Abstract:
An air-actuated clamping assembly that is quickly actuated to secure a workpiece in place during machining operations, such as on a waterjet machine. The clamping operation is completed within seconds after a workpiece is placed (for example, when used in conjunction with a waterjet machine) onto the waterjet machine slats. The system greatly minimizes set-up time, allows for an adjustable clamping force, allows for one operator to set up workpieces, keeps the workpiece firmly in place and prevents movement during the machining process, is adaptable to various waterjet brands and models, and is air-actuated so that typical “house air” can be utilized.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61/242,939, filed Sep. 16, 2009 entitled CLAMPING SYSTEM. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a clamping assembly and, more specifically, to an air-actuated clamping assembly used in conjunction with a waterjet. 
     2. Background Information 
     A waterjet is used to cut metal in an abrasive jet machining process. The waterjet sprays a cutting fluid, typically water filled with abrasive particles, at an extremely high pressure onto a workpiece. The force of the fluid, along with the abrasive particles, is sufficient to cut through the workpiece. The workpiece is typically in the form of a flat plate or a sheet of metal, plastic or other rigid material; other workpiece configurations may be used, however. The workpiece is disposed on a generally flat, horizontal bed formed of spaced vertical slats. A high pressure nozzle is structured to move over the bed. The waterjet further includes a reservoir of abrasive, typically powdered garnet. The abrasive reservoir is in fluid communication with a water conduit and/or the nozzle. Water is pumped through the water conduit at a very high pressure. The abrasive is combined with the water flow in either the water conduit and/or the nozzle where the cutting fluid emerges as a spray. 
     The cutting fluid spray is typically applied at a right angle to the sheet-like workpiece. That is, the nozzle is typically structured to move in a plane that is substantially parallel to the bed. The position of the waterjet nozzle is typically controlled by a computer which follows a geometry provided by an operator. Thus, during the machining process it is necessary to secure the workpiece in order to substantially prevent movement. That is, the workpiece cannot move more than an insubstantial amount or the waterjet nozzle will apply the spray to the wrong location on the workpiece. 
     Typically, the product produced by this machining process is the component cut from the workpiece. These components fall from the workpiece in between the slats on the waterjet bed into a fluid (water and the cutting fluid) filled reservoir. Alternately, the product may be the workpiece that remains on the waterjet bed. A sheet having openings may, for example, be used as a seal or gasket. 
     Accordingly, a technician must secure each workpiece to the waterjet bed. This activity is often referred to as the “set-up” time. Typically, during the set-up time the technician must place the workpiece on the waterjet bed, then align and secure the workpiece. Securing the workpiece is accomplished by applying at least one clamp, and typically a plurality of clamps, to the workpiece. These clamps are generally manual clamps that must be positioned and secured by the technician. Given that the waterjet nozzle is typically computer controlled and may operate quickly, the set-up time may represent a significant portion of the total cutting operation. Further, the technician must ensure that the abrasive reservoir does not run low of abrasive. 
     With the prior art method of clamping there are several inherent negative manufacturing issues. First, prior art methods are time consuming. An operator can be required to take anywhere from about a minute to ten minutes (or more) in order to properly secure a workpiece. Total set-up time in an operator&#39;s day is especially affected when an operator has to perform many different individual set-up operations (often required when there are small lot sizes of varying sized parts being manufactured). Second, such clamping procedures require awkward operations due to the size and nature of the raw material being used, and often require more than one person to assist with the set-up operations. That is, the inherent nature of working with certain large plates presents obvious disadvantages when using manual traditional clamping techniques. Also, at times, two operators are needed for certain clamping set-ups. 
     Third, with prior art clamping methods, the workpiece can at times loosen and become crooked during the machining process. That is, traditional clamping techniques can, at times, result in the workpiece becoming loose if the operator does not properly adjust manual clamping assemblies to create an optimal clamping scenario. Thus, before or during the cutting operation the workpiece may become crooked, which, in turn causes dimensional inaccuracies. 
