HYBRID THREAD CUTTER WITH REAM AND THREAD CUTTING SECTION

Abstract

A hybrid thread cutter (110) defining a longitudinal axis (111) for flaring and threading a hole (120) in a workpiece (100, 122), the hybrid thread cutter (110) comprising: a reamer portion (112) having a front end (154) and a smooth radial outer surface (138) tapering toward the front end (154) along the longitudinal axis (111); and a thread-cutting portion (114) having a plurality of cutting teeth, the thread-cutting portion (114) being arranged together with the reamer portion (112) along the longitudinal axis (111); wherein the reamer portion (112) is configured such that the front end can penetrate into the hole (120) to plastically deform and expand the hole (120) into an enlarged hole (120) without removing material as the thread cutter (110) is advanced along the longitudinal axis (111), and to provide the enlarged hole (120) with a zone of residual compressive stress; wherein the plurality of cutting teeth (161) are configured to cut a thread into the enlarged hole (120) within the zone of residual compressive stress, and wherein the reamer portion (112) is frustoconical, has a surface (140) extending substantially perpendicular to the longitudinal axis (111) and defines the front end (115) of the thread cutter (110).

Description

INTRODUCTIONThe art generally relates to a tap, and more particularly to a hybrid tap having a reamer section and a tap part.Some parts have tapped holes for attachment to another component. Vehicle engine blocks often contain, for example, a threaded bore for receiving, supporting and screwable fastening of a bearing part. More specifically, the engine block may include a threaded bore for the main bearing bolt. Preferably, these and other types of tapped holes have high fatigue strength, high load bearing, and other advantageous performance characteristics.However, the available methods of threading may be suboptimal in some respects. Currently available threading tools, machines, systems, etc. may also not be optimal. These limitations can become more acute in the production of mass production. Accordingly, the performance of the threaded hole and the corresponding threaded cap formed is limited. Moreover, such manufacturing methods and systems may be inefficient or have other problems.Therefore, it is desirable to provide improved methods and systems for manufacturing parts having high quality tapped holes. It is also desirable to provide improved methods and systems for manufacturing threaded hole parts that have high fatigue strength and high toughness. Moreover, it is desirable to make these systems and methods more efficient. Other desirable features and characteristics of the present disclosure will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.WO 2019,049 078 A1 discloses a multiple-operation reaming drilling tool which enables three different finishing operations to be performed during one and the same drilling operation: drilling, sizing and threading. The reaming tool has a reaming drill segment, a sizing segment, a tapping segment and a stop segment.DESCRIPTIONA hybrid tap defining a longitudinal axis is provided. In one embodiment, the hybrid tap includes a reamer section and a tap section having a plurality of cutting teeth. The thread cutting portion is arranged along the longitudinal axis together with the reamer portion. The reamer section is configured to be advanced within a bore of a workpiece to plastically deform and expand the bore into an expanded bore and provide the expanded bore with a residual compressive stress zone. The plurality of cutting teeth is configured to cut a thread into the flared hole within the zone.The reamer section has a smooth radial outer surface.The reamer section has a radially outer surface that tapers with respect to the longitudinal axis.In some embodiments, the thread cutting portion is also tapered along the longitudinal axis.Moreover, in some embodiments, the radially outer surface of the reamer section defines a first cone angle with respect to the longitudinal axis. Additionally, the thread cutting portion defines a second taper angle with respect to the longitudinal axis. The first cone angle is different from the second cone angle.In some embodiments, the thread cutting portion is aligned with the reamer portion along the longitudinal axis.In some embodiments, the reamer section has a front end and a rear end. The front end has a front width and the rear end has a rear width. The back width is at most two percent (2%) greater than the front width to expand the hole at most two percent (2%).In some embodiments, the reamer portion and the thread cutting portion are integrally connected and have common material properties.Moreover, in some embodiments, the reamer portion and the thread cutting portion have different material properties. In some embodiments, the reamer portion and the thread cutting portion are made of different materials. In some embodiments, the reamer portion or the tap portion have a different heat treatment than the other to achieve different material properties. In some embodiments, either the reamer portion or the tap portion has a different coating than the other to achieve different material properties.In some embodiments, the plurality of cutting teeth are disposed in a first land and a second land, wherein a chip opening separates the first land and the second land in a circumferential direction about the longitudinal axis. The chip opening extends along the longitudinal