Step drill bit with alternating sharpened edges for treating obscured fastener openings in cross-laminated joints

Abstract

A drill bit for use in construction using cross-laminated timber (CLT) is provided. The bit has both sharpened and blunt cutting elements, allowing it to process openings in CLT that are partially obscured by misalignment of the laminated components of the CLT without stretching or otherwise altering the shape of the fastener openings. The bit is used at construction sites in prefabricated or otherwise obscured fastener openings, thereby enabling rapid assembly and construction of CLT structures.

Description

[Technical field]

[0001] The present invention relates to the field of cross-laminated timber (CLT) construction, dowels used as fasteners, and on-site preparation for joining building elements.

[0002] More particularly, the invention relates to a drill bit used for preparing pre-made openings into which dowels are driven to join two construction elements, in order to prepare the openings in case of misalignment of the components of the construction elements after the fastener openings have been provided, so that the dowels or fasteners can be nominally inserted therein to complete the construction process. [Background technology]

[0003] The construction of large elements using cross-laminated timber (CLT) is a relatively new field when it comes to using such materials in the construction of large structures. The use of CLT construction is growing wherever sustainable material use and contemporary design are valued. The material has been shown to have strength and durability comparable to standard building materials such as steel and concrete, but new methods of fastening building elements are needed as a result of the science of sustainable materials and issues associated with using standard fasteners with these specialized materials.

[0004] CLT elements are timber panel products made by gluing layers of solid wood together. Each layer of the board is oriented perpendicular to the adjacent layers and is glued to the broad surface of each board, usually symmetrically so that the outer layers have the same orientation. In the past, when such elements were used as part of the decorative parts of the interior or artistic elements of a building, fastening the parts together could involve nailing the elements together or drilling holes through the elements and using existing fasteners such as bolts to fasten the CLT members together with washers and nuts. However, today timber elements of the type described are also used as external structural members in large towers and buildings.

[0005] As can be understood, the use of metals in conjunction with wood products can be successful when the metal elements are not exposed to the elements, for example in artwork within a residence. Metals exposed to external forces can oxidize and change size and shape, causing damage to the wood fibers. Furthermore, when fastening CLT with standard fasteners, which tend to press the wood elements together, the force of tightening the fasteners can also damage the surface wood fibers.

[0006] To mitigate these destructive conditions, CLT construction involves pre-drilling openings for wooden dowels into the panels as they are manufactured, to identify their location in the structural plan. Just as steel elements used in building or bridge construction are often marked to indicate their placement in the structure and have pre-made openings for fasteners, CLT construction includes the creation of openings to facilitate construction, with dowels positioned so that two or more elements can be joined at the construction site. Architectural panels are manufactured in a factory to reference specific locations in the building where the panels will be assembled. When the panel pieces are completed, the openings are provided there.

[0007] Unfortunately, holes made in this way, with stepped areas where each step is located approximately concentrically around a single axis, are found to be partially blocked or obscured by the time the panel is delivered to the construction site due to misalignment of the constituent timber pieces used in the manufacture of the CLT panel. It is found that in such panels, there is no longer a single axis along which all elements are concentric over the length of the opening, thus preventing the smooth insertion of the dowel. In most cases, the misalignment is slight, but is generally sufficient to require extra force to drive the dowel, and in many cases, it is found that the stepped dowel does not fully fill one or more of the steps with the dowel. If the dowel cannot be fully driven into the hole, the user may cut off the part that extends beyond the surface and make it flush with the surface, without realizing that the dowel element that would normally fit at the bottom of the opening is now positioned higher and the opening is not filled or not filled sufficiently. This weakens the connection and can have a detrimental effect on the strength of the structure.

[0008] It is therefore an object of the present invention to provide a means for cleaning up pre-drilled holes in CLT panels at the construction site prior to inserting the dowels, without making the openings any deeper than specified by the designer or engineer, so that each area is again approximately concentric about a single axis passing therethrough, thereby allowing the structural elements to be properly secured when the dowels are installed.

