Patent Application
20250042002
The present disclosure relates to tool bits and, more particularly, to tool bits being composed of multiple materials.
The present disclosure provides, in one aspect, a tool bit including a first end, a second end, and a longitudinal axis extending between the first end and the second end; an insertion end portion adjacent the first end and configured to be connected to a tool; a working end portion adjacent the second end and configured to be inserted into a fastener a first distance measured from the second end, the working end portion including a first segment, a second segment that is fixed to the first segment at a connection interface, the connection interface located a second distance measured from the second end, wherein the first distance is less than the second distance, and a first maximum outer dimension measured perpendicular to the longitudinal axis; and a shank disposed between the insertion end portion and the working end, the shank including a second maximum outer dimension measured perpendicular to the longitudinal axis, wherein the second maximum outer dimension is less than the first maximum outer dimension.
The present disclosure provides, in another aspect, a tool bit including a first end, a second end, and a longitudinal axis extending between the first end and the second end; an insertion end portion adjacent the first end and configured to be connected to a tool, the insertion end being composed of a first material having a first hardness; and a working end portion adjacent the second end and configured to be inserted into a fastener a first distance measured from the second end, the working end portion including a first segment and a second segment, the second segment being fixed to the first segment at a connection interface and being composed of a second material having a second hardness that is greater than the first hardness by a percentage, the connection interface located a second distance measured from the second end, wherein the first distance is less than the second distance, and wherein the second distance is based on a first ratio of a maximum radial dimension at a location along the tool bit to a polar moment at the location, and wherein the first ratio is multiplied by the percentage.
The present disclosure provides, in another aspect, a tool bit including a first end, a second end, and a longitudinal axis extending between the first end and the second end; an insertion end portion adjacent the first end and configured to be connected to a tool, the insertion end being composed of a first material having a first hardness; and a working end portion adjacent the second end and configured to be inserted into a fastener a first distance measured from the second end, the working end portion is composed of a second material having a second hardness that is greater than the first hardness by a percentage, the working end including a first segment and a second segment that is fixed to the first segment via welding along a connection interface, thereby creating a heat affect zone, wherein the connection interface is at a calculated distance measured from the second end and the heat affect zone defines a second distance, wherein the calculated distance is based on a first ratio of a maximum radial dimension at a location along the tool bit to a polar moment at the location, and wherein the first ratio is multiplied by the percentage, wherein the second distance is further added to the calculated distance to determine the calculated distance of the connection interface when the first segment and the second segment are joined via welding.
Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of supporting other embodiments and being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Terms of degree, such as “substantially,” “about,” “approximately,” etc. are understood by those of ordinary skill to refer to reasonable ranges outside of the given value, for example, general tolerances associated with manufacturing, assembly, and use of the described embodiments.
The insertion end portion 14 is configured to be connected to the tool. More particularly, the insertion end portion 14 is configured to be inserted into and received by a bit holder, chuck, or other structure coupled to or part of the tool. For ease of discussion, all of these types of structures will be referred to as bit holders herein. The insertion end portion 14 defines a first end 26 of the tool body that is opposite the working end portion 18. The insertion end portion 14 is composed of a first material. An outer surface on the insertion end portion 14 is at least partially defined by a non-circular profile 30. In the illustrated embodiment, the non-circular profile 30 is a hexagonal or hex-shaped profile configured to be received in a hexagonal or hex-shaped bit holder. In other embodiments, the non-circular profile 30 may be other suitable profiles, such as D-shaped, flattened, oblong, triangular, square, octagonal, star-shaped, irregular, and the like. A portion of the outer surface on the insertion end portion 14 not defined by the non-circular profile 30 is defined by a circular profile 34. In other embodiments, the circular profile 34 may be another profile, such as square, octagonal, star-shaped, irregular, and the like, or the circular profile 34 may be omitted. The circular profile 34 is proximate the connection portion 22.