     In order to address the above-described issues pertaining to the prior art, it would be a welcomed addition in the art to provide an apparatus and process that can avoid the shortcomings in the prior art (such as improving the efficiency of set-up time, minimizing awkwardness, and providing improved clamping), thus driving down the overall cost of manufacturing. 
     SUMMARY OF THE INVENTION 
     The present invention provides a clamping assembly structured to clamp a generally rigid, flat plate or sheet, which is typically metal or plastic, to a waterjet bed. It is noted that such workpieces, i.e. sheets of raw material, typically have substantially straight edges. Further, the waterjet bed typically has substantially straight edges. The workpiece, however, is typically smaller than the waterjet bed. The clamping assembly is structured to bias the workpiece against one of the edges of the waterjet bed, typically, but not necessarily the edge closest to the waterjet operator/technician. 
     The clamping assembly includes an elongated, generally straight clamping bar and an air cylinder assembly. The clamping bar is mounted on one edge of the waterjet bed and is structured to extend generally parallel to the opposing edge of the waterjet bed. The air cylinder assembly is structured to move the clamping bar between a retracted position, wherein the clamping bar does not engage the workpiece, and an extended position, wherein the clamping bar engages the workpiece and biases the workpiece against the opposing edge of the waterjet bed. Because the workpiece has substantially straight edges, the act of biasing the workpiece between two parallel elements, i.e. the clamping bar and the edge of the waterjet bed, both aligns and clamps the workpiece. Because the clamping assembly is automatic, the duration of the set-up time is greatly reduced. Further, the automated system operates in a consistent manner which may allow for an automatic feed assembly for the workpieces. 
     After the workpiece is placed by an operator on the bed of a waterjet machine, the operator can then activate the air cylinder assembly&#39;s control valve in order to commence the automated clamping operation. The air cylinder assembly moves the clamping bar in the direction of the workpiece. The motion of the air cylinder is relatively rapid, contacting the workpiece within seconds. After the initial contact, the clamping bar applies sufficient force to the workpiece to move the workpiece against the opposing waterjet bed edge, thereby securing the workpiece in place for the abrasive jet machining process. When machining is complete, the operator can activate the air cylinder assembly&#39;s control valve in order to release the clamping assembly from applying force to the workpiece. The air cylinder assembly retracts the clamping bar from the workpiece, and the operator may move (or remove) the workpiece. 
     If the product is/are the pieces cut from the workpiece, the product falls through the waterjet bed into a fluid reservoir. The reservoir may include a removable basket. The basket is preferably a wire basket. The basket is disposed sufficiently deep in the reservoir so that, after the spray cuts through the workpiece, the force of the spray is sufficiently dissipated by the fluid in the reservoir to the point the spray does not damage the basket. 
     It is further noted that the clamp assembly may be adapted to fit existing waterjets and may be moved between existing waterjets. That is, the clamp assembly may be made to be removably coupled to many different waterjet beds. Further, the air cylinder may be adapted to be coupled to “house air,” i.e. a compressed air system commonly used in manufacturing facilities and having standardized couplings. The present invention also provides a method for adjusting the clamping force of the clamping assembly, to be controlled by the operator. This is accomplished by adjusting the pressure in the air cylinder using an included air pressure regulator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the clamp assembly will be better understood when read in conjunction with the appended figures: 
         FIG. 1  is an isometric view of a waterjet and clamp assembly. 
         FIG. 2  is an isometric detailed view of the primary clamping components comprising the clamping assembly, as well as the location of a workpiece. 
         FIG. 3  is another isometric view of the clamp system. 
         FIG. 4  is a rear view of the clamp assembly on a waterjet machine. 
         FIG. 5  is an isometric view of the wire basket. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It is to be understood that the Figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, other elements. Those of ordinary skill in the art will recognize that other elements may be desirable in order to implement the present invention. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. 
     As used herein, “coupled” means a link between two or more elements, whether direct or indirect, so long as a link occurs. 
     As used herein, “directly coupled” means that two elements are directly in contact with each other. 
