Patent Publication Number: US-11377767-B2

Title: Feed dog mounting/unmounting mechanism and sewing machine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a feed dog mounting/unmounting mechanism and a sewing machine provided with the mounting/unmounting mechanism. 
     2. Description of the Related Art 
     In a sewing machine described in Patent document 1 listed below, a feed dog is configured such that it can be detachably mounted on a feed base. Specifically, the feed base includes a mounting portion. The mounting portion is configured including a first receiving face, a second receiving face, and a pressing member configured as a plate spring. Furthermore, the feed dog includes a cam portion. With such an arrangement, when the cam portion is pressed downward after it is inserted into a gap between the first receiving face and the second receiving face, the shape of the pressing member is elastically changed by the cam portion. After the completion of the step in which the cam portion is pushed in, the pressing member presses the cam portion toward the first receiving face and the second receiving face, thereby mounting the cam portion on the mounting portion. This allows the feed dog to be detachably mounted on the feed base. 
     RELATED ART DOCUMENTS 
     Patent Documents 
     Patent Document 1 
     Japanese Patent No. 6,441,084 
     SUMMARY OF THE INVENTION 
     Disclosure of the Invention 
     Problem to be Solved by the Invention 
     With this arrangement, in a state in which the feed dog is mounted, it is necessary to maintain the mounting state of the feed dog by the pressing force applied by the pressing member. Accordingly, the pressing force to be provided by the pressing member is designed to be relatively high. On the other hand, when mounting the feed dog, there is a need to mount the cam portion on the mounting portion in a state in which the shape of the pressing member is elastically changed by the cam portion. That is to say, there is a need to mount the cam portion on the mounting portion against the relatively high pressing force provided by the pressing member. This leads to an increased burden on the operator. Thus, there is room for further improvement from the viewpoint of providing improved operating efficiency in the mounting of the feed dog. 
     In consideration of the above-described facts, it is a purpose of the present invention to provide a feed dog mounting/unmounting mechanism and a sewing machine that provides improved operating efficiency in the mounting of the feed dog. 
     Means to Solve the Problem 
     At least one embodiment of the present invention proposes a feed dog mounting/unmounting mechanism. The feed dog mounting/unmounting mechanism includes: a feed base configured to perform a feeding operation; a feed dog detachably mounted on the feed base and having a fixing target portion; a first fixing portion arranged on the feed base and configured to fix the fixing target portion; a lever slidably provided on the feed base and having a second fixing portion configured such that, when the lever is slid toward one side in a sliding direction from an initial position so as to be set to a fixed position, the fixing target portion is fixedly held such that it is interposed between the first fixing portion and the second fixing portion; a lever force-applying member configured to apply a force to the lever toward one direction side in the sliding direction; and a stopper movably provided on the feed base and configured to hold the lever at the initial position and such that, when it is pressed downward by the feed dog when the feed dog is mounted, the stopper is moved so as to allow the lever to slide. 
     At least one embodiment of the present invention also proposes the feed dog mounting/unmounting mechanism. The stopper is configured such that it can be moved between a lever holding position at which the lever is held at the initial position and a pressed position at which the stopper is pressed by the feed dog. The feed base is provided with a stopper force-applying member. The stopper force-applying member applies a force to the stopper toward the lever holding position side. 
     At least one embodiment of the present invention also proposes the feed dog mounting/unmounting mechanism. A lever-side holder face is formed in the lever. A feed base-side holder face is formed in the feed base such that it faces the lever-side holder face in the sliding direction. A gap is formed between the lever-side holder face and the feed base-side holder face at the fixed position. 
     At least one embodiment of the present invention also proposes the feed dog mounting/unmounting mechanism. The feed base is configured including: a feed base main body that forms a lower portion of the feed base; and a feed dog base that forms an upper portion of the feed base, and that is provided with the first fixing portion. The lever is slidably provided between the feed base main body and the feed dog base. The feed dog is mounted on the feed dog base from the upper side. 
     At least one embodiment of the present invention also proposes the feed dog mounting/unmounting mechanism. A stopper housing portion having an opening that faces the upper side is formed in the feed dog main body for housing the stopper and the stopper force-applying member. When the stopper is set to the lever holding position, a part of the stopper is arranged such that it protrudes toward the upper side from the stopper housing portion and such that it is in contact with the lever at the initial position. 
     At least one embodiment of the present invention also proposes the feed dog mounting/unmounting mechanism. The first fixing portion has a first fixing face that is inclined upward as it becomes closer to the other side in the sliding direction of the lever. The second fixing portion has a second fixing face that is inclined upward as it becomes closer to the one side in the sliding direction of the lever. The feed dog is held such that it is interposed between the first fixing face and the second fixing face. 
     At least one embodiment of the present invention also proposes the feed dog mounting/unmounting mechanism. 
     The feed dog is configured including: a main body portion to be mounted on the feed dog base; and a protrusion portion configured such that it protrudes toward the lower side from the main body portion and such that it presses the stopper downward when the feed dog is mounted. 
     At least one embodiment of the present invention proposes a sewing machine including the feed dog mounting/unmounting mechanism having the above-described configuration. 
     Advantage of the Present Invention 
     With one or more embodiments of the present invention, this provides improved operating efficiency in the mounting of the feed dog. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a sewing machine employing a feed dog mounting/unmounting mechanism according to the present embodiment as viewed from the diagonally left-front side. 
         FIG. 2  is a plan view showing the feed dog mounting/unmounting mechanism according to the present embodiment as viewed from the upper side. 
         FIG. 3  is a perspective view showing the feed dog mounting/unmounting mechanism shown in  FIG. 2  as viewed from the diagonally right-front side. 
         FIG. 4  is an exploded perspective view showing the feed dog mounting/unmounting mechanism shown in  FIG. 3 . 
         FIG. 5  is a side view showing the feed dog shown in  FIG. 4  as viewed from the right side. 
         FIG. 6A  is a cross-sectional diagram showing a state in which the lever main body is housed in the lever housing portion when the lever is set to the fixed position shown in  FIG. 4 , and  FIG. 6B  is a cross-sectional diagram showing a state in which the lever is slid frontward from the fixed position and is set to an initial position. 
