Abstract:
A low profile clamp for an embroidery machine uses resilient arms that function as a leaf spring to transmit compressive closing forces to secure articles to be embroidered between clamping windows. A roller is moved in an arcuate path to apply bending stresses to clamp arms. The low profile of the clamp allows it to pass between the presser feet and throat plate protecting the presser feet and needles from serious damage if the panagraph moves the body of the clamp in the space between presser feet and throat plate during machine initialization or at any other time.

Description:
RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/608,578, filed Sep. 10, 2004, the disclosures of which is incorporated herein by reference. 

   TECHNICAL FIELD 
   The present invention relates generally to embroidery machines and more specifically to a clamp for securing articles as they are being embroidered. The invention will be disclosed in connection with a low profile clamp that prevents damage to the embroidery machine if the panagraph moves the clamp into the space between the presser feet and the throat plate. 
   BACKGROUND OF THE INVENTION 
   In the sewing and embroidery industry, fabric holding clamps are widely used for holding individual work pieces during the embroidery process. While such holding clamps are been used for many years, one problem has persisted. Since it is necessary for a holding clamp to apply a compressive force to hold a article being embroidered between a pair of clamping windows, mechanism used to apply the clamping force have relatively large and bulky. For this reason, the base or body portions prior art holding clamps generally have a relatively thick profile. This profile thickness of the prior art holding clamps has lead to considerable problems, including substantial damage to embroidery machines. The holding clamps generally are moved in an X-Y plane by a panagraph to move the fabric being embroidered along the appropriate path to achieve the desired embroidery. On occasion, the panagraph will move the base or body portion of the fabric holding clamp in the space between the presser feet and the throat plate. This is particularly problematic during initialization of the panagraph controls, as the panagraph my move the clamp throughout the panagraph&#39;s entire X-Y movement Unfortunately, this space generally is less than the profile of the clamp, and the thick profile portion of the fabric clamp may be moved into the presser feet and needles, both of which are relatively fragile. As a consequence of this movement, substantial machine damage results, necessitating expensive repairs and downtime. 
   SUMMARY OF THE INVENTION 
   It is an object of at least one embodiment of the present invention to obviate one or more of the shortcomings of prior art clamps for embroidery machines. 
   It is another object of at least one embodiment of the present invention to provide a clamping system that will not damage the embroidery machine if the clamp is moved along a path traversing the space between the presser feet and needles, and the throat plate of an embroidery machine. 
   Another object of at least one embodiment is to provide an improved clamping mechanism for an embroidery machine that applies a clamping force between clamping windows with a simplified clamping mechanism. 
   The above objects are provided merely as non-limiting examples, and do not define the present invention or necessarily apply to every aspect thereof. Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and will also become apparent to those skilled in the art upon consideration of the teachings of the invention. 
   To achieve one or more of these objects, one embodiment of the present invention includes an embroidery machine with a base, a throat plate, a head extending outwardly from the base, and a plurality of presser feet extending from the head toward the throat plate. Each of the presser feet are movable relative to the head toward and away from the throat plate and are associated with a needle adapted to pass through an article to be embroidered. Each of the presser feet also are movable between a retracted position in which the presser feet are spaced by a predetermined space from the throat plate and an extended position in which the presser feet are adapted to engage an article to be embroidered. The article to be embroidered is positioned in a sewing location between the presser feet and the throat plate while the needles pass through the article to be embroidered. A first clamping window is provided with a first embroidery opening. A a second clamping window with a second embroidery opening is also provided with the first and second clamping windows being movable between first relative positions in which the second clamping window is spaced from the first clamping window and second relative positions in which the first and second openings are aligned with each other. The first and second clamping windows are cooperatively operative to clamp an article to be embroidered in the sewing location between the presser feet and the throat plate when the clamping windows are in their second relative positions. A clamp is provided for effectuating relative movement between the first and second clamping windows and applying a compressive force between the first and second windows when the clamping windows are in their second relative positions. When in these second positions, the clamping windows securing an article to be embroidered therebetween. The clamp is secured to the panagraph. The panagraph is operative to effectuate two dimensional movement to the clamp and to move an article secured between the clamping windows relative to the needles in two-directional movement perpendicular to the predetermined space between the presser feet and the throat plate. The clamp is dimensioned and configured to pass through the predetermined space between the presser feet and the throat plate so as to prevent damage if the panagraph positions the clamp in the space between the plates and the throat plate. 
