Abstract:
An actuator system is disclosed for positioning a component interface relative to a work surface, including a first shaft coupled to the worksurface and a counterweight coupled to the first shaft, a second shaft coupled to the worksurface and the component interface coupled to the second shaft, a coupler communicating with the first shaft and the second shaft, a clutch mechanism in operable engagement with the second shaft; and a power source coupled to the second shaft for selectively applying a force to the second shaft when the clutch mechanism is engaged.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an actuator system for positioning a workpiece. More particularly, the present invention relates to a counterbalance actuator system for positioning a workpiece. 
     BACKGROUND 
     It is well known to provide for an actuator to mechanically move or position a workpiece, object or other component for installation on, or attachment to a product in assembly, production or work process activities. Such well known actuators are typically provided for reducing the amount of human effort expended in an assembly or production activity, or for improving the speed, accuracy, quality, repeatability or reliability of the operation. These well known actuators are commonly part of automated assembly or production systems, or may be manually operated or manually-assisted actuators operated by a user on assembly lines or other types of manufacturing or production stations operated by a user. 
     However, in such manually-assisted actuators that include heavy workpiece holders or involve moving and positioning heavy workpieces or objects it may be difficult for a user or operator to repetitively operate the actuator due to the fatigue involved with moving and positioning the weight of the object throughout the extended periods of time that are typically involved with a normal workshift. Such difficulty with manually-assisted actuators may also be compounded when the assembly or production activity requires the application of an assembly force by the user or operator to the workpiece after it has been positioned by the actuator, in order to install or attach the workpiece to a product or other item. Such known actuators have typically attempted to address this shortcoming by providing a counterweight positioned opposite the workpiece holder about a single pivot point to offset the rotational force required to move the workpiece or workpiece holder. The use of such offsetting counterweights coupled to the workpiece holder about a single pivot axis often involves a safety hazard associated with the counterweight moving in close proximity to the operator. 
     Accordingly, it would be advantageous to provide a manually-assisted actuator system for positioning or installing a workpiece on a product that includes a counterbalance system for offsetting the weight of the actuator and/or workpiece to reduce the operator fatigue associated with moving the actuator or workpiece. It would also be advantageous to provide a manually-assisted actuator system that has a spatially-compact counterbalance system that improves the available space around the assembly or production equipment and avoids the movement of a counterweight in close proximity to the operator. It would be further advantageous to provide a manually-assisted actuator system that provides an application or installation force to the workpiece only after the workpiece has been positioned relative to a product. It would be further advantageous to provide a manually-assisted actuator system that has a counterbalance system that is adjustable for adapting to workpieces or workpiece holders or having various weights. It would be further advantageous to provide a manually-assisted actuator system that has a structurally-robust design for construction simplicity, durability of operation and ease of repair. 
     Accordingly, it would be advantageous to provide a manually-assisted actuator system having any one or more of these or other advantageous systems. 
     SUMMARY OF THE INVENTION 
     The invention relates to an actuator system for positioning a component interface relative to a work surface, including a first shaft coupled to the worksurface and a counterweight coupled to the first shaft, a second shaft coupled to the worksurface and the component interface coupled to the second shaft, a coupler mechanically communicating with the first shaft and the second shaft, a clutch mechanism in operable engagement with the second shaft; and a power source coupled to the second shaft for selectively applying a force to the second shaft when the clutch mechanism is engaged. 
     The invention also relates to an actuator system for positioning a workpiece, including means for moving a component interface between a loading position and an installation position, means for counterbalancing the movement of the component interface between the loading position and the installation position, and means for applying a force on the workpiece when the component interface is in the installation position. 
     The invention further relates to an actuator system for receiving and positioning a component, including a drive member, a component interface coupled to the drive member for movement between a component loading position and a component installing position where the component interface is adapted to receive one or more components, a force applicator operatively engaging the drive member, a force generator coupled to the force applicator to selectively apply a force to the drive member, and a counterbalance mass operatively coupled to the drive member to substantially balance the mass of the component interface. 
     The invention further relates to a method for installing a workpiece on a worksurface including loading a workpiece in a holder capable of movement between a workpiece loading position and a workpiece installing position, moving the holder containing the workpiece from the loading position to the installing position, counterbalancing the movement of the holder between the loading position and the installing position, applying a force to the workpiece using a clutch device, and installing the workpiece on the worksurface. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top perspective view of a counterbalance actuator system according to an exemplary embodiment of the present invention. 
