Abstract:
An embroidery frame comprises an inner frame, wherein the inner frame is a circular form. The embroidery frame comprises a middle frame configured to be detachably attachable to the inner frame, wherein the middle frame is a circular form, an inside diameter of the middle frame is longer than an outside diameter of the inner frame, and the inner frame is configured to be mountable in the middle frame. The embroidery frame comprises an outer frame configured to rotatably hold the middle frame, wherein the outer frame is a circular form, an inside diameter of the outer frame is longer than an outer outside diameter of the middle frame, and the middle frame is configured to be mountable in the outer frame. The embroidery frame comprises an engaging portion configured to cause the middle frame to engage with the outer frame at a predetermined rotation angle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Japanese Patent Application No. 2011-213072, filed on Sep. 28, 2011, the disclosure of which is hereby incorporated by reference herein in its entirety. 
       BACKGROUND 
       [0002]    This disclosure relates to an embroidery frame that is configured to be attachable to a sewing machine. 
         [0003]    An embroidery frame for a sewing machine is widely known. The embroidery frame is a circular form and the embroidery frame can be rotated to an intended angle. For example, the embroidery frame comprises a pair of embroidery frames and an outer frame. The pair of embroidery frames comprises a small embroidery frame and a big embroidery frame. The small embroidery frame is in a circular form and the big embroidery frame is also in a circular form. An inside diameter of the big embroidery frame is longer than an outside diameter of the small embroidery frame. A work cloth can be held between the small embroidery frame and the big embroidery frame. The outer frame can hold the pair of embroidery frames such that the pair of embroidery frames is rotatable. A fixation screw is provided on a side face of the outer embroidery frame. A triangular mark is provided on an upper face of the big embroidery frame and a plurality of scale marks indicative of angles are provided on the outer embroidery frame. The pair of embroidery frames can be rotated to the intended angle with respect to the outer embroidery frame by an user of the sewing machine, as the user looks at the triangular mark and the plurality of scale marks. After rotating, the fixation screw can be tightened by the user. In this manner, the pair of embroidery frames can be fixed to the outer embroidery frame. 
       SUMMARY 
       [0004]    When the embroidery frame as described above is used by the user, the user has to adjust the pair of embroidery frames with respect to the outer embroidery frame, as the user looks at the triangular mark and the plurality of scale marks. The process of adjusting the pair of embroidery frames with respect to the outer embroidery frame may be burdensome for the user. 
         [0005]    Various exemplary embodiments of the general principles herein provide an embroidery frame, which enables the user to adjust the pair of embroidery frames with respect to the outer embroidery frame easily. 
         [0006]    Exemplary embodiments herein provide an embroidery frame that comprises an inner frame, a middle frame, an outer frame, and an engaging portion. The inner frame is a circular form. The middle frame is configured to be detachably attachable to the inner frame, wherein the middle frame is a circular form, an inside diameter of the middle frame is longer than an outside diameter of the inner frame, and the inner frame is configured to be mountable in the middle flame. The outer frame is configured to rotatably hold the middle frame, wherein the outer frame is a circular form, an inside diameter of the outer frame is longer than an outer outside diameter of the middle frame, and the middle frame is configured to be mountable in the outer frame. The engagement portion is configured to cause the middle frame to engage with the outer frame at a predetermined rotation angle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Exemplary embodiments of the present disclosure will be described below in detail with reference to the accompanying drawing in which: 
           [0008]      FIG. 1  is an oblique view of a sewing machine  1  on which an embroidery frame  5  is mounted; 
           [0009]      FIG. 2  is a left side view of a needle bar  6 , to which a sewing needle  7  is attached, and an area around the needle bar  6 ; 
           [0010]      FIG. 3  is a left side view of the needle bar  6 , to which a cutwork needle  8  is attached, and the area around the needle bar  6 ; 
           [0011]      FIG. 4  is an oblique view of the embroidery frame  5 ; 
           [0012]      FIG. 5  is an exploded oblique view of the embroidery frame  5 ; 
           [0013]      FIG. 6  is a side view of a middle frame  52 ; 
           [0014]      FIG. 7  is a plan view of the middle frame  52  in a state in which a plurality of first edge engaging portions  531  are facing upward; 
           [0015]      FIG. 8  is a plan view of the middle frame  52  in a state in which a plurality of second edge engaging portions  532  are facing upward; 
           [0016]      FIG. 9  is an explanatory figure that shows a state in which the middle frame  52  is locked at a position of zero degrees; 
           [0017]      FIG. 10  is an explanatory figure that shows a state in which the middle frame  52  is locked at a position of +90 degrees; 
           [0018]      FIG. 11  is an oblique view of an embroidery frame  9  according to another embodiment; 
           [0019]      FIG. 12  is an oblique view that shows an internal structure of the embroidery frame  9 ; 
           [0020]      FIG. 13  is an exploded oblique view of the embroidery frame  9 ; 
           [0021]      FIG. 14  is a plan view of the embroidery frame  9 ; and 
           [0022]      FIG. 15  is a side view of the embroidery frame  9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Hereinafter, embodiments of the present disclosure will be explained with reference to the drawings. A configuration of a sewing machine  1  will be explained with reference to  FIGS. 1 and 2 . In  FIG. 1 , the side where a user of the sewing machine  1  is positioned is defined as the front side, and the opposite side is defined as the rear side. The left-right direction as seen by the user is defined as the left-right direction of sewing machine  1 . That is, the face of the sewing machine  1  on which a switch cluster  25  that will be described later is provided is the front face of the sewing machine  1 . The longitudinal direction of a bed  11  and an arm  13  are the left-right, direction of the sewing machine  1 , and a side on which a pillar  12  is positioned is the right side of the sewing machine  1 . A direction in which the pillar  12  extends is the up-down direction of the sewing machine  1 . 
         [0024]    As shown in  FIG. 1 , the sewing machine  1  is provided with the bed  11 , the pillar  12 , the arm  13 , and a head  14 . The bed  11  is a base portion of the sewing machine  1  and extends in the left-right direction. The pillar  12  extends upward from the right end of the bed  11 . The arm  13  extends to the left from the upper end of the pillar  12  such that it is opposite the bed  11 . The head  14  is a portion that connects to the left end of the arm  13 . A needle plate (not shown in the drawings) is provided in the top face of the bed  11 . A feed dog, a cloth feed mechanism, a feed adjustment pulse motor, and a shuttle mechanism that are not shown in the drawings are provided within the bed  11 , underneath the needle plate. The feed dog may feed, by a specified feed amount, a work cloth on which sewing is performed. The cloth feed mechanism may drive the feed dog. The feed adjustment pulse motor may adjust the feed amount. 
         [0025]    In a case where embroidery sewing is performed with the sewing machine  1 , an embroidery frame  5  that holds a work cloth  100  may be disposed on the top side of the bed  11 . An area on the inner side of the embroidery frame  5  is an embroidery area in which stitches of an embroidery pattern can be formed. A moving unit  19  that is configured to move the embroidery frame  5  may be removably mounted on the bed  11 . A carriage cover  35  that extends in the front-rear direction is provided on the upper part of the moving unit  19 . A Y axis moving mechanism (not shown in the drawings) is provided inside the carriage cover  35 . The Y axis moving mechanism is configured to move a carriage (not shown in the drawings) in Y axis direction (the front-rear direction of the sewing machine  1 ). The embroidery frame  5  has a structure that allows it to be removably mounted on the carriage. A mounting portion (not shown in the drawings) on which the embroidery frame  5  may be mounted is provided on the right side of the carriage. The mounting portion projects to the right from the right side face of the carriage cover  35 . An attachment portion  542  (refer to  FIG. 4 ) that is provided on the embroidery frame  5  may be mounted on the mounting portion. The carriage, the Y axis moving mechanism, and the carriage cover  35  may be moved in an X axis direction (the left-right direction of the sewing machine  1 ) by an X axis moving mechanism (not shown in the drawings). The X axis moving mechanism is provided inside the body of the moving unit  19 . 