axis through the tap portion and is configured to receive chips during cutting of the thread into the enlarged hole.A method of making a hybrid tap is also provided. In one embodiment, the method includes forming a reamer section on a shank having a longitudinal axis. The method also includes forming a thread cutting portion on the shank having a plurality of cutting teeth. The thread cutting portion is arranged along the longitudinal axis together with the reamer portion. The reamer section is configured to be advanced into a hole of a workpiece to plastically deform and expand the hole into an expanded hole and provide the expanded hole with a residual compressive stress zone. In addition, the plurality of cutting teeth is configured to cut a thread into the enlarged hole within the zone.In some embodiments, the method includes attaching a first body to a second body that are collectively arranged along the longitudinal axis. The first body and the second body have different material properties. Forming the reamer portion includes forming the reamer portion on the first body. Forming a thread cutting portion also includes forming the thread cutting portion on the second body.In some embodiments, forming the reamer section and the tap section includes additive manufacturing of at least one of the reamer section and the tap section.Moreover, in some embodiments, the method includes at least one of the following steps: heat treating the reamer portion or the tap portion to provide the one with a different material property than the other; and coating the reamer portion or the tap portion to provide the one with a different material property than the other.In some embodiments, forming the reamer section includes forming the reamer section to have a smooth outer radial surface that tapers with respect to the longitudinal axis. Forming the thread cutting portion also includes forming the thread cutting portion to taper along the longitudinal axis.In some embodiments, forming the reamer section includes forming the reamer section to have a front end and a rear end. The front end has a front width and the rear end has a rear width. The back width is at most two percent (2%) greater than the front width to expand the hole at most two percent (2%).Additionally, a method of forming a threaded bore in a cast workpiece using a hybrid tap in a single stroke is disclosed. In one embodiment, the method includes providing a hole to a cast workpiece. The method also includes advancing a reamer section of the hybrid tap in the hole in a single stroke to plastically deform and expand the hole into an expanded hole and provide the expanded hole with a residual compressive stress zone. The method also includes cutting a thread into the flared hole within the zone using a thread cutting portion of the hybrid thread cutter in a single stroke. The thread cutting portion includes a plurality of cutting teeth. The thread cutting portion is arranged along the longitudinal axis together with the reamer portion.BRIEF DESCRIPTION OF THE DRAWINGSThe exemplary embodiments are described below in connection with the following drawings, wherein like numerals designate like elements, and wherein: FIG. 1 is a side view of a hybrid tap shown in accordance with embodiments of the present disclosure; FIG. 2 is a top view of a workpiece having a hole configured to be threaded with the hybrid tap of FIG. 1 according to embodiments; FIG. 3 is a side view of the hybrid tap of FIG. 1 shown during cold expansion and reaming of the hole in the workpiece of FIG. 2 according to embodiments; FIG. 4 is a side view of the hybrid tap of FIG. 1 showing cutting threads into the enlarged hole of FIG. 3 according to embodiments; FIG. 5 is a schematic side view of a method of manufacturing the hybrid tap of FIG. 1 ; FIG. 6 is a schematic side view of the method of manufacturing the hybrid tap of FIG. 1 according to further embodiments; and FIG. 7 is a schematic side view of the method of manufacturing the hybrid tap of FIG. 1 according to further embodiments.DETAILED DESCRIPTIONThe following detailed description is merely exemplary in nature and is not intended to limit the application and use. Moreover, there is no intention to be bound by any explicit or silent theory set forth in the foregoing introduction, summary, or detailed description that follows.In general, the present disclosure relates to manufacturing systems and methods for threading a hole in a workpiece, part, component, etc. The threaded bore made with these systems and methods may have high fatigue strength, high toughness, and / or other improved properties.In various embodiments, a hybrid threading tool (hybrid tap) is provided that includes both a reamer section and a tap section. The reamer portion and the thread cutting portion may be attached and arranged along a longitudinal axis of the hybrid tool. The reamer section may be disposed at a forward end of the tool. The reamer section may have a smooth, tapered radial outer surface. The reamer section may be configured to plastically deform and expand a hole in a workpiece as the tool is advanced into the hole along the longitudinal axis (without removing material from the workpiece). The reamer insert can thus compact the material in a region of the workpiece in the vicinity of the hole, wherein residual compressive stress remains in this region. The thread cutting portion may be disposed further along the axis from the front end, and may include a plurality of cutting teeth. The plurality