Impact tool with tapered anvil wing design

Abstract

The present invention relates to an anvil for an impact mechanism, wherein the anvil includes a tapering wing that tapers at an angle of about 5 degrees to about 30 degrees. The anvil can also include a shaft extending from the wing, and a drive end adapted to transmit and apply torque to a workpiece. The wing of the anvil also includes a wing impact surface that receives a rotational impact force from a hammer body. For example, the hammer body contacts the wing of the anvil and applies torque thereto.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 220,325, filed July 9, 2021, and U.S. Patent Application No. 17 / 841,221, filed June 15, 2022, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention generally relates to impact tools for driving fasteners, and more specifically, to anvils for impact tools having a gradually narrowing anvil wing design. Background Technology

[0004] Various wrenches and tools are commonly used to apply torque to workpieces such as threaded fasteners. These tools, known as impact wrenches, screwdrivers, drills, or tools, are designed to deliver high torque output by storing energy in a rotating mass and then suddenly transferring it to an output shaft. In operation, the rotating mass, called the hammer, is accelerated by a motor, stores energy, and then suddenly connected to the output shaft via an anvil, generating a high-torque impact. The hammer mechanism is designed such that after the impact force is transmitted, the hammer is allowed to rotate freely and is not locked. Thus, the only reaction force applied to the tool body is the motor accelerating the hammer, so even with very high peak torque, the operator feels very little torque. Traditional hammer designs require a minimum torque before allowing the hammer to rotate independently of the anvil, thus stopping the tool from hammering, and only require low torque to smoothly drive the fastener, allowing for rapid rotation.

[0005] Traditional impact tools are designed with mating surfaces of the impact hammer and anvil, assuming that the hammer and anvil rotate on the same central axis. Assembly clearances and wear cause the surfaces to contact the flat surface of the hammer and the straight blade of the anvil at locations varying depending on the tool. In conventional designs, high stress is applied at the transition point between the anvil blade and the anvil shaft. Therefore, the internal components of the impact tool (e.g., hammer, anvil, and shaft) may be subjected to undesirable stresses that reduce the tool's efficiency and lifespan. Summary of the Invention

[0006] This invention generally relates to an anvil for an impact mechanism, wherein the anvil includes a wing that tapers gradually to a cone angle of about 5 degrees to about 30 degrees. The anvil may also include a shaft extending from the wing, and a drive end adapted to transmit torque and apply torque to a workpiece. The wing of the anvil also includes a wing impact surface that receives rotational impact force from a hammer body. For example, the impact mechanism may also include a hammer body rotatable about a central axis and having a hammer body impact surface or lug. The hammer body lug contacts the wing of the anvil and applies torque or rotational force thereto.

[0007] During operation, the anvil's wing experiences high stress at the intersection of the wing and the anvil's axis. At this intersection, the primary bending stress at the wing transforms into torsional stress in the axis. By incorporating a cone angle of approximately 5 to approximately 30 degrees, the section modulus of the anvil at the wing-axis intersection can be increased without increasing the overall cross-section of the wing, and without sacrificing the hammer's stroke range. This cone angle also provides a larger contact area between the hammer's lug and the anvil's wing, thereby reducing contact pressure, and the reduced stiffness of the wing along its length (due to the cone angle) improves the stress distribution and stress at the hammer's lug.

[0008] In one embodiment, the present invention generally relates to an anvil for an impact mechanism of an impact tool. The anvil includes: a base; a wing extending radially outward from the base and gradually narrowing at an angle of about 5 degrees to about 30 degrees; and a shaft extending axially from the base. Attached Figure Description

[0009] To facilitate understanding of the subject matter sought, various embodiments are shown in the accompanying drawings. By examining these embodiments and considering them in conjunction with the following description, the subject matter sought, its construction and operation, and its many advantages should be readily understood and appreciated.

[0010] Figure 1 This is a side view of an impact tool according to an embodiment of the present invention.

