Patent Application
20160186795
The present invention relates to fasteners, particularly to screw fasteners used to join two or more materials together.
Various types of fasteners, particularly screws, are commonly used for connecting different materials together. It is desirable that the fasteners used maintain a tight grip between the materials being fastened. One example is screws used to install floorboards in vehicles and other automotive applications. In these types of applications the floorboards are subject to a high degree of vibration. Floorboard screws are therefore highly susceptible to losing their grip and disengaging from their installed position, which can jeopardize the stability of the floorboards and the overall safety of the vehicle. This is but one example of why it is desirable to have a screw that can maintain a strong grip on the materials it connects.
It is also desirable to have a screw that is hardened and can withstand the pressure and forces it is subjected to during use without losing its grip on the materials or otherwise deforming.
It is also desirable to have a screw fastener that can be installed in less time and with less force, to make the manufacturing process easier and more efficient.
It is therefore an object of the present invention to provide a novel screw fastener which effects a firmer grip between the two or more materials being fastened, is durable, and can be installed in less time.
A better understanding of the exemplary embodiments will be obtained from a reading of the following detailed description and the accompanying drawings, wherein identical reference characters refer to identical parts and in which:
The shank 18 has both a threaded portion 24 and an unthreaded portion 26. The threaded portion 24 begins within the tapered portion 22 and extends a predetermined length L3 across at least part of the rest of the shank 18 toward the second end 14. The threaded portion 24 is comprised of a single screw thread 28 which wraps around the exterior of the shank 18 in a uniform spiral manner and creates a major diameter D3. The unthreaded portion 26 of the shank 18 has a predetermined length L4. The length of the threaded portion L3 is greater than the length of the unthreaded portion L4.
As also shown in
The screw 10 also has two flats 36 located on its first end 12 that extend from the tapping point 16 inwards a distance L6 and into the threaded portion 24, interrupting the screw thread 28. The flats 10 also allow the screw 10 to more easily auger into a desired material.
Referring to
The screw thread 28 shown in
Referring to
An exemplary embodiment of the screw 10 shown in
In an exemplary embodiment the screw is made from a material such as steel that undergoes case hardening. In an exemplary embodiment, after case hardening a steel screw may exhibit a Rockwell C hardness (“Rc”) value in the range of Rc36-40 for the core hardness, and Rc50-58 for the surface hardness, with a case hardening depth of 0.006-0.011 inches. In such an exemplary embodiment, the steel used may be AISI 1022 steel or AISI 10B21 steel. However, in other embodiments different types of steel may be case hardened to achieve the desired hardness levels. Such hardening serves to reduce the incidence of “spinning” which is a condition caused by failure of the screw threads as they are driven through the materials to be fastened together. Reduction of the occurrence of spinning is highly desirable as a screw that experiences such a screw thread failure has little or no holding power and must, in many instances, be removed to allow a second screw to be inserted in its place.
As was noted earlier herein, embodiments of the invention may be used to secure a first material to a second material. An example provided was the attachment of a floorboard 100 and supporting member 110. In such an application, as well as many others, a large number of screws 10 may be required to be installed in order to properly secure the first and second material together. As will be understood by one ordinarily skilled in the art, a screw that can be installed more quickly has an installation cost advantage over a screw that requires more time to install. Such an advantage becomes more significant as the number of screws to be installed increases. As is illustrated by the test data representing installation times shown in Table 1, an embodiment of the inventive screw 10 exhibits reduced installation times over that of a previously known screw design. As is shown, an embodiment of the invention may be installed an average of 0.05 seconds faster than known designs. Over the course of installing hundreds or thousands of such screws, a significant amount of time may be saved through the use of the invention.
In addition to installation time, the holding power of a screw may be a critical characteristic in certain applications. Screws that have greater holding power may produce a more reliable and durable installation, reducing future repair or failure cost. Breakaway torque is a measure of the torque required to cause a fastener to start to rotate after installation. A higher level of breakaway torque represents an increased resistance to a screw loosening as the result of forces applied to the materials being fastened by the screw. Thus, a higher level of breakaway torque represents a greater amount of holding power. As shown in the test results of Table 2, an embodiment of the invention has a higher average breakaway torque than that of a known design. Thus, such an embodiment may result in an improvement in the holding power over known designs. This improved holding power may result in a more reliable and durable installation.
Embodiments of the invention may comprise a threaded section with various numbers of thread leads, as one ordinarily skilled in the art will understand, a greater number of thread leads will result in a screw that in many instances installs more quickly than those screws with lesser number. As illustrated in
As illustrated in
While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiments and examples herein. The invention should therefore not be limited by the above described embodiments, methods, and examples, but by all embodiments within the scope and spirit of the invention.
This application claims priority to provisional application 62/091,765 filed on Dec. 15, 2014 and is incorporated by reference in its entirety as if fully recited herein.
| Number | Date | Country | |
|---|---|---|---|
| 62091765 | Dec 2014 | US |