of cutting teeth may be configured to cut a thread into the enlarged hole. Thus, the thread can be formed by the thread cutting portion in the region of compressive stress previously created by the reamer portion. Accordingly, the threaded bore may have high fatigue resistance, high load bearing force, and / or other improved properties. Methods for manufacturing and using the hybrid tap are also disclosed in accordance with various embodiments.The hybrid tap may have a variety of configurations. The shape, axial length, taper angle, diameter and / or other characteristics of the reamer section may be adjusted and selected for controlled plastic deformation and expansion of the hole in the workpiece. Likewise, the shape, axial length, taper angle, diameter, and / or other characteristics of the thread cutting portion may be tailored and selected for controlled cutting of the thread in the bore.In some embodiments, the reamer portion and the thread cutting portion may have different material properties. For example, the various parts may be made of different materials, have different heat treatments, different coatings, etc. The material properties may be selected to increase the performance of the reamer and thread cutting portions.The hybrid tools and associated methods of the present disclosure increase comfort and efficiency in forming tapped holes. The tools and associated methods provide tapped holes with increased fatigue strength, higher load bearing force, and other advantages.The systems and methods of the present disclosure may be used to thread a variety of parts. In some embodiments, the tool may be used to form one or more threaded holes in a vehicle engine block, a cylinder head, a lower crankcase extension (LCE), etc. In some embodiments, the threaded bore may be provided in a main bearing bolt hole of an engine block. The manufacturing systems and methods may be useful for threading threads into a casting (e.g., an aluminum casting), and the tools and methods of the present disclosure may be used in parts manufactured with advanced casting methods. However, it should be understood that the threading tools, systems, and methods of the present disclosure may be used for any suitable part without departing from the scope of the present disclosure.Referring now to FIG. 1, a hybrid tap 110 is shown in accordance with embodiments of the present disclosure. The tap 110 may be elongated and extend along a straight longitudinal axis 111 between a first end 115 and a second end 116. The tap 110 may be configured to rub and tap a hole 120 in a workpiece 122. The tap 110 increases manufacturing efficiency when, for example, high quality tapped holes are required in manufactured parts.Generally, the tap 110 may include a reamer portion 112 and a tap portion 114 arranged along the axis 111. Therefore, the tap 110 may be referred to as a hybrid expander / tap 110. During use, the reamer portion 112 of the hybrid tap 110 may be configured to drill the hole 120 (without removing material from the workpiece 122) by plastically deforming and expanding a previously formed hole 120 in the workpiece 122. The tap portion 114 of the tap 110 may then tap a thread into the enlarged hole.More specifically, the reamer section 112 may plastically deform and expand the hole, compressing the area around the expanded hole and remaining in that area. The tap portion 114 may cut into this conditioned area surrounding the enlarged hole as the tap 110 continues to advance into the workpiece 122 leaving a high quality tap hole. In this way, during a single stroke of the tap 110 (i.e., during feed generally along the axis 111, the bore may be enlarged (e.g., abraded, etc.) in a single direction (indicated by arrow 119) toward the workpiece 122) and subsequently threaded. In this way, improvements in manufacturing efficiency and associated advantages are achieved.As shown in FIG. 1, the tap 110 may include an elongated shank 130 that is cylindrical and centered on the axis 111. The shaft 130 may have an outer surface that may be at least partially smooth. In some embodiments, portions of the shank 130 may also be tapered. In some embodiments, the shank 130 may include a handle for gripping and manually operating the tap 110 (e.g., for advancement along the axis 111 and / or for rotation about the axis 111). In other embodiments, the shank 130 may include a chuck for attachment to a machine for automatically operating the tap 110 (e.g., for forward movement along the axis 111 and / or for rotation about the axis 111).The reamer section 112 of the tap 110 may be tapered and conical and have a smooth radial outer surface 138. The radially outer surface 138 may be centered about the axis 111. In the illustrated embodiment, reamer section 112 may be frustoconical and have a surface 140 extending substantially perpendicular to axis 111. The surface 140 may be circular and define the first end 115 (i.e., the front end) of the tap 110. In other embodiments, the face 140 may be disposed at a non-perpendicular angle to the axis 111. In other embodiments, the radially outer surface 138 of the reamer section 112 may taper towards a point defining the first end 115.The reamer section 112 may have a first axial end 154 defined on the face surface 140 (i.e., the first end 115). The reamer section 112 may have a second axial end 156 spaced from the first end 115 along the axis 111. The reamer section 112 may have a length 150 measured along the axis 111 between the first and second axial ends 154, 