         [0026]    The X axis moving mechanism and the Y axis moving mechanism may be respectively driven by an X axis motor and a Y axis motor that are not shown in the drawings. A needle bar  6  (refer to  FIG. 2 ) and the shuttle mechanism (not shown in the drawings) may be driven as the embroidery frame  5  is moved in the X axis direction and the Y axis direction. In this manner, an embroidery sewing operation that sews a specified embroidery pattern in the work cloth  100  that is held in the embroidery frame  5  and an operation that forms a cut in the work cloth  100  in a specified shape are performed. In a case where an ordinary pattern that is not an embroidery pattern is sewn, the moving unit  19  may be removed from the bed  11 , and the work cloth  100  may be disposed on the bed  11 . Then ordinary sewing may be performed by the driving of the needle bar  6  and the shuttle mechanism as the work cloth  100  is moved by the feed dog. 
         [0027]    A vertically rectangular liquid crystal display  15  is provided on the front face of the pillar  12 . Images of various types of items, such as a plurality of types of patterns, names of commands that cause various types of functions to be performed, various types of messages, and the like, may be displayed on the liquid crystal display  15 . 
         [0028]    A transparent touch panel  26  is provided on the front face of the liquid crystal display  15 . Using a finger or a special touch pen, the user may perform a pressing operation on the touch panel  26 . Hereinafter, this operation is referred to as a panel operation. The touch panel  26  may detect a position that is pressed by a finger or a special touch pen etc., and the sewing machine  1  may determine the hem that corresponds to the detected position. Thus, the sewing machine  1  may recognize the selected item. By performing the panel operation, the user can select a pattern to he sewn or a command to be executed. 
         [0029]    The structure of the arm  13  will be explained. A cover  16  is provided in the top part of the arm  13 . The cover  16  is axially supported such that it can be opened and closed by being rotated about an axis that extends in the left-right direction at the upper rear edge of the arm  13 . A thread container portion (not shown in the drawings) is provided underneath the cover  16 , that is, in the interior of the arm  13 . The thread container portion may contain a thread spool (not shown in the drawings) that supplies an upper thread. The upper thread may be supplied from the thread spool to a sewing needle  7  (refer to  FIG. 2 ) through a thread hook portion that includes a tensioner, a thread take-up spring and a thread take-up lever that are not shown in the drawings. The tensioner is provided in the head  14  and configured to adjust the thread tension. The thread take-up lever may be driven reciprocally up and down and pull the upper thread upward. The needle bar  6  may be moved up and down by a needle bar up-and-down moving mechanism (not shown in the drawings) that is provided inside the head  14 . The needle bar up-and-down moving mechanism may be driven by a drive shaft (not shown in the drawings) that is rotationally driven by a sewing machine motor (not shown in the drawings). 
         [0030]    The switch cluster  25 , which includes a sewing star/stop switch  21  and the like, is provided in the lower part of the front face of the arm  13 . The sewing start/stop switch  21  may be used to start and stop the operation of the sewing machine  1 . That is, the sewing start/stop switch  21  may be used by the user to issue commands to start and stop the sewing. 
         [0031]    As shown in  FIG. 2 , the needle bar 6  is provided in the lower portion of the head  14 . One of the sewing needle  7  (refer to  FIG. 2 ) and a cutwork needle  8  (refer to  FIG. 3 ) can be attached to the lower end of the needle bar  6 . A presser bar  45  is provided to the rear of the needle bar  6 . A presser holder  46  may be attached to the lower end of the presser bar  45 . A presser foot  47 , which may press down on the work cloth  100 , may be fixed to the presser holder  46 . 
         [0032]    The cutwork needle  8  will be explained. As shown in  FIG. 3 , a cutting portion  89  is formed at the tip of the cutwork needle  8 . The cutting portion  89  has a sharp-pointed shape in a front view and has a specified width in the front-rear direction in a side view (the left-right direction in  FIG. 3 ). The lower edge of the cutting portion  89  curves obliquely downward from the rear edge to the front edge. When the needle bar  6  is moved up and down in a state in which the cutwork needle  8  is attached to the lower end of the needle bar  6 , a cut that extends in the front-rear direction is formed in the work cloth  100 . The length of the cut is the same as the width of the cutting portion  89  of the cutwork needle  8 . Embroidery sewing and ordinary sewing can be performed when the needle bar  6  is moved up and down in a state in which the sewing needle  7  is attached to the lower end of the needle bar  6 , as shown in  FIG. 2 . 
         [0033]    The embroidery frame  5  will be explained with reference to  FIGS. 4 to 8 . In the explanation that follows, the up-down direction in  FIGS. 4 and 5  is defined as the up-down direction of the embroidery frame  5 . That is, the side on which an outer frame  54  that will be described later is disposed is the bottom side of the embroidery frame  5 , and the side on which a middle frame  52  (an assembled unit  55 ) is disposed is the top side of the embroidery frame  5 . As shown in  FIGS. 4 and 5 , the embroidery frame  5  includes an inner frame  51 , the middle frame  52 , and the outer frame  54 , each of which has a circular frame shape. As shown in  FIG. 4 , the embroidery frame  5  is formed by disposing the middle frame  52  to the outside of the inner frame  51  in the radial direction, and by disposing the outer frame  54  to the outside of the middle frame  52  in the radial direction. The inner frame  51  and the middle frame  52  can be rotated about a rotational axis R 1  shown in  FIG. 5 , in relation to the outer frame  54 . Note that, in the embroidery frame  5  according to the present embodiment, the rotational axis R 1  passes thorough the center of each circle that is formed by each of the inner frame  51 , the middle frame  52 , and the outer frame  54  (specifically, frame portions  511 ,  521 , and  541 , which are described below). Hereinafter, the direction of the rotational axis R 1  is simply referred to as an “axial direction”. 
         [0034]    As shown in  FIGS. 4 and 5 , the inner frame  51  includes a circular frame portion  511 . The frame portion  511  has a thickness in the axial direction (the up-down direction in  FIGS. 4 and 5 ). The middle frame  52  includes a circular frame portion  521  that has an inside diameter that is larger than the outside diameter of the frame portion  511  of the inner frame  51 . The middle frame  52  may be removably mounted on the inner frame  51  by removably mounting the frame portion  521  of the middle frame  52  on the outer side of the frame portion  511  of the inner frame  51  in the radial direction. The work cloth  100  can be held between the inner frame  51  and the middle frame  52  (refer to  FIG. 1 .) 
