Abstract:
A system and method for producing a seam between adhesive coated edges of wetsuit panels. A clamping head assembly is mounted in a fixed position in relation to a work surface that supports wetsuit panels that are to be joined. The clamping head assembly includes a movable pair of jaws that are advanced in an open position toward the supported wetsuit panels to establish contact with the supported panels. After establishing contact, the jaws are closed to force the panel edges together. The jaws are then opened and retracted from the panels. The action of the jaws is governed by a controller such as a programmable logic controller (PLC). The controller may be used to control the operational cycle of the clamping head assembly by sensing the position of the mechanical elements of clamping head assembly.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to devices, systems, and methods useful for producing a seam between parts of a wetsuit. 
         [0003]    2. Description of Related Art 
         [0004]    Wetsuits are typically fabricated from a number of individual panels that are joined together at the edges by various methods. The most common methods for joining are stitching and gluing. The individual panels are usually a closed-cell foam material that may have one or both surfaces clad with a fabric. 
         [0005]    Sewing machines have long been used for the joining of wetsuit panels by stitching; however, glued seams have typically been assembled by hand with the assistance of handheld tools. Efficient glued-seam assembly requires a considerable amount of skill on the part of the assembler since simultaneous handling of a tool, and the panels to be joined, is required. 
         [0006]    The level of skill required for efficient conventional glued-seam assembly typically requires a significant amount of training time for an assembler. The skill level required of an operator and the training time required can limit the output of a wetsuit manufacturing operation. 
         [0007]    Thus, a need exists for an improved system and method for glued seam assembly of wetsuits. There is also a need for system and method that simplifies the task of handling both a tool and the wetsuit panels being assembled. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a system for applying pressure to abutted wetsuit panels to produce a bonded seam. Further, the invention provides for hands-free operation of a tool that provides the pressure to the abutted wetsuit panels. 
         [0009]    In one embodiment of the invention a clamping head assembly is mounted in a fixed position in relation to a work surface that supports wetsuit panels that are to be joined. The clamping head assembly includes a movable pair of jaws that are advanced in an open position toward the supported wetsuit panels to establish contact with supported panels. After establishing contact, the jaws are closed to force the panel edges together. The jaws are then opened and retracted from the panels. The jaws may be maintained in a closed position for a brief period (dwell time) prior to being opened. 
         [0010]    In another embodiment the action of the clamping head assembly described above is initiated by a trigger sensor that detects a signal from an operator (e.g., closure of a foot switch). The signal may provide for a single cycle of operation with each signal occurrence, or may provide for continuous cycling as long as the signal is present. 
         [0011]    In a further embodiment the action of the clamping head assembly described above is governed by a controller such as a programmable logic controller (PLC). The controller may be used to control the operational cycle of the clamping head assembly by sensing the position of the mechanical elements of clamping head assembly. The controller may also provide for timing of the jaw closure and/or the cycle rate. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows a block diagram of a wetsuit seam bonding system in accordance with an embodiment of the present invention. 
           [0013]      FIG. 2  shows a perspective view of a wetsuit seam bonding station in accordance with an embodiment of the present invention. 
           [0014]      FIG. 3A  shows a side view of a dynamic jaw module in accordance with an embodiment of the present invention. 
           [0015]      FIG. 3B  shows a perspective view of a tilting jaw module in accordance with an embodiment of the present invention. 
           [0016]      FIG. 4A  shows a pivot jaw assembly in accordance with an embodiment of the present invention. 
           [0017]      FIG. 4B  shows a sliding jaw assembly in accordance with an embodiment of the present invention. 
           [0018]      FIG. 5  shows a control flow diagram in accordance with an embodiment of the present invention. 
           [0019]      FIG. 6  shows an operational flow diagram in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]      FIG. 1  shows a block diagram  100  of an embodiment of a wetsuit seam bonding system. A workstation  105  is coupled to a controller  135  and a trigger sensor  130 . The workstation  100  includes a work surface  105  for supporting wetsuit panels that are to be joined. The work surface  105  is a substantially flat surface that preferably has a low coefficient of friction with respect to the wetsuit panels so that the panels may be manipulated with a minimum effort. 
         [0021]    A clamping head positioner  115  is coupled to the work surface  105  by a support  110 . It is preferable that the support  110  be a rigid structure that is capable of maintaining a fixed position for the clamping head positioner  115  with respect to the work surface  105  during operation. It is desirable to minimize oscillation or displacement of the clamping head positioner  115  during operation. 
         [0022]    In an alternative embodiment, the clamping head positioner  115  and the work surface  105  are not directly coupled, but are otherwise restrained so that clamping head positioner  115  and work surface  105  maintain a fixed separation during operation. For example the work surface  105  and/or clamping head positioner  115  may supported by or mounted on a floor or wall. 
         [0023]    The clamping head positioner  115  includes an actuator that provides vertical displacement to the clamping head  120 . Examples of actuators that may be used are pneumatic cylinders and solenoids. The clamping head  120  includes a pair of jaws  125 . The opening and closing of the jaws  125  may be synchronized with the vertical displacement of the clamping head  120 . 