156. The reamer section 112 may have a width 152 (i.e., a diameter). The width 152 may vary along the length 150 such that the radially outer surface 138 is tapered or flared with respect to the axis 111. Thus, the width 152 of the reamer section 112 may gradually increase from the first axial end 154 to the second axial end 156. The radially outer surface 138 may also form a cone angle 158. In some embodiments, the outer radial surface 138 may be formed with a single cone angle 158.The cone angle 158 may be between ten and forty-five degrees (10°-45°) in various embodiments. Additionally, in some embodiments, the cone angle 158 may be between thirty and forty-five degrees (30°-45°). However, it will be appreciated that the taper angle 158 may be selected depending on various factors. Moreover, the length 150, width 152, taper angle 158, surface finish, materials, and / or other characteristics of the reamer section 112 may be adjusted depending on certain factors. These factors may include the desired extent of the bore 120, the type of bore (through bore or blind bore), the materials of the workpiece 122, the dimensions of the bore 120, and / or other factors.As shown in FIG. 1, the thread cutting portion 114 may have a first axial end 164 and a second axial end 166. The first axial end 164 may be proximate the second axial end 156 of the reamer section 112. The second axial end 166 of the thread cutting portion 114 may be spaced apart from the first axial end 164 along the axis 111. In some embodiments, the reamer section 112 and the thread cutting section 114 may be arranged end-to-end along the axis 111 such that the second axial end 156 of the reamer section 112 substantially coincides with the first end 164 of the thread cutting section 114. The thread cutting portion 114 may have a length 160 measured along the axis 111 between the first and second ends 164, 166.The thread cutting portion 114 may include a plurality of cutting teeth 161. The cutting teeth 161 may have a saw tooth profile and different thread dimensions to provide the hole 120 with the desired thread. The major diameter of the cutting teeth 161 defines the width 162 (i.e., the diameter) of the thread cutting portion 114. The width 162 may vary along the length 160 of the thread cutting portion 114 such that the thread cutting portion 114 narrows or widens and the width 162 gradually increases from the first end 164 to the second end 166. The cutting teeth 161 may also form a cone angle 168. In some embodiments, the thread cutting portion 114 may have a single cone angle 168 along the axis 111.The taper angle 168 of the thread cutting portion 114 may be different from the taper angle 158 of the reamer portion 112. In some embodiments, the taper angle 168 of the thread cutting portion 114 may be greater than the taper angle 158 of the reamer portion 112.The taper angle 168 may be between ten and forty-five degrees (10°-45°) in various embodiments. Additionally, in some embodiments, cone angle 168 may be between thirty and forty-five degrees (30°-45°). However, it should be appreciated that the taper angle 168 may be selected depending on various factors. The length 160, width 162, taper angle 168, surface finish, materials, and / or other characteristics of the reamer section 112 may be adjusted according to the target thread for the bore 120, the materials used in the workpiece 122, the type of bore, the dimensions of the bore 120, and / or other factors.In some embodiments, the thread cutting portion 114 may include a plurality of threaded lands (e.g., a first land 170 aand a second land 170 b) circumferentially separated by chip openings 169 (e.g., chip grooves). As shown, the cutting teeth 161 may be disposed in the first land surface 170 aand the second land surface 170 b, with the chip opening 169 separating the land surfaces 170 a, 170 b. The chip opening 169 may be a recessed slot extending longitudinally along the thread cutting portion 114 from the first end 164 to the second end 166. The chip opening 169 can also transition into the second axial end 156 of the reamer section 112 and run continuously. The teeth 161 may similarly continuously transition into the second axial end 156 of the reamer section 112.Although only two webs 170a, 170b and one chip opening 169 are shown, there may of course also be more. For example, there may be at least three lands spaced evenly about the axis 111, with the respective chip holes defined between adjacent pairs of lands.The reamer section 112 and the thread cutting section 114 may be arranged longitudinally one behind the other along the axis 111. The reamer section 112 may be disposed proximate to and may define the forward end (i.e., the first end 115) of the tap 110, in some embodiments. The thread cutting portion 114 may be disposed further along the axis 111 and may be directly adjacent to the reamer portion 112. There may be a gradual transition from the outer dimensions of the reamer section 112 to that of the thread cutting section 114.Accordingly, the reamer portion 112 and the tap portion 114 may be coupled and secured to define a unitary, one-piece, hybrid tap 110 that provides the advantages of both expanding (e.g., reaming) the bore 120 and then tapping in the expanded bore. The tap 110 may be used in a single threading operation (i.e., stroke) such that the friction portion 112 initially expands and plastically deforms the hole 120 and the threading portion 114 cuts a thread into the expanded hole as the workpiece 122 is advanced