   In one exemplary embodiment, the clamp further includes at least one arm interconnecting with the clamping windows. 
   In another exemplary embodiment, the at least one arm is formed of resilient material and the clamp utilizes the resilient properties of the at least one arm to apply a compressive force between the clamping wi the at least one arm is rotatably mounted on a first shaft. 
   According to one exemplary embodiment, the clamp includes an actuator with at least one roller, and the at least one roller is moved along a portion of the arm to apply a bending moment on the arm and to apply a compressive force between the clamping windows. 
   In another exemplary embodiment, the at least one roller is mounted on a rotatable actuating shaft extending parallel to the first rotatable shaft. The actuating shaft includes a portion that is offset from the rotatable axis of the actuating shaft with the roller being rotatably mounted on the offset portion. With such a configuration, rotation of the actuating shaft results in arcuate movement (i.e., movement in an arc) of the roller. 
   According to another exemplary embodiment, the at least one arm extends around the first rotatable shaft with a relatively long window interface portion extending on one side the first shaft and interfacing with the clamping windows. A relatively short return portion extends on the opposite side of the shaft. With this configuration, arcuate movement of the at least one roller applies a clamping force to the interface portion by engaging the return portion and applying a bending stress against the return portion. This tends to separate the interface and return portions of the arm. 
   In another embodiment, the actuating shaft is movable between first and second positions. The first position corresponds to the first relative positions of the clamping windows and the second position corresponds to the second relative positions of the clamping windows. 
   According to another exemplary embodiment, a spring is provided for urging the actuating shaft toward the first position. 
   In another exemplary embodiment, an actuator handle is provided for rotating the actuating shaft. 
   In another exemplary embodiment, the clamp further includes a pair of arms interconnecting with the clamping windows. The arms are mounted on a first shaft and are formed of material having sufficient resiliency so as to permit the arms to act as leaf springs. An actuator with a rotatable actuating shaft is provided extending parallel to the first shaft with an offset portion onto which a pair of rollers are mounted. Thus, rotation of the actuating shaft results in arcuate movement of the roller. The actuating shaft is rotatably movable between first and second positions. The first position corresponds to the first relative positions of the clamping windows and the second position corresponds to the second relative positions of the clamping windows. Each of the arms extends around the first shaft and includes a relatively long window interface portion extending on one side the first shaft and interfacing with the clamping windows. A relatively short return portion extends on the opposite side of the shaft. Thus, arcuate movement of the rollers applies a clamping force to the interface portion of the arms by engaging the return portions and applying a bending stress against the return portions. This also tends to separate the interface and return portions of the arms whereby arcuate movement of the rollers applies a clamping force to the interface portion by engaging the return portion and applying a bending stress against the return portion. 
   In another exemplary embodiment, a clamp is provided for use in an embroidery machine. The clamp includes a clamp body adapted to secure a first embroidery clamping window. A clamp arm formed of a resilient material and having a window interface for interconnecting with a second embroidery clamping window, is pivotally attached to the clamp body. The clamp arm is adapted to move a second embroidery clamping window relative to the first clamping window. The clamp is further adapted to operatively apply a force against the window interface to urge the second clamping window into compressing relationship to the first clamping window so as to compressingly hold an article to be embroidered between the first and second windows. An actuator is provided for pivotally rotating the clamp arm with respect to the clamp body. The actuator is further operative to apply a bending stress on a portion of the clamp arm remote from the window interface. The resilient properties of the clamp arm operate to apply a compressive force to the window interface in response to the bending stress. 
   According to another exemplary embodiment, the clamp arm is formed of spring tempered stainless steel. 
   In another embodiment, the clamp is d dimensioned and configured to pass through a space between presser feet and a throat plate on an embroidery machine so as to prevent damage to the embroidery machine if the clamp is positioned between the presser feet and the throat plate of an embroidery machine. 