         FIG. 7  is an explanatory diagram for explaining a procedure for mounting the feed dog shown in  FIG. 3  on the feed base. 
         FIG. 8  is an explanatory diagram for explaining a procedure for unmounting the feed dog shown in  FIG. 3  from the feed base. 
         FIG. 9  is a perspective view showing a tool to be used to unmount the feed dog from the feed base in the feed dog mounting/unmounting mechanism according to the present embodiment. 
         FIG. 10A  is a cross-sectional diagram showing a modification of the feed dog and the stopper shown in  FIG. 4  as viewed from the right side, and  FIG. 10B  is a cross-sectional diagram showing a state shown in  FIG. 10A  in which the feed dog is unmounted from the feed base. 
         FIG. 11A  is a cross-sectional diagram showing a modification of the first fixing target face shown in  FIG. 7 ,  FIG. 11B  is a cross-sectional diagram showing another modification of the lever-side fixing portion shown in  FIG. 7 , and  FIG. 11C  is a cross-sectional diagram showing yet another modification of the lever-side fixing portion shown in  FIG. 7 . 
         FIG. 12  is a perspective diagram showing a modification of the feed dog base shown in  FIG. 4  as viewed from the diagonally right-front side. 
         FIG. 13A  is a perspective diagram showing an example in which a tool to be used for unmounting the feed dog from the feed dog base is attached to the feed dog base, and  FIG. 13B  is a perspective view showing the tool shown in  FIG. 13A . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Description will be made with reference to the drawings regarding a sewing machine  10  employing a feed dog mounting/unmounting mechanism  20  according to the present embodiment. It should be noted that, in the drawings, which are shown as appropriate, the arrow UP indicates the upper side of the sewing machine  10 , the arrow FR indicates the front side thereof, and the arrow RH indicates the right side thereof (one side in the width direction). The directions used in the following description, i.e., the upper-lower direction, the front-rear direction, and the left-right direction, represent the upper and lower, front and rear, and left and right directions of the sewing machine  10 . 
     As shown in  FIG. 1 , the sewing machine  10  includes a sewing machine main body  12 . In a front view as viewed from the front side, the sewing machine main body  12  is configured in an approximately U-shaped structure having an opening that faces the left side. Specifically, the sewing machine main body  12  is configured including a pillar portion  12 A that forms the right end portion of the sewing machine main body  12  such that it extends in the upper-lower direction, an arm portion  12 B configured such that it extends toward the left side from the upper end portion of the pillar portion  12 A, and a bed portion  12 C configured such that it extends toward the left side from the lower end portion of the pillar portion  12 A. Furthermore, the sewing machine main body  12  is provided with a framework (not shown) as an internal structure that that forms a skeleton of the sewing machine main body  12 . The framework is covered by a cover  14  that forms a housing of the sewing machine main body  12 . 
     A needle plate  16  is detachably provided on an upper-left portion of the bed portion  12 C. The needle plate  16  is configured in an approximately rectangular plate shape with the upper-lower direction as its thickness direction. Furthermore, a feed dog mounting/unmounting mechanism  20  (not shown in  FIG. 1 ) is provided as an internal component of the bed portion  12 C below the needle plate  16 . With such an arrangement, when the sewing machine  10  is operated, a sewing target mounted on the upper side of the needle plate  16  is fed in the front-rear direction by the feed dog  22  mounted on the feed dog mounting/unmounting mechanism  20 . 
     As shown in  FIGS. 2 through 6 , the feedback mounting/unmounting mechanism  20  is configured including a feed dog  22 , a feed base  30 , a lever  40 , a lever force-applying spring  50  configured as a “lever force-applying member”, a stopper  60 , and a stopper force-applying spring  70  configured as a “stopper force-applying member”. Description will be made below regarding each component of the feed dog mounting/unmounting mechanism  20 . 
     Regarding the Feed Dog  20   
     The feed dog  22  is configured including a feed dog main body portion  23  configured as a “main body portion”, and a fixing target portion  24 . The feed dog main body portion  23  is configured in an approximately rectangular plate shape with the upper-lower direction as its thickness direction. A through hole  23 A having an approximately rectangular shape is formed as a through hole in a front portion of the feed dog main body portion  23 . Multiple tooth portions (configured in the form of five lines in the present embodiment) are formed in an upper end portion of the feed dog main body  23  such that they extend in the front-rear direction and such that they are arranged side by side in the left-right direction. Specifically, the feed dog main body portion  23  includes a pair of left and right first tooth portions  23 B arranged in both end portions of the feed dog main body  23  in the left-right direction, three second tooth portions arranged between the pair of the left and right first tooth portions  23 B on the rear side of the through hole  23 A, and two third tooth portions  23 C arranged on the front side of the through hole  23 A. Furthermore, multiple teeth are formed on the upper face of each of the first tooth portions  23 B and the second tooth portions  23 C. 
     Furthermore, the feed dog main body portion  23  is configured such that the lower face of its rear end portion is one step lower toward the lower side as compared with the lower face of its front end portion. A restricting recess portion  23 D (see  FIG. 6 ) is formed in the lower face of the rear end portion of the feed dog main body portion  23  such that it is positioned in a central position in the left-right direction and such that its opening faces the lower side. The restricting recess portion  23 D is configured in an approximately rectangular shape with the left-right direction as its longitudinal direction as viewed from the lower side. 
     The fixing target portion  24  is configured in an approximately U-shaped plate shape having an opening that faces the front side with the upper-lower direction as its thickness direction. The fixing target portion  24  is connected to a lower portion of the outer circumferential face in the rear end portion of the feed dog main body portion  23 . The fixing target portion  24  is configured such that it protrudes outward in the left-right direction from the feed dog main body portion  23 . Furthermore, the fixing target portion  24  is configured such that it protrudes toward the rear side. That is to say, the fixing target portion  24  forms the rear end portion of the feed dog  22  and both end portions thereof in the left-right direction. The fixing target portion  24  is arranged such that its lower face is positioned on the same plane as the lower face of the rear end portion of the feed dog main body portion  23 . 
