Abstract:
A device for receiving and processing an elongated workpiece that proceeds along a path is disclosed. The device comprises a plurality of clevis-shaped members, each clevis-shaped member being pivotable about a vertical axis and having a pair of spaced apart upwardly extending posts. The clevis-shaped members are spaced apart relative to the path, and the posts of each clevis-shaped member defining therebetween a centered workstation disposed along the path. At least one actuator is provided, with the actuator operatively engaging each of the clevis-shaped members such that the each clevis-shaped member will pivot about its vertical axis. Accordingly, in response to operation of the actuators the posts of each of the clevis-shaped members shift in unison to center and clamp the workpiece at the workstation.

Description:
RELATED APPLICATIONS 
     This application is a divisional and claims priority from earlier filed U.S. application Ser. No. 09/813,748, filed Mar. 21, 2001, now U.S. Pat. No. 6,648,120, which is a CIP of Ser. No. 09/081,223 filed May 19, 1998, now U.S. Pat. No. 6,231,036. 
    
    
     FIELD OF THE DISCLOSURE 
     The present invention relates generally to clamping devices, and more specifically to a device that clamps a workpiece for processing. 
     BACKGROUND 
     Polyvinyl tubing is commonly used for many purposes, including by way of example rather than limitation, fencing, decking, lawn furniture, etc. In such applications, it is often required that the polyvinyl tubing be processed in one or more ways. For example, in many applications holes or slots must be cut into one or more of the sidewalls in order to accommodate mounting hardware or other associated components, or to otherwise permit a portion of one piece of tubing to be inserted into a portion of another piece of tubing. In other applications, such as polyvinyl decking systems, it may desirable to cut grooves into one surface of the tubing in order to create a non-slip surface. 
     The processing of such components often involves the use of a drill or router which is guided by a template or by a computerized control system. In such a process, the workpiece (e.g., a piece of tubing or some other piece of stock) must be secured in a predetermined location, with the workpiece being aligned and centered. Moreover, in order to ensure processing efficiencies, the workpiece must be quickly inserted and clamped prior to processing, and must further be quickly removed after processing. There exists a continuing need for improved clamping devices. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary view in perspective of a process machine for processing elongated articles, such as polyvinyl tubing, incorporating a clamping mechanism made pursuant to the teachings of the present invention; 
     FIG. 2 is an exploded view of the apparatus illustrated in FIG. 1; 
     FIG. 3 is a fragmentary top plan view of the apparatus illustrated in FIG.  1  and illustrating a workpiece illustrated being conveyed onto the device; 
     FIG. 4 is a view similar to FIG. 3, but illustrating the workpiece installed in the apparatus and with the clamping members engaging the workpiece to hold the workpiece in place for processing; 
     FIG. 5 is a cross-sectional view taken substantially along line  5 — 5  of FIG. 1; 
     FIG. 6 is a view similar to FIG. 5, but illustrating the manner in which the device can be adjusted to accommodate a workpiece of a smaller size than the workpiece illustrated in FIG. 5; 
     FIG. 7 is a fragmentary view in perspective of a clamping device assembled in accordance with the teachings of a second preferred embodiment of the invention; 
     FIG. 8 is an end elevational view taken along line  8 — 8  of FIG. 7; 
     FIG. 9 is a top plan view of the clamping device illustrated in FIG. 7; 
     FIG. 10 is a side elevational view of the device shown in FIGS. 7-9; 
     FIG. 11 is a fragmentary view in perspective of a clamping device assembled in accordance with the teachings of a third preferred embodiment of the invention; 
     FIG. 12 is an end elevational view taken along line  12 — 12  of FIG. 11; 
     FIG. 13 is a top plan view of the clamping device illustrated in FIG. 11; 
     FIG. 14 is a side elevational view of the device shown in FIGS. 11-13; 
     FIG. 15 is a fragmentary view in perspective of a clamping device assembled in accordance with the teachings of a fourth preferred embodiment of the invention; 
     FIG. 16 is an end elevational view taken along line  16 — 16  of FIG. 15; 
     FIG. 17 is a top plan view of the clamping device illustrated in FIG. 15, 
     FIG. 18 is a side elevational view of the device shown in FIGS. 15-17; 
     FIG. 19 is an enlarged fragmentary cross-sectional view taken along line  19 — 19  of FIG. 18; 
     FIG. 20 is a fragmentary view in perspective of a clamping device assembled in accordance with the teachings of a fifth preferred embodiment of the invention; 
     FIG. 21 is an end elevational view taken along line  21 — 21  of FIG. 20; 
     FIG. 22 is a top plan view of the clamping device illustrated in FIG. 20; and 
     FIG. 23 is a side elevational view of the device shown in FIGS.  20 - 22 ; 
    
    
     DETAILED DESCRIPTION 
     The following description of the disclosed embodiment is not intended to limit the scope of the invention to the precise form or forms detailed herein. Instead, the following description is intended to be illustrative of the principles of the invention so that others may follow its teachings. 
