BIT ASSEMBLY

This application claims the benefit of CN 201310275271.3, filed Jul. 2, 2014, and CN 201320390803.3, filed Jul. 2, 2014, the disclosures of which are incorporated herein by reference in their entirety.

The subject disclosure generally relates to bit assemblies, and more particularly, to a bit assembly adapted to reduce impact.

Electrical tools using a bit, driven by impact, are generally known. Since such tools subject a bit to high frequency impacts during operation, there is a higher requirement for the toughness of the bit. A traditional bit is formed from a single metal, thus the hardness of the bit from front end to back end is consistent. Generally, the requirement for the toughness is sacrificed for meeting the requirements for wear resistance and durability. Once the hardness is reduced to enhance the toughness, the wear resistance and durability may be reduced greatly, and even lower than the standard requirement, thus cannot be satisfactory.

In order to solve at least the above-noted problems, hereinafter is described a bit assembly which solves the conflict between the toughness and the hardness of the bit and which is relatively easy to manufacture.

More particularly, an exemplary bit assembly comprises a bit for driving a screw, a shank for holding the bit and for driving the bit to rotate about a pivot axis such that the bit is capable of moving relative to the shank in a predetermined range, and a limiting structure formed between the bit and the shank for preventing the bit from moving beyond the predetermined range.

Further, the bit may be capable of moving along a direction which is along the pivot axis.

Further, the limiting structure may comprise a first stop portion formed on the bit and a second stop portion formed on the shank wherein the first and second stop portions prevent the bit from detaching from the shank.

Further, the limiting structure may also comprise a third stop portion formed on the bit adjacent to the first stop portion and a fourth stop portion formed on the shank adjacent to the second stop portion such that, when the fourth stop portion contacts the third stop portion, the bit is prevented from further moving closer to the shank in a direction along the pivot axis.

Further, the bit may comprise a first connecting portion formed on first end of the bit and a working portion formed on a second end of the bit opposite to the first end and the shank may comprise a driven portion which is capable of being driven to rotate by a torque tool and a second connecting portion for engaging with the first connecting portion so as to connect the bit and the shank.

Further, the first connecting portion may comprise an engaging portion and a first annular groove positioned adjacent to the engaging portion with the first and third stop portions being positioned on opposite ends of the first annular groove and the second connecting portion may define a receiving chamber with one end opened in the direction along the pivot axis and a first annular protrusion may be formed on an open end of the receiving chamber with the engaging portion being received in the receiving chamber and the first annular protrusion being received in the first annular groove and with the second and fourth stop portions being opposite ends of the first annular protrusion.

Further, the engaging portion may be shorter than the receiving chamber in the direction along the pivot axis.

Further, a length of the first annular groove may be greater than that of the first annular protrusion in the direction along the pivot axis.

Further, the engaging portion may be a substantially regular hexagonal and the receiving chamber may be a substantially regular hexagonal with the engaging portion being smaller than the receiving chamber in a direction perpendicular to the pivot axis.

Further, a hardness of the bit may be greater than that of the shank.

Further, the bit assembly may comprise a function accessory mounted to the bit body.

Further, the function accessory may comprise an accessory body which is capable of receiving a portion of the bit body, a stop member mounted to a first end of the accessory body for stopping the bit body from detaching from the accessory body, and a functioning member mounted to a second end of the accessory body opposite to the first end, wherein the function accessory is in sliding connection with the bit body.

Further, the accessory body may define a first stepped hole for at least one end of the bit body passing through the pivot axis and may comprise a first restricting portion arranged on the external surface of the accessory body or in an inner wall of the first stepped hole for fixing the stop member, and a second restricting portion positioned in the first stepped hole for preventing the bit body moving apart from the function accessory.

Further, the second restricting portion may comprise an annular plate formed by the first stepped hole and substantially perpendicular to the pivot axis which is capable of preventing the first connecting portion or the second connecting portion from passing through the first stepped hole.

Further, the first restricting portion may be a second annular groove defined in the inner wall of the first stepped hole and the stop member may be a gasket mounted in the second annular groove.