     A pair of left and right first fixing target faces  24 A are formed in the rear face of the fixing target portion  24 . In a side view, the first fixing target face  24  has a slope that is inclined upward in a linear manner as it becomes closer to the front side. Furthermore, a pair of second left and right fixing target faces  24 B are formed in the front face of the fixing target portion  24  (specifically, a front face of a portion of the fixing target portion  24  configured such that it protrudes outward from the feed dog main body portion  23  in the left-right direction). The second fixing target face  24 B is configured to have a slope that is inclined upward in a linear manner as it becomes closer to the rear side in a side view. That is to say, the first fixing target face  24 A and the second fixing target face  24 B are each configured as a flat sloping face. 
     Furthermore, a positioning groove  24 C is formed in a right-side portion of the fixing target portion  24 . The positioning groove  24 C is configured such that it extends in the front-rear direction and such that it has an opening that faces the rear side and that is configured as a through hole passing through in the upper-lower direction. Furthermore, a notch portion  24 D is formed in a left-end portion of the fixing target portion  24 . In a plan view, the notch portion  24 D is configured to have an opening that faces the left side and the rear side. 
     Regarding the Feed Base  30   
     The feed base  30  is configured as a base on which the feed dog  22  is to be mounted. The feed base  30  is configured including a base  32  configured as a “feed base main body” that forms a lower portion of the feed base  30  and a feed dog base  34  that forms an upper portion of the feed base  30 . 
     Regarding the Base  32   
     As shown in  FIG. 4 , the base  32  is coupled to a feed mechanism (not shown) provided in the interior of the bed portion  12 C of the sewing machine  10 . With such an arrangement, when the sewing machine  10  is operated, the base  32  (i.e., feed base  30 ) is configured to perform a feeding operation. 
     The base  32  is configured in an approximately rectangular block shape with the upper-lower direction as its thickness direction and with the left-right direction as its longitudinal direction. A lever housing portion  32 A is formed in a central portion of the base  32  in the left-right direction so as to house a part of a lever  40  described later. The lever housing portion  32 A is configured in a recessed shape having an opening that faces the upper side and in an approximately rectangular shape in a plan view. A stopper housing portion  32 B is formed in the base  32  such that it is positioned on the right side of the lever housing portion  32 A so as to house a stopper main body  61  of a stopper  60  described later. The stopper housing portion  32 B is configured in a recessed shape having an opening that faces the upper side and in an approximately rectangular shape in a plan view. Furthermore, a pair of left and right screw portions  32 C are formed in both end portions, i.e., the left and right end portions of the base  32 . Each screw portion  32 C is configured in a recessed shape having an opening that faces the upper side. A female screw thread is formed in the inner circumferential face of each screw portion  32 C. 
     Furthermore, a pair of left and right step faces  32 D are formed in the front end portion of the upper face of the base  32  such that they are positioned on the outer sides of the lever housing portion  32 A in the left-right direction. Each step face  32 D is arranged at a position that is one step lower than the upper face of the base  32 . Furthermore, the right-side step face  32 D is arranged adjacent to the front side of the stopper housing portion  32 B. The front face of the upper end portion of the stopper housing portion  32 B is notched by the step face  32 D. 
     Regarding the Feed Dog Base  34   
     The feed dog base  34  is configured in an approximately rectangular plate shape with the upper-lower direction as its thickness direction and with the left-right direction as its longitudinal direction. The feed dog base  34  is arranged on the upper side of the base  32 . A feed dog housing portion  34 A is formed in the feed dog base  34  so as to house the fixing target portion  24  of the feed dog  22  described above. The feed dog housing portion  34 A is configured in a recessed shape having an opening that faces the upper side, and such that it extends in the left-right direction. The bottom face of the feed dog housing portion  34 A is configured as a mounting face  34 B. The mounting face  34 B is configured along a plane that is orthogonal to the upper-lower direction. Furthermore, a counterbored portion  34 C is formed in the right-end portion of the feed dog base  34  such that it has an opening that faces the upper side and the right side. Moreover, a cylindrical fixing hole  34 D is formed as a through hole in each of the left end portion and the counterbored portion  34 C of the feed dog housing portion  34 A such that they match the screw portions  32 C of the base  32 . With such an arrangement, a screw SC 1  is inserted into each fixing hole  34 D from the upper side and is screwed into the screw portion  32 C, thereby fixedly coupling the feed dog  34  to the base  32 . 
     A holder housing portion  34 E is formed in a central portion of the feed dog base  34  in the left-right direction so as to house a lever-side holder portion  44  of the lever described later. The holder housing portion  34 E is configured in a recessed shape having an opening that faces the upper side, and in an approximately rectangular shape in a plan view. The lower face of the holder housing portion  34 E is arranged so as to be lower than the mounting face  34 B. Furthermore, a hole portion  34 F is formed in a front portion of the holder housing portion  34 E in the form of a through hole having an approximately rectangular opening passing through in the upper-lower direction. Moreover, the rear face of the holder housing portion  34 E is configured as a feed base-side holder face  34 G. 
     A positioning boss  34 H is provided to a right-side portion of the feed dog housing portion  34 A such that it is positioned corresponding to the positioning groove  24 C of the feed dog  22 . The positioning boss  34 H is configured in an approximately cylindrical shape with the upper-lower direction as its axial direction, and such that it protrudes from the mounting face  34 B toward the upper side. With such an arrangement, in a state in which the feed dog  22  is fixedly mounted on the feed base  30 , the positioning boss  34 H is designed such that it is inserted into the positioning groove  24 C so as to determine the relative position of the feed dog  22  with respect to the feed dog base  34  in the left-right direction. 
     Furthermore, a pair of outer-side portions in the left-right direction of the holder housing portion  34 E formed in the rear end portion of the feed dog base  34  are configured as base-side fixing portions  34 J configured as a pair of left and right “first fixing portions”. That is to say, the base-side fixing portions  34 J are arranged adjacent to the rear side of the feed dog housing portion  34 A. Furthermore, each base-side fixing portion  34 J is configured such that it protrudes upward with respect to the mounting face  34 B, and such that its front face is configured as a rear face of the feed dog housing portion  34 A. The front face of each base-side fixing portion  34 J is configured as a base-side fixing face  34 K configured as a “first fixing face”. Each base-side fixing face  34 K is configured as a slope that is inclined upward in a linear manner as it becomes closer to the front side in a side view. That is to say, the base-side fixing face  34 K is configured as a flat sloping face. 