[0011] Figure 2 This is a perspective view of the impact mechanism according to an embodiment of the present invention.

[0012] Figure 3A This is a perspective view of the end of the anvil of the impact mechanism according to an embodiment of the present invention.

[0013] Figure 3B yes Figure 3A A side perspective view of the anvil.

[0014] Figure 4A This is a perspective view of the end of the anvil of the impact mechanism according to an embodiment of the present invention.

[0015] Figure 4B yes Figure 4A A side perspective view of the anvil.

[0016] Figure 5A This is a perspective view of the end of the anvil of the impact mechanism according to an embodiment of the present invention.

[0017] Figure 5B yes Figure 5A A side perspective view of the anvil.

[0018] Figure 6AThis is a perspective view of the end of the anvil of the impact mechanism according to an embodiment of the present invention.

[0019] Figure 6B yes Figure 6A A side perspective view of the anvil.

[0020] Figure 7A This is a perspective view of the end of the anvil of the impact mechanism according to an embodiment of the present invention.

[0021] Figure 7B yes Figure 7A A side perspective view of the anvil.

[0022] Figure 8A This is a perspective view of the end of the anvil of the impact mechanism according to an embodiment of the present invention.

[0023] Figure 8B yes Figure 8A A side perspective view of the anvil.

[0024] Figure 9A This is a perspective view of the end of the anvil of the impact mechanism according to an embodiment of the present invention.

[0025] Figure 9B yes Figure 9A A side perspective view of the anvil. Detailed Implementation

[0026] While the invention may have many different embodiments, and embodiments of the invention (including preferred embodiments) are shown in the accompanying drawings and described in detail herein, it should be understood that the present disclosure is merely an example of the principles of the invention and is not intended to limit the broad aspects of the invention to any one or more embodiments shown herein. As used herein, the term "invention" is not intended to limit the scope of the claimed invention, but is used only for discussing exemplary embodiments of the invention for illustrative purposes.

[0027] The present invention generally relates to an anvil for an impact mechanism, wherein the anvil includes a wing that tapers gradually to a cone angle of about 5 degrees to about 30 degrees. The anvil may also include a shaft extending from the wing, and a drive end adapted to transmit and apply torque to a workpiece. The wing of the anvil also includes a wing impact surface that receives rotational impact force from a hammer. For example, the impact mechanism may also include a hammer that is rotatable about a central axis and has a hammer impact surface or lug. The hammer lug contacts the wing of the anvil and applies torque or rotational force thereto.

[0028] During operation, the anvil's wing experiences high stress at the intersection of the wing and the anvil shaft. At this intersection, the primary bending stress at the wing transforms into torsional stress in the shaft. By incorporating a cone angle of approximately 5 to approximately 30 degrees, the section modulus of the anvil at the wing-shaft intersection can be increased without increasing the overall cross-section of the wing, and without sacrificing the hammer's stroke range. This cone angle also provides a larger contact area between the hammer's lug and the anvil's wing, thereby reducing contact pressure, and the decreasing stiffness of the wing along its length (due to the cone angle) improves the stress distribution and stress at the hammer's lug.

[0029] Reference Figure 1 An exemplary impact tool 100 according to an embodiment of the present invention is shown. The impact tool 100 may have a housing 102 including a main housing portion 104 and a handle portion 106. A motor 108 and an impact mechanism 110 may be disposed in the main housing portion 104. The impact mechanism 110 may include a hammer 112 and an anvil 114, the anvil 114 including or coupled to an output drive portion 116. The drive portion 116 is adapted to apply torque to a workpiece, such as a fastener (e.g., a flange nut or bolt), via an adapter (drill bit or sleeve) coupled to the drive portion 116. As shown, the drive portion 116 is a "male" connector (e.g., a drive lug, which may include a square or other polygonal cross-sectional shape) designed to mate with or engage with a female counterpart. However, the drive portion 116 may alternatively include a "female" connector designed to engage with a male counterpart. The drive unit 116 can also be configured to directly engage the workpiece without needing to be connected to an adapter (drill bit or sleeve). The drive unit 116 is operatively connected to and driven by the motor 108 (which may be a pneumatic motor, or a brushed or brushless motor) via the impact mechanism 110.

