Impact wrench impact part mounting structure

Abstract

This utility model discloses an impact wrench impact part mounting structure, including a camshaft. A hammer head is movably sleeved on the outer circumferential side of the front end of the camshaft. A shoulder is provided at the rear end of the camshaft. A helical compression spring is compressed between the shoulder and the hammer head. A truncated cone protrudes from the end face of the shoulder facing the hammer head, opposite to the rear end face of the hammer head. A steel ball for force transmission is provided between the force-receiving groove of the hammer head and the raceway groove of the matching camshaft. A receiving groove is recessed on the front end face of the hammer head. Two symmetrical impact bosses protrude from the bottom wall of the receiving groove, and the other positions are flat. A settling step is recessed in part of the rear end face of the hammer head, and a positioning boss is formed in the non-recessed part. A positioning groove adapted to the positioning boss is recessed on the end face of the truncated cone. When the hammer head and the shoulder approach and abut against each other, the positioning boss falls into the positioning groove, and the middle part of the raceway groove extends forward beyond the force-receiving groove, allowing the steel ball to just come out from the middle of the raceway groove. This structure can improve structural strength and extend service life.

Description

Technical Field

[0001] This utility model belongs to the technical field of handheld power tools, specifically relating to an impact wrench impact part mounting structure. Background Technology

[0002] Electric wrenches are widely used in industrial production, machinery manufacturing, and household repair. They are tools driven by an electric motor, characterized by ease of use, labor-saving operation, and high efficiency. In situations requiring impact torque, they can also provide and output impact torque through an impact mechanism. (See also...) Figure 1 The impact mechanism in an electric wrench mainly consists of a camshaft 1, a hammer head 2, a spring, and an output shaft 6. The motor in the electric wrench provides power, which is transmitted to the camshaft via a planetary reducer that increases torque and speed. The camshaft rotates because the output shaft 6 (not integral) is located at the front end of the camshaft 1. A hammer head 2, designed to strike the output shaft 6, is mounted on the outer circumference of the camshaft to provide impact force. This structural form is used in existing products and is also disclosed in domestic and international patents, such as CN219704922U. The design of the camshaft driving the hammer head to strike the output shaft is ingenious. Two raceway grooves 11, symmetrical about their axis, are designed and manufactured on the outer circumference of the camshaft 1. (See [reference needed]). Figure 1-4 The raceway groove 11 itself extends in a roughly symmetrical V-shape, with a circular arc cross-section; steel balls 3 of suitable diameter are rolled in the two raceway grooves—serving as force transmission components from the camshaft 1 to the hammer head 2. The hammer head is sleeved on the outside of the camshaft through an inner hole, and two force-receiving grooves 21 are correspondingly formed on the inner wall of the hammer head, which are paired with the raceway groove 11 one-to-one. (See also...) Figure 5-7 One side wall of the force-receiving groove 21 is V-shaped to fit the raceway groove 11, forming the force-receiving side 211. The opening of the V-shaped force-receiving side 211 faces forward, opposite to the V-shaped orientation of the raceway groove 11. The aforementioned spring acts between the camshaft and the hammer head, providing a forward force to the hammer head. The lower half of the aforementioned steel ball 3 falls within the raceway groove 11, while the upper half, which is higher than the raceway groove, is located within the force-receiving groove 21 and contacts the force-receiving side 211. The force-receiving side 211 transitions to the bottom wall of the force-receiving groove 21 with an arc (fitting the diameter of the steel ball). The other side of the force-receiving groove 21 extends axially through the hammer head 2 for assembly.

[0003] The front end face of the hammerhead 2 is recessed with a receiving groove 25. Two centrally symmetrical impact protrusions 26 protrude from within the receiving groove 25. The radial line connecting the centers of the two impact protrusions 26 is perpendicular to the radial line connecting the centers of the two force-bearing grooves 21. Two centrally symmetrical mounting grooves 27 are recessed on the bottom wall of the receiving groove 25. The depth of the mounting grooves 27 gradually increases radially inward, extending inward to penetrate the force-bearing groove 21.