     As used herein, “fixedly coupled” or “fixed” means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other. 
     As used herein, directional terms, such as, but not limited to, “front,” “back,” “right,” “left,” “upper,” “lower,” etc. correspond to the orientation of the waterjet. That is, a waterjet typically includes a control panel which is located near the “front” of the waterjet. 
     As used herein, and when discussing the orientation of a frame assembly, “roll” corresponds to rotation about a longitudinal axis, “pitch” corresponds to rotation about a lateral axis, and “yaw” corresponds to rotation about a generally vertical axis. 
     As shown in  FIG. 1 , a waterjet  10  typically includes a bed assembly  12  and a nozzle assembly  14 . The bed assembly  12  includes a housing  16  defining a reservoir  18  for a liquid. The bed assembly  12  further includes a plurality of slats  20  which form a bed  22 , i.e. a generally planar surface defined by the upper surface of the slats  20 . The slats  20  are, typically, flat, thin, and elongated members made of metal. The slats  20  are oriented so that a long, thin edge is disposed at the top of the bed  22 . The slats  20  are spaced from each other so that cut product and/or scrap may fall between the slats  20  into the reservoir  18 . The upper surface of the bed  22 , when the slats are new, is generally flat. The housing  16  defines a generally vertical, upwardly extending edge  24  that extends around the bed  22 . Alternately, the bed assembly  12  may include a mounting frame (not shown). The mounting frame is coupled to the housing  16  and/or bed  22  and extends, generally, about the circumference of the bed  22  or a portion of the bed  22 . Such a mounting frame is typically structured or shaped to support a specific workpiece  1 , discussed below. That is, for example, if the workpiece  1  forms a product like a gasket, and, if that gasket has a particular exterior profile, the mounting frame may have a corresponding profile. Thus, the exterior profile of the workpiece  1  may be cut, or cast, prior to the time the workpiece  1  is on the waterjet  10 . By matching the workpiece  1  exterior profile to the mounting frame, the workpiece  1  will be aligned. Thereafter, the clamp assembly  40  (discussed below) maintains the workpiece  1  in place. 
     The nozzle assembly  14  includes a water supply conduit  15  (shown schematically), which is coupled to a water supply (not shown), a high pressure pump (not shown), a movable arm assembly  30 , a particulate reservoir  32  ( FIG. 9 ), and a nozzle (not shown). The particulate reservoir  32  is structured to contain a particulate abrasive, such as, but not limited to, powdered garnet. The particulate reservoir  32  is in fluid communication with the water supply conduit at a point downstream of the high pressure pump. In operation, the particulate abrasive is incorporated into the water at the nozzle, thereby creating a cutting fluid. The nozzle is coupled to, and in fluid communication with, the water conduit at a point downstream of the high pressure pump and the mixing chamber. The nozzle is structured to spray the cutting fluid in a controlled manner, typically in a thin, line-like pattern. The direction of the spray as it exits the nozzle is considered to be the longitudinal axis of the nozzle/spray. 
     The cutting fluid only acts as cutting fluid when the particulate abrasive is included in the fluid. Thus, when the particulate reservoir  32  is empty, or below a predetermined amount of particulate abrasive, the cutting fluid is ineffective. To ensure the waterjet  10  does not operate when the particulate reservoir  32  is below a predetermined amount of particulate abrasive, a sensor  39  may be included. The particulate reservoir sensor  39  provides a signal to the movable arm assembly control system  38 , discussed below, when the particulate reservoir  32  is below a predetermined amount of particulate abrasive. When the movable arm assembly control system  38  receives a signal indicating a low level of abrasive, the cutting operations are discontinued until the particulate reservoir  32  is refilled. 
     The nozzle is mounted on the movable arm assembly  30 . The movable arm assembly  30  is structured to move the nozzle over the bed  22 . Typically, the nozzle and/or the spray is structured to be generally normal, i.e. generally perpendicular to, the plane of the bed  22 . The nozzle/spray may be adapted to pitch and yaw about the longitudinal axis of the nozzle/spray. The movable arm assembly  30  typically moves the nozzle in a plane that is generally parallel to the upper surface of the bed  22 . The nozzle may also be moved vertically relative to the upper surface of the bed  22 . 