[0030] A trigger 118 for controlling the operation of motor 108 is operatively coupled to motor 108 and housed within housing 102. A selector lever 120 is also operatively coupled to trigger 118 and / or motor 108 to allow selection or control of the rotational drive direction (e.g., clockwise or counterclockwise). Motor 108 can be operatively coupled in a known manner via trigger 118 (housed in housing 102) to power source 122 (e.g., battery or other power source), motor speed circuitry, and / or controller, and operatively coupled to drive unit 116 to provide torque to tool 100, and further to drive unit 116 via impact mechanism 110. Motor 108 can be a brushless or brushed type motor, a pneumatic motor, or any other suitable motor.

[0031] Trigger 118 is adapted to selectively switch power supplied to motor 108 on and off, or to allow power / voltage to flow from power source 122 to motor 108 or to stop power / voltage from flowing from power source 122 to motor 108. Trigger 118 can be biased to the OFF position such that it is actuated or pressed inward relative to housing 102 to move to the ON position, thereby operating tool 100, and released to move to the OFF position, thereby stopping operation of tool 100 via the biasing characteristic of trigger 118. Trigger 118 can also be a variable speed trigger. In this respect, relative actuation of trigger 118 causes motor 108 to operate at a speed that varies increasing as trigger 118 is actuated further.

[0032] During operation, motor 108 selectively rotates hammer 112 in either a first rotational drive direction or a second rotational drive direction (e.g., clockwise or counterclockwise), which rotates anvil 114 and drive unit 116 to apply torque to the workpiece. Under high torque, hammer 112 disengages from anvil 114, and motor 108 causes hammer 112 to rotate independently of anvil 114. To apply high torque output, hammer 112 engages anvil and transmits the high torque output to anvil 114, thereby generating a high torque impact. Impact mechanism 110 is designed such that after the impact force is transmitted, hammer 112 disengages from anvil 114 and is allowed to rotate freely. Thus, the only reaction force applied to the body of tool 100 is the acceleration of hammer 112 by motor 108, so even with very high peak torque transmitted, the operator feels very little torque or impact force. Impact mechanism 110 typically requires a predetermined minimum torque to separate (or disengage) hammer 112 from anvil 114 after impact. Under low-resistance torque operating conditions, the predetermined torque requirement allows the hammer 112 to remain engaged with and rotate together with the anvil 114, thereby stopping the tool 100 from hammering or impacting, and instead smoothly driving and rapidly rotating the workpiece.

[0033] Reference Figure 1 and Figure 2 In one embodiment, the hammer body 112 of the impact mechanism 110 may include a hammer body base 124 and one or more hammer body lugs 126, and the hammer body 112 is rotatable about its central axis (operated via a motor 108). As shown, the hammer body lugs 126 project from the hammer body base 124 and radially inward toward the central axis of the hammer body 112. Each hammer body lug 126 defines a hammer impact surface 128 that contacts the anvil 114 (e.g., the anvil wing 134 on the anvil impact surface 138 described below) during impact operation. The hammer body 112 may include or be coupled to a drive shaft 130, which is axially aligned with the hammer body center and receives rotational force from the motor 108.