[0004] During assembly, the spring is fitted onto the camshaft 1. External force causes the hammer 2 to be fitted onto the camshaft 1 from front to back, compressing the spring. When compressed to its limit, the rear end face of the hammer 2 abuts against the planetary gear mounting bracket at the rear end of the camshaft 1. (See [reference needed]). Figure 8 At this point, the middle (highest point) of the raceway groove 11 is slightly higher than the bottom wall of the receiving groove 25. Rotating the hammer head 2 aligns the middle of the raceway groove 11 with the mounting groove 27. With the help of the mounting groove 27, the steel ball 3 can and can only be installed into the raceway groove 11 from this angle. Releasing the hammer head 2, under the action of the spring, the hammer head 2 moves forward until the force-bearing side 211 contacts the upper half of the steel ball 3. Disassembly is performed in reverse order of the assembly process. This design results in a larger fitting length between the hammer head 2 and the camshaft 1, ensuring reliable engagement, and preventing the steel ball from easily detaching during operation. However, in high-torque electric wrenches, the mounting groove 27, being close to the impact boss 26, which serves as the core part for transmitting impact, can easily cause stress concentration in the hammer head, leading to crack initiation and affecting the hammer head's service life. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, the purpose of this utility model is to provide an impact wrench impact part mounting structure that solves the problem that current electric wrenches require a mounting groove on the hammer head for installing and removing steel balls, but the mounting groove being close to the impact boss that transmits impact force can easily affect the service life of the hammer head. This achieves the effect of meeting the requirements for installing and removing steel balls while avoiding the impact of the mounting groove on the strength of the hammer head.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An impact wrench impact unit mounting structure includes a camshaft. A hammer head is movably mounted on the outer circumferential side of the front end of the camshaft. A shoulder is protruding on the outer circumferential side of the rear end of the camshaft. A helical compression spring is compressed between the shoulder and the hammer head. A frustum is protruding on the end face of the shoulder facing the hammer head, opposite to the rear end face of the hammer head. Two centrally symmetrical raceway grooves are recessed on the outer circumferential side of the camshaft. The raceway grooves are V-shaped and open towards the rear end of the camshaft. Two force-receiving grooves are formed on the inner wall of the hammer head, which are paired with the raceway grooves one-to-one. The force-receiving side of the force-receiving groove is also V-shaped and opens towards the front end of the camshaft. A steel ball for force transmission is provided between the force-receiving groove and the matching raceway groove. The front end face of the hammer head is recessed and has a receiving groove. The bottom wall of the receiving groove is raised and has two impact protrusions that are centrally symmetrical. Except for the impact protrusions, the bottom wall of the receiving groove is flat. The rear end face of the hammer head is recessed to form a settling step, and the non-recessed part forms a positioning boss. The end face of the camshaft frustum is recessed to form a positioning groove that matches the positioning boss. Alternatively, a settling step may be formed by a circumferential recess on the rear end face of the hammer head, and a positioning boss may be formed on the non-recessed part. A positioning groove that matches the positioning boss may be correspondingly recessed on the end face of the camshaft frustum. When the hammer head and the camshaft shoulder approach and abut against each other, the positioning boss falls into the positioning groove, the middle part of the camshaft raceway groove extends forward beyond the force-bearing groove, and the steel ball can just be dislodged from the middle of the raceway groove.

[0007] Furthermore, the positioning boss can only fall into the positioning groove from a single circumferential angular position; specifically, when the positioning boss falls into the positioning groove, the middle part of the raceway groove and the middle part of the force-bearing side correspond in circumferential angular position.

[0008] Furthermore, the number of positioning bosses is one or several at circumferential intervals.

