Abstract:
An ergonomic sander handle for clamping onto a sanding device so that the ergonomic handle can be comfortably gripped by a worker and used to apply the sanding device to a surface, is provided. The ergonomic handle includes an elongate body, a clamp head and a bearing. The elongate body is typically a cylindrical aluminum tube with padding for easy and comfortable gripping. One end of the elongate body is attached the clamp head that attaches to the sanding device. The other end of the elongate body is attached to the bearing which may include a pair of roller balls. To sand a surface, the worker grips the elongate body in a power grip (without significant wrist flexion or deviation) and applies pressure to urge sanding device and the bearing onto the surface. The power grip minimizes loads on the wrist and hand which reduces the likelihood of musculoskeletal trauma.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to the field of hand operable sanding devices. More particularly, the present invention relates to an easily gripped handle that can be affixed to an existing palm sander device that reduces cumulative hand and wrist trauma.  
         BACKGROUND OF THE INVENTION  
         [0002]    Sanding is an abrasive process that requires that two surfaces rub together and is extremely time consuming and tedious when performed manually. Various power-driven sanders have been available for some time and frequently require the use of two hands due to excessive weight. Belt sanders are one type of hand sander that is available but these are generally used for roughly removing large amounts of material. Belt sanders themselves are heavy and are not recommended for one-handed operation. Two handed sanders have limited usefulness on vertical and overhead surfaces because of their size and weight.  
           [0003]    Sanders that can be operated with one hand include oscillating and random orbit palm sanders. Random orbit palm sanders are pneumatically powered and typically have a small power head with a trigger paddle attached to the top. On the bottom of the random orbit palm sander is a small, typically about six-inch diameter, sanding disc that is fixed to a spinning pad. A random orbit action is achieved by use of an eccentric weight or cam in the drive which causes the pad to orbit a center point while spinning at a high speed with respect to the power head. The random orbit pattern is necessary to produce a mechanical action that results in a swirl free finish. However, the random oscillation transfers considerable vibration to the operator&#39;s hand and the operator must grip the power head tightly with his or her fingers to both control the action and maintain palm pressure on the trigger paddle. Oscillating sanders are generally less effective in producing a swirl-free surface and are therefore not as desirable in many applications.  
           [0004]    Regardless of the type, oscillating, random orbit or other, all power hand sanders produce some vibration. Operators cannot be completely isolated from vibration because the operator must apply pressure to some degree in order for the sanding disc to remove material from the surface being sanded. Heavier sanders aid in pressure application but, as mentioned above, they are limited to use in vertical and overhead surfaces.  
           [0005]    One industry that requires a significant amount of sanding labor is the aerospace industry. Sanding is typically required on both the aluminum fuselages and on composite control surfaces and panels of aircraft before the application of paint or for the removal of old paint in a paint hanger. Because of the nature of the fuselage and its surface shapes, one-handed control of the sander and use of the sander on vertical surfaces and overhead surfaces is necessary. The tight grip required to use the sanders in a paint hanger can reduce blood flow to the fingers and result in musculoskeletal stress that is further exacerbated by vibration. In addition, when sanding a vertical or overhead surface in a fuselage, the operator&#39;s wrist is typically extended which results in greater musculoskeletal stress. Prolonged exposure to these conditions can lead to Raynaud&#39;s disease and/or carpal tunnel syndrome. Raynaud&#39;s disease is commonly called “white finger” and results in numbness, cold skin and a blue color when exposed to cold temperatures. Raynaud&#39;s disease can be a permanent condition. Carpal tunnel syndrome is an inflammation of the flexor tendons of the fingers which pass through a channel on the palmer side of the wrist formed by the carpal bones and the transverse carpal ligament. These flexor tendons become inflamed with repetitive overuse and place pressure on the nearby median nerve. Pressure on the median nerve causes numbness and/or pain in the lower arm. Carpal tunnel syndrome can also result in permanent dysfunction.  
           [0006]    Small oscillating detail sanders solve some of the repetitive motion problems by having a very short stroke at a very high frequency with a low weight. This greatly reduces vibration that is transmitted to the hand of the operator. However, the area and mass of the sanding pad must be kept too small to be of any practical value on large surfaces, such as those encountered when sanding an aircraft fuselage. Automated sanding machines have been used on fuselages, but oftentimes fail to reliably negotiate vertical and overhead surfaces.  
