Cloth opening device for buttonholing machine

Abstract

 The invention relates to a cloth opening device (8) for a buttonholing machine (1). The cloth opening device (8) includes a pair of cloth receiving plates (22L, 22R) and a pair of cloth opening means (23L, 23R) which moves the pair of cloth receiving plates (22L, 22R) along the left-right directions. Each of the cloth opening means (23L, 23R) includes two links (25, 26), each of which having a base end portion supported by a feed base (11) and a swingable free end portion. The links (25, 26) are arranged such that longitudinal directions thereof are oriented along front-rear directions, and are arranged to face each other in up-down directions such that the base end portion of one of the links (25, 26) is closer to the free end portion of the other of the links (25, 26) than to the base end portion of the other of the links (25, 26). The two links (25, 26) include a first joint portion (47) at which the two links (25, 26) are joined. The first joint portion (47) is located between the base end portion and the free end portion of each of the links (25, 26). Each of the links (25, 26) includes a second joint portion (25C, 26C) which is joined to the corresponding cloth receiving plate (22L, 22R) and is located between the respective free end and the first joint portion. Selected Drawing: Fig. 3

Description

[0001] The present invention relates to a cloth opening device for a buttonholing machine, the cloth opening device having a pair of cloth receiving plates which is arranged on respective sides of a buttonhole of a workpiece and is configured to open and close the buttonhole by moving toward and away from each other.

[0002] Conventionally, there is known a buttonholing machine which can form an eyelet buttonhole or a closed-eye buttonhole in a workpiece and form overlock stitches along a circumference of the buttonhole automatically.

[0003] Such a buttonholing machine includes a bed portion, a feed base which is provided on a bed portion and on which a workpiece is set, a feed mechanism which moves the feed base in front-rear directions and in left-right directions, and a cloth cutting device which forms a slit in the workpiece. The cloth cutting device has a knife receiver (a fixed knife) which is fixed to the bed portion and a cloth cutting knife (a movable knife) which is moved toward and away from the knife receiver. On the feed base, a cloth opening device is arranged to open the slit formed in the workpiece.

[0004] The front-rear directions are directions in which an arm portion of a main body of the buttonholing machine extends, and in which a free end of the arm portion is oriented toward the front. Further, the left-right directions are directions extending between right and left when viewed to face the free end of the arm portion from a location in front of the free end of the arm portion.

[0005] Some cloth opening devices, for example, as disclosed in JP 2722777 B2, use a link mechanism in order to reduce a space required, in the left-right directions, for arranging the cloth opening device on the feed base.

[0006] The cloth opening device disclosed in JP 2722777 B2 includes a pair of cloth receiving plates which is provided on a feed base so as to be positioned on right and left sides of a knife receiver extending in the front-rear directions, and cloth pressers provided on the respective cloth receiving plates. A slit extending in the front-rear directions is formed in a workpiece placed on the cloth receiving plates by bringing a cloth cutting knife (a hammer) into contact with the knife receiver and, in a state in which both sides of the slit are pressed by the cloth pressers, the cloth receiving plates are moved away from each other to open the slit.

[0007] The cloth opening device further includes a pair of link mechanisms corresponding to the pair of cloth receiving plates. Each of the link mechanisms has a plurality of links which are joined to each other to extend in the front-rear directions. An intermediate portion of each of links is supported by the feed base such that both ends of the link are swingable. Further, each of the link mechanisms is configured such that the moving amounts (rotation angles) of a front free end and a rear free end are the same. Front and rear ends of each of the cloth receiving plates are joined to the front free end and the rear free end of the corresponding one of the link mechanisms, respectively, via joint portions (pins), so that the cloth receiving plates are moved along the left-right directions by actuating the respective link mechanisms.

[0008] After pressing and holding a workpiece on the cloth receiving plates by the cloth pressers, and before forming overlock stitches, the cloth cutting knife is moved down and brought into contact with the knife receiver to match the knife receiver, whereby a part of the workpiece sandwiched between the cloth cutting knife and the knife receiver is pressed and cut to form a slit. Thereafter, in a state in which both sides of the slit of the workpiece are pressed by the cloth pressers, respective cloth opening means are driven to move the cloth receiving plates in separating directions, i.e., to move the cloth receiving plates away from each other in the left-right directions, whereby the slit is opened such that an opening width of the slit becomes substantially uniform along the front-rear directions.

[0009] In this state in which the workpiece is stretched, a needle and a looper are driven while moving the workpiece together with the feed base such that the needle relatively moves along the circumference of the slit, whereby the overlock stitches are formed around the slit.

[0010] The conventional cloth opening device will be further described in detail with reference to Fig. 8.

[0011] The link mechanism 103 is a part of the cloth opening means 102. The link mechanism 103 includes a first link 104 and a second link 105 which are joined to each other to extend in the front-rear directions. The first link 104 and the second link 105 are attached to the feed base 106 at fulcrums 104F, 105F, each of which are located in the middle in the respective links 104, 105. Further, link mechanism 103 is configured such that the moving amounts of the front free end and the rear free end are the same.