[0034] Reference Figure 2 , Figure 3A and Figure 3B In one embodiment, the anvil 114 of the impact mechanism 110 may include an anvil base 132, one or more anvil wings 134 extending radially outward from the anvil base 132, an anvil shaft 136 extending axially from the anvil base 132, and a drive portion 116 near the end of the anvil shaft 136. The anvil 114 is rotatable about its central axis (via operation of the motor 108 and the hammer 112). Each anvil wing 134 defines an anvil impact surface 138 that contacts a corresponding hammer impact surface 128 during impact operation. Each anvil wing 134 may also taper gradually at a cone angle (θ) of approximately 5 degrees to approximately 30 degrees, which also provides an anvil impact surface 138 that tapers gradually at this cone angle (θ). As shown, the drive portion 116 is a 3 / 4-inch square drive lug with a cone angle (θ) of approximately 15 degrees. The anvil 114 may also include an undercut or recessed portion 140 extending circumferentially around the anvil shaft 136. The outer diameter of the recessed portion 140 is smaller than the outer diameter of the anvil shaft 136. For example, the outer diameter of the recessed portion 140 may be approximately 25% to approximately 100% of the outer diameter of the anvil shaft 136, approximately 25% to approximately 75% of the outer diameter of the anvil shaft 136, and / or approximately 25% to approximately 50% of the outer diameter of the anvil shaft 136. The recessed portion 140 may help reduce inertia (i.e., the mass of the anvil 114) and increase the elastic effect on the anvil shaft 136, which helps reduce stress at the transition from the anvil shaft 136 to the drive portion 116.

[0035] The highest stress on the anvil wing 134 occurs at the intersection of the anvil wing 134 and the anvil base 132. At this intersection, the primary bending stress at the anvil wing 134 transforms into torsional stress in the anvil shaft 136. A larger anvil shaft 136 or anvil base 132 can be added to connect the anvil wing 134 and the anvil shaft 136 to provide an intermediate transition, thereby reducing ejection at the transition point from bending stress to torsional stress. At the intersection of the anvil wing 134 and the anvil base 132, a radius (R) can be provided to provide a smooth geometric transition from the anvil base 132 to the anvil wing 134. The radius (R) also increases the section modulus at the intersection of the anvil wing 134 and the anvil base 132, thereby reducing bending stress. However, a larger radius will result in a smaller wing contact area or anvil impact surface 138. The anvil wing 134 can be extended to increase the contact area, but this will reduce output torque due to the higher anvil inertia from the additional wing material. In one example, the radius (R) is approximately 100% to approximately 150% of the radius of the anvil base 132. The radius R of the anvil wing 134... WIt can also be approximately 100% to approximately 250% of the radius of the anvil base 132, more specifically, approximately 150% to approximately 200% of the radius of the anvil base 132.

[0036] The hammer 112 and anvil 114 also provide an angle (β) between the centerline of the hammer lug 126 and the centerline of the anvil wing 134. Minimizing the overlap angle (2β) provides additional clearance for the hammer 112 to rotate (hammer stroke range = 180° - overlap angle), thereby mitigating potential impact (also known as clipping) on ​​the bottom surface of the anvil wing 134 during operation. In one example, this angle (β) is approximately 20 to approximately 40 degrees. This range provides sufficient material cross-section in the anvil wing 134 and hammer lug 126 to withstand impact stress and allow for a wide range of hammer rotation without clipping.

[0037] By gradually narrowing the anvil wing 134 with a cone angle (θ), the section modulus of the anvil 114 at the intersection of the anvil wing 134 and the anvil base 132 will increase without increasing the overall cross-section of the anvil wing 134. Conventional straight wings with the same section modulus at the intersection result in very high anvil inertia due to the additional material at the wingtip, and thus produce lower output torque. Furthermore, by gradually narrowing the anvil wing 134 with a cone angle (θ), the section modulus of the anvil at the critical position can be increased without sacrificing the stroke range of the hammer.