     Referring now to the drawings, a machine  10  for cutting openings in the side walls of an elongated workpiece  12  (FIG. 3) includes a fixed support or table generally indicated by the numeral  14 , which includes a pair of longitudinal side frame members  16 , and a pair of transversely extending upper end frame members  18  which interconnect the side frame members  16 . Legs  20  extend downwardly from each end of both side frame members  16 . A lower transverse member  22  interconnects the legs  20  on each end of the machine  10 . Levelers  24  extend downwardly from each end of both lower transverse members  22 . A pair of elevators  26  are installed on each of the lower transverse members  22  and consist of an outer member  28  and an inner member  30  which extends from, and retracts into, the outer member  28 . The inner member  30  extends through the corresponding upper end frame member  18 . The elevators  26  may be operated manually, such as by a crank, pneumatically, or in any other manner. 
     A conveyor generally indicated by the numeral  32  is supported along the center line defined by the side frame members  16  by the elevators  26 . The conveyor  32  includes a pair of side frame members  34  which extend substantially parallel to the side frame members  16  of the fixed support or table  14 . Conveyor  32  further includes transverse end members  36  which are secured to the inner members  30  of elevators  26 . Accordingly, by operation of the elevators  26 , the conveyor  32  may be raised and lowered relative to the fixed support or table  14 . Conventional rollers  38  extends between the side members  34  and are journaled for rotation relative thereto. It will be noted that in the disclosed embodiment intermittent gaps  39  are provided between sets of the rollers  38  in which the spacing between rollers is substantially greater than the normal spacing between the rollers  38 . 
     A clamping and holding mechanism assembled in accordance with a first preferred embodiment of the invention is generally indicated by the numeral  40 . The clamping and holding mechanism  40  includes a pair of longitudinally extending, transversely spaced clamping members  42  which extend generally parallel to the side frame members  16 . A shaft  44  is mounted between a pair of extensions  46  extending upwardly from the end frame member  18  on one end of the support or table  14 . Glides  48  are mounted on one end of each of the clamping members  42  and are slidably engaged with the shaft  44 , to thereby restrain the clamping members  42  to movement transverse to the conveyor  32  and restraining the clamping members  42  against longitudinal movement. The clamping members  42  are actuated by camming members generally indicated by the numeral  50 . 
     As shown in FIG. 2, each of the camming members  50  includes an axle  52  which is rotatably supported in a corresponding one of a number of cross members  54  which extend between the side frame members  16  intermediate the end frame members  18 . A radially extending plate  56  is mounted for rotation with each axle  52  on the end thereof that projects above the cross members  54 . A crank arm  58  is mounted for rotation with some of the axles  52  and is mounted on the end thereof extending below the cross members  54 . Each of the crank arms  58  is operated by a pneumatic actuator  60  which extends between each crank arm  58  and a bracket  62  mounted on one of the side frame members  16 . Alternatively, the actuators  60  may be attached directly to an end of the plate  56 . In order to reduce the number of actuators  60 , one or more tie rods  64  may be pivotally connected between a corresponding end of adjacent plates  56 , so that rotation of any of the plates  56  will be transferred to rotate all of the other plates  56  in the same direction. Arms  66  are rigidly mounted adjacent opposite ends each of the plates  56  and extend upwardly therefrom. Each of the arms  66  engage a corresponding one of the clamping members  42 . 
