Socket-type tools, e.g., wrenches, are used widely in many applications from automotive, to plumbing to a host of other applications. In these applications it is important for the bit, e.g., drill, socket, etc., to remain engaged with the socket driver during use. This ensures not only proper use of the tool, but also maintains safe handling of the tool during its use. It, of course, is of the utmost importance from a tooling manufacturer's perspective to ensure that the user is safe while using the tool.
To ensure that the bit is retained within the socket during use, manufactures have devised methods to retain the bit within the socket. Many of these methods are also designed to allow the bit driver to separate from the socket so as to allow replacement or interchangeability of the bit. However, an overriding concern when designing such a semi permanent engagement mechanism, which allows for interchanging or replacing the bit for a particular application, is to ensure that the bit driver and the socket remain in coupling engagement with each other during normal use.
One approach for coupling a drive bit to a drive socket, for example, is the use of a coupling pin. Although this approach ensures that the drive bit remains in the socket, it does require separate parts, e.g., a pin, and additional manufacturing tolerances and steps which greatly increase its costs. By way of illustration, the manufacturing tolerances must be such so as to allow the transverse holes of the bit and socket to perfectly aligned and be accurately sized to allow the pin to be placed therein for securing the bit within the socket. If alignment is not perfect, the pin may become loose and fall out or may be sheared in use. This method is also cumbersome, since the pin has to always be removed in order to replace the bit.
Other known methods include a spring-biased ball which can be engaged within the socket or the bit, itself. In either of these approaches, when the bit is inserted into the socket, the ball will be biased into a complimentary recess for holding the bit within the socket. Although this approach may be effective, it is still costly to manufacture due to the added parts required for the assembly, in addition to the actual cost of manufacturing the bit socket, itself. Also, it is known that the spring becomes worn, after many uses, which can contribute to the failure of the engagement between the two parts.
U.S. Pat. No. 5,960,681 is very illustrative of many examples of different types of retaining members, some of which are described above. In the background section, this patent describes additional methods including, for example, the use of a friction ring for bit detention. U.S. Pat. No. 5,960,681 describes such a system as simplifying the changing of the bit, but does not provide a very secure retention. U.S. Pat. No. 5,960,681 additionally describes a number of patents which use “O” rings intended to engage with recesses or regions of a tool bit, as well as a bit with frictional retention in the drive socket in which appropriate recesses are provided in the flat surfaces of the bit itself.
Lastly, in the detailed description, U.S. Pat. No. 5,960,681 describes protuberances on alternate walls of the socket, i.e., an important feature is that the protuberances 24a-34c are arranged on alternate or successive ones of the flat surfaces 28-33, so that diametrically opposing surfaces always include one such surface which is provided with a protuberance and the opposing surface is without a protuberance. According to U.S. Pat. No. 5,960,681, the protuberances are in the form of inwardly projecting bosses or projections which are generally flat. The protuberance are formed by a broaching tool which moves some material to the bottom of the cavity such that the remaining material, e.g., the material which is not moved, forms the protuberances.