     In operation, the nozzle sprays the cutting fluid with a sufficient force to cut a workpiece  1 . The cutting fluid may also erode the upper surface of the slats  20  which form the bed  22 . This erosion shall hereinafter be ignored and it is assumed that the bed  22  has a generally planar upper surface. 
     The movable arm assembly  30  further includes a control system  38 . The movable arm assembly control system  38  is structured to position the nozzle and control the flow of the cutting fluid through the nozzle. The movable arm assembly control system  38  typically includes a computer (or other programmable logic circuit) and at least one control routine (none shown). 
     The workpiece  1  is, typically, a planar member of a rigid material. The workpiece  1  is typically metal or plastic. The workpiece  1  is disposed on the bed  22  and the nozzle moves above the workpiece  1 . As the nozzle sprays the cutting fluid, the cutting fluid cuts the workpiece  1 . The desired product  2  ( FIG. 5 ) may be either, and on some occasions, both, the portions that are cut from the workpiece  1  and/or the portion that remains on the bed  12 . If the product  2  is the cut portion, the product typically falls between the slats  20  into the reservoir  18 . The reservoir  18  may include a basket  19 , preferably made from a mesh or wire, structured to capture the product  2 . The reservoir  18  has a sufficient depth so that the force of the spray is dissipated by the liquid in the reservoir  18  to the point where the spray does not erode the basket  19 . 
     To ensure that the workpiece  1  is held secure during the cutting operation, a clamp assembly  40  is provided. The clamp assembly  40  may be incorporated into the waterjet  10 , or may be a portable device that can be moved between different waterjets  10 . As shown in  FIGS. 1-3  and  7 , the clamp assembly  40  includes a primary plate  42 , a mounting plate  44 , a coupling  46  and an air cylinder assembly  60 . The clamp assembly  40  may include an alignment assembly  80 . As shown, the clamp assembly  40  is coupled to, or positioned by, the back side of the waterjet  10 , but as will become clear when the operation of the clamp assembly  40  is discussed, below, the clamp assembly  40  may be coupled to, positioned by, any side of the waterjet  10 . 
     The primary plate  42  is, preferably, an elongated rigid plate. The primary plate  42  is structured to move, and typically slide, across the bed  22 . The mounting plate  44  extends generally perpendicular to the plane of the primary plate  42  and is, preferably, fixed to the back edge of the primary plate  42 . The mounting plate  44  is structured to allow the air cylinder assembly  60  to be coupled to the primary plate  42 . That is, the coupling  46  is coupled to the back side of the mounting plate  44 . The coupling  46  is structured to be coupled to the piston rod, described below. The mounting plate  44  preferably extends over most of the back edge of the primary plate  42  so as to provide an additional attachment surface for the alignment assembly  80 . Alternately, the mounting plate  44  could be a mounting bracket (not shown) coupled to the primary plate  42 . 
     The air cylinder assembly  60  includes an air actuated piston (not shown) and a control system  64 . As is known, the air actuated piston includes an outer cylinder  66 , and a rod  61  coupled to an inner piston member (not shown) disposed within the outer cylinder  66 . The outer cylinder  66  is sealed on at least one end, typically the back end. The piston and associated rod  61  are structured to move between two positions, a first, retracted position, wherein the piston is disposed adjacent to the outer cylinder back end, and a second, extended position, wherein the piston is spaced from the outer cylinder  66  back end. As the piston moves, the rod  61  moves too. When a fluid, typically air, is introduced between the piston and the cylinder back end, the piston member is moved away from the cylinder back end, i.e. the piston moves to the extended position. When the fluid is removed from between the piston and the cylinder back end, the piston member is moved toward the cylinder back end, i.e. the piston moves to the retracted position. It is noted, the outer cylinder  66  may have two sealed ends and the fluid (air) may be alternately introduced to either side of the piston resulting in the desired motion. The piston rod  61  has a distal end  63  that extends from the outer cylinder  66 . The piston rod distal end  63  is coupled to the coupling  46 . 