           [0007]    Therefore, it would be advantageous to have an operable sanding device that is easily gripped with one hand or both hands and can be used to negotiate large sanding surfaces. In addition, it would be advantageous to have a sanding device that is light in weight and transmits minimal vibrations to reduce the incidence of cumulative trauma to the hand and wrist of the operator.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention includes an ergonomic sander handle for a sanding device that reduces the incidence of cumulative trauma to the hand of a worker using the sanding device. The sander handle provides an ergonomic grip by having an elongated tubular body attached to the sanding device at one end and a bearing at the other end. The handle can be gripped by the worker with a single hand in an anatomically friendly position without flexion or deviation of the hand and wrist. In addition, the ergonomic handle is of light-weight construction to reduce loads on the hand and wrist of the operator when sanding vertical and overhead surfaces, such as the fuselage of an airplane.  
           [0009]    In one aspect of the invention, an ergonomic handle for clamping onto a sanding device so that the ergonomic handle can be gripped by a worker and used to apply the sanding device to a surface, is disclosed. The ergonomic handle includes an elongate body, a clamp head and a bearing. The elongate body has a head end and an opposing tail end. The clamp head is attached to the head end of the elongate body and is operable to clamp the sanding device. The bearing is attached to the tail end of the elongate body, opposite the clamp head. In use, the worker clamps the clamp head onto the sanding device, grips the elongate body, applies the sanding device and bearing to the surface and moves the sanding device and bearing along the surface during sanding.  
           [0010]    In another aspect of the invention, an ergonomic sander that can be gripped by a worker and used to sand a surface, is disclosed. The ergonomic sander includes an elongate body, a sanding head and a bearing. The elongate body has a head end and an opposing tail end. The ergonomic sander also includes a sanding head that is attached to the head end of the elongate body and has a sanding interface operable to sand the surface. The bearing is attached to the tail end of the elongate body, opposite the sanding head. In use, the worker clamps the clamp head onto the sanding device, grips the elongate body, applies the sanding device and bearing to the surface and moves the sanding device and bearing along the surface during sanding.  
           [0011]    The bearing can include a fluoropolymer resin pad (e.g., a Teflon® material) or a pair of freely rotating roller balls. The bearing can include a hinge that allows it to pivot with respect to the tail end of the elongate body. The bearing can also include a height-adjustable bracket mounted to the tail end of the elongate body and operable to adjust the height of the handle with respect to the bearing. The bearing serves as a support for the elongate body that allows the downward application of pressure on the elongate body with a power grip. Changing the bearing height and the bearing&#39;s ability to pivot on the hinge allows the bearing to adjust to various non-planar surfaces. The bearing can also include an air bearing which comprises a plurality of holes in the resin pad. Air bled from the exhaust of the sanding device or air supply line is fed through plumbing and the holes in the resin pad to reduce friction between the resin pad and the surface being sanded.  
           [0012]    The elongate body can have a tubular shape covered with padding to reduce grip fatigue. A trigger may also be included that is operable to control power to the sanding device. The trigger has an elongated paddle shape that is attached to the clamp head and extends along the elongate body. The trigger can be attached to the clamp head using a pivot pin that allows the trigger to pivot when grasped. The trigger may also include an adjustment bolt positioned to contact a power switch on the sanding device. The adjustment bolt is adjustable to change the angular orientation of the trigger with respect to the elongate body. Alternatively, the trigger could be attached directly to the sanding head. The paddle shape allows the trigger to be grasped from several positions along the elongate body. Changing the orientation of the trigger allows for adjustment to suit different hand sizes and finger lengths.  
           [0013]    The clamp head typically includes a pair of jaws connected by a jaw pin. The pair of jaws are operable to clamp the sanding device by at least partially encircling the sanding device. The pair of jaws may also include a draw bolt inserted through each jaw of the pair of jaws. Tightening of the draw bolt draws the jaws together in a pinching motion. The clamp head can also include a pivot mount in which the head end of the elongate body is free to slide and pivot. The pivot mount includes a slot and the head end of the body includes a ball mounted in the slot for sliding and pivoting therein.  