     Accordingly, when the pneumatic actuators  60  are operated to turn the crank arm  58  in the counterclockwise direction (viewed from above), the plates  56  will be rotated in the same direction and, because the arms  66  are rigidly connected to the plates  56  but pivotal and slidable relative to the clamping members  42 , the clamping members  42  will move transversely toward the center line of the conveyor  32 . In the disclosed embodiment, longitudinal movement of the clamping members  42  is prevented by virtue of the glides  48  slidably mounted on the shaft  44 . When the pneumatic actuators are operated to rotate the crank arms  58  and plates  56  in the clockwise direction, the clamping members  42  are spread apart. One of the clamping members  42  carries a spring loaded pin  68  (FIGS. 3 and 4) that is urged outwardly from the inner edge of the clamping member to engage an end of the workpiece  12  as most clearly illustrated in FIG. 4, to thereby locate the workpiece in a predetermined position relative to the machine  10  when the work piece is processed as will hereinafter be explained. 
     A router carriage generally indicated by the numeral  70  includes a bridge  72  having opposite ends  74  which are provided with glides  76  to slidably engage a corresponding one of rails  78  which are mounted on the side frame members  16  and extend upwardly therefrom. Accordingly, the bridge  72  may slide along the side frame members  16  between the ends of the table or export  12 . The height of the bridge is established by a number of uprights  80   50  that transverse portions  82  clear the conveyor  32  and the clamping members  42 . Shafts  84  extend between corresponding pairs of the uprights  80  substantially parallel to the side frame members  16 . A router support  86  is slidably mounted on the shafts  84  for movement longitudinally along the conveyor  32 . The router support  86  carries a pair of transversely extending shafts  88  which slidably engage the router  90  to guide the router for movement transverse to the conveyor  32 . Accordingly, by sliding relative to the shafts  84  and  88 , the router  90  can be positioned at any point along the upper side of the workpiece  12  when the workpiece  12  is installed in the machine  10  and engaged by the clamping members  42 . The router  90  is guided by a conventional follower arm  92  which traces on the pattern  96  incorporated within a template  94 , in a manner well known to those skilled in the art. Necessary electrical connections to the router  90  are made by electrical wiring extending through a clamp  98  attached to the carriage  70 . 
     In operation, the workpiece  12  is placed upon the rollers  38  from the right hand end of the machine  10  (viewing FIGS.  1 - 4 ). The workpiece  12  is supported by the rollers  38 , and the operator may easily push the workpiece  12  into the machine  10  until the end of the workpiece  12  engages the pin  68  to locate the workpiece relative to the machine  10 . The height of the conveyor  32  may be adjusted by operation of the elevators  26  to bring the workpiece  12  to the proper height where it may be engaged by the router  90  and in which the end of the workpiece will engage the spring loaded pin  68 . For example, in FIG. 5, a relatively large cross section workpiece is being processed, so such that the elevators  26  are used to lower the conveyor  32 . In FIG. 6 a smaller cross section workpiece is illustrated in which the conveyor  32  has been raised to properly position the workpiece  12  relative to the router  90 . 
     After the workpiece  12  has been installed in the machine  10 , the pneumatic actuators  60  are operated to rotate the camming members  50 . Since the axle  52  of each camming member  50  is located along the centerline of the machine  10 , rotation of the camming members  50  in the counterclockwise direction (viewed from above) causes the clamping members  42  to move towards the center line of the conveyor  32 , each clamping member  42  moving towards the center line from opposite directions. Accordingly one of the clamping members  42  will engage the side of the workpiece before the other clamping member  42  engages the other side of the workpiece, unless the workpiece is aligned along the center line. The work piece will be moved transversely as the clamping members  42  close against opposite sides of the workpiece, thereby aligning the center line of the workpiece along the center line of the machine  10 . 
     Processing of the workpiece using the router  90  may then begin. The carriage  70  is moved manually along the tracks  78  along the template  96 , which extends along the side of the machine. After the follower arm  92  is installed in the pattern  96  defined in the template  94 , operation of the router  90  is initiated to cut the desired apertures in the workpiece  12 . Accordingly, the carriage  70  is moved manually along the workpiece to cut successive apertures or other features into the workpiece  12 . Of course, it is within the scope for the invention to use the clamping mechanism with more automated types of machines, in which the router or equivalent cutting or processing device is indexed by numerical control along the length of the workpiece. It is also obviously within the scope of the invention to provide other types of processing of the workpiece other than by router, and processing of different types of workpieces, such as shafts, elongated metal parts, etc. 