         [0035]    As shown in  FIGS. 5 and 6 , a plurality of first engaging portions  530  are provided on both edges in the axial direction of the frame portion  521 , that is, on the upper edge and the lower edge. As described above, the axial direction corresponds to the up-down direction of the embroidery frame  5 . Therefore, the plurality of first engaging portions  530  are provided in a plurality of positions around the circumference of the middle frame  52  that respectively correspond to a plurality of predetermined rotation angles (rotation angles of the middle frame  52  in relation to the outer frame  54 ). The plurality of first engaging portions  530  include a plurality of first edge engaging portions  531  and a plurality of second edge engaging portions  532 . In the present embodiment, when a second engaging portion  547  that will be described later engages with one of the first engaging portions  530 , the middle frame  52  can be locked at one of the predetermined rotation angles in relation to the outer frame  54 . Each of the first engaging portions  530  may be formed in the frame portion  521  as a recessed portion that is recessed in a direction away from the outer frame  54 , that is, a direction toward the inner side of the middle frame  52  in the radial direction. In the present embodiment, each of the first engaging portions  530  is formed as a through-hole that passes through the frame portion  521  in the direction away from the outer frame  54 . 
         [0036]    Among the first engaging portions  530 , the first edge engaging portions  531  are provided on one edge of the frame portion  521  in the axial direction (the upper edge in the present embodiment). As shown in  FIG. 7 , in the present embodiment, four first edge engaging portions  531  are provided at intervals of 45 degrees (45°) as seen from the central axis of the middle frame  52 . The second edge engaging portions  532  are provided on the other edge of the frame portion  521  in the axial direction (the lower edge in the present embodiment). The first edge engaging portions  531  and the second edge engaging portions  532  are provided around the circumference of the frame portion  521 , with at least some of the positions in which the first edge engaging portions  531  are provided corresponding to different rotation angles from those to which at least some of the positions in which the second edge engaging portions  532  are provided correspond. As shown in  FIG. 8 , in the present embodiment, six second edge engaging portions  532  are provided at intervals of 30 degrees (30°) as seen from the central axis of the middle frame  52 . 
         [0037]    Note that in the present embodiment, the position of the one of the first edge engaging portions  531  that is on the opposite side from an adjustment portion  525  (described later) in the radial direction of the middle frame  52  is defined as the position that corresponds to a rotation angle of zero degrees, as shown in  FIG. 7 . In relation to a line that connects the central axis of the middle frame  52  with this one of the first edge engaging portions  531 , the clockwise direction in a plan view is defined as positive (+), and the counterclockwise direction in a plan view is defined as negative (−). As shown in  FIG. 7 , the four first edge engaging portions  531  are provided at the positions of −45 degrees, zero degrees, +45 degrees, and +90 degrees. Similarly, the position of the one of the second edge engaging portions  532  that is on the opposite side from the adjustment portion  525  in the radial direction of the middle frame  52  is defined as the position that corresponds to a rotation angle of zero degrees, as shown in  FIG. 8 . In relation to a line that connects the central axis of the middle frame  52  with this one of the second edge engaging portions  532 , the clockwise direction in a plan view is defined as positive (+), and the counterclockwise direction in a plan view is defined as negative (−). As shown in  FIG. 8 , the six second edge engaging portions  532  are provided at the positions of −60 degrees, −30 degrees, zero degrees, +30 degrees, +60 degrees, and +90 degrees. As shown in  FIGS. 7 and 8 , the first edge engaging portions  531  and the second edge engaging portions  532  are provided at locations around approximately half of the circumference of the frame portion  521 , on the opposite side from the location where the adjustment portion  525  is provided. 
         [0038]    As shown in  FIGS. 5 and 7 , the middle frame  52  includes the adjustment portion  525 , which can adjust the diameter of the middle frame  52  according to the thickness of the work cloth  100  that is clamped between the inner frame  51  and the middle frame  52 . The adjustment portion  525  includes a parting portion  526 , a pair of screw mounting portions  527 , and an adjusting screw  528 . The parting portion  526  is a location where a portion in the circumferential direction of the frame portion  521  of the middle frame  52  is discontinuous through the axial direction. The pair of the screw mounting portions  527  project to the outside in the radial direction and are positioned opposite one another on opposite sides of the parting portion  526  in the frame portion  521 . The lengths of the screw mounting portions  527  in the axial direction (the up-down direction in  FIG. 5 ) are the same as the length of the frame portion  521  in the axial direction. Holes  5271 ,  5272  are provided in the pair of the screw mounting portions  527 , each of the holes  5271 ,  5272  passing through one of the screw mounting portions  527  in a direction that is orthogonal to the face that is opposite the other one of the screw mounting portions  527 , that is, in the direction in which the pair of the screw mounting portions  527  are opposite one another (the left-right direction in  FIG. 7 ). Of the two holes  5271 ,  5272 , a threaded hole is formed in the hole  5272  (the hole on the right side in  FIG. 7 ). 
         [0039]    The adjusting screw  528  is a screw that includes a head portion  5281  that projects outward in the radial direction at one end of the adjusting screw  528  (refer to  FIG. 5 ). In a case where the diameter of the middle frame  52  is adjusted, first, the adjusting screw  528  is inserted from the side of the hole  5271  (the left side in  FIG. 7 ), in which a threaded hole is not formed, toward the hole  5272 , in which the threaded hole is formed. Then the adjusting screw  528  is rotated and passes through the inside of the hole  5272 . At this time, the head  5281  of the adjusting screw  528  presses against the screw mounting portion  527 , changing the size of the gap between the pair of the screw mounting portions  527 . Thus, in addition to connecting the pair of the screw mounting portions  527 , the adjusting screw  528  is able to adjust the gap between the pair of the screw mounting portions  527 . The diameter of the middle frame  52  can be adjusted by adjusting the gap between the pair of the screw mounting portions  527 . For example, the diameter of the middle frame  52  becomes greater as the gap between the pair of the screw mounting portions  527  becomes wider, so a thicker work cloth  100  can be clamped between the middle frame  52  and the inner frame  51 . 
         [0040]    A flange portion  529  that projects outward in the radial direction is provided in a central portion in the axial direction of the outer circumferential side face of the frame portion  521 , except where the screw mounting portions  527  are located. In a case where the middle frame  52  is mounted on the outer frame  54 , the flange portion  529  is supported by a second supporting portion  555  (described later) of the outer frame  54  (refer to  FIG. 4 ). 
         [0041]    As shown in  FIGS. 4 and 5 , the outer frame  54  includes a circular frame portion  541 . The frame portion  541  includes a first supporting portion  554  and the second supporting portion  555 . The first supporting portion  554  is a portion that is formed by cutting out an upper portion of the approximately half of the circumference of the frame portion  541 . The second supporting portion  555  is the portion of the frame portion  541  other than the first supporting portion  554 . The upper edge of the first supporting portion  554  is positioned at approximately half the height of the second supporting portion  555 . In a case where the middle frame  52  is mounted on the outer frame  54 , the screw mounting portions  527  of the middle frame  52  are supported by the first supporting portion  554 , and the flange portion  529  of the middle frame  52  is supported by the second supporting portion  555  (refer to  FIG. 4 ). The first supporting portion  554  is provided around approximately half of the circumference of the frame portion  541 , so the user is able to move the screw mounting portions  527  in the circumferential direction through the range in which the first supporting portion  554  is provided. This makes it possible for one of the first engaging portions  530  to engage with the second engaging portion  547 . 