further. The threads thereby produced can have a high fatigue strength and a high load-holding force. Thus, the threads made with the tap 110 may hold a bolt and maintain the bolt load over a long service life.In particular, during use, the tap 110 may be directed toward the workpiece 122 with the first end 115 with the tap 110 and the hole 120 aligned along the axis 111 (FIG. 1 ). In some embodiments, the tap 110 may be manually operated. In other embodiments, the shank 130 may be attached to an actuation machine configured to automatically advance the tap 110 into the hole 120 along the axis 111, extract the tap 110 from the hole 120 along the axis 111, and / or rotate the tap 110 about the axis 111 relative to the workpiece 122.The hole 120 is shown in FIGS. 1 and 2. The bore 120 may be formed in the workpiece 122 in various ways without departing from the scope of the present disclosure. First, the hole 120 may be cast into the workpiece 122 (e.g., a cast aluminum motor part). In other embodiments, the hole 120 may be drilled, punched, or otherwise formed in the workpiece 122. The bore 102 may have a smooth inner surface 195 defining a first diameter dimension 190 (initial diameter). The hole 120 may be a through hole that extends through the entire wall thickness of the workpiece 122, as shown. In other embodiments, the hole 120 may be a blind hole recessed through a portion of the thickness of the workpiece 122. The workpiece 122 may be any type of component. For example, in some embodiments, the workpiece 122 may be an engine block. Also, the workpiece 122 may be an aluminum alloy engine block. The hole 120 may ultimately be used as a main bearing pin hole for the engine block.The width 152 (FIG. 1 ) at the first end 115 of the tap 110 may be less than the first diameter dimension 190 (FIGS. 1 and 2 ) of the bore 120 to allow the tap 110 to be advanced into the bore 120. As the tap 110 is advanced, the outer radial surface 138 of the reamer section 112 may abut the inner diameter surface 195 of the bore 120. Reamer section 112 may be advanced further along axis 111 and into bore 120, as shown in FIG. 3. The reamer section 112 can be advanced longitudinally until the second axial end 156 is received in the bore 120. The reamer portion 112 may apply sufficient force to the workpiece 122 to plastically deform and radially expand the inner diameter surface 195 of the hole 120 from the first diameter dimension 190 to the expanded width 192 (FIGS. 1 and 2 ).The shape and dimensions of the reamer section 112, the applied insertion pressure, and / or other variables may be chosen to control the plastic deformation and expansion of the hole 120. The taper angle 158, the feed rate of the tap 110, the applied insertion pressure, and / or other parameters may be selected to control the extent of the hole 120. The reamer section 112 may be advanced into the workpiece 122 such that the extended width 192 is substantially equal to the width 152 at the second axial end 156 of the reamer section 112. Thus, the width 152 at the second axial end 156 may be selected to control the extended width 192 of the hole 120.The reamer section 112 may also compact the material of the workpiece 122 as it extends the hole 120 from the first diameter dimension 190 to the extended width 192. More specifically, the plastic deformation performed during the radial expansion of the hole 120 may reduce the porosity of the material within a zone 199. Zone 199 is schematically illustrated in FIGS. 1 and 2 as an annular region extending radially outward from inner surface 195 and defined radially between the dimensions of extended width 192 and outer perimeter width 194. By compacting the material within the zone 199, the reamer portion 112 of the tap 110 may increase residual compressive stress within the zone 199.It will be appreciated that the reamer section 112 can expand and compress the hole 120 by a cold working process. Moreover, the reamer section 112 may be configured to warm-machine the workpiece 122 in expanding the hole 120. In other words, a heat source may be present to generate heat above the recrystallization temperature of the workpiece 122 during plastic deformation and expansion of the hole 120. This may allow the material to recrystallize during deformation. As with the depicted embodiments of cold forming, the hot forming process may compact the zone 199, reduce porosity therein, and / or provide other advantages.The feed rate, acceleration, pressure, etc. of the reamer section 112 may be selected depending on various factors with respect to the workpiece 122. For example, these variables may be adjusted depending on the change in ductility of the material of the workpiece 122 during expansion. One or more variables can be adjusted depending on the amount of heat generated during expansion. The variable(s) may be(can) selected according to the degree of densification (reduction in porosity) of the workpiece 122. These settings may provide a predetermined residual stress to the workpiece 122 within the zone 199.Additionally, in some embodiments, reamer section 112 may be advanced along axis 111 to expand hole 120 while screw tap 110 remains in a fixed angular position. In other embodiments, the tap 110 may be rotated about the axis 111 as the reamer section 112 enters and expands the hole 120. However, as the tap portion 114 approaches the workpiece 122, the tap 110 may be rotated about the axis 111 to allow the cutting teeth 161 to ablate material and begin cutting the