[0038] Furthermore, the resulting area has a gradually narrowing anvil wing 134 A larger contact area is provided between the hammer lug 126 and the anvil wing 134, thereby reducing contact pressure. The contact area of ​​each anvil wing surface (e.g., anvil impact surface 138) can be approximately 0.01 square inches to approximately 0.2 square inches, more specifically, approximately 0.02 square inches to approximately 0.1 square inches. When both anvil wings 134 (e.g., anvil impact surface 138) simultaneously contact the hammer lug 126 (e.g., at the hammer impact surface 128), the total system contact area during operation is twice the contact area of ​​each anvil wing surface. By varying the cone angle (θ), the stiffness of the anvil wing 134 can be gradually reduced along its length to improve stress distribution and stress at the root of the hammer lug 126. A cone angle (θ) of approximately 5 degrees to approximately 30 degrees provides a minimum overlap angle and improves stress distribution at the hammer lug 126 and the anvil wing 134.

[0039] Reference Figure 4A and Figure 4BAn embodiment of anvil 414 is shown. Anvil 414 is similar to anvil 114 and may include one or more features of anvil 114. For example, anvil 414 may include anvil base 432, one or more anvil wings 434 having anvil impact surfaces 438 extending radially outward from anvil base 432, anvil shaft 436 extending axially from anvil base 432, and a drive portion 416 near the end of anvil shaft 436. Anvil 414 may also include an undercut or grooved portion (not shown) extending circumferentially around anvil shaft 436.

[0040] In this example, the drive section 416 is a 3 / 4-inch square drive lug, and each anvil wing 434 may also taper gradually at a cone angle (θ) of approximately 5 degrees to approximately 30 degrees, more specifically approximately 10 degrees. The radius (R) may be approximately 0.7 inches to approximately 0.8 inches, more specifically approximately 0.75 inches, of the anvil wing radius R. W It can be about 1 inch, and the impact (contact) surface area on each anvil impact surface 438 can be from about 0.06 square inches to about 0.08 square inches, more specifically about 0.07 square inches.

[0041] Reference Figure 5A and Figure 5B The document describes an anvil 514. Anvil 514 is similar to anvil 114 and may include one or more features of anvil 114. For example, anvil 514 may include an anvil base 532, one or more anvil wings 534 extending radially outward from the anvil base 532 and having an anvil impact surface 538, an anvil shaft 536 extending axially from the anvil base 532, and a drive portion 516 near the end of the anvil shaft 536. Anvil 514 may also include an undercut or groove portion 540 extending circumferentially around the anvil shaft 536.

[0042] In this example, the drive section 516 is a 3 / 4-inch square drive lug, and each anvil wing 534 may also taper gradually at a cone angle (θ) of approximately 5 degrees to approximately 30 degrees, more specifically approximately 12 degrees. The radius (R) may be approximately 0.575 to approximately 0.65 inches, more specifically approximately 0.625 inches, of the anvil wing radius R. W It can be about 1 inch, and the impact (contact) surface area on each anvil impact surface 538 can be from about 0.05 square inches to about 0.07 square inches, more specifically about 0.06 square inches.

[0043] Reference Figure 6A and Figure 6BAnother embodiment of anvil 614 is described. Anvil 614 is similar to anvil 114 and may include one or more features of anvil 114. For example, anvil 614 may include anvil base 632, one or more anvil wings 634 having anvil impact surfaces 638 extending radially outward from anvil base 632, anvil shaft 636 extending axially from anvil base 632, and a drive portion 616 near the end of anvil shaft 636. Anvil 614 may also include an undercut or grooved portion (not shown) extending circumferentially around anvil shaft 636.

[0044] In this example, the drive section 616 is a 3 / 8-inch square drive lug, and each anvil wing 634 may also taper gradually at a cone angle (θ) of approximately 5 degrees to approximately 30 degrees, more specifically approximately 7.5 degrees. The radius (R) may be approximately 0.5 inches to approximately 0.6 inches, more specifically approximately 0.55 inches, of the anvil wing radius R. W It can be approximately 0.6 inches to approximately 0.7 inches, more specifically approximately 0.68 inches, and the impact (contact) surface area on each anvil impact surface 638 can be approximately 0.02 square inches to approximately 0.04 square inches, more specifically approximately 0.03 square inches.