     Referring now to FIGS. 7 through 10, a clamping and holding device assembled in accordance with the teachings of a second embodiment of the invention is shown and is referred to by the reference numeral  140 . It will be understood that the clamping and holding device  140  may be suitably mounted to any suitable frame or support, such as, for example, the table  14  discussed above with respect to the first embodiment. In the disclosed embodiment, the clamping and holding mechanism  140  may be mounted to one or more of the cross members  54  (shown in fragment in FIGS. 7,  8  and  10 ) of the table  14 . The clamping and holding device  140  includes a pair of elongated clamp rails  142   a ,  142   b  which function to engage the work piece  12  in a manner similar to that discussed above with respect to the first disclosed embodiment. It will be noted that the clamp rails  142   a ,  142   b  are disposed on opposite sides of a path along which the workpiece  12  proceeds, with the path being indicated in FIG. 7 by the reference character A. The clamp rails  142   a ,  142   b  are engaged by a plurality of clamp members  144  which are spaced apart along the path A. 
     Referring now to FIG. 8, each of the clamp members  144  includes a pair of uprights  146   a ,  146   b , each of which has an upper end  146   c  which engages an adjacent one of the clamp rails  142   a ,  142   b . Each of the uprights  146   a ,  146   b  also includes a lower end  146   d . The lower ends  146   d  of the uprights  146   a ,  146   b  are mounted to a cross member  148 , and the cross member  148  is mounted to an axle  152 . The axle  152  is mounted to the cross member  54  (discussed above with respect to the first embodiment and shown in fragment in FIGS. 7,  8  and  10 )  50  as to be pivotable about its longitudinal axis. In the disclosed embodiment, the axle  152  is pivotably mounted to the cross member  54  by a pair of journaled supports  154 . A lower end  156  of the axle  152  extends below the lower support  154 , and a lever arm  158  is mounted to the lower end  156  of the axle  152  and extends laterally therefrom. Alternatively, the axle  152  may be suitably mounted to a single journaled support  154 . Further, the lever arm may extend from a central portion or an upper portion of the axle  152 . Also, it will be noted when viewing FIG. 7 that not all of the clamp members  144  need include a lever arm  158 . However, for each of the clamp members  144  including the lever arm  158 , an actuator  160  is provided, each of which is connected to one of the lever arms  158  and also to a fixed support (not shown), such as a fixed portion of the table  14 . Alternatively, the actuator  160  may be connected directly the cross member  148 . It will be understood that a number of different mechanisms may be employed to pivot the clamp members  144 , such as, by way of example and not limitation, a gear mechanism or a suitable linkage mechanism. The operation of the actuators  160  is controlled by a controller  161  (illustrated schematically in FIG.  10 ). It will be understood that the actuators  160  (or any of the actuators discussed herein with respect to any of the disclosed embodiments) may be any suitable commercially available actuators, such as pneumatic actuators, hydraulic actuators, air over oil actuators, electric linear actuators, servo motors, stepper motors, or any other type of powered actuators. 
     Referring now to FIGS. 7 and 9, the upper end  146   c of each of the uprights  146   a ,  146   b  may be pivotably connected to its corresponding clamp rail  142   a ,  142   b , respectively, by a pivot  162 . By virtue of the pivots  162 , in response to rotation of the cross members  148  in the clockwise direction caused by the extension of the actuator  160 , the clamp rail  142   a  will move to the left when viewing FIG. 9, while the clamp rail  142   b  will move to the right when viewing FIG.  9 . It will be understood of course that the clamp rails  142   a  and  142   b  will also move inwardly toward a workstation disposed along the path A. When the operation of the actuator  160  is reversed, the clamp rails  142   a  and  142   b  will move in the opposite directions and away from the path A. As an alternative, the upper ends  146   c  of the uprights  146   a  and  146   b  may pivotably and slidably engage their corresponding clamp rails  142   a ,  142   b . In such an alternative situation, each of the clamp rails  142   a  and  142   b  would be provided with a guide, such as the guides  48  which engage a transverse shaft  44  in a manner similar to that discussed above with respect to the first disclosed embodiment and which arrangement is shown in FIGS. 1,  2  and  3 . It will be understood that in such an alternative arrangement the guides  48  engaging the shaft  44  will prevent longitudinal movement of the clamp rails  142   a ,  142   b , such that they will move inward and outward in a manner similar to the movement of the rails  42  in the first embodiment. 