thread.More specifically, the cutting teeth 161 may contact the workpiece 122 proximate the first axial end 164 as the tap 110 further penetrates the workpiece along the axis 111. The tap 110 may be rotated about the axis 111 as it advances further axially along the axis 111 (FIG. 4 ). The teeth 161 of the tap 110 may cut a plurality of threads 141 into the inner diameter surface 195 of the enlarged bore 120. The teeth 161 may cut and remove material from the workpiece 122 to cut the threads 141. The chips 149 of the material may be received in the chip openings 169 and move therein along the axis 111 toward the second end 116. In this way, the hole 120 may be threaded (e.g., tapped) within the zone 199 prepared by the reamer section 112. In other words, the threads 141 may be cut into the region 199 that has increased residual stress by the work performed by the reamer section 112. The threads 141 may be radially included in the zone 199 (i.e., the major diameter of the thread may be at most equal to the third width 194). The threads 141 may be cut within the region 199 of increased residual stress. As a result, the threaded hole can have high fatigue strength and high load holding force.The thread cutting portion 114 may be configured to cut the threads 141 having a known smaller diameter and a known larger diameter. Those having ordinary skill in the art will understand that the small diameter is measured with respect to the axis 111 and is the smallest diameter defined at the tips or crown tips of the cut threads 141, and that the large diameter is measured with respect to the axis 111 and is the largest diameter defined at the roots of the cut threads 141. It will therefore be appreciated that the teeth 161 on the tap 110 may have a larger diameter corresponding to the larger diameter of the threads 141 and a smaller diameter corresponding to the smaller diameter of the threads 141. In some embodiments, the smaller diameter of the cutting portion 114 may be selected to approximately correspond to the second width 192 of the hole 120. In some embodiments, the major diameter of the cutting portion 114 may also be selected to be at most equal to the third width 194 of the hole 120. Accordingly, the threads 141 may be cut within the compacted zone 199.The dimensions of the reamer section 112 and that of the tap section 114 (including relative dimensions) can be chosen for the tap 110 to provide the hole 120 with the desired properties. In some embodiments, the width 152 of the reamer section 112 at the second axial end 156 may be at most two percent (2%) greater than the width 152 at the first axial end 154. With this arrangement, the reamer section 112 can expand the hole 120 by at most about two percent (2%) during use. Moreover, in some embodiments, the width 162 of the thread cutting portion 114 may be at most one to two millimeters (1-2 mm) greater than the width 152 of the reamer portion 112 at the second axial end 156. Additionally, the tap 110 may be configured with larger cone angles 158, 168 for a workpiece 122 having higher material ductility. In contrast, the tap 110 may be configured with smaller cone angles 158, 168 for a workpiece 100 having a higher hardness. If the hole 120 is a blind hole, the tap 110 may be configured with a cutting portion 114 having a shorter length 160. Likewise, in cases where the hole 120 is a blind hole, the tap 110 may be configured with larger taper angles 158, 168, while in cases where the hole 120 is a through hole, the taper angles 158, 168 may be smaller.In some embodiments, the reamer portion 112 and the thread cutting portion 114 may have common material properties. For example, the reamer section 112 may be made of the same material as the thread cutting section 114 (e.g., tool steel). Also, the parts 112, 114 may have a common coating, heat treatment, material hardness, etc. In these embodiments, the tap 110 may be manufactured by forming the reamer section 112 and the tap section 114 on a single common shank 130, and the sections 112, 114 may be subjected to the same heat treatment, coating, etc. Thus, the reamer section 112 and the thread cutting section 114 may be integrally connected and have common material properties.In alternative embodiments, the reamer section 112 and the thread cutting section 114 may have different material properties. For example, in some embodiments, one of the portions 112 114 may have a higher material hardness than the other. There may be one or more hardened surfaces that may have a hardness of at least RC48. Additionally, in some embodiments, the reamer section 112 may have a higher material toughness than the thread cutting section 114. To provide the portions 112, 114 with different material properties, the portions 112, 114 may be separately formed from different materials and then firmly joined (e.g., by welding). In further embodiments, the tap 110 may be formed using additive manufacturing techniques, and these techniques may be used to form the tap 110 with the attached portions 112, 114 and with different material properties. In other embodiments, one of the portions 112, 114 may be subjected to a different heat treatment than the other to achieve the different material properties (e.g., one of the portions may be subjected to a first heat treatment and the other may be subjected to a different second heat treatment or one of the portions may be heat treated but the other may not). In other embodiments, one of the portions 112, 114 may be coated differently than the