[0009] Other objects and advantages of the present invention will become apparent as the description proceeds. Summary of the Invention

[0010] According to the invention, a drill bit having one or more regions, including a stepped region, is provided for the specific task of cleaning up openings in wood panels without stretching the opening along the long axis of the bit. The bit is designed with cutting edges and grooves that allow material to be removed from the walls of the opening so that the opening is faithful to the shape of the dowel to be inserted therein. The bit is used in all holes of a structural element just before joining the element to another structural element, and the opening of the other element to be fixed together is similarly treated just before joining. After cleaning up, adhesive can be applied to the dowels assigned to the openings, the elements to be joined can be brought close to each other, and then the dowel can be more easily driven from one structural element into the adjacent element, thereby joining these elements.

[0011] In another embodiment, a dowel can be used as a biscuit so that the opening in the element becomes a blind hole, and after the opening is cleaned up with the bit of the present invention, the dowel is inserted into one panel, the opening in the other panel is similarly cleaned up, and the elements are pressed together until the dowel adheres to both elements. It will be appreciated that in some cases simply pressing the dowel into the opening is sufficient to hold the panels together, but in a preferred embodiment the dowel is used in conjunction with an adhesive that helps the dowel and panel act as a homogenous element, and the two panels join and act accordingly.

[0012] More specifically, a drill bit for treating a pre-made, deformed opening in cross-laminated timber (CLT) is provided, the bit including one or more cutting edges arranged axially along the bit and designed to cut material and one or more flutes designed to allow material cut by the bit to exit the opening, the most proximal of the one or more cutting edges of the bit having a first portion sharpened to properly shape the inner wall of the pre-made, now deformed opening, and an unsharpened portion to stop axial movement of the bit when a barrier against the blade is reached.

[0013] In some embodiments, the sharpened first portion of the cutting edge of the drill bit comprises 50% of the cutting edge, although it will be understood that the sharpened first portion of the cutting edge can comprise 20%-50% or more of the cutting edge, generally with the outer edge of the blade being sharpened. Additionally, a drill bit having 2-3 stepped portions in some embodiments can have 2-4 stepped portions, or indeed any number of stepped portions.

[0014] In the case of a three stepped opening, the cutting edge of the bit is sharpened only at the most proximal and second most proximal stepped portions so that the hole functions to remove only the amount of material necessary to mate with the fastener, although it will be understood that the drill bit will have a sharpened portion of the blade that extends only to a depth equal to the area of ​​the opening that has deformation.

[0015] In a preferred embodiment, the barrier for stopping the progress of the blade inside the hole is a shoulder in a stepped portion of the opening being treated.

[0016] In another embodiment, a multi-stage drill bit is provided for processing a pre-formed and subsequently deformed multi-stage opening in cross-laminated timber (CLT) with portions substantially concentric along an axis, the drill bit being axially disposed along the bit at a proximal step of the bit and including a blade designed to cut material and one or more grooves for allowing material cut by the bit to exit the opening, the blade of the bit being conical with a conical surface that is larger toward the proximal side of the bit and narrower toward the distal end of the bit, the blade being sharp at the larger portion of the cone and blunt at the narrower portion of the cone such that the blade of the bit properly shapes the inner wall of the pre-formed opening and is stopped when the blunt portion of the blade reaches the shoulder of the first step.