           [0014]    The sander handle of the present invention reduces the risk of injury due to vibration and poor grip posture by allowing a random orbit sanding device to be held and controlled in a power grip. In the power grip the wrist is held in a neutral position, or slightly extended. The power grip allows good blood flow to the hand and fingers, reducing the incidence of Raynaud&#39;s disease and carpal tunnel syndrome. The ergonomic handle can be held securely overhead with the fingers relaxed. In addition, the ergonomic handle separates the forces required to control sanding direction and pressure from the more precision forces required to control the trigger. As a result, the operator can put more force on the sanding interface with less hand and wrist fatigue while still maintaining control using only one hand. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:  
         [0016]    [0016]FIG. 1 is a side elevation view of a conventional random orbit palm sander;  
         [0017]    [0017]FIG. 2 is a side elevation view of an ergonomic handle of one embodiment the present invention clamped to the palm sander of FIG. 1;  
         [0018]    [0018]FIG. 3 is a perspective view of the ergonomic handle of FIG. 2 gripped in the hand of a worker;  
         [0019]    [0019]FIG. 4 is an exploded view of a clamp head of the ergonomic handle shown in FIG. 2;  
         [0020]    [0020]FIG. 5A is a rear elevation view of a bearing of the ergonomic handle shown in FIG. 1;  
         [0021]    [0021]FIG. 5B is a perspective view of the bearing shown in FIG. 5A;  
         [0022]    [0022]FIG. 6 is a perspective view of a sliding cam clamp head of one embodiment of the present invention;  
         [0023]    [0023]FIG. 7 is a perspective view of a ball fore grip on the sliding cam clamp head shown in FIG. 6; and  
         [0024]    [0024]FIG. 8 is a cut away view of a ball set screw forming a pivot mount of one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.  
         [0026]    [0026]FIG. 1 depicts a conventional pneumatically-powered sanding device, more particularly, a random orbit palm sander  10 . The random orbit palm sander  10  has a power head  11 , a trigger  12 , and a sanding pad  13 . A small diameter sanding disc (not shown) is typically fixed to the sanding pad  13 . The random orbit action is generally achieved by use of an eccentric weight or cam in the drive of the sanding device  10  which causes the pad to orbit a center point while spinning at a high speed. Power can be supplied in various manners including electrical power, but in the illustrated embodiment power is supplied to the power head through a pneumatic connection  35 . Power to the head is controlled by the trigger  12  which is activated when the user grips the power head in one hand and encloses fingers around the power head with the palm of the hand itself in extension with respect to the wrist.  
         [0027]    [0027]FIG. 2 depicts one embodiment of the present invention including an ergonomic handle  100  attached to the random orbit palm sander  10 . The ergonomic handle includes an elongate body  14 , a clamp head  19 , and a bearing  27 . The clamp head  19  includes a pair of jaws  20  that wrap securely around a power head  11  of the sanding device  10 . The clamp head  19  is also attached to a head end  15  of the elongate body  14 . The bearing  27  is attached to a tail end  16  of the elongate body  14 , opposite the head end, and preferably includes a pair of roller balls  28 . The ergonomic handle  100  is employed by the worker by gripping the elongate body  14  in a single hand and placing the sanding device  10  and the bearing  27  in contact with a surface  110 , as shown in FIG. 3. The worker activates power to the sanding device  10  by depressing a paddle trigger  36  which causes the trigger to rotate about an axle pin  37  and to depress the trigger  12  on the sanding device  10 . Once power to the sanding device  10  is activated, the worker applies pressure to the elongate body  14  which compresses the sanding device  10  and the bearing  27  onto the surface  110 . The worker then sweeps the sanding device  10  using the ergonomic handle  100  in a broad motion which, coupled with the pressure (downward in the illustrated embodiment) and oscillation of the sanding disk, sands the surface  110 .  
         [0028]    As shown in FIG. 4, the clamp head  19  preferably includes the pair of jaws  20 , a first jaw pin  21 , a clamp head draw bolt  23  and a clamp head clevis  39 . The pair of jaws  20  are connected using the draw bolt  23  which fits through a retaining element  41  on one of the jaws and a cylindrical jaw pin  21  in the other one of the jaws. In more detail, the other one of the jaws  20  has a receptacle  43  that is aligned with the retaining element  41 . Although the receptacle can be configured in different manners, the receptacle of the illustrated embodiment includes a pair of spaced apart members which are connected to opposite sides of the respective jaw and which define openings through which the jaw pin  21  extends. The cylindrical draw pin  21  fits into the receptacle and defines a hole  46  extending transverse to the length-wise direction of the jaw pin. The retaining element  41  defines a slot  47  that is aligned with the hole  46  of the jaw pin. The draw bolt  23  passes through the slot  47  defined by the retaining element  41  and the hole  46  defined by the cylindrical jaw pin  21  to secure the jaws together. After the pair of jaws  20  are fit around the molded power head  11  of the sanding device  10  they can be tightened with the clamp head draw bolt  23 . Tightening the clamp head draw bolt results in a pinching action of the jaws  20  causing them to grip the molded power head  11  of the sanding device  10 .  