         [0042]    A parting portion  545  where a portion of the frame portion  541  is discontinuous through the axial direction is provided in the frame portion  541 , approximately in the center of the circumferential direction of the second supporting portion  555 . A pair of arms  543  that project outward in the radial direction are provided on the frame portion  541  in positions that are slightly separated from the respective sides of the parting portion  545 . The pair of the arms  543  are joined by an arm joining portion  544  at the ends of the arms  543  that are opposite the ends that are connected to the frame portion  541 . The arm joining portion  544  extends approximately parallel to the direction (hereinafter called the tangent line direction) in which extends a line that is tangent to the circular frame portion  541  at the parting portion  545 . 
         [0043]    The attachment portion  542 , which extends approximately parallel to the tangent line direction, is provided on the edge of the arm joining portion  544  that is on the opposite side from the middle frame  52 . The attachment portion  542  is configured such that it can be mounted on the mounting portion (not shown in the drawings) of the carriage that is provided inside the carriage cover  35  of the sewing machine  1 . 
         [0044]    As shown in  FIG. 4 , the second engaging portion  547  is provided in a space that is bounded by the parting portion  545 , the pair of the arms  543 , and the arm joining portion  544 . As shown in  FIG. 5 , the second engaging portion  547  includes an engaging member  548 , a coil spring  549 , and a shaft portion  550 . The engaging member  548 , which has the shape of a rectangular parallelepiped, is disposed between the parting portion  545  and the arm joining portion  544  such that a pair of opposite faces of the engaging member  548  are approximately parallel to the tangent line. The length of the engaging member  548  in a width direction (the tangent line direction) is slightly shorter than the distance between the pair of the arms  543  (the inside dimension). A hole  551  is provided in a central portion of the engaging member  548  in the width direction and the up-down direction. The hole  551  passes through the engaging member  548  approximately orthogonally to the pair of the faces of the engaging member  548  that are approximately parallel to the tangent line. A grip portion  553  that projects upward is provided in the upper part of the engaging member  548 , in the center in the width direction. The grip portion  553  is formed into a shape that the user can easily grip with his fingers when the user pulls the engaging member  548  away from the middle frame  52 . A cylindrical projecting portion  552  that projects toward the middle frame  52  is provided on the upper edge of the grip portion  553 . The projecting portion  552  is made in a size that allows it to be inserted into one of the plurality of the first engaging portions  530  (refer to  FIG. 4 ). 
         [0045]    The shaft portion  550  is a cylindrical member. An end portion  5501  of the shaft portion  550  has a diameter that is smaller than that of the rest of the shaft portion  550 . A hole that is not shown in the drawings is provided in the face of the arm joining portion  544  on the parting portion  545  side. The shaft portion  550  is fixed to the arm joining portion  544  by firmly pressing the end portion  5501  of the shaft portion  550  into the hole. 
         [0046]    As shown in  FIGS. 4 and 5 , the opposite end of the shaft portion  550  from the end portion  5501 , that is, the end of the shaft portion  550  that is disposed on the middle frame  52  side, is inserted into the hole  551  in the engaging member  548 . The engaging member  548  is able to slide in the axial direction of the shaft portion  550 . However, because the engaging member  548  is held between the pair of the arms  543 , it cannot rotate in relation to the shaft portion  550 . The expandable and compressible coil spring  549  is mounted around the outer circumferential face of the shaft portion  550 . The coil spring  549  is compressed between the face of the arm joining portion  544  and the face of the engaging member  548  that are opposite one another. The engaging member  548  is thus energized toward the middle frame  52  by the elastic force of the coil spring  549 . In a case where the middle frame  52  is not mounted on the outer frame  54 , the face of the engaging member  548  on the frame portion  541  side is pressed by the elastic force of the coil spring  549  into contact with the outer circumferential face of the frame portion  541  on both sides of the parting portion  545 . The projecting portion  552  projects through the upper side of the parting portion  545  into the inner side of the frame portion  541 . When the user grips the grip portion  553  and pulls the engaging member  548  away from the middle frame  52 , the engaging member  548  and the projecting portion  552  move away from the middle frame  52  in opposition to the elastic force of the coil spring  549 . 
         [0047]    Next, the mode in which the inner frame  51 , the middle frame  52  and the outer frame  54  are combined will be explained. In the present embodiment, in a case where the middle frame  52  and the outer frame  54  are combined such that the first edge engaging portions  531  are positioned on the upper side of the outer frame  54 , the second engaging portion  547  can be engaged with one of the first edge engaging portions  531 . The state of the middle frame  52  in this case, that is, the state in which the first edge engaging portions  531  are on the upper side of the outer frame  54 , is called a first state. Furthermore, in a case where the middle frame  52  and the outer frame  54  are combined such that the second edge engaging portions  532  are positioned on the upper side of the outer frame  54 , the second engaging portion  547  can be engaged with one of the second edge engaging portions  532 . The state of the middle frame  52  in this case, that is, the state in which the second edge engaging portions  532  are on the upper side of the outer frame  54 , is called a second state. As described previously, the first edge engaging portions  531  are provided at intervals of 45 degrees, and the second edge engaging portions  532  are provided at intervals of 30 degrees. Therefore, in the first state, the middle frame  52  can be locked in relation to the outer frame  54  in a position that corresponds to one of the rotation angles, among the plurality of the positions that are provided in correspondence to the plurality of rotation angles at intervals of 45 degrees. In the second state, the middle frame  52  can be locked in relation to the outer frame  54  in a position that corresponds to one of the rotation angles, among the plurality of the positions that are provided in correspondence to the plurality of rotation angles at intervals of 30 degrees. 
         [0048]    A method will be explained for combining the inner frame  51 , the middle frame  52 , and the outer frame  54  such that the work cloth  100  can be rotated in 45-degree units using the first edge engaging portions  531  in a state in which the middle frame  52  is in the first state. First, the user may place the middle frame  52  on a desktop or the like such that the first edge engaging portions  531  are on the top side. Next, the user may place the work cloth  100  on the top side of the middle frame  52 . Then the user may insert the inner frame  51  into the inner side of the middle frame  52  while pressing the work cloth  100  downward with the bottom edge of the inner frame  51 . The work cloth  100  may be thus clamped between the inner frame  51  and the middle frame  52 . The user, by adjusting the adjustment portion  525 , may adjust the diameter of the middle frame  52  in accordance with the thickness of the work cloth  100 . The face of the work cloth  100  on which the sewing will be performed may enter a state of being stretched taut on the inner side of the inner frame  51  by the bottom edge of the inner frame  51 . In the explanation that follows, the frame that is formed by the combining of the inner frame  51  and the middle frame  52  is called the assembled unit  55  (refer to  FIGS. 1 ,  4 ,  9 ,  10 ). 
         [0049]    Next, the user may set the assembled unit  55  into the outer frame  54  from the top side of the outer frame  54 , such that the screw mounting portions  527  are supported by the first supporting portion  554  and the flange portion  529  is supported by the second supporting portion  555 . This may determine the position of the assembled unit  55  in the axial direction. At this time, the user may grip the grip portion  553  with his fingers and pull the engaging member  548  away from the middle frame  52 , retracting the projecting portion  552  to the outside of the frame portion  541 , such that the projecting portion  552  does not make contact with the middle frame  52 . Then, in order to position the assembled unit  55  at the desired angle in relation to the outer frame  54 , the user may rotate the assembled unit  55  such that the position of one of the first edge engaging portions  531  that are provided at 45-degree intervals corresponds to the position of the projecting portion  552 . 