The connection portion 22 is positioned between the working end portion 18 and the insertion end portion 14 (e.g., between the working end portion 18 and the circular profile 34). The connection portion 22 includes a circular cross-sectional shape and defines a maximum radial dimension R3 (e.g., a maximum radius;
The working end portion 18 is configured to engage with a fastener (e.g., a screw). More particularly, the working end portion 18 is configured to drive the fastener into a workpiece. With reference to
With continued reference to
In the illustrated embodiment, the working end portion 18 is composed of the first material and the second material. The second material defines the second segment 42 (e.g., the first and second portions 50, 54), and the first material defines a remainder of the working end portion 18 (e.g., the first segment 38) not defined by the second material. In the depicted embodiment, the second material has a hardness that is greater than a hardness of the first material. In other words, the second segment 42 is harder than the first segment 38. In some embodiments, the hardness of the second material is at least 5% greater than the hardness of the first material. In other embodiments, the hardness of the second material is between 5% and 30% greater than the hardness of the first material.
In the depicted embodiment, the first material is a tool steel. In some embodiments, the first material may be a low carbon steel, such as AISI 1018. AISI 1018 low carbon steel includes a balance of toughness, strength, and ductility. AISI 1018 low carbon steel includes approximately 0.14% to 0.2% carbon and 0.6% to 0.9% manganese. In other embodiments, the first material may be a high carbon steel, such as AISI 1065. AISI 1065 high carbon steel includes a high tensile strength. AISI high carbon steel includes approximately 0.6% to 0.7% carbon and 0.6% to 0.9% manganese. In additional embodiments, the first material may be an alternative material. The tool steel may have a hardness, for example between about 45 HRC and about 60 HRC. In some embodiments, the tool steel may have a hardness of between about 45 HRC and about 55 HRC.
In the depicted embodiment, the second material is a high speed steel (HSS), such as PM M4. PM M4 high speed steel includes a fine grain size, small carbides, and a high steel cleanliness, which together provide high wear-resistance, high impact toughness, and high bend strength. PM M4 high speed steel includes approximately 1.4% carbon, 4% Chromium, 5.65% tungsten, 5.2% molybdenum, and 4% vanadium. In additional embodiments, the second material may be an alternative material (e.g., carbide). The high speed steel may have a hardness, for example, of 60 HRC or greater.
By using the high or low carbon steel as the first material and the PM M4 high speed steel as the second material, the cost to manufacture the tool bit 10 is minimized while the strength of the tool bit 10 is maintained. The cost to manufacture the tool bit 10 is minimized due to the material being used for the first material generally being inexpensive. The second material compensates for a lower strength of the first material.
The illustrated method 62 includes providing a first stock of material (step 66) composed of the first material and providing a second stock of material (step 70) composed of the second material. Step 74 includes fixing the first stock of material to the second stock of material (e.g., the forward segment 42 composed of the second material is secured to the rearward segment 38 composed of the first material). The segments 38, 42 are fixed together at the connection interface 46. In the illustrated embodiment, the segments 38, 42 are fixed together by a welding process. The first and second stocks of material may be welded via spin welding, resistance welding, laser welding, friction welding, and the like. In other embodiments, the segments 38, 42 are fixed together by a different process (e.g., a brazing process or the like). In the depicted embodiment, the first stock of material is a hex-shaped blank and the second stock of material is a cylinder-shaped blank. In additional embodiments, the first and second stocks of material may differ in shape.
An axial length of the second stock of material extending from the connection interface 46 is determined (step 78) as discussed in more detail below. The first stock of material and the second stock of material may then be machined or shaped (steps 82, 86) to form the tool bit 10. Shaping the second stock of material (step 86) is based on the determined length (step 78) of the second stock of material. The first stock of material forms the first end 26 to the connection interface 46, and the second stock of material forms the second end 58 to the connection interface 46. In other words, the first stock of material is shaped to form the insertion end portion 14, the connection portion 22, and the rearward portion 38. The second stock of material is shaped to form the working end portion 18 from the second end 58 to the connection interface 46 (e.g., the forward segment 42). In other embodiments, the method 62 can be different (e.g., the axial length of the second stock can be determined before the first and second stock of material are fixed together).
