Miscellaneous hardware (e.g. – bushing – carpet fastener – caster – Insulated handle
Reexamination Certificate
1999-10-18
2001-12-04
Knight, Anthony (Department: 3626)
Miscellaneous hardware (e.g., bushing, carpet fastener, caster,
Insulated handle
C016S430000, C016S110100
Reexamination Certificate
active
06324728
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to attachments for power tools, and more particularly to an ergonomic attachment for inline power tools which reduces stress related injuries to the hand, wrist, and forearm of inline power tool operators.
Inline power tools, such as pneumatic and electric nut drivers are commonly used in many industries, especially in electronic assembly areas. These tools are used for tightening fasteners, such as screws, bolts, nuts, and the like. Most industrial applications require some form of radial or ulnar wrist deviation. The power tools produce an extensive amount of torque and vibration, which is transmitted to the operator's hands and wrists. Prolonged usage of these tools has been known to cause cumulative trauma and repetitive stress injuries, such as carpal tunnel syndrome and tenosynovitis to the hands, wrists, and forearms of workers who use the tools on a daily basis.
Cumulative trauma injuries to the hand, wrist, and forearm are the result of prolonged and repetitive exposure to damaging stress. Prolonged and repetitive use of inline power tools frequently causes fatigue, strain, pain, and injury to an operator's hand, wrist, and forearm. Accordingly improvements have been proposed to more naturally orient the user's extremities and/or distribute the forces associated with operating these types of power tools.
There have been a number of patents issued relating to ergonomic attachments for powered hand tools. For example, U.S. Pat. No. 5,544,554 discloses an ergonomic torque wrench mounting apparatus in which a pneumatic torque wrench is mounted on a torque arm or cantilevered support attached to a rigid surface, such as a workbench. While this apparatus does effectively eliminate torque exposed to the operator, it is very large, cumbersome, and expensive to implement. In addition, the operator must still apply a downward force to tighten the fastener, which may harm the hand and wrist. Most torque arm apparatus take up a lot of room on the workbench, and are limited with respect to the position and angle with which the tool can be used.
At least one manufacturer, D-G Industries of Brea, Calif. has introduced an ergonomic power tool attachment marketed under the trademark Bio-Brace™. This device includes an attachment mechanism, which slides over the body of the tool and is clamped in place by a clamping screw. A U-shaped support mechanism rigidly attached to the attachment mechanism cradles the underside of the wrist and forearm of an operator to absorb the torque and vibration associated with operating the power tool.
The Bio-Brace™ device appears to be relatively heavy, and being under the forearm, adds to the weight of the tool. The device may also add to the resisted ulnar deviation of the wrist when holding the tool. The Bio-Brace™ attaches to the power tool using a specialized donut-type attachment mechanism, which is not universal. In other words, users are required to obtain a new specific donut-type attachment for different sized tools. This adds to the expense of the device and significantly decreases its versatility.
Therefore, there is a need to provide an ergonomic attachment for inline power tools that is easier to implement, less cumbersome, and less expensive than prior art devices.
SUMMARY OF THE INVENTION
The present invention is an ergonomic attachment for inline power tools. The attachment is designed to reduce the forces, stresses, and tensions experienced by operators of inline power tools, by damping and transferring the forces to the forearm of an operator. The ergonomic attachment includes a universal, removable attachment mechanism, which attaches to the base of an inline power tool. The attachment mechanism includes a bracket and a U-shaped member, which extends around the base of the inline power tool and fastens to the bracket by fasteners. Pivotally attached to the attachment mechanism is a padded ergonomic support member. The ergonomic support member includes an elongated horizontal portion and an inverted U-shaped portion. The elongated horizontal portion extends substantially parallel to the operator's forearm when in use. The inverted U-shaped portion extends around the top surface of the operator's forearm. The attachment is spring loaded with a helical spring connected between the attachment mechanism and the support member. The spring forces the inverted U-shaped portion of the support member downwardly against the top of an operator's forearm.
It is an object of the present invention to reduce repetitive stress injuries to operators of automatic assembly power tools. The present invention transfers stress to a user's forearm to redistribute the load from the hand and wrist to the more robust and fatigue resistant structures of the forearm.
The attachment device is designed to reduce stress-related trauma associated with prolonged use of these types of power tools. The device addresses force distribution, primarily force imposed on the tool being redistributed to the user's forearm. The device also allows the user to orient his or her own extremities. The horizontal member is substantially parallel to the longitudinal axis of the user's forearm when in use.
Inline power tools continue to be ubiquitous in manufacturing processes and despite research, continue to present significant ergonomic hazards, including high torque, upper extremity vibration, awkward postures associated with frequency and torque. The device of the present invention is designed to reduce the torque and vibration exerted on the wrist by using the forearm to absorb the torque and vibration.
The device effectively eliminates torque at the hand machine interface and reduces the subsequent force at the forearm to approximately 10% of the tool rated torque. Consequently, if a specific tool were required to exert 50″ pounds torque, the force to the forearm would be between five and seven pounds, well within acceptable levels. It provides a very lightweight alternative, using aluminum parts. It decreases the resisted ulnar deviation force by holding the tool by the spring pressure, which translates some of the force of the tool to the radial forearm. And it allows the worker to operate the tool in any position, including full forearm supination or pronation, full wrist radial deviation or ulnar deviation, full wrist flexion or extension. In addition, the attachment dampens vibrations by decreasing the force couple of the hand and the tool interface, and decreases the peak torque reaction by increasing the angular inertia of the tool. The universal attachment using wing nut technology makes it relatively easy to put on a specific tool and remove it if there is a specific tool used for an application.
Preliminary test data shows an approximate 50% decrease in peak EMG (electromyography) readings of the wrist flexor and extensor muscles of operators using the attachment device.
Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the following drawings and detailed description of the invention.
REFERENCES:
patent: 3624044 (1971-11-01), Wu
patent: 4962561 (1990-10-01), Hamilton
patent: 5125130 (1992-06-01), Stanish
patent: 5156429 (1992-10-01), Adams
patent: 5455981 (1995-10-01), Wiese
patent: 5544554 (1996-08-01), Brightly
patent: 5588903 (1996-12-01), Pennison
patent: 5716087 (1998-02-01), Backish et al.
Human Factors Society, 1988, pp 61-69; “Evaluation of Powered Screwdriver Design Characteristics”.
D-G Industries brochure; “DGI Ergonomic Power Tool Accessories”.
Baxter William K.
Blankenheim Services, LLC
Godfrey & Kahn S.C.
Knight Anthony
Rodriguez Ruth C.
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