     With such an arrangement, in a state in which the feed dog  22  is fixedly mounted, the first fixing target face  24 A of the fixing target portion  24  formed in the feed dog  22  is arranged adjacent to the front side of the base-side fixing face  34 K such that the first fixing target face  24 A comes in contact with the base-side fixing face  34 K. With this arrangement, the base-side fixing face  34 K and the first fixing target face  24 A are engaged with each other so as to restrict the movement of the fixing target portion  24  toward the rear side and the upper side in the fixed state. Furthermore, in a side view, the slope angle of the base-side fixing face  34 K in the front-rear direction is designed to be slightly smaller than that of the first fixing target face  24 A of the fixing target portion  24  in the front-rear direction. Accordingly, in a state in which the first fixing target face  24 A and the base-side fixing face  34 K come in contact with each other, such an arrangement provides line contact between them instead of plane contact. Specifically, such an arrangement is designed such that the upper end portion of the base-side fixing face  34 K comes in contact with the first fixing target face  24 A. 
     Furthermore, a restricting protrusion  34 L (see  FIGS. 4 and 6 ) is provided to a central portion of the front end portion of the feed dog base  34  in the left-right direction such that it protrudes upward. The restricting protrusion  34 L is configured in an approximately rectangular shape with the left-right direction as its longitudinal direction. With such an arrangement, in the state in which the feed dog  22  is fixedly mounted, the restricting protrusion  34 L is inserted into an internal space formed in the restricting recess portion  23 D of the feed dog  22 . Specifically, with such an arrangement, the restricting protrusion  34 L is inserted into the interior of the restricting recess portion  23 D of the feed dog  22  such that no gap is formed between the rear face of the restricting protrusion  34 L and the rear face of the restricting recess portion  23 D in the front-rear direction. Such an arrangement restricts the movement of the feed dog  22  toward the front side with respect to the feed dog base  34 . 
     Regarding the Lever  40   
     As also shown in  FIGS. 6A and 6B , the lever  40  includes a lever main body  41 . The lever main body  41  is configured in an approximately rectangular block shape. With such an arrangement, the lever main body  41  is housed within the lever housing portion  32 A of the base  32  such that it can be slid in the front-rear direction. Specifically, the lever  40  is configured such that it can be slid between an initial position (position shown in  FIG. 6B ) and a fixed position (position shown in  FIG. 6A ) to which the lever  40  is to be slid rearward (toward one side in the sliding direction) from the initial position. Furthermore, in a state in which the lever main body  41  is housed within the lever housing portion  32 A, the lever main body  41  is arranged such that its upper end portion protrudes upward from the base  32 . Furthermore, the feed dog base  34  is arranged on the upper side of the lever main body  41  such that they are adjacent to each other. With this, the feed dog base  34  restricts the upward movement of the lever main body  41  (lever  40 ). 
     A pair of left and right spring housing recess portions  41  are formed in the lever main body  41 . Each spring housing recess portion  41 A is configured in a recessed shape having an opening that faces the rear side. Each spring housing recess portion  41 A houses a lever force-applying spring  50  configured as a “lever force-applying member”. Each lever force-applying spring  50  is configured as a compression coil spring. Each lever force-applying spring  50  is arranged such that its rear end portion is engaged with the bottom face of the spring housing recess portion  41 A, and such that its front end portion is engaged with the front face of the lever housing portion  32 A of the base  32 . With this, the lever  40  is forced toward the rear side by the lever force-applying spring  50 . 
     As shown in  FIGS. 4 and 7 , an arm portion  42  is provided to each of the respective side faces in the left-right direction of the lever main body  41 . The arm portions  42  are configured such that they extend outward in the left-right direction from an upper-front end portion of the lever main body  41 . Each arm portion  42  is arranged adjacent to the upper side of the step face  32 D of the base  32 . A lever-side fixing portion  43  configured as a “second fixing portion” is formed in a tip portion of each arm portion  42 . The lever-side fixing portion  43  is configured such that it protrudes toward the upper side from each arm portion  42 . Each lever-side fixing portion  43  is arranged on the front side of the feed dog base  34  and above the mounting face  34 B of the feed dog base  34 . Furthermore, each lever-side fixing portion  43  is arranged with a predetermined space on the front side of the above-described base-side fixing face  34 K. Specifically, in the initial position of the lever  40 , the distance between the base-side fixing portion  34 J and the lever-side fixing portion  43  in the front-rear direction is designed to be longer than the length of the fixing target portion  24  of the feed dog  22  in the front-rear direction. 
     The rear face of the lever-side fixing portion  43  is configured as a lever-side fixing face  43 A, which is configured as a “second fixing face”. The lever-side fixing face  43 A is configured to have a slope that is inclined upward in a linear manner as it becomes closer to the rear side in a side view. That is to say, the lever-side fixing face  43 A is configured as a flat sloping face. With such an arrangement, in a state in which the feed dog  22  is fixedly mounted, the lever-side fixing face  43 A comes in contact with the second fixing target face  24 B of the feed dog  22  from the front side such that the lever  40  is arranged at a fixed position. With this, the lever-side fixing face  43 A and the second fixing target face  24 B are engaged with each other, thereby restricting the movement of the fixing target portion  24  toward the front side and the upper side in the fixed state. That is to say, with such an arrangement, the fixing target portion  24  is fixed such that it is interposed between the base-side fixing portion  34 J and the lever-side fixing portion  43  in the front-rear direction by the force applied by the lever force-applying spring  50 . Furthermore, in a side view, the slope angle of the lever-side fixing face  43 A in the front-rear direction is designed to be slightly smaller than that of the second fixing target face  24 B in the front-rear direction. Accordingly, in a state in which the second fixing target face  24 B and the lever-side fixing face  43 A come in contact with each other, such an arrangement provides line contact between them instead of plane contact. Specifically, such an arrangement is designed such that the upper end portion of the lever-side fixing face  43 A comes in contact with the second fixing target face  24 B. 