         [0050]    When the assembled unit  55  is set into the outer frame  54 , the screw mounting portions  527  of the middle frame  52  are supported by the first supporting portion  554  of the outer frame  54 . Furthermore, the flange portion  529  of the middle frame  52  is supported by the second supporting portion  555  of the outer frame  54 . This may determine the position of the assembled unit  55  in the axial direction. 
         [0051]    When the user takes his fingers off of the grip portion  553 , the engaging member  548  may be energized in the direction of the middle frame  52  by the elastic force of the coil spring  549 , and the projecting portion  552  may be inserted into the corresponding one of the first edge engaging portions  531  (refer to  FIGS. 4 and 9 ). The second engaging portion  547  may be thus engaged with one of the first engaging portions  530  (one of the first edge engaging portions  531 ), and the middle frame  52  (the assembled unit  55 ) can be locked in relation to the outer frame  54 . 
         [0052]    The assembled unit  55  may be pushed in the direction away from the attachment portion  542  (the upper right direction in  FIG. 4 ) by the elastic force of the coil spring  549 . Therefore, even in a case where a slight gap exists between the outer circumferential face of the middle frame  52  and the inner circumferential face of the outer frame  54 , due to the reducing of the diameter of the middle flame  52 , a backlash can be suppressed and the middle frame  52  (the assembled unit  55 ) can be reliably fixed in position in relation to the outer frame  54 . The inner frame  51 , the middle frame  52 , and the outer frame  54  can be combined as described above to obtain the completed form of the embroidery frame  5 . Through the attachment portion  542 , the user may attach the completed form of the embroidery frame  5  to the carriage of the moving unit  19  that is mounted on the sewing machine  1  (refer to  FIG. 1 ). Hereinafter, in order to simplify the explanation, this operation is described simply as attaching the embroidery frame  5  to the sewing machine  1 . 
         [0053]    Next, a method for forming a cutwork in the work cloth  100  using the embroidery frame  5  will be explained with reference to  FIGS. 9 and 10 . As an example of a cutwork, an example will be explained in which a plurality of areas  83  are cut out on inner sides of four flower petal patterns  82  in a flower pattern  81  that is shown in  FIG. 9 . Note that in  FIGS. 9 and 10 , only the portion of the work cloth  100  that is on the inner side of the inner frame  51  is shown. For the outer frame  54 , only the engaging member  548  of the second engaging portion  547  is shown. Furthermore,  FIGS. 9 and 10  show the state of the embroidery frame  5  when the embroidery frame  5  is attached to the sewing machine  1  (refer to  FIG. 1 ), and the lower side, the upper side, the left side, and the right side of the drawings respectively correspond to the front side, the rear side, the left side, and the right side of the sewing machine  1 . In the explanation that follows, the embroidery sewing and the forming of the cuts may be accomplished by a control circuit such as a CPU or the like of the sewing machine  1 , which is not shown in the drawings, to control the movement of the carriage, the up and down movements of the needle bar  6 , and the like according to embroidery data that have been set in advance. 
         [0054]    As shown in  FIG. 9 , first the flower pattern  81  is sewn as an embroidery pattern in the work cloth  100 . The flower pattern  81  is formed in the work cloth  100  that is held in the embroidery frame  5  by performing embroidery sewing in the form of satin stitches along the outlines of the four flower petal patterns  82 . Thereafter, in order to cut out the areas  83  on the inner sides of the four flower petal patterns  82 , the user replaces the sewing needle  7  (refer to  FIG. 2 ) with the cutwork needle  8  (refer to  FIG. 3 ). At this time, the cutting portion  89  of the cutwork needle  8  is fixed in place such that it extends in the front-rear direction, as shown in  FIG. 3 . As described previously, when the needle bar  6  moves up and down, a cut is formed by the cutting portion  89  in the front-rear direction of the sewing machine  1 . Therefore, in order to cut out all of the four areas  83  in the work cloth  100 , it is necessary to change the rotation angle of the middle frame  52  (the assembled unit  55 ) in relation to the outer frame  54  a plurality of times. For example, first, a cut is formed in the work cloth  100  in a state in which the one of the first edge engaging portions  531  that is in the zero-degree position is engaged with the second engaging portion  547 , as shown in  FIG. 9 . In  FIG. 9 , needle drop points  71  for the cutwork needle  8  when the cuts are formed in the work cloth  100  in this state are shown as white circles. The cuts are formed in the work cloth  100  in the front-rear direction of the sewing machine  1 , such that the white circles are joined. 
         [0055]    Then the sewing machine  1  displays the rotation angle of the embroidery frame  5  on the liquid crystal display  15 , in order to report to the user the angle to which the embroidery frame  5  should be rotated. For example, in a case where “+90 degrees” is displayed, the user grips the grip portion  553  of the engaging member  548  with his fingers and pulls the engaging member  548  in the direction away from the middle frame  52  (the leftward direction in  FIG. 9 ), thereby separating the projecting portion  552  from the first edge engaging portion  531  that is in the zero-degree position. The engagement between the projecting portion  552  and the first edge engaging portion  531  that is in the zero-degree position is thus released, making it possible to rotate the middle frame  52  (the assembled unit  55 ). As shown in  FIG. 10 , the user rotates the assembled unit  55  90 degrees in the counterclockwise direction in a plan view, thereby moving the first edge engaging portion  531  that is in the +90-degree position to a position where it faces the projecting portion  552 . The user release his grip on the grip portion  553 , and the projecting portion  552  engages with the first edge engaging portion  531  that is in the +90-degree position. Thus the middle frame  52  is locked in relation to the outer frame  54 , in a state in which the rotation angle of the middle frame  52  (the assembled unit  55 ) in relation to the outer frame  54  is +90 degrees. In  FIG. 10 , needle drop points  72  for the cutwork needle  8  when the cuts are formed in the work cloth  100  in this state are shown as black circles. When the rotating of the middle frame  52  (the assembled unit  55 ) and the forming of the cuts are further repeated in the same manner, the cutwork is completed for the flower pattern  81 , in which all of the areas  83  have been cut out on the inner sides of the four flower petal patterns  82 . 
         [0056]    In the explanation above, the rotating of the middle frame  52  (the assembled unit  55 ) is performed, and the cuts are formed, using, among the first engaging portions  530 , the first edge engaging portions  531  that are positioned at 45-degree intervals. In this case, the user is able to rotate the middle frame  52  at intervals of 45 degrees. However, there may be cases in which the user wants to rotate the middle frame  52  to an angle that is less than 45 degrees, as in a case of a cutwork for a complicated pattern, for example. In this case, the user may invert the middle frame  52  vertically, switching the middle frame  52  from the first state to the second state. Then, as described previously, the user may clamp the work cloth  100  between the inner frame  51  and the middle frame  52 , which is in the second state. In the second state, the second edge engaging portions  532 , which are disposed at 30-degree intervals, are positioned on the top side of the outer frame  54 , so the projecting portion  552  can be inserted into one of the second edge engaging portions  532 . The user is therefore able to rotate the middle frame  52  at 30-degree intervals. By switching the state of the middle frame  52  in relation to the outer frame  54  in this manner, the user can easily switch between a positional relationship in which the projecting portion  552  can engage with one of the first edge engaging portions  531  and a positional relationship in which the projecting portion  552  can engage with one of the second edge engaging portions  532 . The convenience for the user can be improved accordingly. 