other to achieve the different material properties (e.g., one of the portions may have a first coating and the other may have a different second coating, or one of the portions may be coated, but the other may not). Coatings for the parts 112, 114 may be selected from a group consisting of titanium nitride (TiN), titanium carbonitride or carbonitride (TiCN), chrome sheet, nitride, aluminum chromium nitride (AlCrN), and aluminum chromium titanium nitride (AlCrTiN), in some embodiments. TiN may be chosen, for example, to increase chip flow in threading softer materials. TiCn can be chosen for its high hardness and wear resistance. In addition, a chromium plate may be selected for its friction reducing properties. Nitride can be chosen because of its high hardness. AlCrN can be chosen for its thermal properties. AlCrTiN may be chosen for its thermal and / or wear resistant properties. TiCN and / or TiN may also be selected for their thermal properties and high hardness.The methods of making the hybrid tap 110 will now be discussed in terms of embodiments and with reference to FIGS. 5-7. In some embodiments, the shaft 130 may be made in one piece and provided with a smooth outer surface. The shaft 130 may then be machined (i.e., material removed) to form the cutting teeth 161, the chip holes 169, and / or other features of the tap 110. In some embodiments, the tap 110 may then be polished, heat treated, coated, and / or otherwise machined. In some embodiments, these methods may result in the reamer portion 112 and the thread cutting portion 114 having common material properties.In other embodiments, shown in FIG. 5, the reamer section 112 and the thread cutting section 114 may be formed separately (in phantom). The tapered outer radial surface 138 of the reamer section 112 may be formed on one body 310, and the cutting teeth 161 of the thread cutting section 114 may be formed on another body 312. Then, the reamer section 112 and the thread cutting section 114 may be connected end to end. In some embodiments, the reamer section 112 and the thread cutting section 114 may be fixedly joined by welding. Moreover, in some embodiments, the thread cutting portion 114 may be made of one material and the reamer portion 112 may be made of another material. For example, the thread cutting portion 114 may be made of a material having a higher material hardness than that of the reamer portion 112. In some embodiments, the reamer section 112 may also be formed from a material that has a higher material toughness than that of the thread cutting section 114.In further embodiments shown in Figure 6, the tap 110 may be additively manufactured. For example, an additive manufacturing apparatus 320 may be used. An emitter 322 may emit energy into a bed 300 of powder material to form the tap 110 layer by layer. The armature 110 can be additively manufactured and grow progressively. In the embodiment shown, the tap 110 may be formed stepwise along the axis 111; however, in other embodiments, the tap 110 may be formed stepwise in another direction (e.g., perpendicular to the axis 111). This process can be convenient and highly efficient. In addition, this additive manufacturing process may provide the parts 112, 114 with common material properties. In other embodiments, the additive manufacturing process may provide the parts 112, 114 with different material properties. In other embodiments, the additive manufacturing process may be used to separately form the parts 112, 114, and after the forming, the parts 112, 114 may be joined end-to-end (e.g., by welding).Moreover, in the embodiments shown in FIG. 7, the manufacture of the tap 110 may include the use of a heat treatment device 302. In some embodiments, the heat treatment device 302 may be used to subject the faucet 110 to at least one heat treatment. In some embodiments, the portions 112, 114 may both be heat treated in the same manner to obtain common material properties. In other embodiments, the portions 112, 114 may be differentially heat treated to obtain different material properties. In some embodiments, one of the portions 112, 114 may also be heat treated instead of the other to achieve different material properties. In addition, to achieve different material properties, the heat treatment device 302 may be used to heat treat at least one of the portions 112, 114 in the separated state, and the portions 112, 114 may be subsequently joined end-to-end (e.g., by welding).As shown in Figure 7, the manufacture of the tap 110 may also involve the use of a coating apparatus 301. In some embodiments, the coating device 301 may be used to provide the faucet 110 with at least one coating. In some embodiments, the portions 112, 114 may be provided with a common coating. In other embodiments, the portions 112, 114 may be provided with different coatings to impart different material properties. In some embodiments, one of the portions 112, 114 may also be coated instead of the other to provide different material properties.Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that there are a variety of variations. It should also be appreciated that the example embodiment or embodiments are only examples and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description is intended to teach a person of ordinary skill in the art a practical guide to the implementation of the example embodiment or embodiments. It is to be understood that various changes may be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and their legal equivalents.