[0017] A more detailed description of the present invention is provided in the following description and claims, and is illustrated in the accompanying drawings. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a perspective view of a wooden element of variable length with openings made for joining. [Diagram 2] FIG. 2 is a view of the timber element of FIG. 1 in position for fastening. [Diagram 3] 3 is a cross-sectional view of the element of FIG. 2 taken along line 3-3 of FIG. 2. [Figure 4] FIG. 4 shows a drill bit of the present invention in the opening of FIG. 3. [Figure 5A] FIG. 1 is a diagram of a factory-made opening in wood. [Figure 5B] 5B is a diagram of an opening made in a factory in a different type of wood than that in FIG. 5A; [Figure 6A] FIG. 1 is a diagram of a dowel in place within an opening made in a piece of wood at a factory. [Figure 6B] 6B is a diagram of a dowel in place within an opening made in a different type of wood than FIG. 6A at the factory. [Figure 7A] FIG. 1 is a perspective view of a drill bit of the present invention. [Figure 7B] FIG. 7B is an enlarged view of region B in FIG. 7A. [Figure 8] FIG. 7B is a view of the distal end of the drill bit of FIG. 7A. [Figure 9] FIG. 7B is a plan view of the drill bit of FIG. 7A. [Figure 10] FIG. 7B is an elevational view of the drill bit of FIG. 7A. [Figure 11] FIG. 13 is a diagram of an alternative drill bit showing an unspecified number of steps. [Figure 12] FIG. 13 is a cross-sectional view of adjacent wood elements showing attempted insertion of a dowel prior to use of the drill bit of the present invention. [Figure 13] 1 is a cross-sectional view of adjacent wood elements during use of the drill bit of the present invention; [Figure 14] FIG. 2 is a cross-sectional view of adjacent wood elements after the drill bit of the present invention has been used. [Figure 15]FIG. 13 is a cross-sectional view of adjacent wood elements with a dowel inserted after using the drill bit of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] While the present invention is susceptible of embodiment in various forms, the drawings show several presently preferred embodiments which will be described in more detail below. It is to be understood that the present disclosure is to be considered as an example of the invention and is not intended to limit the invention to the specific embodiments illustrated. It is to be further understood that the heading of this section of the present application ("Description of the Preferred Embodiments") relates to requirements of the United States Patent Office and should not be considered as limiting the subject matter disclosed herein.

[0020] Referring to the drawings, Figures 1 and 2 show one type of joining of two wood panels for which the drill bit of the present invention is intended to be used. Elements 10 and 12 are joined at approximately a right angle using fastener openings 14 in element 10 and fastener openings 16 in element 12, aligned before fasteners such as dowels are driven therein to join the elements together. In a preferred embodiment of the present invention (as shown most clearly in Figures 12 and 15), the fasteners used are stepped wood fasteners, meaning that along the major axis of the fastener there are segments of decreasing circumference from the proximal end to the distal end of the fastener. Figure 3 shows a cross section of the joint taken from line 3-3 in Figure 2. In cross section, it can be seen that wood elements 10 and 12 are made using layers 18 of wood stacked together with their respective grains 20 oriented vertically per layer to create a cross-laminated timber (CLT) wood element. In Figures 1, 2 and 3 the openings of the timber elements 10, 12 are shown and as is evident from Figure 3 the type of fastener used to hold the two elements 10, 12 together is a stepped fastener, i.e. a fastener with areas of different diameters along the same axis. The preferred fastener in the assembly of CLT structures is a wooden dowel 24, as shown in Figures 12 and 15 and in cross section in Figures 6A and 6B. In the present situation the smaller diameter opening 16 is at the distal end and the larger opening 14 at the proximal end, whereby a stepped fastener can be placed in the opening.

[0021] In the manufacture of CLT panels 10, 12 for architectural use, it is common for the fastener openings 14, 16 to be provided at the time of manufacture and the wood elements 10, 12 to be shipped to the site ready for assembly, with the exact location specified in the building plans. It will be appreciated that since the desired fasteners are stepped fasteners that provide greater strength at wider diameters as required, the holes or openings made to cooperate with such fasteners will also have steps, and that when the fastener is placed in the opening, each step in the fastener must match a corresponding step in the opening. It is a basic key and keyhole relationship. This is clearly shown in both Figures 3 and 4 as well as Figures 12-15. Figures 5a and 5b show the joint between elements 10 and 12 before the fastener enters the hole 25. Figures 5a and 5b show the ideal opening 25 as it appears in the factory before shipping, with all of the layers 18 shown with perfectly aligned openings therethrough.

[0022] As shown in Figure 6A, the fastener openings 14 must be precisely positioned so that the shoulder 24s and shaft 24t of each layer of fastener are positioned to provide maximum strength for the connection with the cooperating wood element, and in Figure 6A it can be seen that the most proximal shoulder 24s of the fastener is properly positioned in the central portion of the constituent layers, and then the most distal shoulder 24s' is placed in the second wood element 12 with the stiff portion or shaft 24t of the fastener straddling the actual connection 26 of the two wood elements 10, 12 to provide an uninterrupted span of the fastener there. With this system of fastener opening creation and pre-staging, it has become apparent that with time, movement, and changing ambient conditions, the laminated layers of CLT can and often do shift, which is the problem that this invention is intended to solve.