[0009] Compared with the prior art, the present invention has the following beneficial effects: In this invention, the impact wrench's impact part mounting structure eliminates the need for two mounting slots for inserting steel balls on the bottom wall of the hammer head's receiving groove. Instead, a settling step is created on the rear end face of the existing-sized hammer head to allow for positioning, forming a positioning boss in the non-recessed portion. A positioning groove, matching the positioning boss, is recessed into the end face of the camshaft's frustum. During assembly, the bottom of the hammer head's settling step abuts against the end face of the camshaft's frustum, and the positioning boss falls into the positioning groove. The middle of the raceway groove extends forward beyond the force-bearing groove. At this point, because the distance the hammer head moves towards the camshaft exceeds the depth of the settling step, the steel ball can easily be inserted or removed from the middle of the raceway groove. During normal use, the hammer head will not move to the aforementioned position abutting against the camshaft, and the steel ball remains difficult to dislodge. The newly designed settlement steps, positioning bosses, and positioning grooves are further away from the core part that transmits impact compared to the original mounting grooves. They do not reduce the original structural strength too much. This effectively solves the problem that the hammer head needs to have mounting grooves for installing and removing steel balls, but the mounting grooves can easily affect the service life of the hammer head. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the impact wrench impact part mounting structure according to an embodiment. Figure 2 for Figure 1 A separate schematic diagram of the camshaft; Figure 3 for Figure 2 Top view; Figure 4 for Figure 2 A 3D view of the intermediate camshaft; Figure 5 This is a schematic diagram of a hammerhead in the prior art, with a viewpoint of... Figure 1 The right-view angle; Figure 6 for Figure 5 Sectional view of AA; Figure 7 for Figure 5 A 3D view of the hammerhead; Figure 8 for Figure 5 A schematic diagram showing the assembly and installation of steel balls in the middle hammerhead; Figure 9 This is a separate schematic diagram of the improved hammer head in the impact part mounting structure of the impact wrench in the embodiment; Figure 10 To and Figure 9 A schematic diagram of an improved camshaft adapted to the hammer head; Figure 11 This is a schematic diagram of the mounting structure for assembling and installing a steel ball in the impact part of an impact wrench, as shown in the embodiment. Figure 12 A structural schematic diagram of an alternative design for an improved hammerhead; Figure 13 To and Figure 12 A schematic diagram of an improved camshaft adapted to the hammer head; Among them, camshaft 1, raceway groove 11, shoulder 12, frustum 121, positioning groove 122, hammer 2, force groove 21, force side 211, flange 22, outer ring 23, annular cavity 24, receiving groove 25, impact boss 26, mounting groove 27, settling step 28, positioning boss 281, steel ball 3, helical compression spring 4, flat bearing 5, output shaft 6. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0012] Please see Figures 1-7The impact wrench impact part mounting structure includes a camshaft 1. A hammer 2 is movably mounted on the outer circumferential side of the front end of the camshaft 1. A shoulder 12 is protruding on the outer circumferential side of the rear end of the camshaft 1. A helical compression spring 4 is compressed between the shoulder 12 and the hammer 2. The helical compression spring 4 is also mounted on the camshaft 1. A frustum 121 is protruding on the end face of the shoulder 12 facing the hammer 2, opposite to the rear end face of the hammer 2. The diameter of the frustum is smaller than the inner diameter of the helical compression spring 4, and it is located inside the helical compression spring 4, serving as the working part opposite to the rear end face of the hammer. The outer circumferential side of the camshaft 1 is concave... The camshaft 1 has two centrally symmetrical raceway grooves 11. The raceway grooves 11 are V-shaped and open towards the rear end of the camshaft 1. The cross-section of the raceway grooves 11 is arc-shaped. The inner wall of the hammer head 2 has two force-receiving grooves 21 that are paired with the raceway grooves 11. The force-receiving side 211 of the force-receiving groove 21 is also V-shaped and opens towards the front end of the camshaft 1. A steel ball 3 is provided between the force-receiving groove 21 and the matching raceway groove 11 for force transmission. As a medium for relative motion, the wall of the force-receiving side 211 and the bottom wall of the force-receiving groove 21 are arc-shaped (matching the diameter of the steel ball 3).

[0013] Please refer to the assistance provided. Figure 9 and Figure 10 The front end face of the hammer head 2 is recessed with a receiving groove 25, and the bottom wall of the receiving groove 25 is raised with two centrally symmetrical impact bosses 26. Apart from the impact bosses 26, the bottom wall of the receiving groove 25 is flat, and no further mounting grooves are provided. The rear end face of the hammer head 2 is recessed with a settling step 28, and the non-recessed portion forms a positioning boss 281. A positioning groove 122, adapted to the positioning boss 281, is recessed on the end face of the frustum 121. Please refer to [link to relevant documentation]. Figure 11 When the hammer head 2 and the shoulder 12 approach and abut against each other, the positioning boss 281 falls into the positioning groove 122, the middle part of the raceway groove 11 extends forward beyond the force groove 21, and the steel ball 3 can just be dislodged from the middle part of the raceway groove 11.

[0014] In the embodiment of the impact wrench impact part mounting structure, the dimensions of the camshaft and hammer head are existing. The improvement is that the two mounting slots for inserting steel balls are no longer provided on the bottom wall of the hammer head's receiving groove. Instead, a settling step is provided on the rear end face of the existing hammer head to allow for positioning, forming a positioning boss in the non-recessed portion. A positioning groove adapted to the positioning boss is recessed on the end face of the camshaft's frustum. During assembly, the bottom of the hammer head's settling step abuts against the end face of the camshaft's frustum, and the positioning boss falls into the positioning groove. The middle of the raceway groove extends forward beyond the force-bearing groove. At this point, because the distance the hammer head moves towards the camshaft is greater than the depth of the settling step, the steel ball can just be removed or inserted from the middle of the raceway groove. During normal use, the hammer head will not move to the aforementioned position abutting against the camshaft, and the steel ball is still not easily dislodged. The newly designed settlement steps, positioning bosses, and positioning grooves are further away from the core part that transmits impact compared to the original mounting grooves. They do not significantly reduce the original structural strength. This effectively solves the problem that the mounting grooves on the hammer head are needed for the installation and removal of steel balls, but the mounting grooves can easily affect the service life of the hammer head.