     FIG. 2 is a bottom perspective view of a counterbalance actuator system according to an exemplary embodiment of the present invention. 
     FIG. 3 is a first side view of a counterbalance actuator system according to an exemplary embodiment of the present invention. 
     FIG. 4 is an second side view of a counterbalance actuator system according to an exemplary embodiment of the present invention. 
     FIG. 5 is a top view of a counterbalance actuator system with a force transmission device in an engaged position according to an exemplary embodiment of the present invention. 
     FIG. 6 is a top view of a counterbalance actuator system with a force transmission device in a disengaged position according to an exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, an counterbalance actuator system  10  having an actuator portion  20 , a counterbalance portion  60 , and a force application portion  80  is shown according to an exemplary embodiment. Actuator system  10  is provided for the repetitive movement and positioning of a workpiece (such as an object, part, component, etc.) or other item adapted for installation on, or attachment to, another item, product or assembly or other surface adapted for receiving a workpiece or product. Actuator system  10  may include a base  12  (e.g. worksurface, platform, stand, etc.) shown as a generally flat plate but may be any suitable structure for adapting to a particular product assembly configuration. Base  12  may have a first side  14  and a second side  16  that generally separates the actuator system  10  into an actuator portion  20  as shown above base  12  and a counterbalance portion  60  as shown below base  12 , however the elements and components of these portions to be described may be configured in any suitable position and relationship for performing the counterbalance actuating system function to be described. In an alternative embodiment, a base may be omitted and the elements and components of the system may be assembled for use directly with a product or other item for receiving a workpiece. In other alternative embodiments, the counterbalance portion may be provided in any convenient location to suit applicable workspace requirements. 
     Referring to FIG. 1, actuator portion  20  is shown according to an exemplary embodiment. Actuator portion  20  includes one or more bearing housings  22  (e.g. holders, supports, blocks, plates, etc.) mounted to base  12  by welding, threaded fasteners, unitary formation or other suitable method and are made of steel, aluminum or other suitable material for housing an anti-friction device shown as a roller bearing  24 . In a particularly preferred embodiment, bearings  24  are an inner ring bearing such as part number ER-18T, manufactured by Sealmaster of Florence, Ky. or equivalent. Bearings  24  and bearing housings  22  are preferably positioned on base  12  in axial alignment for receiving the outboard ends of a shaft  26  oriented along a common axis with, and extending between, bearings  24 . A component interface such as a workpiece holder  28  (shown schematically as a nest) is provided for receiving a workpiece. Workpiece holder  28  is coupled to shaft  26  by mounting arms  29  in a non-slip manner so that rotation of shaft  26  causes workpiece holder  28  to rotate between an installation position  30  (e.g. closed position the location of which may vary depending on the sizes and shapes of the workpiece and the item to which it may be joined) where the workpiece is positioned for attachment or installation on a product, and a loading position  32  (e.g. open position as shown in FIG. 4, the location of which may vary to accommodate the installation requirements for a particular workpiece) where the workpiece holder  28  is positioned for loading a new workpiece. In a particularly preferred embodiment, workpiece holder  28  has a shape configured to receive a particular component and is made of Renboard, but may be made from poured polyurethane, wood, metal, plastic, polymer or other materials suited for use in positioning a workpiece. In a preferred embodiment, actuator portion  20  may be manually operated by a user to move workpiece holder  28  between loading position  32  and installation position  30 . Mounting arms  29  may be adjustably coupled to shaft  26  using clamps  34  or any other conventional fastening device. In alternative embodiments, workpiece holder  28  may have any suitable shape and size adapted for receiving and moving a workpiece. 
     A rotational drive device  40  such as a sprocket or pulley is coupled to shaft  26  in a non-slip manner such as by set screws, a shrink or interference fit, unitary formation, threaded onto shaft  26 , or by any other suitable method and configured to engage a motion transfer member  42  (shown as a continuous chain, but could be a belt or other suitable transfer device). As workpiece holder  28  is moved by a user between loading position  32  and installation position  30 , shaft  26  and rotational drive device  40  rotate about a common axis with bearings  24  and impart movement to motion transfer member  42 . In a particularly preferred embodiment, rotational coupler  40  is a sprocket such as part number H40JA15-#40, manufactured by Tsubaki, Inc. of Wheeling, Ill. or equivalent, and motion transfer device  42  is a #40 roller chain manufactured by Tsubaki, Inc. of Wheeling, Ill. or equivalent. 