   In another exemplary embodiment, an embroidery machine having a base, a head extending outwardly from the base is provided. The head has a plurality of needles extending therefrom. The needles are movable between a first retracted position and an extended position. A clamping mechanism is provided for holding an article to be embroidered beneath the head. The clamping mechanism includes first and second clamping frames having a first and second embroidery openings respectively. The first and second clamping frames are movable between first relative positions in which the clamping frames are separated and second relative positions in which the clamping frames compressingly engage an article to be embroidered therebetween. The clamping mechanism is dimensioned and configured to fit in the space between the retracted position of the needles and the throat plate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the invention, and together with the description serves to explain the principles of the invention. In the drawings: 
       FIG. 1  is a perspective view showing an embroidery machine and clamp constructed according to the principles of the present invention; 
       FIG. 2  is a perspective view of the embroidery illustrated in  FIG. 1  with an article to be embroidered clamped between the two clamping windows; 
       FIG. 3  is a perspective view showing the clamp and embroidery windows of  FIG. 1  partially unassembled; 
       FIG. 4  is a plan view of the clamp and embroidery windows utilized on the embroidery machine illustrated in  FIG. 1 ; 
       FIG. 5  is a side view of the clamp shown in  FIG. 6  as it is assembled and in a clamp open position; 
       FIG. 6  is a side view of the clamp of  FIG. 7  showing the clamp in a clamp closed position; 
       FIG. 7  is a plan view of the clamp of  FIG. 1  with the clamping windows removed depicting the clamp mechanism in the clamp open position of  FIG. 5 ; 
       FIG. 8  is a perspective view of the clamp mechanism of  FIG. 7  showing one of the rollers in the clamp open position; 
       FIG. 9  is a plan view similar to  FIG. 7 , but depicting the clamp mechanism in the clamp closed position of  FIG. 6 ; 
       FIG. 10  is a perspective view of the clamp mechanism of  FIG. 9  showing one of the rollers in the clamp closed position; 
       FIG. 11  is a perspective view of the embroidery machine illustrated in  FIG. 1  showing the clamp positioned between the presser feet and the throat plate; and 
       FIG. 12  is a perspective view showing the tubular arms attached to the clamp. 
   

   Reference will now be made in detail to exemplary embodiments of the invention, an example of which is illustrated in the accompanying drawings. 
   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   Referring now to the drawings,  FIG. 1  shows one form of an embroidery machine  10  constructed in accordance with the principles of the present invention. The machine, which is conventional except for the low profile clamp, which is described in detail below, includes a base  12 , which supports a head  14  extending outwardly therefrom. A plurality of presser feet, collectively referenced by the numeral  16 , extend downwardly from the head  14 . As those skilled in the art will readily appreciate, the presser feet are movable from a first retracted position (shown in  FIG. 1 ) to an extended position where they engage an article to be embroidered. Each of the presser feet  16  is associated with a needle  18 . The outer end of each of the needles  18  pass though a fabric or other article (not shown in  FIG. 1 , see  FIG. 2 ) interposed between the presser foot  16  and a throat plate  20 . As will be apparent to those skilled in the art, the lower (in the illustrated orientation) end of the needles interact with a bobbin or other type of hooking mechanism (not shown) positioned beneath the article being embroidered. As also will readily appreciated by those in the art, the bobbin or other mechanism (not shown) grabs a loop of the thread carried by the needles and wraps it around either another piece of thread or another loop in the same piece of thread, as is conventional in sewing machines. 
   As best seen in  FIG. 2 , a fabric  21  or other article to be embroidered is secured by a clamping mechanism, generally designed by the numeral  23 , constructed in accordance with the principles of the present invention. As more easily appreciated from viewing  FIGS. 1 and 2  in conjunction with  FIG. 3 , this clamping mechanism  23  is located beneath the presser feet  16  and includes a pair of clamping windows, a lower clamping window  22  and an upper clamping window  24 . The lower clamping window  22  is obscured by the fabric  21  in  FIG. 2  and partially obscured by the upper clamping window  24  in  FIG. 1 , but is clearly shown in  FIGS. 3–5 . In the exemplary embodiment illustrated, each of the clamping windows  22 ,  24  have centrally disposed openings of generally rectangular configuration. It may be desirable to vary the size and configuration of the central openings in the clamping windows. Toward that end, the clamping windows  22 ,  24  preferably are interchangeably fitted to a clamp body  26  so that different sized and shaped clamping windows can be utilized with the same clamp body  26 , depending upon the article to be embroidered. Depending upon the article to be embroidered, the window openings may be circular, oval or any other configuration. 