         [0024]    The clamping head positioner  115  and the clamping head  120  are coupled to a controller  135 . The controller  135  controls the timing of the vertical displacement of the clamping head  120  and may also control the timing of the opening and closing of the jaws  125 . 
         [0025]    For example, when a pneumatic cylinder is used as the actuator for providing vertical displacement of the clamping head  120 , the controller may be used to control the gas flow to the pneumatic cylinder. On/off solenoid valves may be used, in which case the vertical displacement rate of the clamping head  120  may be adjusted by changing the working gas pressure. Alternatively, the vertical displacement rate of the clamping head  120  may be adjusted by using a proportional valve to meter gas from a constant pressure gas source. 
         [0026]    Clamping head positioner  115  may include a sensor for determining the position of the clamping head  120  with respect to the clamping head positioner  115 . For example a pneumatic cylinder with an integrated magnetic sensor may be used to provide the vertical displacement. Since the clamping head positioner  115  is essentially fixed with respect to the work surface  105 , the displacement between the clamping head positioner  115  and the clamping head  120  may be used to determine the displacement between the jaws  125  and the work surface  105 . 
         [0027]    The clamping head  120  may include a light source for illuminating a portion of a workpiece to aid in the alignment of the workpiece with respect to the jaws  125 . The light source may be a solid-state laser. 
         [0028]    The maximum value for the vertical separation (h) between the jaws  125  and the work surface  105  is preferably a value that is sufficient to allow for the unhindered positioning of wetsuit panels or a partially assembled wetsuit beneath the jaws  125 . The minimum value for the jaw separation (s) is that required to allow the jaws to provide sufficient compression to mated edges of wetsuit panels that are being bonded. 
         [0029]    The separation (h) may be established through force limit or by displacement limit. The force limit may be established by a preset limit on the force used to drive the vertical displacement of the clamping head, or it may be determined by a feed back loop. When force feedback is used, the load against the jaws  125  is sensed and the downward vertical displacement of the jaws  125  is halted when the force between the jaws  125  and the wetsuit panels reaches a predetermined value. Force feedback allows the vertical separation (h) to vary from cycle to cycle, and is useful when the thickness of the material beneath the jaws  125  varies over a large range. 
         [0030]    The vertical separation (h) may be established by using a mechanical stop to limit the vertical displacement of the clamping head  120 . For example, a pneumatic cylinder may be cycled between its inherent limits. A displacement limited separation (h) is not easily modified on a per cycle basis, but may provide faster cycle times since a feedback loop is not required. The vertical separation (h) may be adjusted by changing the position of the clamping head positioner  115  with respect to the support  110 . 
         [0031]    The jaws  125  are typically maintained in an open position until the minimum vertical separation (h) is reached during a downstroke of the clamping head  120 , or contact is established with the workpiece. When a displacement limit is used, closure of the jaws  125  is initiated after jaws  125  have reached the displacement limit. A short delay may be inserted between the arrival at the lowest position and the closure of the jaws to allow for damping of oscillations in the system. 
         [0032]    Similar to the displacement of the clamping head  120 , the closure of the jaws  125  may be force limited or displacement limited. The minimum jaw separation (s) may be determined by feedback from a force sensor, setting the maximum force used to close the jaws  125  or it may be determined by a mechanical stop. Once the jaws  125  are closed, a dwell time may be observed prior to opening of the jaws  125  and the retraction of the clamping head  120 . 
         [0033]    In one embodiment detection of an occurrence of signal by the trigger sensor  130  may be used to cause the controller  135  to initiate a single clamping cycle. In an alternative embodiment the controller  135  may repeat the clamping cycle as long as the signal is detected by the trigger sensor  130 . Logically speaking, the operation may be either edge-triggered or level-triggered. 
         [0034]    The trigger sensor  130  may be a foot switch, motion detector, optical scanner, acoustic recognition device, or other sensing device that is capable of interpreting an action on the part of the operator. An operator&#39;s voice or movement of an operator&#39;s head or eyes may be used as signal for the trigger sensor  130 . 
         [0035]      FIG. 2  shows a perspective view of an embodiment of a wetsuit seam bonding workstation  200  similar to the workstation  100  of  FIG. 1 . A work surface  205  is coupled to first pneumatic cylinder  215  by a support  210 . The first pneumatic cylinder  215  provides for the vertical displacement of a second pneumatic cylinder  220  that serves to actuate a pair of jaws  225 . 
         [0036]      FIG. 3A  shows a side view of a dynamic jaw module  300 . A first double-acting air cylinder  305  is similar to the clamping head positioner  115  of  FIG. 1  and is coupled to a second double-acting air cylinder  320  by brackets  315 . Double-acting air cylinder  320  provides for the opening and closing of pair of jaws  325 . 
         [0037]    In order to maximize the operational speed and precision of the dynamic jaw module  300  it is desirable to minimize the mass of moving parts, particularly those parts that are subject to rapid acceleration. Double-acting air cylinders are preferable to single-acting air cylinders due to the absence of return spring resistance on the downstroke and a greater available force on the return stroke. 