     Shaft  26  also preferably includes a force transfer device  44  shown schematically as a torque arm or lever arm positioned in a rotatable relationship with shaft  26  so that the position of force transfer device  44  remains essentially constant while shaft  26  is free to rotate between the loading position  32  and the installation position  30 . A selectively releasable engagement device, shown schematically as a clutch  50  has a first flange  52  fixed to force transfer device  44  in a rotatable relationship with shaft  26  so that the position of first flange  52  and force transfer device  44  remains essentially constant allowing shaft  26  to rotate freely between loading position  32  and installation position  30 . As shown in FIGS. 5 and 6, a second flange  54  of clutch  50  is fixed to shaft  26  in facing alignment with first flange  52  so that when clutch  50  is actuated, second flange  54  shifts axially from a disengaged position to an engaged position to couple second flange  54  with first flange  52 . In the engaged position first flange  52  and force transfer device  44  are rotationally coupled to shaft  26  via second flange  54 . In operation, clutch  50  is disengaged when workpiece holder  28  is moved between the loading position  32  and the installation position  30 . When workpiece holder  28  reaches installation position  30 , the workpiece is positioned for attachment or installation on a product and clutch  50  is actuated. Actuation of clutch  50  locks second flange  54  to first flange  52  and force transfer device  44  so that a force may be applied to force transfer device  44  (as will be further described) and transmitted through shaft  26  to workpiece holder  28  for attachment or installation of a workpiece to a product. In a particularly preferred embodiment, clutch  50  is a flange-mount tooth-clutch model number 906806 manufactured by Nexen Group, Inc. of Vadnais Heights, Minn. or equivalent. Clutch  50  may be pneumatically (e.g. air or gas), hydraulically, electrically or mechanically actuated and may be provided with appropriate pneumatic or hydraulic lines, electrical conductors, or mechanical linkages (not shown). 
     Referring to FIG. 2, counterbalance portion  60  is shown according to an exemplary embodiment. In a preferred embodiment, counterbalance portion  60  is mounted to second side  16  of base  12  to provide a compact assembly and to conceal, shield and separate its operation from actuator portion  20  for improved safety and ease of operation by a user, however counterbalance portion  60  may be located in any convenient spatial relationship with actuator portion  20  to suit the particular needs of a desired application. Counterbalance portion  60  includes a set of anti-friction devices shown schematically as two bearings  62 , coupled to lower side  18  of base  12  and providing freely-rotational support to a shaft  64 . In a particularly preferred embodiment, bearings  62  are D-Lok type pillow block bearings part number 128704 manufactured by Dodge of Greenville, S.C., or equivalent, but may be any suitable anti-friction device such as bushings or roller bearings. Shaft  64  is preferably a bar made of steel, aluminum or other suitable material and having a circular cross section, although other materials and shapes may be used to suit a particular application. 
     Referring further to FIGS. 1 and 2, a rotational drive device or coupler  66  such as a sprocket or pulley is coupled to shaft  64  in a non-slip manner such as by set screws, a shrink or interference fit, unitary formation, threaded onto shaft  64 , or by any other suitable method and configured to engage motion transfer member  42 . In operation, rotation of shaft  26  will impart a corresponding rotation to shaft  64  via rotational drive devices  40 ,  66  and motion transfer device  42 . The relative degree of rotation between shaft  26  and shaft  64  is dictated by the diameter ratio of rotational drive devices  40 ,  66 . In a particularly preferred embodiment, the diameter ratio of rotational couplers  40 ,  66  is one to one (1:1), however other ratios may be used in alternative embodiments such as to gain mechanical advantage or provide varying rotational travel distances for an counterbalance weight. 
     Referring to FIGS. 2,  3  and  4  an adjustable counterbalance weight  68  is operably coupled to shaft  64  according to a preferred embodiment. In a particularly preferred embodiment, counterbalance portion  60  includes one or more adjustable extension devices, shown schematically as rods  70 , coupled at a first end in a non-slip manner to shaft  64  and adapted to receive counterbalance weight  68  at any of a plurality of locations extending from the first end to the opposite end of rods  70 . Weight  68  may be positioned along rods  70  at any appropriate position to create a moment that is generally equal and opposite to the moment created by workpiece holder  28  (and a workpiece if desired) extending from shaft  26 . Rods  70  and weight  68  are rotated upward by shaft  64  when shaft  26  is rotated by downward movement of workpiece holder  28  and vice-versa so that the moment created by workpiece holder  28  and weight  68  are substantially offsetting. Weight  68  is selected having an appropriate mass to counterbalance workpiece holder  28  and may be selectively positioned along rods  70  to fine-tune the counter balance by suitable adjustment of retainers  72 . In operation, as workpiece holder  28  is rotated between loading position  32  and installation position  30  and back to loading position  32 , weight  68  is rotated in an opposing, balanced, and generally semi-circular relationship. In a particularly preferred embodiment, rods  70  are threaded rods and retainers  72  are hex nuts for threading onto rods  70  to clamp weight  68  in a desired position. In other alternative embodiments, the counterbalance portion may include non-threaded extensions members or weights that are integrally formed with a rotating shaft, and the weight and the extension members may be clamped, welded, pinned, interference fit, or joined in a sliding-detent manner. In further alternative embodiments, one or more extensions and weights may be used. 