     As shown in  FIGS. 4 and 5 , the lever-side holder portion  44  is provided to the upper face of the lever main body  41 . The lever-side holder portion  44  is configured in an approximately rectangular block shape. The lever-side holder portion  44  is connected to a central portion in the left-right direction of the rear end portion of the lever main body  41 . Furthermore, the lever-side holder portion  44  is configured such that it protrudes toward the rear side from the lever main body  41 . The lever-side holder portion  44  is arranged such that it is inserted into the hole portion  34 F of the feed dog base  34  and such that it is housed within the holder housing portion  34 E of the feed dog base  34 . The rear face of the lever-side holder portion  44  is configured as a lever-side holder face  44 A. With this, when the lever  40  is set to the fixed position, the lever-side holder face  44 A is arranged with a predetermined gap G on the front side with respect to the feed base-side holder face  34 G of the feed dog base  34 . 
     Regarding the Stopper  60   
     As shown in  FIGS. 4 and 7 , the stopper  60  includes a stopper main body  61 . The stopper main body  61  is configured in an approximately rectangular block shape, and is housed within the stopper housing portion  32 B of the base  32  such that it can be moved in the upper-lower direction. Specifically, the stopper  60  is configured such that it can be moved between a lever holding position (position shown in  FIG. 7A ) and a pressed position (position shown in  FIG. 7E ) to which the stopper  60  is to be moved downward from the lever holding position. Furthermore, when the stopper  60  is set to the lever holding position, the stopper main body  61  is arranged adjacent to the lower side of the feed dog base  34 , thereby restricting the upward movement of the stopper main body  61 . 
     A recess-shaped spring housing portion  61 A having an opening that faces the lower side is formed in the lower face of the stopper main body  61 . A stopper force-applying spring  70  configured as a “stopper force-applying member” is housed within the spring housing portion  61 A. The stopper force-applying spring  70  is configured as a compression coil spring. The stopper force-applying spring  70  is arranged such that its upper end portion is engaged with the top face of the spring housing portion  61 A, and such that its lower end portion is engaged with the bottom face of the stopper housing portion  32 B. With this, the stopper  60  is forced upward by the force applied by the stopper force-applying spring  70 . 
     With such an arrangement, before the feed dog  22  is mounted, the stopper  60  is arranged at the lever holding position. Furthermore, the upper end portion of the stopper main body  61  is arranged on the upper side of the step face  32 D of the base  32 . In this state, the front face of the upper-end portion of the stopper main body  61  is exposed toward the front side from the stopper housing portion  32 B. Furthermore, when the stopper  60  is set to the lever holding position, the right-side arm portion  42  of the lever  40  comes in contact with the upper end portion of the stopper main body  61  from the front side. With this arrangement, the lever  40  is held at the initial position by the stopper  60 . 
     Furthermore, a pressing target portion  62  is provided to the upper face of the stopper main body  61 . The pressing target portion  62  is configured in an approximately rectangular columnar shape such that it protrudes toward the upper side from the stopper main body  61 . A slope face  62 A is formed in a rear portion of the upper face of the pressing target portion  62 . The slope face  62 A is configured to have a slope that is inclined toward the lower side as it becomes closer to the rear side in a side view. 
     With this, when the stopper  60  is set to the lever holding position, the upper end portion of the pressing target portion  62  is arranged such that it protrudes toward the upper side with respect to the mounting face  34 B of the feed dog base  34 . Furthermore, after the feed dog  22  is mounted on the feed dog base  34 , the pressing target portion  62  is pressed downward by the lower face of the feed dog  22  so as to move the stopper  60  downward from the lever holding position. More specifically, with such an arrangement, when the feed dog  22  is mounted on the mounting face  34 B, the stopper  60  is moved to the pressed position. Furthermore, when the stopper  60  is at a position before the pressed position, the contact state between the stopper main body  61  and the lever  40  is designed to be released. This allows the lever  40  to be slid rearward from the initial position. 
     Operation and Effects 
     Next, description will be made regarding the operation and effects of the present embodiment while explaining a procedure for mounting and unmounting of the feed dog  22  on the feed base  30 . 
     Regarding a Procedure for Mounting the Feed Dog  22  on the Feed Base  30   
     Description will be made below with reference to  FIG. 7  regarding a procedure for mounting the feed dog  22  on the feed base  30 . It should be noted that  FIG. 7  shows a procedure for mounting the feed dog  22  on the feed base  30  in chronological order. 
     Before the feed dog  22  is mounted on the feed base  30 , the stopper  60  is forced upward by the stopper force-applying spring  70  such that it is set to the lever holding position. Furthermore, in this state, the lever  40  is held at the initial position. In addition, the arm portion  42  of the lever  40  is pressed in contact with the upper end portion of the stopper  60  by the force applied by the lever force-applying spring  50  (see  FIG. 7A ). 
     Subsequently, when the feed dog  22  is mounted on the feed base  30 , the feed dog  22  is arranged on the upper side of the feed base  30  in a state in which it is tilted toward the rear side. In this state, the rear end portion of the fixing target portion  24  of the feed dog  22  is inserted into a space on the lower side of the base-side fixing face  34 K of the feed dog base  34  (see  FIG. 7B ). Furthermore, the fixing target portion  24  of the feed dog  22  is arranged adjacent to the upper side of the pressing target portion  62  of the stopper  60 . 
     In this state, the front end portion of the feed dog  22  is pressed downward. With this, the front end portion of the fixing target portion  24  of the feed dog  22  is displaced downward. In addition, the fixing target portion  24  presses the pressing target portion  62  of the stopper  60  downward. As a result, the stopper  60  is moved downward from the lever holding position against the force applied by the stopper force-applying spring  70  (see  FIG. 7C ). That is to say, the upper end portion of the stopper  60  is moved downward while sliding along the arm portion  42  of the lever  40 . 
     Subsequently, before the stopper  60  is set to the pressed position, the contact state between the stopper  60  and the arm portion  42  of the lever  40  is released. Specifically, before the fixing target portion  24  of the feed dog  22  is mounted on the mounting face  34 B of the feed dog base  34 , the contact state between the stopper  60  and the arm portion  42  of the lever  40  is released. This allows the lever  40  to be slid from the initial position toward the rear side. Accordingly, the lever  40  is slid rearward due to the force applied by the lever force-applying spring  50 . As a result, the lever-side fixing face  43 A of the lever  40  comes in contact with the second fixing target face  24 B of the fixing target portion  24  of the feed dog  22  (see  FIG. 7D ). 