     In operation, the workpiece  12  proceeds along the path A supported by a suitable conveyor, such as the conveyor  32  discussed above with respect to the first disclosed embodiment. Once the workpiece  12  has reached the desired location, which is typically defined when the leading end of the workpiece  12  comes into contact with the spring loaded pin  68  (discussed above with respect to the first disclosed embodiment) or any other suitable stop (not shown), the actuators  160  are activated. Viewing FIG. 9, when the actuators  160  are extended, each of the clamp members  144  will pivot about its respective axle  152  in a generally clockwise direction when viewed from above. Again, the pivoting action of the clamp members  144  is provided by the actuators  160  engaging the lever arm  158  on selected ones of the clamp members  144 . The rotation of the clamp members  144  causes the clamp rails  142   a  and  142   b  to move closer to the center line of the path A, such that the inward edges of the clamp rails  142   a ,  142   b  will come into contact with the side edges of the workpiece  12 , thus centering and clamping the workpiece  12  at the desired workstation. The processing operations such as the drilling of holes, the cutting of grooves, or other operations, are then carried out using the router  90  or other required tools in the manner discussed in greater detail above with respect to the first disclosed embodiment. 
     When the processing of the workpiece  12  is complete, the actuators  160  are retracted, which once again moves the rails  142   a  and  142   b  outwardly and away from the workpiece  12 , thus permitting the workpiece  12  to be conveyed off the machine  10 . Another workpiece may then be processed in a similar manner. 
     Referring now to FIGS. 11 through 14, a clamping and holding device assembled in accordance with the teachings of a third embodiment of the invention is shown and is referred to by the reference numeral  240 . The clamping and holding device  240  may be suitably mounted to any suitable frame or support, such as the table  14  discussed above with respect to the first embodiment. The clamping and holding mechanism  240  may be mounted to one or more of the cross members  54  (shown in fragment in FIG. 11) of the table  14 . The clamping and holding device  240  includes an elongated link arm  242  which interconnects a plurality of clamp members  244  which are spaced apart along the path A. 
     Referring now to FIG. 12, each of the clamp members  244  includes a pair of uprights  246   a ,  246   b , each of which has an upper end  246   c . Each of the uprights  246   a ,  246   b  also includes a lower end  246   d . The lower ends  246   d  of the uprights  246   a ,  246   b  are mounted to a cross member  248 , and each of the cross member  248  is mounted to an axle  252 . The axle  252  is mounted to the cross member  54  so as to be pivotable about its longitudinal axis. In the disclosed embodiment, the axle  252  is pivotably mounted to the cross member  54  by a pair of journaled supports  254 . The link arm  242  is mounted to each of the clamp members  244 , such that the rotational movement of all of the clamp members  244  about their respective axes will be synchronized (i.e., they will all move in unison). In the disclosed embodiment the link arm  244  is mounted to the cross members  248 . Alternatively, the link arm  242  may be mounted to the uprights  246   a  or  246   b . A number of actuators  260  are provided, each of which is connected to the link arm  242 . Alternatively, the actuators  260  may be mounted to a lever arm (not shown) or other suitable mechanism engaging the axle  252 , or the actuators  260  may be mounted directly to the clamp members  244  in order to rotate the clamp members  244 . The operation of the actuators  260  is controlled by a controller  261  (illustrated schematically in FIG.  14 ). 
     In operation, the workpiece  12  proceeds along the path A supported by a suitable conveyor, such as the conveyor  32  discussed above with respect to the first disclosed embodiment. Once the workpiece  12  has reached the desired location, which again may be defined when the leading end of the workpiece  12  comes into contact with the spring loaded pin  68  (discussed above with respect to the first disclosed embodiment) or any other suitable stop (not shown), the actuators  260  are activated by the controller  261 . Viewing FIG. 13, when the actuators  260  are extended, each of the clamp members  244  will pivot about its respective axle  252  in a generally clockwise direction when viewed from above. The pivoting action of the clamp members  244  is synchronized by the link arm  242 . The rotation of the clamp members  244  causes the uprights  246   a ,  246   b  to move closer to the center line of the path A, such that the inward portions of the uprights  246   a ,  246   b  will come into contact with the side edges of the workpiece  12 , thus centering and clamping the workpiece  12  at the desired workstation. Once again, the processing operations such as the drilling of holes, the cutting of grooves, or other operations, are then carried out using the router  90  or other required tools in the manner discussed in greater detail above with respect to the first disclosed embodiment. 