         [0057]    As has been explained, in the present embodiment, it is possible to lock the middle frame  52  at one of a plurality of predetermined rotation angles in relation to the outer frame  54  by engaging the second engaging portion  547  with one of the first engaging portions  530 . Therefore, it may be easier for the user to adjust the angle of the middle frame  52  in relation to the outer frame  54  than in a case where the user adjusts the angle of the middle frame in relation to the outer frame while checking a graduated scale or markings, as with the known embroidery frame. The user is also able to adjust the rotation angle of the middle frame  52  to the desired angle just by selecting one of the first engaging portions  530  that corresponds to the desired angle. 
         [0058]    Because the coil spring  549  energizes the projecting portion  552  toward the middle frame  52 , the projecting portion  552  can be inserted into the first engaging portion  530 . The middle frame  52  can thus be reliably locked at the set angle in relation to the outer frame  54 . Furthermore, in a case where the middle frame  52  is rotated in relation to the outer frame  54 , the engagement of the projecting portion  552  with the first engaging portion  530  can easily be released by the user&#39;s pushing or the like on the engaging member  548  to apply force to the coil spring  549  in the direction away from the middle frame  52 . The user is thus able to rotate the middle frame  52  easily. 
         [0059]    The user can adjust the diameter of the middle frame  52  by adjusting the gap between the screw mounting portions  527 , that is, the length of the parting portion  526 . The user is therefore able to adjust the diameter of the middle frame  52  in accordance with the thickness of the work cloth  100  that is clamped between the inner frame  51  and the middle frame  52 , causing the work cloth  100  to be held appropriately by the inner frame  51  and the middle frame  52 . Furthermore, the first supporting portion  554  can support the screw mounting portions  527 , and the second supporting portion  555  can support the flange portion  529 , so the outer frame  54  is able to hold the middle frame  52  appropriately. 
         [0060]    In the case of the known embroidery frame, in the state in which the work cloth is held in the embroidery frame, the graduated scale or markings that are used for adjusting the angle of the embroidery frame may be covered by the work cloth. Then it may be difficult for the user to see the graduated scale or markings. In this sort of case, it may be difficult for the user to efficiently perform the work of adjusting the rotation angle. In the present embodiment, the user is able to lock the middle frame  52  at a specified angle in relation to the outer frame  54  even though no graduated scale or markings are used, so the rotation angle can be adjusted efficiently. 
         [0061]    Furthermore, in the case of the known embroidery frame, the middle frame may be locked in relation to the outer frame using a screw, so the operation may be burdensome. In the present embodiment, the user is able to release the locking of the middle frame  52  in relation to the outer frame  54  just by gripping the grip portion  553  of the engaging member  548  with his fingers and pulling the engaging member  548  in the direction away from the middle frame  52 . The user is also able to lock the middle frame  52  in relation to the outer frame  54  just by releasing his fingers from the grip portion  553  after the rotation angle has been adjusted. Thus, according to the embroidery frame  5  according to the present embodiment, the operations of locking and releasing the middle frame  52  in relation to the outer frame  54  are simple, and the convenience for the user can be improved. 
         [0062]    Note that the timing at which the user releases the grip portion  553  is not limited to the case where the one of the plurality of the first engaging portions  530  is in the position that corresponds to the projecting portion  552 , as in the previously described example. The user may also take his fingers off the grip portion  553  when a portion of the outer circumferential face of the frame portion  521  where none of the first engaging portions  530  are located is positioned in the position that corresponds to the projecting portion  552 . In that case, the energizing force of the coil spring  549  may cause the projecting portion  552  to come into contact with the outer circumferential face of the frame portion  521 . In this state, when the user rotates the middle frame  52  (the assembled unit  55 ) in relation to the outer frame  54 , the tip of the projecting portion  552  may slide along the outer circumferential face of the frame portion  521 . When the middle frame  52  rotates to a position where one of the first engaging portions  530  is aligned with the projecting portion  552 , the projecting portion  552  may be inserted into the one of the first engaging portions  530  by the elastic force of the coil spring  549 , and the rotation of the middle frame  52  is locked. Therefore, just by rotating the middle frame  52 , the user is able to lock the rotation of the middle frame  52  at the angle where the one of the first engaging portions  530  is provided 
         [0063]    Next, an embroidery frame  9  according to another embodiment will be explained with reference to  FIGS. 11 to 15 . As shown in  FIGS. 11 to 13 , the embroidery frame  9  includes an inner frame  91 , a middle frame  92 , and an outer frame  94 , each of which has a circular frame shape. As shown in  FIG. 11 , the embroidery frame  9  is formed by disposing the middle frame  92  to the outside of the inner frame  91  in the radial direction and by disposing the outer frame  94  to the outside of the middle frame  92  in the radial direction. The inner frame  91  and the middle frame  92  can be rotated about a rotational axis R 2  shown in  FIG. 13 , in relation to the outer frame  94 . Note that, in the embroidery frame  9  according to the present embodiment, the rotational axis R 2  passes thorough the center of each circle that is formed by each of the inner frame  91 , the middle frame  92 , and the outer frame  94  (specifically, frame portions  911 ,  921 , and  941 , which are described below). Hereinafter, the direction of the rotational axis R 2  is simply referred to as an “axial direction”. In the same manner as the embroidery frame  5  according to the first embodiment, the embroidery frame  9  has a structure in which the work cloth  100  can be clamped between the inner frame  91  and the middle frame  92 , and the middle frame  92  can be rotated in relation to the outer frame  94 . 
         [0064]    As shown in  FIGS. 11 to 13 , the inner frame  91  includes a circular frame portion  911 . The frame portion  911  has thicknesses in the axial direction and the radial direction. The inner flame  91  includes an adjustment portion  915  that allows the diameter of the inner frame  91  to be adjusted. The diameter of inner frame  91  may be adjusted according to the thickness of the work cloth  100  that is clamped between the inner frame  91  and the middle frame  92 . The adjustment portion  915  includes a parting portion  916 , a pair of screw mounting portions  917 , and an adjusting screw  918 . The parting portion  916  is a location where a portion in the circumferential direction of the frame portion  911  of the inner frame  91  is discontinuous through the axial direction. The pair of the screw mounting portions  917  are provided in upper portions of the frame portion  911  on both sides of the parting portion  916 . The pair of the screw mounting portions  917  project to the outside in the radial direction and are positioned opposite one another. The pair of the screw mounting portions  917  are provided with holes  9171 ,  9172 , which are through-holes in a direction that is orthogonal to the faces of the screw mounting portions  917  that are opposite one another (refer to  FIG. 13 ). Of the two holes  9171 ,  9172 , the hole  9172  (the hole on the lower right in  FIG. 13 ) is provided with an embedded nut (not shown in the drawings) in which a threaded hole is formed. 