To determine a location of the connection interface 46 (step 78), the torsional stress τR1 is calculated at the radius R1. The torsional stress τR1 is related to an applied torque τR1, the radius R1 that the stress is occurring at, and a polar moment of inertia of the cross section JT
The torsional stress τR2 allowed at the radius R2 may then be calculated based on the torsional stress τR1 at the radius R1. The torsional stress τR2 allowed at the radius R2 is a percentage P of the torsional stress τR1 at the radius R1. The percentage P is based on the difference in hardness between the first material and the second material. For example, if the first material was 80% the hardness of the second material, the torsional stress τR2 allowed at the radius R2 would be 80% the torsional stress τR1 at the radius R1. The torsional stress τR2allowed at the radius R2 is expressed in Equation 2.
In addition to the torsional stress τR2 allowed at the radius R2 being expressed in Equation 2, the torsional stress τR2 allowed at the radius R2 may be related to the applied torque TR2, the radius R2, and a polar moment of inertia of the cross section JT
Equation 2 may be equated to Equation 3. Since the applied torque is the same through the drill bit, the torque TR1 at the radius R1 is the same as the torque TR2 at the radius R2. This expression is shown in Equation 4.
The connection interface 46 may be selected such that the ratio of the radius R2 to the polar moment of the cross section JT
In some embodiments, the tool bit 10 may have a reduced diameter portion (e.g., the illustrated connection portion 22) that allows the tool bit 10 to twist along its length. If the tool bit 10 includes this type of reduced diameter portion, the allowed torsional stress at the radius R2 is calculated to account for the reduced diameter portion. The radius R3 is located within the reduced diameter portion. The allowed torsional stress at the radius R2 is illustrated in Equation 5, which is similar to Equation 4.
The connection interface 46 may be selected in view of both Equation 5 and Equation 4. In other words, the ratio of the radius R2 to the polar moment of the cross section JT
An axial distance of the connection interface 46 from the second end 58 may be determined (step 78) based on the ratio of the radius R2 to the polar moment of the cross section JT
Determining the axial distance of the connection interface 46 of the #2 square bit, as described above, can be applied to different sizes and/or types of bits 10. The table below provides some examples of different sizes and types of bits 10 and maintains that the hardness of the first material is 80% of the hardness of the second material. Specifically, the first column in the table below represents the type and size of the bit 10 (e.g., PH1 is a size #1 Phillips-head bit, PZ1 is a size #1 Pozidriv-head bit, SQ1 is a size #1 square-head bit, and T10 is a size #10 Torx-head bit). In other words, the number associated with the type/geometry of the bit represents the standard size of the bit head. The table below shows, for example, the axial distance of the connection interface 46 of a size #1 Phillips-head bit relative to the tip 58 is about 0.087 inches. Specifically, a typical axial distance between the tip 58 and the radius R1 (e.g., a depth at which a #1 Phillips-head bit is received within a fastener) is about 0.075 inches. At that axial length, the polar moment of the cross section JT
In other types of tool bits 10, a T15 bit includes a distance between the connection interface 46 and the tip 58 of about 0.12 inches with a fastener engagement depth of about 0.07 inches, a T25 bit includes a distance between the connection interface 46 and the tip 58 of about 0.16 inches with a fastener engagement depth of about 0.1 inches, and a T27 bit includes a distance between the connection interface 46 and the tip 58 of about 0.175 inches with a fastener engagement depth of about 0.11 inches.
With reference to
In some scenarios, the tool bit 10 may be stress relieved or heat treated after the first material is welded to the second material. In such scenarios, the heat affect zone 90 may be neglected, and an offset for the connection interface 46 would not need to be calculated.
Although the disclosure has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the disclosure as described. Various features and advantages of the disclosure are set forth in the following claims.
The present application is a continuation of U.S. patent application Ser. No. 18/141,746 filed on May 1, 2023, now U.S. Pat. No. 12,122,019, which is a continuation of U.S. patent application Ser. No. 17/798,284 filed on Aug. 8, 2022, now U.S. Pat. No. 11,673,239, which is a national stage filing under 35 U.S.C. § 371 of International Application No. PCT/US2021/017549 filed on Feb. 11, 2021, which claims priority to U.S. Provisional Patent Application No. 62/975,787 filed on Feb. 13, 2020, the contents of all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62975787 | Feb 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 18141746 | May 2023 | US |
| Child | 18912895 | US | |
| Parent | 17798284 | Aug 2022 | US |
| Child | 18141746 | US |