   The clamp body  26  moves the clamping windows  22 ,  24  between a first clamp open position and a second clamp closed position, as shown in  FIGS. 5 and 6  respectively. In the second closed position, also shown in  FIG. 1 , the centrally disposed openings of the windows  22  and  24  are aligned with each other and windows  22 ,  24  are compressingly urged against each other to secure an interposed article, such as fabric  21  shown in  FIG. 2  to be embroidered. 
   In the exemplary embodiment illustrated, relative movement of the windows  22 ,  24  is achieved through the agency of one or more clamp arms  28 . The clamp arms  28  preferable are formed of a resilient material, such as spring tempered stainless steel. As most clearly illustrated in  FIGS. 7 and 9 , the clamp arms  28  are pivotally secured to the body portion of the clamp along a first rotatable shaft or rod  29 , with each clamp arm including a window interface  31  that pivotally attaches the clamp arm to the upper window  24 . An actuator  30  effectuates rotational movement of the clamp arm relative to the clamp base. 
   As perhaps best seen in  FIG. 8 , the illustrated clamp arms  28  extend around the rod  29 . Each arm  28  includes a relatively long window interface portion  28   a  on one side (as illustrated, the top side) of the rotatable shaft  29  and a relatively short (relative to the window interface portion) return portion  28   b  on the opposite side. The actuator  30  includes a rotable shaft  30   a  that extends parallel to the first rotatable shaft  29 . The actuator shaft includes an offset portion  30   b . Rollers  33  are rotatably mounted on this offset portion  30   b  of actuator shaft  30 . When the actuator  30  is rotated and moved from the clamp open position of  FIG. 5  to the clamp closed position of  FIG. 6 , the rollers  33  move along an arcuate path in contact with the return arm portion  28   b . The positions of the rollers relative to the arm in the clamp open position and clamp closed position are shown in  FIGS. 8 and 10  respectively. This movement of the rollers  33  applies a bending stress against the return portion of the clamp arms  28   a , and tends to separate the interface  28   a  and return portions  28   b  of the arm  28 . The resilient properties of the clamp arms are then operative to apply a compressive force to the window interfaces in response to the bending stress applied to the return portions  28   a  of the clamp arms  28 . A spring  35  mounted around the first shaft  29  with its opposite ends secured to the clamp body  36  and the offset portion  30   b  of actuating shaft  30 . This spring  35  urges the actuating shaft  30  toward the clamp open position. The clamp arms  28  thus operate both as arms to effectuate relative movement of the windows and as leaf springs to apply a compressive force between the windows to secure an article therebetween. 
   Among other advantages, the above-described configuration permits an extremely low profile clamp. More particularly, as illustrated in  FIG. 11 , this configuration permits it has a sufficiently low clamp profile that the clamp can be configured and dimensioned to pass in the vertical space between the presser feet (while in the retracted position) and the throat plate. Such a low profile is highly advantageous, as it significantly reduces serious damage to the embroidery machine. For example, when the clamp is attached to an X-Y drive bar  37  of a panagraph, no damage will be caused to the needles or presser feet if the panagraph cycles the clamp through its full X-Y movement while the clamp is secured to the paragraph. Such full X-Y movement occurs on many machines during machine initialization. 
   The foregoing descriptions of the exemplary embodiments of the invention have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and modifications and variations are possible and contemplated in light of the above teachings. While a number of exemplary and alternate embodiments, methods, systems, configurations, and potential applications have been described, it should be understood that many variations and alternatives could be utilized without departing from the scope of the invention. It should be reiterated that not all aspects of the invention need to be used in combination with all other aspects, and a variety of combinations of such aspects are possible. 
   Thus, it should be understood that the embodiments and examples have been chosen and described in order to best illustrate the principals of the invention and its practical applications to thereby enable one of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited for particular uses contemplated. Accordingly, it is intended that the scope of the invention be defined by the claims appended hereto.