         [0065]    As shown in  FIG. 13 , the adjusting screw  918  is a threaded member that includes a head portion  9181  and a shaft portion  9183 . The head portion  9181  is a large-diameter portion that the user may grip with his fingers to rotate the adjusting screw  918 . The shaft portion  9183  is a small-diameter portion that extends as a single piece from the head portion  9181 . A male threaded portion  9182  is formed from approximately the center in the axial direction of the shaft portion  9183  to the tip. A narrow groove  9184 , into which a retaining ring  9185  may be fitted, is also formed in the shaft portion  9183  in a location that is close to the head portion  9181 . Note that, for ease of explanation, the retaining ring  9185  is omitted from all of the drawings except  FIG. 13 . The adjusting screw  918  may be mounted in the pair of the screw mounting portions  917  by passing the shaft portion  9183  through the hole  9171  and screwing the male threaded portion  9182  into the threaded hole in the not that is embedded in the hole  9172 . In this state, the retaining ring  9185  can be fitted into the narrow groove  9184  of the shaft portion  9183 . The adjusting screw  918  can be thus held such that it can rotate in the screw mounting portion  917  on the side where the hole  9171  is located and cannot move in the axial direction. 
         [0066]    If the user grips the head portion  9181  with his fingers and performs a rotation operation, the screw mounting portion  917  on the side where the hole  9172  is located moves through the nut in the axial direction of the shaft portion  9183 . The direction of movement of the screw mounting portion  917  may be determined by the direction of rotation of the adjusting screw  918 . Thus the adjusting screw  918  may be coupled with the pair of the screw mounting portions  917  and is able to adjust the gap between the pair of the screw mounting portions  917  such as to make the gap wider or narrower. The adjusting of the gap between the pair of the screw mounting portions  917  adjusts the diameter of the inner frame  91  in accordance with the thickness of the work cloth  100 . For example, to the extent that the gap between the pair of the screw mounting portions  917  becomes narrower, the diameter of the inner frame  91  becomes smaller, so the embroidery frame  9  is able to clamp the work cloth  100  that has a greater thickness between the middle frame  92  and the inner frame  91 . 
         [0067]    A marker  919  is provided on an edge face on the top side of the inner frame  91 . In a case where a camera (not shown in the drawings) that is configured to capture an image of the marker  919  is provided in the head  14  of the sewing machine  1 , for example, the sewing machine  1  is able to detect the rotation angle of the middle frame  92  in relation to the outer frame  94  based on the position of the marker  919  in the image that is captured by the camera. 
         [0068]    As shown in  FIGS. 11 to 13 , the middle frame  92  includes a circular frame portion  921  that has an inside diameter that is larger than the outside diameter of the frame portion  911  of the inner frame  91 . The middle frame  92  may be removably mounted on the inner frame  91  by removably mounting the frame portion  921  of the middle frame  92  on the outer side of the frame portion  911  of the inner frame  91  in the radial direction. As shown in  FIGS. 12 to 15 , a plurality of first engaging portions  930  are provided on the outer circumferential side face of the lower edge portion of the frame portion  921 . In the present embodiment, each of the first engaging portions  930  is formed as a recessed portion  931  that is formed approximately in the shape of a V. The recessed portions  931  are recessed in the direction away from the outer frame  94 , that is, in the direction toward the inner side of the middle frame  92  in the radial direction. The recessed portions  931  are formed at intervals of a specified angle around the entire outer circumferential side face of the lower edge portion of the frame portion  921  of the middle frame  92 . In the present embodiment, ninety recessed portions  931  are provided at intervals of four degrees, as an example. In the present embodiment, the recessed portions  931 , in their entirety, are formed in the shape of a gear. Hereinafter, the portion of the middle frame  92  where the recessed portions  931  form the gear is called a ear portion  934 . In the present embodiment the middle frame  92  can be locked in relation to the outer frame  94  at one of a plurality of predetermined rotation angles (one rotation angle every four degrees) by engaging a second engaging portion  947 , which will be described later, with one of the plurality of the recessed portions  931 . 
         [0069]    A flange portion  929  is provided in a central portion in the axial direction of the outer circumferential side face of the frame portion  921 , on the upper side of the gear portion  934 . The flange portion  929  projects to the outside in the radial direction around the entire circumference of the frame portion  921 . A support portion  936  is provided on an inner circumferential side face of the lower edge of the frame portion  921 . The support portion  936  projects to the inside in the radial direction around the entire circumference of the frame portion  921 . The support portion  936  is a portion that supports a lower edge face of the inner frame  91 . 
         [0070]    As shown in  FIGS. 11 to 13 , the outer frame  94  includes a circular frame portion  941 . A support portion  946  is provided on an inner circumferential side face of the lower edge of the frame portion  941 . The support portion  946  projects to the inside in the radial direction around the entire circumference of the frame portion  941 . The support portion  946  is a portion that supports a lower edge face of the middle frame  92  (refer to  FIG. 15 ). An attachment portion  942  is provided on the outer side of the frame portion  941  in the radial direction. The shape and function of the attachment portion  942  are the same as those of the attachment portion  542  in the first embodiment (refer to  FIG. 4 ). 
         [0071]    A box-shaped coupling portion  943  that couples the frame portion  941  and the attachment portion  942  is provided between the frame portion  941  and the attachment portion  942 . As shown in  FIGS. 12 and 14 , the second engaging portion  947  is provided in the interior of the coupling portion  943 , near the edge on the side of the frame portion  941  (the side that faces toward the middle frame  92 ). In the present embodiment, the second engaging portion  947  is formed as a flat spring  948  that includes a base end portion  957  and a free end portion  955 . 
         [0072]    As shown in  FIG. 15 , a threaded attachment portion  956  is provided inside the coupling portion  943  on one side (the upper side in  FIG. 14 ) in the width direction of the coupling portion  943  (the direction parallel to the attachment portion  942 ). The threaded attachment portion  956  is a cylindrical member that projects upward from a bottom face of the coupling portion  943 . A threaded hole (not shown in the drawings) is formed in the up-down direction in the threaded attachment portion  956 . As shown in  FIGS. 14 and 15 , the base end portion  957  of the flat spring  948  is disposed on the top side of the threaded attachment portion  956  such that the flat face of the base end portion  957  is horizontal. A hole (not shown in the drawings) is provided in the center of the base end portion  957 . The base end portion  957  of the flat spring  948  is fixed to the threaded attachment portion  956  by screwing a screw  958 , which passes through the hole, into the threaded hole of the threaded attachment portion  956  from above. 
         [0073]    As shown in  FIG. 14 , the free end portion  955 , which extends from the base end portion  957  of the fiat spring  948 , is bent downward (toward the rear of  FIG. 14 ) at the right edge (the right side in  FIG. 14 ) of the base end portion  957  and extends toward the front (toward the bottom of  FIG. 14 ). A protruding portion  952  that is formed approximately in the shape of a V, such that it protrudes toward the middle frame  92 , is provided at the front end of the free end portion  955 . The tip of the protruding portion  952  is able to engage with one of the recessed portions  931 . The elastic force of the flat spring  948  energizes the protruding portion  952  in such a direction that the tip of the protruding portion  952  is inserted into the recessed portion  931  and presses against the recessed portion  931 . 
         [0074]    The engaging of the tip of the protruding portion  952  with one of the recessed portions  931  and its pressing against the recessed portion  931  by the elastic force of the flat spring  948  can lock the middle frame  92  such that it cannot be rotated in relation to the outer frame  94 . When the user rotates the middle frame  92  in relation to the outer frame  94 , one of the oblique faces of the recessed portion  931  (one of the oblique faces of the V shape) pushes the protruding portion  952  in the direction away from the middle frame  92 , in opposition to the elastic force of the fiat spring  948 . At this time, the free end portion  955  of the flat spring  948  bends such that the engagement of the protruding portion  952  and the recessed portion  931  is released. Then the protruding portion  952  engages with the recessed portion  931  that is adjacent to the recessed portion  931  with which the protruding portion  952  was engaged previously. 