Further, the first restricting portion may comprise a second annular protrusion or a section of an external thread arranged on the external surface of the accessory body and the stop member may be a sleeve which mounted to the accessory body by the second annular protrusion or the section of the external thread.

Further, the stop member may define a through-hole which is capable of allowing the working portion or the driven portion to pass there through and a first annular bench portion which is capable of preventing the first connecting portion or the second connecting portion from passing through the through-hole.

Further, the functioning member may be an annular magnet.

Further, the first stepped hole may comprise an accommodated portion adjacent to one end of the accessory body for receiving the functioning member.

Further, the function accessory may be made of a transparent material, and the bit body or the function accessory may comprise an illuminated portion formed by an illuminated material.

With the combination of the bit body and the shank as described, the working member and the driven member are made of different materials and form a sliding connection so that they have a certain buffer space in the axial direction and the circumferential direction thereby reducing the effect of the impact on the service life.

The following will describe an exemplary specific embodiment of a bit assembly with reference to the drawings.

FIGS. 1-5 illustrate a bit assembly 100, in exemplary form of an impact screwdriver bit, which will be subjected to a periodic impact during operation. The bit assembly 100 mainly includes a bit body 101 having a bit 10 and a shank 20.

The bit 10 is mainly used to achieve the function of striking screws by contacting the screws. The shank 20 is used to transmit a torque to the bit 10 so as to drive the bit 10 to rotate about a pivot axis 101a.

It is well known for the person skilled in the art that the bit 10 has a pivoting axis 101a and how to determine this pivoting axis 101a, thus it is unnecessary to go into details here.

It should be noted that in order to describe the features and relative relations of various parts of the described bit assembly the descriptions used herein will refer to a common space which is defined by a cylindrical coordinate with the pivot axis 101a as the central axis. The axial direction of the pivot axis 101a is the axial direction of the cylindrical coordinate; the radial direction of the pivot axis 101a is the radial direction of the cylindrical coordinate; and the circumferential direction of the pivot axis 101a is the circumferential direction of the cylindrical coordinate. Without any special instruction, the axial direction, radial direction and circumferential direction in this description refer to the aforesaid axial direction, radial direction and circumferential direction referenced to the pivot axis 101a.

As a preferred embodiment, the bit 10 has an illuminated portion formed by an illuminated material. The illuminated portion is positioned on the bit 10 so that, without sufficient light, the illuminated portion can perform an illuminating function.

The bit 10 and the shank 20 form a sliding connection with a predetermined range. A limiting structure 200 is formed between the bit 10 and the shank 20 for preventing the bit 10 from moving beyond the predetermined range.

The bit 10 is moveable at least in the direction along the pivot axis 101a, and the limiting structure 200 of the bit 10 and the shank 20 has an outer profile intersecting with the direction along the pivot axis 101a.

As shown in FIG. 2, the bit 10 includes a first end forming a working portion 11 and a second end opposite to the first end forming a first connecting portion 12. The shank 20 has a first end forming a second connecting portion 22 and a second end opposite to the first end forming a driven portion 21. The working portion 11 is used to strike the screws and the driven portion 21 is mainly used to mate with the torque tools. The working portion 11 includes a head portion 111 for contacting the screws and neck portion 112 for connecting the head portion 111 to the first connecting portion 12.

The limiting structure 200 includes a first stop portion 201 formed on the bit 10 and a second stop portion 202 formed on the shank 20 which prevent the bit 10 from detaching from the shank 20.

The limiting structure 200 also includes a third stop portion 203 formed on the bit 10 adjacent to the first stop portion 201 and a fourth stop portion 204 formed on the shank 20 adjacent to the second stop portion 202 so that, when the fourth stop portion 204 contacts the third stop portion 203, the bit 10 is prevented from further moving closer to the shank 20 along the direction along the pivot axis 101a.

The first connecting portion 12 includes an engaging portion 121 and defines a first annular groove 122 adjacent to the engaging portion 121, the first and third stop portions 201,203 are positioned on opposite ends of first annular groove 122.