[0023] It can be seen particularly in Figure 3 (and Figure 12) that the constituent layers 18 of wood in the upper element (the cross section of which is taken along a plane perpendicular to the plane of the grain of the wood element, and the cross section of the lower element viewed as being taken through a single layer parallel to the axis of the grain) tend to shift during the period between when the opening 25 is made and when the elements 10, 12 are delivered to the construction site. Note that the axis of the opening 14A shown layer by layer is shown as a bent line due to the shift, and the cylindrical segment of the opening is no longer concentric. As shown in Figure 12, the shift prevents the fastener 24 from fitting into the opening 14 provided therefor.

[0024] The prior art solution used to fit fasteners 24 within pre-made openings 14 was to prepare holes 25 using the original drill bit 30 used to make holes 25, as shown in FIG. 4. However, using the original drill bit 30 in this operation was prone to causing damage to the opening because the precision available in the field was not possible in the ideal conditions of the factory, and operators preparing the opening with the original drill bit were particularly prone to damaging the hole, including drilling shoulders 24s at each stepped layer and drilling deeper into the lowest (or most distal) layer 27 by drilling 25d deeper than originally. Such actions would place the fastener deeper in the opening, affecting the strength of the fastener and joint and altering the engineering to the detriment of the structure. It will also be appreciated that using the original drill bit in the field could very well result in damaged, oversized, or distorted openings due to the lack of control available in the factory.

[0025] The present invention provides a drill bit 40 similar in size and configuration to the original drill bit used to create hole 25, shown in Figures 7A and 7B, but with sharp edges 42 and dull edges 44 strategically located on the bit 40 to aid in processing opening 14 but not to cut beyond the original parameters of the opening. While a typical drill bit is constructed with sharpened surfaces throughout to provide cutting power to the bit, those skilled in the art will understand that it is undesirable herein for the bit to cut the entire depth of fastener hole 25 beyond the original shape of fastener opening 14.

[0026] 7A, a drill bit 40 of the present invention is shown. It will be seen that the bit 40 includes stepped drilling regions 46, 47, and 48 to allow for the creation of an opening for a stepped fastener 24. The bit 40 is shown as having cutting edges 50 and grooves 52 that allow the drill bit to cut into wood and remove the cut wood from the opening in a manner well known to those skilled in the art. However, in the bit of the present invention, as shown most clearly in FIG. 7B, the cutting edges 50 of the bit 40 are made sharp on the proximal side of the cutting blade 42 and blunt on the distal side 44 of the blade. In a preferred embodiment, the sharpened surface is approximately half of the blade face and the blunt area is the remaining half of the blade. It will be appreciated that because the cutting surface of the bit includes a conical region, the sharpened portion of the blade 42 is the portion most distal from the shaft 48 or axis of the drill bit 40, while the blunt edge 44 of the cutting surface is the surface portion closest to the shaft 48 or axis of the bit 40. The relative positions of the sharp and blunt elements are important to understanding the process since the cleanup in this invention is directed to the periphery of the hole and the blunt surface is used to stop the process at the right moment as described below. It will be understood by those skilled in the art that the ratio of sharp to blunt can be varied to obtain the desired results without departing from the scope of the novelty of the present invention.

[0027] It will also be appreciated that any misalignment in the wood layers 18 will only affect the wood elements 10 where the fastener holes are made perpendicular to the laminated wood layers 18, and will not occur in the portions of the wood elements 14 (see lower wood element in FIG. 1) where the bit cuts against the grain of the wood, at least not to the extent that repairs are required.

[0028] Thus, in making the cleanup drill bit of the present invention, the sharpened area of ​​the bit can be made only in the most proximal layer of the bit and still be effective enough to treat any slippage in the wood layers around it without affecting the layers below. In area 46 of bit 40, the remaining blades of bit 49 can be left blunt, and as can be seen in FIG. 3, these blades only reach the inner periphery of fastener opening 25 at location 56 where there is no slippage in the wood and therefore no need to treat that location.

[0029] 7A and 7B, the bit removes material from the periphery of the opening (material that has shifted into the opening due to the action of ply shear), but the bit 40 does not cut any deeper into the shoulder 24s because the lower or inner portion 44 is not sharpened. The blunt edge 44 of the blade 50 on the bit 40 actually stops the bit 40 when the blunt edge 44 hits the shoulder 24s, indicating that the process is complete.