         [0075]    If the rotating of the middle frame  92  is continued further, the engaging and the releasing of the engagement of the protruding portion  952  with one of the recessed portions  931  are repeated. In the present embodiment, the plurality of the recessed portions  931  are provided at four-degree intervals, an the user is able to set the rotation angle of the middle frame  92  in relation to the outer frame  94  at four-degree intervals. 
         [0076]    The method for combining the inner frame  91 , the middle frame  92 , and the outer frame  94  will be explained. First, the user may place the middle frame  92  on a desktop or the like such that the gear portion  934  is on the bottom side. Then the user may insert the inner frame  91  into the inner side of the middle frame  92 , in the same manner as in the previously described first embodiment, and the work cloth  100  may be clamped between the inner frame  91  and the middle frame  92 . By adjusting the adjustment portion  915 , the user may adjust the diameter of the inner frame  91  in accordance with the thickness of the work cloth  100 . In the explanation that follows, the frame that is formed by the combining of the inner frame  91  and the middle frame  92  is called an assembled unit  95  (refer to  FIG. 11 ). Note that in the present embodiment, the work cloth  100  is omitted from the drawings. 
         [0077]    Next, the user may place the assembled unit  95  into the outer frame  94  from the top side of the outer frame  94 . At this time, the user may place the assembled unit  95  into the frame portion  941  such that the protruding portion  952  engages with one of the plurality of the recessed portions  931 . When the assembled unit  95  is placed into the frame portion  941 , a state is created in which the protruding portion  952  is engaged with one of the recessed portions  931 . Thus the second engaging portion  947  and the first engaging portion  930  may be engaged, and the middle frame  92  (the assembled unit  95 ) may be locked in relation to the outer frame  94 . The inner frame  91 , the middle frame  92 , and the outer frame  94  can be combined as described above to obtain the completed form of the embroidery frame  9 . The user is able to attach the completed form of the embroidery frame  9  to the sewing machine  1  (refer to  FIG. 1 ) and to rotate and lock the middle frame  92  (the assembled unit  95 ) in relation to the outer frame  94 . 
         [0078]    An example of a method for performing the setting of the rotation angle of the middle frame  92  in relation to the outer frame  94  will be explained. For example, an image that includes the marker  919  that is provided on the edge face on the top side of the inner frame  91  may be captured by the camera (not shown in the drawings) that is provided in the head  14  of the sewing machine  1 . A control circuit of the sewing machine  1  may specify the current rotation angle of the middle frame  92  based on the position of the marker  919  in the image and display the rotation angle on the liquid crystal display  15 . In this case, the user is able to adjust the rotation angle of the middle frame  92  at four-degree intervals while referring to the rotation angle of the middle frame  92  that is displayed on the liquid crystal display  15 . 
         [0079]    As described above, according to the embroidery frame  9  according to the present embodiment, the user is able to lock the middle frame  92  in relation to the outer frame  94  at any one of a plurality of predetermined rotation angles at four-degree intervals. Therefore, the angle can be adjusted more easily than the angle can be adjusted by checking a graduated scale or markings. Furthermore, the user is able to adjust the rotation angle of the middle frame  92  to the desired angle by selecting the desired recessed portion  931  from among the plurality of the recessed portions  931 . 
         [0080]    Furthermore, the tip of the protruding portion  952  can be inserted into the recessed portion  931  and can be pressed against the recessed portion  931  by the energizing of the protruding portion  952  toward the middle frame  92  by the elastic force of the flat spring  948 . Thus the middle frame  92  can he reliably locked in relation to the outer frame  94  at one of the predetermined angles. The engaging and the releasing of the engagement of the protruding portion  952  with the recessed portions  931  may be repeated, and the middle frame  92  can be rotated in relation to the outer frame  94 , simply by the user&#39;s performing of the rotation operation on the middle frame  92 . The user is thus able to easily rotate the middle frame  92  to the desired angle. Moreover, the operation of adjusting the rotation angle may be easier than it is with the known embroidery frame, in which the middle frame may he locked in relation to the outer frame by a screw so the convenience for the user can be improved. 
         [0081]    Note that the present disclosure is not limited to the embodiments that are described above, and various types of modifications can be made. The shapes and sizes of the first engaging portions  530 ,  930  and the second engaging portions  547 ,  947  are not limited to the examples that are shown in the embodiments that are described above, as long as the second engaging portions  547 ,  947  and the corresponding first engaging portions  530 ,  930  can engage with each other. The frames on which the first engaging portions  530 ,  930  and the second engaging portions  547 ,  947  are respectively provided may also be the reverse of what they are in the embodiments that are described above. That is, the first engaging portions  530 ,  930  may respectively be provided on the outer frames  54 ,  94 , and the second engaging portions  547 ,  947  may respectively be provided on the middle frames  52 ,  92 . For example, the first engaging portions  530  may be provided on the frame portion  541  of the outer frame  54  such that they are recessed in the direction away from the middle frame  52 , that is, toward the outside in the radial direction of the outer frame  54 , and the second engaging portion  547  may be provided on the middle frame  52  such that it includes a projecting portion  552  that is energized toward the outer frame  54 . To take another example, a gear portion that includes the first engaging portions  930  may be provided on the inner circumferential side face of the outer frame  94  such that the first engaging portions  930  are recessed in the direction away from the middle frame  92 , that is, toward the outside in the radial direction of the outer frame  94 , and the second engaging portion  947  (the flat spring  948 ) may be provided on the middle frame  92  and be energized toward the outer frame  94 . 
         [0082]    The first engaging portions  530 ,  930  can be provided in positions that correspond to any rotation angles other than the angles that are used as examples in the embodiments that are described above. 
         [0083]    The structure for switching the positional relationship of the middle frame  52  and the outer frame  54  between the positional relationship in which the second engaging portion  547  can engage with one of the first edge engaging portions  531  and the positional relationship in which the second engaging portion  547  can engage with one of the second edge engaging portions  532  is not limited to the example in the first embodiment that is described above. For example, the first engaging portions  530  (the first edge engaging portions  531  and the second edge engaging portions  532 ) that engage with the second engaging portion  547  may also be changed by switching the state of the second engaging portion  547  instead of by switching the state of the middle frame  52 . Specifically, the second engaging portion  547  may also be configured such that it can be inverted vertically, such that it can be switched between a state in which the projecting portion  552  is positioned on the top side and a state in which the projecting portion  552  is positioned on the bottom side. In that case, the second engaging portion  547  may be configured such that when the projecting portion  552  is positioned on the top side, it can engage with one of the first edge engaging portions  531  on the top side, and when the projecting portion  552  is on the bottom side, it can engage with one of the second edge engaging portions  532  on the bottom side. 
         [0084]    The apparatus and methods described above with reference to the various embodiments are merely examples. It goes without saying that they are not confined to the depicted embodiments. While various features have been described in conjunction with the examples outlined above, various alternatives, modifications, variations, and/or improvements of those features and/or examples may be possible. Accordingly, the examples, as set forth above, are intended to be illustrative. Various changes may be made without departing from the broad spirit and scope of the underlying principles.