Claims

A hybrid tap (110) defining a longitudinal axis (111) for expanding and tapping a hole (120) in a workpiece (100, 122), the hybrid tap (110) comprising: a reamer section (112) having a forward end (154) and a smooth radial outer surface (138) tapering toward the forward end (154) along the longitudinal axis (111); and a tap section (114) having a plurality of cutting teeth, the tap section (114) being disposed together with the reamer section (112) along the longitudinal axis (111); wherein the reamer portion (112) is configured such that the leading end can enter the hole (120) to plastically deform and expand the hole (120) into an expanded hole (120) without removing material upon advancement of the tap (110) along the longitudinal axis (111), and to provide the expanded hole (120) with a residual compressive stress zone; wherein the plurality of cutting teeth (161) are configured to cut a thread into the expanded hole (120) within the residual compressive stress zone, and wherein the reamer portion (112) is frustoconical, has a surface (140) extending substantially perpendicular to the longitudinal axis (111) and defining the leading end (115) of the tap (110).The hybrid tap (110) of claim 1, wherein the tap portion (114) is tapered along the longitudinal axis (111).The hybrid tap (110) of claim 1, wherein the tap portion (114) is disposed end-to-end with the reamer portion (112) along the longitudinal axis (111).The hybrid tap (110) of claim 1, wherein the reamer section (112) has a rear end (156), wherein the front end (154) has a front width and wherein the rear end (156) has a rear width; and wherein the rear width is at most two percent (2%) greater than the front width to expand the hole (120) by at most two percent (2%).The hybrid tap (110) of claim 1, wherein the reamer portion (112) and the tap portion (114) are integrally connected and have common material properties.The hybrid tap (110) of claim 1, wherein the reamer section (112) and the tap section (114) have different material properties; and at least one of: wherein the reamer section (112) and the tap section (114) are made of different materials; wherein one of the reamer section (112) and the tap section (114) has a different heat treatment than the other to provide the different material properties; and wherein one of the reamer section (112) and the tap section (114) has a different coating than the other to achieve the different material properties.The hybrid tap (110) of claim 1, wherein the plurality of cutting teeth (161) are disposed in a first land and a second land, a chip opening separating the first land and the second land in a circumferential direction about the longitudinal axis (111), the chip opening extending through the tap portion along the longitudinal axis (111) and configured to receive chips during cutting of the thread into the enlarged hole (120).A method of forming a threaded bore in a molded workpiece (100, 122) using a hybrid tap (110) according to any preceding claim in a single stroke, comprising: providing a molded workpiece (100, 122) with a hole (120); advancing a reamer portion (112) of the hybrid tap (110) in the hole (120) in a single stroke to plastically deform and expand the hole (120) into an expanded hole (120) and provide the expanded hole (120) with a zone of residual compressive stress; and cutting a thread (141) into the enlarged hole (120) within the zone in a single stroke using a thread cutting portion (114) of the hybrid thread cutter (110), wherein the thread cutting portion (114) has a plurality of cutting teeth (161), and the thread cutting portion (114) is arranged together with the reamer portion (112) along the longitudinal axis (111) of the hybrid thread cutter (110).

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