[0030] Those skilled in the art will appreciate that any number of shoulders (as shown in FIG. 11) may be provided without departing from the scope of the novelty of the present invention, and that the bits of the present invention may have sharpened segments on any blade, as desired, depending on the number of layers of wood and the length of the laminate. The elements of bit 40 are more clearly shown in FIGS. 8-11.

[0031] FIG. 4 shows a prior art bit 30 in a fastener opening 25 where the opening axis 14A is completely straight through the opening 25, enlarging the opening so that the fastener 24 selected for that opening is slightly undersized for the opening and embeds too deeply in the opening, weakening the connection.

[0032] A series of figures from 12 to 15 are included to illustrate the steps of preparing the opening for the fastener, where it is first shown that the fastener 24 cannot be placed in the desired position at the junction of the two wood elements 10, 12 due to misalignment of the constituent layers, which is illustrated by showing the inability to properly press the fastener 24 into the opening 14, and the fastener is jammed near the midpoint into the opening. In 13, the bit 30 of the invention is now used to prepare the opening. This operation is carried out by using therein a drill with a drill bit 40 and operating the bit inside the hole 25 until the bit stops due to the action of the invention. This means that the wall is cut by the blade portion 42 of the bit 40 and the bit is operated until the blade portion 44 hits a shoulder element inside the hole and the blade stops. The bit can then be removed from the hole 25, which is now shown in a better, prepared state, as shown in 14. The fastener 24 can then be placed as required, as shown in 15.

[0033] While illustrative embodiments of the present invention have been shown and described, it should be understood that various modifications and substitutions could be made by those skilled in the art without departing from the novelty and scope of the invention.

Claims

1. A bit having one or more edges arranged axially along the bit and designed to cut wood, and one or more grooves designed to allow the wood cut by the bit to exit through an opening, the bit having means for operatively rotating to cut the wood and operative to move axially along the bit within the preformed opening; the one or more edges of the bit have a first portion that is sharpened for cutting wood into a pre-made opening in cross-laminated timber (CLT) as the bit rotates and enters the opening, and an unsharpened portion that stops axial movement of the bit when it hits a shoulder of the wood as the bit rotates and moves axially along the bit through the opening. A multi-stage drill bit for treating pre-made and deformed openings in cross-laminated timber (CLT).

2. 2. The multi-stage drill bit of claim 1, wherein the sharpened first portion of an edge comprises 50% of said edge.

3. 2. The multi-stage drill bit of claim 1, wherein the sharpened first portion of an edge comprises between 20% and 50% of the edge.

4. The multi-stage drill bit of claim 1 , comprising two to three stepped portions.

5. The multi-stage drill bit of claim 1 , comprising 2 to 4 stepped portions.

6. a conical shape such that the conical surface is larger toward the proximal end of the bit and narrows toward the distal end of the bit; a blade that is sharp at the larger portion of the cone and blunt at the narrower portion of the cone; A drill bit comprising a blade arranged axially along the bit and designed to cut material, and one or more flutes for allowing the material cut by the bit to exit through an opening, the blade of the bit properly shapes the inner wall of the pre-made opening and is stopped when the blunt portion of the blade reaches the shoulder of the first step; A multi-stage drill bit for processing a multi-stage opening having portions that are approximately concentric along an axis, the multi-stage opening having portions that have been prefabricated and then deformed in cross-laminated timber (CLT).

7. 7. The drill bit of claim 6, wherein the sharpened first portion of the blade comprises 50% of the blade.

8. 7. The drill bit of claim 6, wherein the sharpened first portion of the blade comprises between 20% and 50% of the blade, and generally the outer edge of the blade is sharpened.

9. The drill bit of claim 6, comprising two to three stepped portions.

10. The drill bit of claim 6, comprising 2 to 4 stepped portions.

11. The drill bit of claim 6 having any number of stepped portions.

12. 7. The drill bit of claim 6, wherein the sharpened portion of the blade extends only to a depth equal to an area of ​​the opening having a deformation.

13. 7. The drill bit of claim 6, wherein the barrier for stopping the blade is a shoulder of a stepped portion of the opening being prepared.

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