         [0029]    In addition to engaging the power head  11 , the clamp head  19  is connected to the elongate body  14 . In the illustrated embodiment, the head end  15  of the elongate body  14  fits into the clamp head clevis  39  to form a pivot mount. The pivot mount includes a slot  25  defined by the clamp head clevis  39  which receives a ball set screw  26  attached to a head fitting  17  of the elongate body  14  and allows handle angle adjustment as described later.  
         [0030]    The clamp head  19  can be configured differently, however. By way of example, FIG. 6 depicts another embodiment of the clamp head  19  having a sliding cam that allows for a lower profile with fewer protuberances. The sliding cam is formed by an elongated, closed-end retaining element  141  and a second jaw pin  22 . The second jaw pin is also cylindrically shaped and defines a hole, but it slidably fits into a second receptacle  44  defined by the jaw carrying the retaining element  141 . The clamp head draw bolt  23  fits through the hole defined by the first pin  21 , an elongated slot defined by the retaining element  141  and the hole defined by the second pin  22  to secure the jaws  20  together. FIG. 7 depicts yet another embodiment of the clamp head  19  that includes a ball grip  34  that allows two-handed use of the ergonomic handle  100  and the sanding device  10 .  
         [0031]    The bearing  27  allows the tail end of the ergonomic handle  100  to slide freely over the surface  110  as the ergonomic handle and sanding device  10  are employed to sand the surface. FIGS. 5A and 5B depict the bearing  27  which preferably includes a pair of roller balls  28  mounted in a height-adjustable bracket  31  which is attached to a tail fitting  40  at the tail end  16  of the elongate body  14 . The pair of roller balls  28  are mounted in a pair of sockets  29  defined by the bracket  31  and are held there by a pair of set screws  45 . The sockets  29  are drawn metal cans that capture and house the roller balls. The set screws  45  in the bracket  31  preferably contact only the sockets (i.e., the metal cans)  29 , and not the roller balls  28  to avoid damage to the roller balls. The roller balls  28  are preferably plastic balls, but can be constructed of various other materials, such as metal. The roller balls  28  and their sockets  29  are common to the art and can be purchased in a range of sizes and materials, and are therefore not described herein in additional detail. The presence of the pair of roller balls  28  allows the tail end of the ergonomic handle  100  to be rested securely and without wobble on the sanding surface  110 .  
         [0032]    The bearing  27  could also employ other types of bearing surfaces or bearings, such as additional roller balls or fluoropolymer resin (e.g., TEFLON®) pads. The resin pads are interchangeable with the roller balls  28  and are preferably used when sanding on composite surfaces. The resin pads are preferably machined to fit into the sockets  29  in the bracket  31 . The resin pads distribute the downward pressure applied to the handle  100  over a wider area to minimize the risk of denting the composite surface.  
         [0033]    In another embodiment, the resin pads could include a plurality of holes through which bleed air from the exhaust of the sanding device  10  or air directly from an air supply line can be directed. Directing air through holes in the resin pads creates a cushion of air a few molecules thick under the resin pad. The cushion of air creates an air bearing that reduces the friction between the resin pads and the sanding surface  110 . The effectiveness of the air bearing depends, in-part, on the available air flow under the resin pad and the surface area of the resin pad. The air bearing is generally more effective with a greater surface area and more air flow. The air bearing has the advantage of not requiring high air pressure, just high air flow which is possible with most air supply systems.  
         [0034]    The tail fitting  40  of the elongate body  14  is attached to the bracket  31  via a pivot pin  32  about which the bracket is free to rotate. The pivot pin  32  extends through a pair of slots  50  defined by two spaced, upright members  51  of the bracket  31 . The bracket  31  is height-adjustable by way of a washer  48  and a wing nut  49  that secure the ends of the pivot pin  32 . The relative angle and position of the elongate body  14  with respect to the bearing  27  can be adjusted by loosening the wing nut  49  and sliding the tail fitting up or down inside the upright members  51  of the bracket and re-tightening the wing nut.  