         [0038]      FIG. 3B  shows a perspective view of a tilting jaw module  301  that is similar to the dynamic jaw module  300  of  FIG. 3A . The tilting jaw module includes a rotary actuator  330  coupled to a rotating mount  335  that permit an operator to alter the vertical angle of the jaws with respect to the work surface. The vertical angle may be adjusted in response to a signal from the operator during assembly. For example, a wetsuit may have a seam between panels with unequal thickness, for which the vertical jaw angle may be adjusted. 
         [0039]      FIG. 4A  shows an embodiment of a pivot jaw assembly  400 . A pair of jaws  405  is mounted on a pivot shaft  410 . A jaw-closing cylinder  420  has a wedge cutout that acts to close the jaws  405  when it engages the ends of the jaws  405 . The jaw-closing cylinder  420  and pivot shaft may be incorporated in a pneumatic cylinder. A spring  415  acts to return the jaws to an open position when the jaw closing cylinder  420  is disengaged. 
         [0040]    Since the tips of the jaws  405  travel in an arc, a long stroke or a thin panel may result in an unacceptably large force component normal to the work surface. The normal force component may be reduced by increasing the distance between the pivot shaft and the jaw tips. 
         [0041]      FIG. 4B  shows an embodiment of a sliding jaw assembly  401 . A pair of jaws  425  is mounted on a pair of parallel shafts  430 . The shafts  430  constrain the movement of the jaws  425  to a linear path that is parallel to the shafts  430 . The sliding jaw assembly  401  may be used as an alternative to the pivot jaw assembly  400  of  FIG. 4A  to eliminate jaw motion normal to the work surface during jaw closure. 
         [0042]    The jaws  425  have a relief  435  on the inner clamping surfaces. A finite amount of compression of the wetsuit panels is required to develop the friction that allows the jaws  425  to compress the mated panel edges together. Most of the compression is obtained at the heel  440 , while the relief  435  reduces vertical compression of the panel edges that may degrade the seam. The relief  435  allows the jaws  425  to be operated closer to the seam with a shorter stroke. 
         [0043]      FIG. 5  shows a control flow diagram  501  for an embodiment of the controller  135  of  FIG. 1 . The flow diagram  501  includes a cycle of actions that may occur automatically after an appropriate signal is provided by an operator. 
         [0044]    At step  505  a trigger signal from an operator is detected. The trigger signal may be conditioned by a sensor such as trigger sensor  130  of  FIG. 1  and input to controller  135  as an electric current or voltage. 
         [0045]    At step  510  a downstroke of the clamping head  120  is initiated. Initiation of the downstroke may be accomplished by operation of one or more pneumatic valves or the switching of one or more solenoid actuators. 
         [0046]    At step  515  the clamping head position is detected. The clamping head position may be monitored continuously during the downstroke or the arrival at a specific position may be detected. The position being detected may be correlated with a reactive force produced by contact with a workpiece. 
         [0047]    At step  520  the jaws  125  are closed. The closure of the jaws may be displacement limited or force limited. For systems in which the clamping head downstroke is accomplished at high speed, jaw closure may delayed by the controller after the detection of the clamping head position to allow a short period of time for damping of mechanical oscillations and relaxation of the workpiece that is being compressed. 
         [0048]    At step  525  the jaws  125  are held in a closed position for a preset dwell time to allow intimate contact to be established between the mated edges of the wetsuit panels that are being bonded. A mechanical system will typically have an inherent delay; however, the inherent delay in a high-speed machine may be too short to allow for optimum bonding, thus a programmed dwell time may be used to enhance bonding. 
         [0049]    At step  530  the jaws are opened and at step  535  the clamping head  120  is returned to its starting position. In contrast to the downstroke and jaw closure operations, it is preferred that steps  530  and  535  are performed without an intermediate delay. In order to provide optimum performance, it is desirable to minimize inherent delays in the system and insert programmed delays as necessary. 
         [0050]      FIG. 6  shows a flow diagram  600  for use by an operator in conjunction with the system shown in  FIG. 1 . At step  605  adhesive is prepared on the edges of wetsuit panels to be joined. The adhesive may be prepared by application of adhesive to the edge or by reactivation of a previously applied adhesive (e.g., by the application of solvent). 
         [0051]    At step  610  the prepared edges of the panels are aligned and brought into contact. At step  615  the mated panel edges are aligned between jaws  125  and the work surface  105 . At step  620  a trigger signal is sent by the operator to initiate an automated clamp cycle similar to that shown in  FIG. 5 . At step  630  the panels are reposition with respect to the jaws  125 . 
         [0052]    At step  635  steps  620 - 630  are repeated until the length of the mated panel edges has been compressed by the jaws  125 . It is to be understood that the repetition of step  620  may be either the transmission of a new signal (edge trigger) or the continuation of the initial signal (level trigger). Edge triggers and level triggers may be alternately used during the fabrication of a single wetsuit. 
         [0053]    While the invention has been described in detail with reference to preferred embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention.