1. Technical Field
The present disclosure relates generally to a ball joint and, more particularly, to a ball joint used in a manipulator in robotics.
2. Description of Related Art
Ball joints are widely used in industrial machining, such as in a manipulator. A ball joint generally has a ball socket and a ball head rotatably received therein. The ball head has an outer surface corresponding to an inner surface of the ball socket, allowing for smooth movement therein. However, the ball joint is frequently manufactured by extrusion molding, and the inner surface of the ball socket being spherical can be easily malformed during manufacture. As a result, the ball socket may not precisely fit the ball head.
Therefore, there is room for improvement within the art.
The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Referring to
The ball head 23 includes a spherical head 231 and a rotatable post 233 extending from the spherical head 231.
Referring to
Each socket cover 211 includes an annular main body 2111 and a handle portion 2113 extending from an edge of the main body 2111. The main body 2111 defines a receiving portion 2112 having a first end 2114 and a second end 2115. A diameter of the first end 2114 is equal to the diameter of the spherical head 231, and a diameter of the second end 2115 is less than the diameter of the spherical head 231. Two flat annular resisting surfaces 22 are formed on the inner surface of the main body 2111, and the annular resisting surfaces 22 are joined with each other to form an obtuse angle. The main body 2111 also defines four fixing holes 2117 uniformly arranged at an edge of the main body 2111, and two pin holes 2118 corresponding to the positioning pins 212. The handle portion 2113 defines two assembly holes 2119 corresponding to the second fasteners 219.
The washer 215 includes an annular main portion 2151 and two parallel legs 2153 extending from an edge of the main portion 2151. The main portion 2151 defines four positioning holes 2155 corresponding to the fixing holes 2117 of the socket cover 211, and two through holes 2157 corresponding to the pin holes 2118 of the socket cover 211. An inner diameter of the main portion 2151 is equal to the diameter of the first end 2114. In the illustrated embodiment, the washer 215 is made of plastic.
During assembly of the ball joint 200, the spherical head 231 is positioned into the receiving portion 2112 of one socket cover 211 from the first end 2114. The washer 215 is disposed on the first end 2114 of the socket cover 211, and then the other socket cover 211 is disposed on the washer 215. The two socket covers 211 align with each other to form a receiving cavity 210 for receiving the spherical head 231. Since the diameter of the second end 2115 of the receiving portion 2112 is less than the diameter of the spherical head 231, the second end 2115 prevents the spherical head 231 from withdrawing from the ball socket 21. The rotatable post 233 extends beyond the socket cover 211 from the second end 2115 at the receiving portion 2112. The handle portions 2113 of the socket covers 211 cooperatively form a hollow cylindrical connecting portion (not labeled). The positioning pins 212 extend through the pin holes 2118 of the socket covers 211 and the through holes 2157 of the washer 215. The second fasteners 219 extend through the assembly holes 2119 of the handle portion 2113; and the second fasteners 219 engage the nuts 213. The first fasteners 214 extend through the fixing holes 2117 of one socket cover 211, the positioning holes 2155 of the washer 215, the fixing holes 2117 of the other socket cover 211, and the spring washers 217, respectively; and then the first fasteners 214 engage the nuts 217. Thus, the socket covers 211 and the washer 215 are fixed together with the washer 215 sandwiched between the washer 215.
Referring to
In use, the rotatable post 233 and the handle portion 2113 are connected to different parts of a manipulator. Since the ball socket 21 has four annular resisting surfaces 22 tangent with the outer surface of the spherical head 231, the spherical head 231 is capable of smoothly rotating in the receiving cavity 210 of the ball socket 21. In alternative embodiments, the ball socket 21 may define one or more resisting surfaces 22 having different angles formed between two adjacent resisting surfaces. Increased number of the annular resisting surfaces 22 formed at the ball socket 21 enhances the smoothness of the spherical head 231 during rotation. The resisting surfaces 22 are cylindrical and thus easily machined by a milling cutter.
In addition, the ball socket 21 is detachable, whereby when one of the socket covers 211 and the washer 215 is broken, only the broken one needs to be replaced. Furthermore, the ball socket 21, if not formed by extrusion molding, can be made thinner and lighter.
It should be pointed out that the rotatable post 233 can define an annular groove 235 (as shown in
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages.
Number | Date | Country | Kind |
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200910309558.7 | Nov 2009 | CN | national |