[0045] See attached document Figure 7A and Figure 7B Another embodiment of anvil 714 is shown. Anvil 714 is similar to anvil 114 and may include one or more features of anvil 114. For example, anvil 714 may include an anvil base 732, one or more anvil wings 734 extending radially outward from anvil base 732 and having anvil impact surfaces 738, an anvil shaft 736 extending axially from anvil base 732, and a drive portion 716 near the end of anvil shaft 736. Anvil 714 may also include an undercut or grooved portion (not shown) extending circumferentially around anvil shaft 736. Anvil 714 may include an additional base 742 extending circumferentially around anvil shaft 736 between anvil shaft 736 and anvil wings 734. This additional base 742 may help provide an intermediate stress transfer from anvil wings 734 to anvil shaft 736. The additional base 742 can also be incorporated into any other anvil design described herein (e.g., anvil 114, anvil 414, anvil 514, anvil 614, anvil 814 and / or anvil 914).

[0046] In this example, the drive section 716 is a 1 / 2-inch square drive lug, and each anvil wing 734 may also taper gradually at a cone angle (θ) of approximately 5 degrees to approximately 30 degrees, more specifically approximately 5 degrees. The radius (R) may be approximately 0.475 inches to approximately 0.6 inches, more specifically approximately 0.525 inches, and the radius R of the anvil wing... WIt can be about 1 inch, and the impact (contact) surface area on each anvil impact surface 738 can be from about 0.03 square inches to about 0.05 square inches, more specifically about 0.04 square inches.

[0047] See attached document Figure 8A and Figure 8B Another embodiment of anvil 814 is shown. Anvil 814 is similar to anvil 114 and may include one or more features of anvil 114. For example, anvil 814 may include anvil base 832, one or more anvil wings 834 having anvil impact surfaces 838 extending radially outward from anvil base 832, anvil shaft 836 extending axially from anvil base 832, and a drive portion 816 near the end of anvil shaft 836. Anvil 814 may also include an undercut or grooved portion (not shown) extending circumferentially around anvil shaft 836. Anvil 814 may include additional bases (not shown), such as additional base 742 extending circumferentially around anvil shaft 836.

[0048] In this example, the drive section 816 is a 1 / 2-inch square drive lug, and each anvil wing 834 may also taper gradually at a cone angle (θ) of approximately 5 degrees to approximately 30 degrees, more specifically approximately 12.5 degrees. The radius (R) may be approximately 0.5 inches to approximately 0.7 inches, more specifically approximately 0.6 inches, and the radius R of the anvil wing... W It can be about 1 inch, and the impact (contact) surface area on each anvil impact surface 838 can be from about 0.05 square inches to about 0.07 square inches, more specifically about 0.06 square inches.

[0049] Reference Figure 9A and Figure 9B Another embodiment of anvil 914 is shown. Anvil 914 is similar to anvil 114 and may include one or more features of anvil 114. For example, anvil 914 may include anvil base 932, one or more anvil wings 934 having anvil impact surfaces 938 extending radially outward from anvil base 932, anvil shaft 936 extending axially from anvil base 932, and a drive portion 916 near the end of anvil shaft 936. Anvil 914 may also include an undercut or grooved portion (not shown) extending circumferentially around anvil shaft 936. Anvil 914 may include additional bases (not shown), such as additional base 742 extending circumferentially around anvil shaft 936.

[0050] In this example, the drive section 916 is a 1 / 2-inch square drive lug, and each anvil wing 934 can also gradually narrow with a cone angle (θ) of approximately 5 degrees to approximately 30 degrees, more specifically approximately 21 degrees. The radius (R) can be infinite, and the radius R of the anvil wing...W It can be about 1 inch, and the impact (contact) surface area on each anvil impact surface 938 can be from about 0.03 square inches to about 0.05 square inches, more specifically about 0.04 square inches.