     Referring now to FIGS. 15 through 19, a clamping and holding device assembled in accordance with the teachings of a fourth embodiment of the invention is shown and is referred to by the reference numeral  340 . The clamping and holding device  340  may be suitably mounted to any suitable frame or support, such as the table  14  discussed above with respect to the first embodiment. The clamping and holding mechanism  340  may be mounted to one or more of the cross members  54  (shown in fragment in FIG. 15) of the table  14 . The clamping and holding device  340  includes a plurality of counter-pivoting clamp members  344  and a plurality of counter-pivoting clamp members  345 , all of which are spaced apart along the path A. 
     Each of the clamp members  344  includes a first clamp  344   a  and a second clamp  344   b , which counter-rotate relative to each other about a common pivot axis  347 . The clamp  344   a  includes a pair of uprights  344   c  mounted to a common cross member  348   a , while the clamp  344   b  includes a pair of uprights  344   d  mounted to a common cross member  348   b . The uprights  344   d  are both pivotably mounted to the cross member  348   b , and are both operatively connected to a drive motor  349  by a drive belt  351 . 
     Referring now to FIG. 19, the clamp  344   a  is mounted to a hollow pivot axle  352  which is rotatably mounted within a pair of journaled supports  354   s . The clamp  344   b  is mounted to a pivot axle  355  which is rotatably received within the hollow pivot axle  352 . Each of the axles  352   a  and  352   b  includes a lever  358   a ,  358   b , respectively, which extends outwardly. An actuator  360   a  engages the lever  358   a , while an actuator  360   b  engages the lever  358   b . The clamps  344  are similar in all respects to the clamps  345 , except for the omission of the rotatable uprights and the motors  349 . 
     In operation, the workpiece  12  proceeds along the path A. The workpiece may supported by a suitable conveyor, such as the conveyor  32  discussed above with respect to the first disclosed embodiment. However, forward motion of the workpiece  12  along the path A is caused by rotation of the uprights  344   d  in response to operation of the motors  349 . Accordingly, the conveyor  32  need not include a separate driving mechanism. Still further, the conveyor  32  may be dispensed with in its entirety, with the functions of supporting the workpiece  12  being performed solely by the clamps  344   a  and  344   b , and the function of moving the workpiece  12  along the path A being performed solely by the rotating uprights  344   d  on the clamps  344   b.    
     Once the workpiece  12  has reached the desired location, which again may be defined when the leading end of the workpiece  12  comes into contact with the spring loaded pin  68  (discussed above with respect to the first disclosed embodiment) or any other suitable stop (not shown), the actuators  360   a  and  360   b  are activated. Viewing FIG. 17, operation of the actuators  360   a  and  360   b  will cause the uprights  344   c  of the clamp  344   a  and the uprights  344   d  of the clamp  344   b  to move inwardly in unison toward the path A, thus engaging, centering and holding the workpiece  12  at the work station. The counter-rotating pivoting action of the clamps  344   a  and  344   b  is synchronized by synchronizing the operation of the actuators  360   a  and  360   b  using any suitable control system (not shown) which control system would be within the ability of one skilled in the art. Once again, the processing operations such as the drilling of holes, the cutting of grooves, or other operations, are then carried out using the router  90  or other required tools in the manner discussed in greater detail above with respect to the previous embodiments. 
     Referring now to FIGS. 20 through 23, the clamping and holding device  340  is shown in which the clamp members  344  described above are eliminated, and instead only the clamp members  345  are employed. It will be understood that in such a situation the conveyor  32  discussed above with respect to the first disclosed embodiment, or any other suitable conveyor, must still be employed. In all other respects, the alternative arrangement of FIGS. 20 through 23 is essentially the same as that outlined above with respect to FIGS. 15 through 19. 
     Those skilled in the art will appreciate that, although the teachings of the invention have been illustrated in connection with certain embodiments there is no intent to limit the invention to such embodiments, On the contrary, the intention of this application is to cover all modifications and embodiments fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.