     In this state, the feed dog  22  is further pressed downward. As a result, when the fixing target portion  24  is mounted on the mounting face  34 B of the feed dog base  34 , the stopper  60  is moved to the pressed portion. Furthermore, the lever  40  is further slid rearward, and is set to the fixed position. In this state, the fixing target portion  24  of the feed dog  22  is fixed to the feed base  30  in a state in which it is interposed between the lever-side fixing portion  43  of the lever  40  and the base-side fixing portion  34 J of the feed dog base  34  in the front-rear direction (see  FIG. 7E ). Furthermore, in this state, the upper face of the stopper main body  61  of the stopper  60  is arranged with a gap below the arm portion  42  of the lever  40 . Moreover, in this state, the restricting protrusion  34 L of the feed dog base  34  is inserted into the restricting recess portion  23 D of the feed dog  22 . 
     Regarding a Procedure for Unmounting the Feed Dog  22  from the Feed Base  30   
     When the feed dog  22  is to be unmounted from the feed base  30 , the feed dog  22  is unmounted from the feed base  30  using an unmounting tool T. Accordingly, first, description will be made regarding a configuration of the unmounting tool T. As shown in  FIG. 9 , the unmounting tool T is configured in a longitudinal rod shape having an approximately L-shaped bent portion. The unmounting tool T is configured such that its one end is configured as a bit portion T 1  having a flat-blade cross-sectional shape, and such that the other end thereof is configured as a grip portion T 2  to be held by the user. It should be noted that, instead of such a unmounting tool T, the user may unmount the feed dog  22  from the feed base  30  using another tool such as a flat-head screwdriver or the like. 
     Next, description will be made with reference to  FIG. 8  regarding a procedure for unmounting the feed dog  22  from the feed base  30 . It should be noted that  FIG. 8  shows a procedure for unmounting the feed dog  22  from the feed base  30  in chronological order. In  FIG. 8 , the diagrams shown on the left side each show a plan view of a portion around the rear end portion of the feed dog mounting/unmounting mechanism  20 . The diagrams shown on the right side each show a plan view of a portion around the stopper  60  of the feed dog mounting/unmounting mechanism  20 , which corresponds to the drawing shown on the left side. 
     In a state in which the feed dog  22  is mounted on the feed base  30 , the lever-side holder face  44 A of the lever-side holder portion  44  of the lever  40  is arranged with a predetermined gap G on the front side of the feed base-side holder face  34 G of the feed dog base  34 . When the feed dog  22  is to be unmounted from the feed base  30 , the bit portion T 1  of the unmounting tool T is inserted into the gap G between the lever-side holder face  44 A and the feed base-side holder face  34 G (see  FIG. 8A ). 
     In this state, the bit portion T 1  of the unmounting tool T is rotated (see  FIG. 8B ).  FIG. 8B  shows an example in which the bit portion T 1  is rotated in a counterclockwise manner. Upon rotating the bit portion T 1  of the unmounting tool T, one end of the bit portion T 1  is pressed in contact with the feed base-side holder face  34 G of the feed dog base  34 . Furthermore, the other end of the bit portion T 1  is pressed into contact with the lever-side holder face  44 A of the lever  40 . This presses the lever-side holder portion  44  frontward. That is to say, the lever-side holder portion  44  is pressed frontward by the bit portion T 1  of the unmounting tool T using the principle of leverage. With this, the lever  40  is slid frontward from the fixed position against the force applied by the lever force-applying spring  50 . 
     When the lever  40  is slid frontward from the fixed position, the lever-side fixing face  43 A of the lever  40  is relatively moved frontward with respect to the second fixing target face  24 B of the feed dog  22 . Furthermore, the pressing target portion  62  of the stopper  60  is arranged below the fixing target portion  24  of the feed dog  22 . In this state, the stopper  60  is forced upward by the stopper force-applying spring  70 . Accordingly, upon sliding the lever  40  frontward from the fixed position, the pressing target portion  62  of the stopper  60  presses the fixing target portion  24  of the feed dog  22  upward, thereby displacing the lower face of the fixing target portion  24  upward away from the mounting face  34 B of the feed dog base  34 . Specifically, the feed dog  22  is lifted up such that it is tilted toward the rear side in a state in which the second fixing target face  24 B of the feed dog  22  is in contact with the lever-side fixing face  43 A of the lever  40  and the first fixing target face  24 A of the feed dog  22  is in contact with the base-side fixing face  34 K of the feed dog base  34 . 
     Upon further rotating the bit portion T 1  of the unmounting tool T in the state shown in  FIG. 8B , the lever  40  is further slid frontward. In addition, this releases the contact state between the lever-side fixing face  43 A of the lever  40  and the second fixing target face  24 B of the fixing target portion  24  of the feed dog  22  (see  FIG. 8C ). 
     Subsequently, when the lever  40  has been slid partway up to the initial position, the stopper  60  is moved upward by the force applied by the stopper force-applying spring  70 , and is set to the lever holding position. With this, the fixing target portion  24  of the feed dog  22  is pressed upward by the pressing target portion  62  of the stopper  60 , thereby unmounting the feed dog  22  from the feed base  30 . Furthermore, in this stage, the upper end portion of the stopper main body  61  of the stopper  60  is arranged adjacent to the rear side of the arm portion  42  of the lever  40 . With this, the lever  40  is held at the initial position by the stopper main body  61  (see  FIG. 8D ). 
     As described above, in the feed dog mounting/unmounting mechanism  20 , the lever  40  is provided on the feed base  30  such that it can be slid in the front-rear direction. Furthermore, the lever  40  is forced rearward by the lever force-applying spring  50 . With this, upon sliding the lever  40  rearward from the initial position, the fixing target portion  24  of the feed dog  22  is fixed in a state in which it is interposed between the base-side fixing portion  34 J of the feed base  30  and the lever-side fixing portion  43  of the lever  40  in the front-rear direction. 