[0015] As a variation, or an interchangeable form, the end face of the frustum 121 can be recessed to form a settling step 28, while the non-recessed portion forms a positioning boss 281. A positioning groove 122, matching the positioning boss, can be recessed on the rear end face of the hammer head 2; the aforementioned effect can be achieved in the same way. Of course, this can also be understood as a change in the area ratio between the settling step and the positioning boss on the rear end face of the hammer head 2.

[0016] Specifically, a flange 22 protrudes from the outer circumferential side of the hammer head 2. An outer ring 23 protrudes from the outer edge of the flange 22 towards the shoulder 12, forming an annular cavity 24 between the outer ring 23 and the outer circumferential side of the hammer head 2. The front end of the helical spring 4 slides within the annular cavity 24. A planar bearing 5 is provided on the bottom wall of the annular cavity 24, and the front end of the helical spring 4 abuts against one side of the planar bearing 5. In use, the helical spring 4 rotates basically synchronously with the camshaft 1, while the hammer head 2 rotates relative to the camshaft 1. The planar bearing 5 ensures that the helical spring 4 continuously provides forward force to the hammer head 2 while allowing for flexible rotation relative to the hammer head 2, thus avoiding affecting the spring's lifespan. The planar bearing 5 can be a planar thrust bearing with needle rollers, reducing axial space occupation and resulting in a compact overall structure. The outer ring 23 extends forward to form a front annular structure, the inner side of which forms a receiving groove 25.

[0017] When the positioning boss 281 falls into the positioning groove 122, the middle part of the raceway groove 11 and the middle part of the force-bearing side 211 correspond in circumferential angle, that is, they are located on the same axial direction. In this way, the positioning boss 281 and the positioning groove 122 also serve as circumferential positioning, facilitating the assembly and disassembly process. The circumferential dimensions of the positioning boss 281 and the positioning groove 122 are matched. After the positioning boss 281 falls into the positioning groove 122, it can no longer rotate circumferentially. In the radial direction, the hammer head 2 is restricted from radial movement because it is sleeved on the camshaft 1.

[0018] To achieve the aforementioned positioning function, specifically, the number of positioning protrusions 281 can be one or several circumferentially spaced, such as the three shown in the embodiment diagram, effectively ensuring the function is realized. When there are multiple positioning protrusions 281, they are not evenly distributed circumferentially, so that the circumferential angle position of the positioning protrusions 281 falling into the positioning grooves 122 is unique.

[0019] During implementation, the height of the positioning boss 281 and the depth of the positioning groove 122 can be selected as 1.5cm.

[0020] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of this utility model that do not depart from the spirit and scope of this technical solution should be covered within the scope of the claims of this utility model.

Claims

1. An impact wrench impact part mounting structure includes a camshaft, a hammer head movably mounted on the outer circumferential side of the front end of the camshaft, a shoulder protruding on the outer circumferential side of the rear end of the camshaft, a helical compression spring compressed between the shoulder and the hammer head, a frustum protruding on the end face of the shoulder facing the hammer head opposite the rear end face of the hammer head; two centrally symmetrical raceway grooves are recessed on the outer circumferential side of the camshaft, the raceway grooves are V-shaped and open towards the rear end of the camshaft; two force-receiving grooves are formed on the inner wall of the hammer head, which are paired with the raceway grooves one-to-one, the force-receiving grooves are also V-shaped and open towards the front end of the camshaft, and a steel ball for force transmission is provided between the force-receiving groove and the matching raceway groove; The front end face of the hammerhead is recessed and has a receiving groove, and the bottom wall of the receiving groove is raised and has an impact boss; its characteristic is: Except for the protruding impact boss, the bottom wall of the receiving groove is flat in all other positions; The rear end face of the hammer head is recessed to form a settling step, and the non-recessed part forms a positioning boss. The end face of the frustum is recessed to form a positioning groove that matches the positioning boss. When the hammer head and the shaft shoulder come together and abut against each other, the positioning boss falls into the positioning groove, and the middle part of the raceway groove extends forward beyond the force-bearing groove, allowing the steel ball to come out from the middle of the raceway groove.

2. The impact wrench impact part mounting structure according to claim 1, characterized in that: The circumferential angle position of the positioning boss falling into the positioning groove is unique.

3. The impact wrench impact part mounting structure according to claim 2, characterized in that: When the positioning boss falls into the positioning groove, the middle part of the raceway groove and the middle part of the force-bearing groove correspond in circumferential angle.

4. The impact wrench impact section mounting structure according to any one of claims 1 to 3, characterized by: The number of positioning bosses is one or several at circumferential intervals.

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