     Thus, when the air cylinder assembly  60  is actuated, the piston rod  61  moves, either to the extended position of the retracted position. As the piston rod  61  moves, the primary plate  42  moves as well. As noted above, the workpiece  1  is typically a planar member of a rigid material. When the piston rod  61  moves toward the extended position, the primary plate  42  is moved into contact with the workpiece  1 . As the piston rod  61  continues to move toward the extended position, the workpiece  1  is biased against the housing  16 . That is, the workpiece  1  is clamped between the primary plate  42  and the housing  16  (or alternately against a mounting frame). Additionally, free-floating spacer plates (not shown) can be placed in between the primary plate  42  and the workpiece  1  to take up any “gap” which might be present. 
     The air cylinder assembly control system  64  includes a control valve (not shown), air hoses  72 , a regulator  74 , and a control device  76 . The control device  76 , which may be a knob as shown or an automatic actuator (not shown), is structured to open and close the control valve. The control valve is structured to be coupled to a source of compressed air (not shown). The regulator  74  is disposed between the control valve and the air cylinder assembly  60 . The regulator  74  is structured to limit the pressure supplied to the air cylinder assembly  60 , and therefore limit the force created by the primary plate  42  on the workpiece  1 . The regulator  74  is, preferably, adjustable. The control valve, the regulator  74  and the air cylinder assembly  60  are coupled to each other by the air hoses  72 . 
     The alignment assembly  80  is structured to substantially maintain the primary plate  42  in a single orientation. That is, by virtue of resting on the bed  22 , the primary plate  42  cannot significantly roll or pitch relative to the longitudinal axis of the piston rod  61 . The primary plate  42  may, however, yaw, depending upon the rigidity of the link between the piston rod  61 , the coupling  46 , and the primary plate  42 . The alignment assembly  80  includes at least one alignment head assembly  82  and a rigid frame  84 . The frame  84  is structured to support the air cylinder assembly  60  and the at least one alignment head assembly  82 . Preferably, the air cylinder assembly  60  and the at least one alignment head assembly  82  are in a fixed position with substantially parallel longitudinal axes. 
     Preferably, the alignment assembly  80  includes two alignment head assemblies  82 . Each alignment head assembly  82  includes a rod  86 , at least one, and preferably two fixed mounting blocks  88  and a movable mounting block  90  (which is the coupling  46 ). The fixed mounting blocks  88  are coupled to the frame  84  and each includes a bearing  89  with an opening  90 . The fixed mounting blocks openings  90  are aligned. The movable mounting block  90  is, preferably, elongated and fixed to the mounting plate  44 . The movable mounting block  90  longitudinal axis extends generally perpendicular to the longitudinal axis of the piston rod  61 . The alignment head assembly rod  86  is coupled to the movable mounting block  90  and is slidably disposed through the fixed mounting block bearing  89 . The alignment head assembly rod  86  is substantially parallel to the piston rod  61 . In this configuration, the alignment assembly  80  is structured to substantially maintain the primary plate  42  in a single orientation. If there are two alignment head assemblies  82 , the alignment head assemblies  82  are preferably disposed on opposite sides of the air cylinder assembly  60 . 
     Further, the frame  84  is preferably structured to be coupled to the waterjet  10 . To accommodate waterjets  10  of different configurations, the frame  84  may have an adjustable length. That is, the back side of the waterjet housing  16  may have different lengths. The frame  84  is preferably structured to be adjustable to these lengths. The frame  84  may include a downwardly extending flange that is structured to be disposed over the back edge of the waterjet housing  16 . The frame  84  may also include one or more fasteners structured to engage the waterjet housing  16 . These screws may have an extended length to accommodate waterjets that have a thinner back side to the housing (thinner meaning the overall length/width, not the thickness of the material that forms the housing  16 ).