     Here, the feed base  30  is provided with the stopper  60  configured such that it can be moved in the upper-lower direction. The lever  40  is held at the initial position by the stopper  60 . With this, when the feed dog  22  is mounted on the feed base  30 , the stopper  60  is pressed downward by the feed dog  22 . This moves the stopper  60  so as to allow the lever  40  to slide from the initial position. With this, the lever  40  is slid from the initial position to the fixed position by the force applied by the lever force-applying spring  50  so as to fix the fixing target portion  24  such that it is interposed between the base-side fixing portion  34 J and the lever-side fixing portion  43 . Accordingly, the fixing target portion  24  can be fixed between the base-side fixing portion  34 J and the lever-side fixing portion  43  without a need to slide the lever  40  frontward against the force applied by the lever force-applying spring  50 . That is to say, such an arrangement allows the feed dog  22  to be mounted on the feed base  30  without being affected by the force applied by the lever force-applying spring  50 . Accordingly, such an arrangement provides improved operating efficiency in the mounting of the feed dog  22 . 
     Furthermore, the stopper  60  is configured such that it can be moved between the lever holding position at which the lever  40  is held at the initial position and the pressed position at which the lever  40  is pressed downward from the lever holding position by the feed dog  22 . Moreover, the stopper force-applying spring  70  is provided to the base plate of the feed base  30 . The stopper force-applying spring  70  applies force to the stopper  60  toward the lever holding position side. Accordingly, when the feed dog  22  is to be unmounted from the feed base  30 , the lever  40  is slid from the fixed position to the initial position so as to release the holding state in which the fixing target portion  24  is held by the base-side fixing portion  34 J and the lever-side fixing portion  43 . This allows the feed base  30  to be pressed upward by the stopper  60 . This provides improved operating efficiency in the unmounting of the feed dog  22  from the feed base  30 . 
     Furthermore, the lever-side holder portion  44  of the lever  40  is housed within the holder housing portion  34 E of the feed dog base  34 . In this state, the lever-side holder face  44 A of the lever-side holder portion  44  is arranged on the front side of the feed base-side holder face  34 G of the holder housing portion  34 E so as to form the gap G between the lever-side holder face  44 A and the feed base-side holder face  34 G. This allows the bit portion T 1  of the unmounting tool T to be inserted into the gap G between the lever-side holder face  44 A and the feed base-side holder face  34 G, so as to slide the lever  40  from the fixed position to the initial position using the unmount tool T. This provides improved operating efficiency in the unmounting of the feed dog  22  from the feed base  30 . 
     Furthermore, the feed base  30  is configured including the base  32  that forms a lower portion of the feed base  30  and the feed dog base  34  that forms an upper portion of the feed base  30 . Moreover, the lever  40  is provided such that it can be slid between the base  32  and the feed dog base  34 . The feed dog  22  is mounted on the feed dog housing portion  34 A of the feed dog base  34  from the upper side. With such a simple configuration, the lever  40  can be slidably provided on the feed base  30 . Furthermore, the feed dog  22  can be mounted on the feed base  30  coupled to the lever  40 . 
     Furthermore, the stopper housing portion  32 B is formed in the base  32  such that it has an opening that faces the upper side. With this arrangement, the stopper main body  61  of the stopper  60  and the stopper force-applying spring  70  are housed in the stopper housing portion  32 B. With such an arrangement, when the stopper  60  is set to the lever holding position, the stopper  60  is arranged such that the upper end portion of the stopper main body  61  thereof protrudes toward the upper side from the stopper housing portion  32 B and is in contact with the arm portion  42  of the lever  40  at the initial position. This allows the lever  40  to be held at the initial position in a simple manner. Furthermore, by housing the stopper main body  61  within the stopper housing portion  32 B, the contact state between the lever  40  and the stopper  60  can be released, thereby allowing the lever  40  to be slid from the initial position. 
     Furthermore, the base-side fixing portion  34 J of the feed dog base  34  has the base-side fixing face  34 K. The base-side fixing face  34 K is formed such that it has a slope inclined upward as it becomes closer to the front side. Moreover, the lever-side fixing portion  43  of the lever  40  has the lever-side fixing face  43 A. The lever-side fixing face  43 A is configured to have a slope that is inclined upward as it becomes closer to the rear side. With such an arrangement, the fixing target portion  24  of the feed dog  22  is held by the base-side fixing face  34 K and the lever-side fixing face  43 A such that it is interposed between them in the front-rear direction. This allows the movement of the fixing target portion  24  to be restricted in the front-rear direction and the upper-lower direction. 
     Furthermore, the first fixing target face  24 A of the fixing target portion  24  of the feed dog  22  is configured to have a slope that is inclined upward as it becomes closer to the front side corresponding to the base-side fixing face  34 K. Moreover, the second fixing target face  24 B of the fixing target portion  24  is configured to have a slope that is inclined upward as it becomes closer to the rear side corresponding to the lever-side fixing face  43 A. Accordingly, by designing the slope angles of the first fixing target face  24 A and the second fixing target face  24 B as appropriate, such an arrangement allows the first fixing target face  24 A and the base-side fixing face  34 K to be set to a line contact state, and allows the second fixing target face  24 B and the lever-side fixing face  43 A to be set to a line contact state. This allows the contact portion between the first fixing target face  24 A (second fixing target face  24 B) and the base-side fixing face  34 K (lever-side fixing face  43 A) to be designed with high precision. Accordingly, such an arrangement provides an improved fixing state for the fixing target portion  24 . 
     It should be noted that, in the present embodiment, the stopper  60  is configured including the stopper main body  61  and the pressing target portion  62  formed such that it protrudes toward the upper side from the stopper main body  61 . However, as shown in  FIGS. 10A and 10B , the pressing target portion  62  may be omitted in the stopper  60 . In this case, a protrusion portion  24 E may be formed in the fixing target portion  24  of the feed dog  22 . The protrusion portion  24 E is configured in a shape that is the reverse of that of the pressing target portion  62  in the upper-lower direction in a side view such that it protrudes toward the lower side from the fixing target portion  24 . With such an arrangement, when the feed dog  22  is to be mounted on the feed base  30 , the stopper main body  61  of the stopper  60  is pressed downward by the protrusion portion  24 E. With this arrangement, after the feed dog  22  is unmounted from the feed base  30 , the stopper  60  is arranged such that it does not protrude toward the upper side with respect to the mounting face  34 B of the feed base  34 . Accordingly, such an arrangement suppresses a situation in which the stopper  60  is inadvertently pressed downward in a state in which the feed dog  22  is unmounted from the feed base  30 . As a result, such an arrangement is capable of suppressing a situation in which the lever  40  is slid to the fixed position in a state in which the feed dog  22  is unmounted from the feed base  30 . 