     Referring further to FIGS. 2,  3  and  4  a positioner  74  (e.g. cushioning device, travel stop, bumper, shock absorber, etc.) may be provided and attached to second side  16  of base  12  to limit and cushion or dampen the impact from weight  68  as it reaches the end of its travel range when workpiece holder  28  is in loading position  32  (as shown in FIG.  4 ). In a particularly preferred embodiment, positioner  74  is an adjustable shock absorber, part number ACE-0225 manufactured by CE Controls, Inc. of Farmington Hills, Mich., or equivalent, but may be any suitable component such as a block of rubber or other resilient material for cushioning and limiting the range of travel of weight  68 . In alternative embodiments, the positioner may be a hard-stop, a rotational interlock, or other device for limiting the travel of the counterbalance weight or workpiece holder to a desired position, and may be located to engage any portion of the system for limiting travel. 
     Referring to FIG. 3, a force application portion  80  of system  10  is shown according to an exemplary embodiment. Force application portion  80  may be actuated when workpiece holder  28  is moved to installation position  30  such that an installation or application force may be applied on workpiece holder  28  to assist with the installation or assembly of the workpiece to an item, product or other assembly object. A force generating device such as a power source  82 , shown schematically as a piston-and-cylinder, is attached by one or more brackets  83  to second side  16  of base  12  and positioned so that the output of power source  82  is directed to a receiving portion end of force transfer device  44 . When workpiece holder  28  has reached installation position  30  and clutch  50  is activated to rotationally couple force transfer device  44  to shaft  26 , power source  82  is actuated for a predetermined period of time to apply a predetermined force to the workpiece via workpiece holder  28 , shaft  26  and force transfer device  44 . Pneumatic or hydraulic tubing associated with force generating device  82 , shown schematically as lines  84 , may be provided for controlling and operating the force actuation according to any conventional control and supply system. Electrical components such as switches, interlocks, timers, valves and controls (not shown) may also be provided to operate force application portion  80  according to any preferred embodiment. In a particularly preferred embodiment, force generating device  82  is an M class air cylinder, part number 1750D02-01A-03 manufactured by Numatics Actuator of Highland, Mich., or equivalent, operating on a conventional 80 pound per square inch compressed air supply to deliver a force corresponding to an installation pressure in the range of 1.5-3.0 pounds per square inch between the workpiece and the item to which the component is to be joined. A bonding agent such as adhesive or heat may be applied to the workpiece before or during the application of the force when workpiece holder  28  is in the installing position to improve the retention of the workpiece on the item to which the workpiece is joined. The force generated by power source  82  may be adjustable and may be applied for an adjustable period of time that is preferably automatically controlled by a programmable logic controller or timer (not shown), or other suitable device. In alternative embodiments, other operating pressures, or different force generating devices may be used such as hydraulic cylinders, spring actuators, linear actuators, motors or solenoid devices, and the duration of force application may be manually controlled. 
     According to other exemplary embodiments, the actuator system for positioning a workpiece may be associated with any application for the repetitive positioning of an object, including commercial, industrial and residential uses. The movement of the workpiece may also be adapted for linear movement or a combination of rotary and linear movement using suitable conventional linkage devices. It is important to note that the terms used to identify elements or components of the system are intended to be broad terms and not terms of limitation. 
     It is important to note that the construction and arrangement of the elements of the actuator system for positioning a workpiece as shown in the preferred and other exemplary embodiments is illustrative only. Although only a few embodiments of the present inventions have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, interchangeable relationships, use of materials, processes, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, the counterbalance portion of the system may be integrated onto a single shaft with the actuator portion and the force actuation portion may be integrated directly with the workpiece holder. Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the appended claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present inventions as expressed in the appended claims.