached to a concrete saw.  FIG. 3  depicts blade guard  100  with cover  120  in place over blade housing  102 , while  FIG. 4  depicts cover  120  removed and blade  130  visible.  FIG. 5  depicts cover  120  that fits over blade housing  102  to enclose saw blade  130  in greater detail. As can be seen in the figures, the shape defined by cover  120  generally corresponds to the shape defined by flange  126  so that base plate  122 , flange  126  and cover  120  all cooperate to substantially enclose saw blade  130 . Cover  120  can be manufactured from the same general types of materials as blade housing  102 , and need not be of the same type of material. Such materials include metal, plastics, wood, composites, or any other suitable material. 
     Referring to  FIGS. 6A and 6B , blade shoe  106  improves upon existing blade shoe designs by employing a spring plate  206  that removably attaches to a backing plate  204 , in contrast to the existing approach of using a single cast, forged, or machined plate. The spring plate, when mounted to the backing plate, presents a convex shape that compresses upon lowering to the work surface, thereby adding additional even pressure across the work surface immediately adjacent to the blade kerf. Furthermore, owing to its flexibility, the spring plate can better conform to surface irregularities (such as rises, ridges dips, and crowns) that are smaller than the length of blade shoe  106 . The prior art blade shoe would simply ride over these irregularities, resulting in varying amounts of pressure being applied to the work surface, and increasing the chance of spalling. The conforming spring plate ensures a more consistent pressure over these surface irregularities. 
     Additionally, the spring plate presents the surface in direct contract with the work surface, as opposed to the backing plate. The spring plate is preferably manufactured from less expensive materials, is overall less expensive due to less material utilized, and will wear first while substantially preserving the backing plate. The spring plate can preferably be adjusted in position so as to allow repositioning of the spring plate as it wears, thereby extending the useful life of the spring plate. Once the spring plate can no longer be repositioned to maintain functionality, it can be replaced without the need to replace the entire blade shoe  106  assembly. 
     As can be seen in  FIGS. 6A and 6B , blade shoe  106  is comprised of a backing plate  204 , to which is removably mounted a spring plate  206  that contacts the work surface. Backing plate  204  is roughly rectangular in shape, with at least one mounting point  208  affixed on either end. Centered along the longitudinal axis of blade shoe  106  is blade slot  210 , through which the saw blade passes into the work surface. Mounting points  208  interface with connectors  108  for mounting on blade guard  100 . Backing plate  204  is constructed from any suitable material that is capable of sustaining the downward pressure placed by the concrete saw in use upon the work surface. Suitable materials include aluminum, steel, plastics, composites, or any other similarly suitable material now known or later developed. 
     Spring plate  206  has a centrally located slot  302  sized so as to receive a saw blade, and located along the longitudinal axis of spring plate  206 . One end of spring plate  206  possesses a plurality of notch sets  304 . Spring plate  206  removably mounts to backing plate  204  via a slot on one end of backing plate  204  provided by one mounting point  208 , and a catch on the other end of backing plate  204  presented by the opposing mounting point  208  located longitudinally distal from the slot that engages a corresponding notch set  304 . The details of each mounting point  208  will be described in greater detail below. The slot and catch mechanism together center spring plate  206  along the longitudinal axis of backing plate  204  so that centrally located slot  302  lines up with corresponding blade slot  210  on backing plate  204 . Plurality of notch sets  304  are positioned on spring plate  206  such that the slot and catch mechanism retain spring plate  206  in a flexed condition, so as to cause spring plate  206  to exert pressure upon a work surface when compressed by lowering the concrete saw. 
     Turning to  FIGS. 6A and 6B , the details of blade shoe  106 , and specifically preferred implementation of the aforementioned slot and catch mechanism, are shown. On the leading end of backing plate  204  is an attachment point receiver  306 , which is slotted to receive a hook on first end  112 . By using a slot and hook configuration, it can be seen that blade shoe  106  is pivotably attached to first end  112 ; that is, blade shoe  106  can rotate about first end  112  within the plane of blade housing  102  and saw blade  130 . Receiver  306  fits upon one end of backing plate  204 , and includes a slot to retain the front end of spring plate  206 . On the trailing end of spring plate  206  is a combination of second attachment point receiver  308  along with a spring plate retention fitting  310 . Receiver  308 , like receiver  306 , includes a slot to receive a hook on first end  112  to facilitate a pivoting mounting point. Receiver  308  is also sized to slidably receive spring plate retention fitting  310 . Notch sets  304  engage against spring plate retention fitting  310  to securely retain spring plate  206  is a semi-compressed state. Receiver  306 , receiver  308 , and spring plate retention fitting  310  are all manufactured out of materials similar to backing plate  204 , such as metal, plastic, composites, or any other suitable material now known or later developed that is capable of withstanding the pressures and forces exerted during concrete saw operation. 
     Receivers  306  and  308  each include an opposing protrusion  134  that is disposed adjacent to corresponding protrusions  136  from flange  126 . The combination of opposing protrusions  134  and protrusions  136 , together with blade housing  102 , combine to substantially completely enclose saw blade  130  while the concrete saw is in operation. The combination of protrusions also serves to keep cutting dust away from attachment points  108 , so that tensioning devices  118  are able to provide a consistent pressure to blade shoe  106 . Opposing protrusions  134  can either be integral with receivers  306  and  308 , or separate pieces that are attached to receivers  306  and  308 . Where opposing protrusions  134  are separate pieces, they can be attached to receivers  306  and  308  either removably or permanently, in the same ways in which protrusions  136  may be attached to flange  126 . 
     It will be appreciated by a person skilled in the relevant arts that the combination of receivers  306  and  308 , and spring plate retention fitting  310 , are one possible method of mounting blade shoe  106  to blade housing  102 , and retaining spring plate  206 . Any device that allows blade shoe  106  to pivotably mount to blade housing  102 , and can retain spring plate  206  in a semi-compressed fashion, will work equally well and is not a departure from the disclosed invention. Furthermore, while spring plate retention fitting  310  is depicted as a separate piece that interfaces with receiver  308 , spring plate retention fitting  310  could be integral with receiver  308 , formed by a single piece for receiver  308 . 
     Spring plate  206  is preferably manufactured out of spring steel, but can be manufactured from any suitable material that is capable pliable so that it can be retained under stress without breaking, and will exert a force when compressed. Such materials may include metals, plastics, rubbers, and composites, or other materials possessing the requisite properties now known or later developed. 
     The disclosure above encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in a particular form, the specific embodiments disclosed and illustrated above are not to be considered in a limiting sense as numerous variations are possible. The subject matter of the inventions includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions and/or properties disclosed above and inherent to those skilled in the art pertaining to such inventions. Where the disclosure or subsequently filed claims recite “a” element, “a first” element, or any such equivalent term, the disclosure or claims should be understood to incorporate one or more such elements, neither requiring nor excluding two or more such elements. 
     Applicant(s) reserves the right to submit claims directed to combinations and subcombinations of the disclosed inventions that are believed to be novel and non-obvious. Inventions embodied in other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of those claims or presentation of new claims in the present application or in a related application. Such amended or new claims, whether they are directed to the same invention or a different invention and whether they are different, broader, narrower or equal in scope to the original claims, are to be considered within the subject matter of the inventions described herein.