         [0035]    The elongate body  14  is typically constructed of a padded aluminum tube having the head fitting  17  at its head end  15  and the tail fitting  40  at its tail end  16 . The fittings are secured to the ends of the elongate body  14  in one embodiment by a handle draw bolt  33  which runs the length of the elongate body. The head fitting  17  includes the ball set screw  18  as shown in FIG. 8. The head fitting  17  fits into the clamp head clevis  39  and the ball  26  at the end of ball set screw  18  slides within the slot  25  defined by the clamp head  19 . The slot  25  and the ball  26  form a pivot mount that allows the relative orientation of the elongate body  14  to change with respect to the clamp head  19  and the sanding device  10 .  
         [0036]    The paddle trigger  36  of the illustrated embodiment has an elongate shape that extends along a part of the length of the elongate body  14 . The front end of the paddle wraps around either side of the elongate body  14  and comes together on the top of the sanding device  10  just over the trigger  12 . The paddle trigger  36  rotates about an axle pin  37  mounted to the clamp head clevis  39 . The top end of the paddle trigger  36  also includes an adjustment bolt  38  that contacts the trigger  12  and sets the paddle trigger  36  angle with respect to the angle of the elongate body  14 . This adjustment is necessary because the elongate body  14  and the paddle trigger  36  pivot independently on the axle pin  37 .  
         [0037]    The ergonomic handle  100  is attached to the sanding device  10  by encircling the power head  11  with the pair of jaws  20 . The pair of jaws are opened by rotation about the jaw pin  21  when the draw bolt  23  has been loosened. The clamp head  19  is then secured to the sanding device power head  11  by tightening the draw bolt  23 . The worker adjusts the bearing  27  to the desired height by loosening the wing nut  49  and sliding the pivot pin  32  up or down along the pair of slots  50  defined by the upright members  51 . After the desired position is reached, the wing nut  49  is tightened to secure the pivot pin  32  in the slot  50  defined by the bracket  31 . Adjusting the height of the bearing  27  changes the angle of the handle  100  with respect to the sanding device  10  and allows an optimum power grip (i.e., little or no flexion and deviation of the hand and wrist) on a range of surface types. The worker adjusts the angle of the paddle trigger  36  with respect to the elongate body  14  by adjusting the adjustment bolt  38 .  
         [0038]    Once the ergonomic handle  100  has been adjusted to a desired configuration, the worker can begin sanding. The ergonomic handle  100  is grasped in a single hand and the sanding pad  13  and the bearing  27  is placed on the surface  110 . The worker applies downward pressure (or upward pressure in the case of overhead surfaces) on the elongate body  14  of the ergonomic handle  100  using a power grip having minimal flexion and extension of the hand and wrist. The worker grips the paddle trigger  36  with fingertips and pulls the paddle trigger toward the elongate body  14  which causes the paddle trigger to rotate about its axle pin  37 . The top end of the paddle trigger  36  having the adjustment bolt  38  rotates downward to depress the trigger  12  on the power head  11  of the sanding device  10  activating a supply of air pressure through the pneumatic connection  35 . Other methods of providing power and actuating the sander are also possible. Once the sanding pad  13  begins its random orbit, the worker moves the sanding pad and the bearing  27  along the surface  110  in a smooth motion while maintaining downward pressure on the ergonomic handle  100 .  
         [0039]    The present invention is not limited to retrofitting existing sanding devices. The ergonomic handle  100  could also be manufactured along with the sanding device  10  to construct an ergonomic sander. The ergonomic sander can have a similar elongate body for easy grasping of the sander and a bearing for supporting one end of the sander. However, the elongate body could be formed integrally with a housing for the sanding device power head and a bracket for the bearings. Also, other types of power such as electrical and hydraulic could be used to produce the random orbit motion of the pad  13 . The present invention is not limited to random orbit motion sanders, but could also include other sanding devices such as oscillating sanders and belt sanders.  
         [0040]    The ergonomic handle  100  of the present invention reduces the risk of injury due to vibration and poor grip posture by allowing a random orbit sanding device to be held and controlled in a power grip. In the power grip the wrist is held in a neutral position, or slightly extended. The power grip allows good blood flow to the hand and fingers, reducing the incidence of Raynaud&#39;s disease and carpal tunnel syndrome. The ergonomic handle can be held securely overhead with the fingers relaxed. In addition, the ergonomic handle separates the forces required to control sanding direction and pressure from the more precision forces required to control the trigger. As a result, the operator can put more force on the sanding interface with less hand and wrist fatigue while still maintaining control using only one hand.  
         [0041]    Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.