[0051] As described herein, the anvil comprises an anvil wing that tapers gradually from approximately 5 degrees to approximately 30 degrees. The taper angle helps to increase the section modulus of the anvil at the intersection of the wing and the shaft without increasing the overall cross-section of the wing, and without sacrificing the hammer's stroke range. This taper angle also provides a larger contact area between the hammer's lug and the anvil wing, thereby reducing contact pressure, and the decreasing stiffness of the wing along its length (due to the taper angle) improves stress distribution and stress at the hammer's lug.

[0052] As used herein, the term "connection" can refer to any physical, electrical, magnetic, or other direct or indirect connection between two or more components or parts. The term "connection" is not limited to a fixed, direct connection between components or parts.

[0053] The foregoing description and accompanying drawings are illustrative only and not intended to be limiting. While specific embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications can be made therein without departing from the broader aspects contributed by the inventors. The actual scope of protection sought will be defined in the appended claims when viewed from an appropriate perspective based on the prior art.

Claims

1. An anvil for an impact mechanism of an impact tool, the anvil comprising: The base, which has a base radius; A wing that extends radially outward from the base and tapers gradually at a cone angle of about 5 degrees to about 30 degrees as the wing extends outward from the base, and wherein the intersection of the wing and the base includes a radius of about 100% to about 150% of the radius of the base, the radius providing a transition from the base to the wing; as well as A shaft extending axially from the base.

2. The anvil according to claim 1, further comprising: The drive unit near the end of the shaft.

3. The anvil according to claim 2, wherein, The drive unit has a square cross-sectional shape.

4. The anvil according to claim 1, wherein, The cone angle is approximately 15 degrees.

5. The anvil according to claim 1, further comprising: A groove portion extending circumferentially around the axis.

6. The anvil according to claim 5, wherein, The groove portion has a groove outer diameter, and the shaft has a shaft outer diameter, wherein the groove outer diameter is smaller than the shaft outer diameter.

7. The anvil according to claim 6, wherein, The outer diameter of the groove is approximately 25% to approximately 75% of the outer diameter of the shaft.

8. The anvil according to claim 6, wherein, The outer diameter of the groove is approximately 25% to approximately 50% of the outer diameter of the shaft.

9. The anvil according to claim 1, wherein, The wing includes a contact area of ​​approximately 0.01 square inches to approximately 0.2 square inches adapted to contact the hammer lug.

10. An impact mechanism for an impact tool, the impact mechanism comprising: Anvil, the anvil comprising: The base of the anvil has a base radius; A wing extending radially outward from the base of the anvil and tapering gradually at a conical angle of approximately 5 to approximately 30 degrees as the wing extends outward from the base of the anvil, wherein the intersection of the wing and the base of the anvil comprises a radius of approximately 100% to approximately 150% of the radius of the base, the radius providing a transition from the base to the wing; and A shaft extending axially from the base of the anvil; and Hammer body, the hammer body comprising: Hammer base; and A hammer lug protrudes from the base of the hammer and is adapted to impact the wing at the contact area of ​​the wing.

11. The impact mechanism according to claim 10, wherein, The anvil also includes a drive portion near the end of the shaft.

12. The impact mechanism according to claim 11, wherein, The drive unit has a square cross-sectional shape.

13. The impact mechanism according to claim 10, wherein, The anvil also includes a groove portion extending circumferentially around the axis.

14. The impact mechanism according to claim 13, wherein, The groove portion has a groove outer diameter, and the shaft has a shaft outer diameter, wherein the groove outer diameter is approximately 25% to approximately 75% of the shaft outer diameter.

15. The impact mechanism according to claim 14, wherein, The outer diameter of the groove is approximately 25% to approximately 50% of the outer diameter of the shaft.

16. The impact mechanism according to claim 10, wherein, The contact area is approximately 0.01 square inches to approximately 0.2 square inches.

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