The second connecting portion 22 defines a receiving chamber 221 with one end opened in the direction along the pivot axis 101a and includes a first annular protrusion 222 formed on the open end of the receiving chamber 222.

The engaging portion 121 is received in the receiving chamber 221 and the first annular protrusion 222 is received in the first annular groove 122 and the second and fourth stop portions 202,204 are at opposite ends of the first annular protrusion 222.

As shown in FIG. 7, before the engaging portion 121 is received into the receiving chamber 221, the first annular protrusion 222 has not been formed. After the engaging portion 121 is inserted in the receiving chamber 221, the whole may be processed by stamping, and the top end 222a of the receiving chamber 221 is distorted plastically and bent inwards to form the first annular protrusion 222 as shown in FIG. 5.

The engaging portion 121 is preferably shorter than the receiving chamber 221 in the direction along the pivot axis 101a and the length of the first annular groove 122 is preferably greater than that of the first annular protrusion 222 in the direction along the pivot axis 101, the engaging portion 121 is substantially regular hexagonal in shape and the receiving chamber 221 is substantially regular hexagonal in shape, and the engaging portion 121 is preferably smaller than the receiving chamber 221 in a direction perpendicular to the pivot axis 101a. The service life of the bit body 101 is increased by the axial and circumferential space between the bit 10 and the shank 20. The axial and circumferential space is capable of reducing the impact between the bit 10 and the shank 20 when they are moving relatively.

Referring to FIGS. 7-10, the bit assembly 100 may further include a function accessory 102 mounted to the bit body 101.

The function accessory 102 includes an accessory body 30 which is capable of receiving a portion of the bit body 101, a stop member 40 mounted to a first end of the accessory body 30 for stopping the bit body 101 from detaching from the accessory body 30, and a function member 50 mounted to a second end of the accessory body 30 opposite to the first end, wherein the function accessory 102 is in sliding connection with the bit body 101.

As a preferred embodiment, the accessory body 30 defines a first stepped hole 301 for at least one end of the bit body 101 passing through along the pivot axis 101a, and includes a first restricting portion 31 arranged on the external surface of the accessory body 30 for fixing the stop member 40, and a second restricting portion 32 positioned in the first stepped hole 301 for preventing the bit body 101 moving apart from the function accessory 102.

The function accessory 102 is preferably made of a transparent material.

The illustrated second restricting portion 32 further includes an annular plane 321 formed by the first stepped hole 301 and arranged substantially perpendicular to the pivot axis 101a which is capable of preventing the first connecting portion 12 or the second connecting portion 22 from passing through the first stepped hole 301.

The illustrated first restricting portion 31 includes a second annular protrusion 311 or a section of external thread arranged on the external surface of the accessory body 30, and the stop member 40 is a sleeve 401 which is mounted to the accessory body 30 by the second annular protrusion 311 or the section of external thread. The stop member 40 includes a third annular protrusion 41 or section of internal thread arranged on an inner surface of the sleeve 401.

The illustrated stop member 40 defines a through-hole 42 which allows the working portion 11 or the driven portion 21 to pass there through and an annular step portion which prevents the first connecting portion 12 or the second connecting portion 22 from passing through the through-hole 42.

The illustrated first stepped hole 301 includes an accommodated portion 301a adjacent to one end of the accessory body 30 for receiving the function member 50. The function member 50 is preferably an annular magnet.

As shown in FIG. 9, a further accessory body 30′ defines a first stepped hole 301′ for allowing at least one end of the bit body 101 to pass there through along the pivot axis 101a and which includes a first restricting portion 31′ arranged in an inner wall of the first stepped hole 301′. The first restricting portion 31′ is an annular groove 311′ defined in the inner wall of the first stepped hole 301′ and the stop member 40′ is a gasket mounted in the annular groove 311′. The gasket is preferably made of elastic material.

The specific embodiments described above are only intended to illustrate the ideas and principles of the present invention, not to restrict the content of the present invention. Those having ordinary skill in the art can appreciate that besides the above preferred embodiments, the present invention may also include many other alternative or modified embodiments, which are still intended to fall within the scope of the following claims.