     Furthermore, in the present embodiment, the first fixing target face  24 A of the feed dog  22  and the base-side fixing face  34 K of the feed dog base  34  are each configured as a flat sloping face. Furthermore, the second fixing target face  24 B of the feed dog  22  and the lever-side fixing face  43 A of the lever  40  are each configured as a flat sloping face. Instead of such an arrangement, at least one from among the first fixing target face  24 A and the base-side fixing face  34 K may be configured as a curved slope face. Also, at least one from among the second fixing target face  24 B and the lever-side fixing face  43 A may be configured as a curved slope face. For example, as shown in  FIG. 11A , the first fixing target face  24 A may be configured as a curved face that protrudes toward the base-side fixing face  34 K. In this case, such an arrangement also allows the first fixing target face  24 A and the base-side fixing face  34 K to be set to a line contact state, and also allows the second fixing target face  24 B and the lever-side fixing face  43 A to be set to a line contact state. 
     Description has been made in the present embodiment regarding an arrangement in which the second fixing target face  24 B of the feed dog  22  and the lever-side fixing face  43 A of the lever  40  are arranged such that they are in contact with each other so as to restrict the front end portion of the fixing target portion  24  from moving upward. Also, a restricting portion may be formed in the lever-side fixing portion  43  of the lever  40  for restricting the upward movement of the fixing target portion  24 . 
     For example, as shown in  FIG. 11B , a restricting portion  43 B is formed in the lever-side fixing face  43 A of the lever  40  such that it protrudes toward the rear side and such that its lower face is orthogonal to the upper-lower direction. On the other hand, an engagement recess portion  24 F is formed in the second fixing target face  24 B of the feed dog  22  such that it has an opening that faces the upper side and the front side and such that its bottom face is orthogonal to the upper lower direction. With such an arrangement, the engagement recess portion  24 F is arranged adjacent to the lower side of the restricting portion  43 B, thereby engaging the restricting portion  43 B and the engagement recess portion  24 F in the upper-lower direction. With this, the upward movement of the fixing target portion  24  is effectively restricted, thereby allowing the feed dog  22  to be satisfactorily maintained in a fixed state. 
     Also, for example, as shown in  FIG. 11C , a restricting portion  43 B is formed in the upper end portion of the lever-side fixing portion  43  of the lever  40  such that it protrudes toward the rear side and such that its lower face is orthogonal to the upper-lower direction. With such an arrangement, the front end portion of the fixing target portion  24  is arranged adjacent to the lower side of the restricting portion  43 B, thereby engaging the restricting portion  43 B and the front end portion of the fixing target portion  24  in the upper-lower direction. With this, the upward movement of the fixing target portion  24  is effectively restricted, thereby allowing the feed dog  22  to be satisfactorily maintained in a fixed state. 
     Description has been made in the present embodiment regarding an arrangement in which the base-side fixing portion  34 J is monolithically formed in the feed dog base  34 . Also, as shown in  FIG. 12 , the feed dog base  34  and the base-side fixing portion  34 J may be formed as separate components. Also, the base-side fixing portion  34 J may be fixedly mounted on the feed dog base  34  by screws SC 2 , so as to provide the base-side fixing portion  34 J integrally with the feed dog base  34 . This enables fine adjustment of the position of the base-side fixing portion  34 J in the front-rear direction. That is to say, this arrangement enables fine adjustment of the distance between the base-side fixing portion  34 J and the restricting protrusion  34 L in the front-rear direction. In other words, this arrangement enables fine adjustment of the position of the base-side fixing portion  34 J so as to eliminate a gap between the rear face of the restricting protrusion  34 L of the feed dog base  34  and the rear face of the restricting recess portion  23 D of the feed dog  22 . As a result, such an arrangement is capable of suppressing the occurrence of rattling in the feed dog  22  even if an external force is applied to the feed dog  22  downward. 
     Also, in the present embodiment, the unmounting tool T may be provided to the feed dog mounting/unmounting mechanism  20 . For example, as shown in  FIGS. 13A and 13B , a rotational shaft T 3  is provided to one end of the unmounting tool T having a longitudinal rod shape. The rotational shaft T 3  is formed such that it extends in a direction that is orthogonal to the direction in which the unmounting tool T extends. Furthermore, the bit portion T 1  is provided to one end side portion of the unmounting tool T such that it extends in parallel with the rotational shaft T 3 . With such an arrangement, the rotational shaft T 3  is rotationally coupled to the feed dog base  34  with the axial direction of the rotational shaft T 3  as the upper-lower direction. Furthermore, the bit portion T 1  is inserted into the gap G. With this, upon rotating the unmounting tool T around the axis of the rotational shaft T 3 , the lever  40  at the fixed position is slid frontward, thereby allowing the feed dog  22  to be unmounted from the feed base  30 . Accordingly, such an arrangement provides improved user convenience. 
     Description has been made in the present embodiment regarding an arrangement in which the unmounting tool T is used to unmount the feed dog  22  from the feed base  30 . Also, the feed dog  22  may be unmounted from the feed base  30  without using the unmounting tool T. That is to say, the user may press the lever-side holder portion  44  of the lever  40  frontward with a finger so as to slide the lever  40  at the fixed position frontward. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
           10  sewing machine,  20  feed dog mounting/unmounting mechanism,  22  feed dog,  23  feed dog main body portion (main body portion),  24  fixing target portion,  24 E protrusion portion,  30  feed base,  32  base (feed base main body),  32 B stopper housing portion,  34  feed dog base,  34 G feed base-side holder face,  34 J base-side fixing portion (first fixing portion),  34 K base-side fixing face (first fixing face),  40  lever,  43  lever-side fixing portion (second fixing portion),  43 A lever-side fixing face (second fixing face),  44 A lever-side holder face,  50  lever force-applying spring (lever force-applying member),  60  stopper,  70  stopper force-applying spring (stopper force-applying member), G gap (gap between lever-side holder face and feed base-side holder face).