FIELD OF THE INVENTION

The present invention concerns the field of Cross Laminated Timber (CLT) construction, dowels used as fasteners and on-sight preparation for the joinder of construction elements. More particularly the present invention concerns a drill bit used to sort-out the premade openings into which dowels for joining two construction elements are driven. The drill bit is employed so that, in the event that the constituents of the construction elements have slipped since fastener openings were created, those opening can be sorted to permit the dowel, or fastener, to be nominally inserted therein to complete the construction process.

BACKGROUND OF THE INVENTION

Construction of large elements, using cross laminated timbers (CLT) is a relatively new field when it comes to the use of such materials to create large structures. The use of CLT construction is moving forward in places where the use of sustainable materials and contemporary design are important. The materials have been found to be as strong and durable as standard construction materials, such as steel and concrete; but new methods of fastening the construction elements have become necessary as a result of the science of sustainable materials and the problems associated with the use of standard fasteners with these specialized materials.

CLT elements are wood panel product made from gluing layers of solid-sawn lumber together. Each layer of boards is oriented perpendicular to adjacent layers and glued on the wide faces of each board, usually in a symmetric way so that the outer layers have the same orientation. In the past, when such elements were used as decorative parts of interiors or parts of artistic elements of buildings, fastening of parts could include nailing elements together or drilling of holes through elements with the use of traditional fasteners, such as bolts, tying the CLT members together with washers and nuts. Today however, wood elements of the type described are being used as external structural members of even large towers and buildings.

As will be understood, the use of metal in association with wood products can be a successful exercise when the metal elements are not exposed to nature, such as in art work within a housing. Metal exposed to external forces can oxidize, changing size and shape and causing damage to the wood fibers. Further, tying CLT with such standard fasteners which tend to squeeze the wood elements together, by the force of tightening the fastener, can cause the surface wood fibers to be damaged.

In order to alleviate these destructive conditions, CLT construction has taken to pre-drill openings, for wood dowels, into the panels as the panels are constructed and identified for location in the plans of the structure. In the same manner that steel elements for use in the construction of buildings or bridges are often marked as to the their placement in structure with opening for fasteners pre-made, CLT construction now includes the creation of openings to facilitate the construction using dowels placed so that two or more elements can be joined together at the construction site. Panels for construction are created in a factory and referenced for specific locations in the building to which they will be formed. As the pieces are finished, the openings are created therein.

Unfortunately, it has been found that the holes thus made, which comprise stepped sections wherein each step is generally concentrically oriented about a single axis there through, by the time the panel is delivered to the construction site, have been partially blocked or obscured due to the shifting of the constituent wood pieces used in the construction of a CLT panel. It can be seen in such panels that there no longer exists a single axis with all elements concentric thereto, through the length of the opening thus impeding the easy placement of a dowel therein. While in most cases the shifting is slight, it has been found that the shifting is generally sufficient to cause the need for extra force to drive the dowel and often, with stepped dowels, one or more of the steps can no longer be well filled by the dowel. If a dowel cannot be driven sufficiently into a hole, the user may cut the part extending from the surface off, so that it is flush with the surface, without realizing that the dowel element that usually fits at the bottom of the opening is equally elevated and the opening is not filled or well filled. This will result in a weakened connection that can prove fatal to the strength of the structure.

It is therefore an object of the present invention to provide a means for cleaning up the pre-drilled holes in a CLT panel at the site of construction, without making the openings any deeper than specified by the designer or engineer but instead making each section again generally concentric about a single axis there through, prior to the insertion of the dowel and thereby allowing the dowel, when set, to properly fasten the elements of the structure.

Other objects and advantages of the present invention will become apparent as the description proceeds.

SUMMARY OF THE INVENTION

In accordance with the present invention, a drill bit having one or more sections, including stepped sections, is provided for the specific task of cleaning up the openings in a wood panel, without enlarging the opening in the direction of the long axis of the bit. The bit is designed with cutting edges and flutes to allow material to be shaved from the walls of the opening so that the opening is true to the shape of a dowel to be inserted therein. The use of the bit is made in every hole of the structural elements just prior to the joinder of that element to other elements of the structure, with the opening in the other elements to be fastened together being identically cleaned just prior to joinder. Once cleaned-up the dowel assigned to the opening can be coated with an adhesive, the elements to be joined together can be put into proximity with each other, and the dowel can then be more easily driven through one element of the structure into its adjoining element thereby joining those elements together.

In another embodiment, the dowel can be used as a biscuit such that the openings in the elements are only through one part of the panel, the dowel is inserted into one panel, after the opening is cleaned-up by the bit of the present invention, the opening of the other panel is likewise cleaned-up and the elements are pressed together until the dowel adheres to both elements. It will be understood that in some instances a pressed fit of the dowel within the opening is sufficient to hold the panels together, in a preferred embodiment, the dowel will be used concomitantly with an adhesive which will tend to cause the dowel and panel to act as an homogenous element; the two panels joined together to act accordingly.

More specifically, a drill bit, for cleaning out an opening previously made which has become distorted in cross laminated timbers, (CLT), is provided, the bit comprising one or more cutting edges placed axially along the bit and designed to cut material and one or more flutes designed to force the material cut by the bit out of the opening. The proximal-most of the one or more cutting edges of the bit has a first portion sharpened to properly shape the interior walls of the opening previously made and presently distorted, and has an unsharpened portion to stop the axial movement of the bit when a barrier to the blade is reached.

In some embodiments, the sharpened first portion of the cutting edge of the drill bit comprises 50% of the cutting edge. But it will be understood that the sharpened first portion of the cutting edge can comprises between 20% and 50% or more of the cutting edge; generally sharpened on the outer edge of the blade. Further, the drill bit in some embodiments comprises between 2 and 3 stepped portions can have between 2 and 4 stepped portions or in fact any number of stepped potions.

So as to function to remove only that amount of material necessary for the hole to fit a fastener and in the situation of a three stepped opening, the cutting edges of the bit are sharp in only the first and second most proximal stepped portions. But it will be understood that the drill bit will have sharpened portions of the blades so as to extend only to a depth equal to those sections of the opening having distortions.

In a preferred embodiment, the barrier for stopping the blade's progress within the hole is a shoulder of stepped portion of the opening to be cleaned.

In another embodiment a multi-step drill bit, for cleaning out a multi-step opening, comprising generally concentric portions along an axis, previously made in a cross laminated timber, (CLT) and then distorted, is provided, the drill bit comprising a blade, placed axially along the bit at the proximal most step of the bit, designed to cut material and one or more flutes to force the material cut by the bit out of the opening. The blades of the bit being conically shaped so that the cone is larger towards the proximal side of the bit and narrows towards the distal end of the bit and the blade being sharp at the large part of the cone and dulled at the narrow part of the cone so that the blade of the bit properly shapes the interior walls of the opening previously made and is caused to stop when the dull part of the blade reaches the shoulder of the first step.

A more detailed explanation of the invention is provided in the following description and claims and is illustrated in the accompanying drawings.