[0012] That is, a distance 104La from the fulcrum 104F to the joining point 104C at which the first link 104 and the cloth receiving plate 107 are joined and a distance 104Lb from the fulcrum 104F to the joining point 104D at which the two links 104, 105 are joined are the same (104La = 104Lb). Further, a distance 105La from the fulcrum 105F to the joining point 105C at which the second link 105 and the cloth receiving plate 107 are joined and a distance 105Lb from the fulcrum 105F to the joining point 104D are the same(105La= 105Lb).

[0013] The cloth opening means further includes an input arm 108 which extends to the right from the middle of the first link 104, an air cylinder 110 having an output shaft 110a and serving as an actuator, and a joint 109 having one end joined to a distal end of the input arm 108 and the other end joined to a distal end of the output shaft 110a of the air cylinder 110. The output shaft 110a of the air cylinder 110 is configured to move along the front-rear directions.

[0014] Accordingly, in the link mechanism 103 of the conventional cloth opening device 101, the joining point 104C, the fulcrum 104F, the joining point 104D, the fulcrum 105F, and the joining point 105C are aligned substantially along the front-rear directions, from the rear to the front in this order.

[0015] When the output shaft 109 of the air cylinder 110 is retracted, the first link 104 rotates clockwise in Fig. 8 around the fulcrum 104F, and along with the clockwise rotation of the first link 104, the second link 105 rotates counterclockwise in Fig. 8 around the fulcrum 105F, whereby the cloth receiving plate 107 is moved to the right, i.e., in a direction separating from a moving path of the cloth cutting knife which is not shown.

[0016] In the conventional cloth opening device 101, the fulcrums 104F, 105F to be fixed to the feed base 106 are located in the middle of the first link 104 and the second link 105 respectively, so that arc motions are provided to distal ends of the links 104, 105, i.e., to the joining point 104C and the joining point 105C. Accordingly, when opening the slit, the cloth receiving plate 107 and the cloth presser relatively move with a displacement in the front-rear directions, so that the workpiece moves from a correct position.

[0017] Therefore, the links 104, 105 are configured such that 104La < 105La to increase the radius of the arc motion of the second link 105, so that the displacement in the front-rear directions during the movement of the cloth receiving plate 107 is reduced as a whole.

[0018] However, in the conventional cloth opening device 101, the fulcrums 104F, 105F to be fixed to the feed base 106 are located in the middle of the first link 104 and the second link 105 respectively, and the moving amounts of the front free end and the rear free end are set to be equal to each other. That is, link ratios (lever ratios) in each of the links 104, 105 is 1:1, more specifically, the distance 104La and the distance 104Lb of the first link 104 are set to be equal to each other (104La = 104Lb), and the distance 105La and the distance 105Lb of the second link 105 are set to be equal to each other (105La = 105Lb). Thus, the output of the air cylinder 110 cannot be made smaller by changing the link ratios, and therefore, a further space-saving cannot be realized.

[0019] Moreover, in the conventional cloth opening device 101, because the output of the air cylinder 110 cannot be made smaller, the space occupied by the cloth opening means 102 inside the feed base 106 is large. Thus, the arrangement locations and installation capacities for other mechanisms such as a driving mechanism for the cloth pressers are limited, so that the degree of freedom in design is hindered.

[0020] It is an object of the present invention to provide a space-saving cloth opening device for a buttonholing machine.

[0021] According to a first aspect of the present invention, a cloth opening device for a buttonholing machine includes a pair of cloth receiving plates which are adapted to hold a workpiece on upper surfaces thereof and are arranged on a feed base to face each other in a left-right directions on opposite sides of a moving path of a cloth cutting knife, and a pair of cloth opening means which moves the pair of cloth receiving plates along the left-right directions such that each of the cloth opening means moves a corresponding one of the cloth receiving plates toward or away from the moving path to open or to close a slit that is formed in the workpiece by the cloth cutting knife. Each of the cloth opening means includes two links, each of which having a base end portion supported by the feed base and a swingable free end portion, and an actuator which actuates the links. The two links are arranged such that longitudinal directions thereof are oriented along front-rear directions which are orthogonal to the left-right directions, and are arranged to face each other in up-down directions such that the base end portion of one of the links is closer to the free end portion of the other of the links than to the base end portion of the other of the links. The two links have a first joint portion at which the two links are joined. The first joint portion is located between the base end portion and the free end portion of each of the links. Each of the two links has a second joint portion which is joined to the corresponding cloth receiving plate and is located between the respective free end and the first joint portion.

[0022] According to this configuration, because the two links arranged to face each other in the up-down directions, the length in the front-rear directions can be easily shortened. Further, because the link ratio can be set such that the distance between the fulcrum and the second joint portion is longer than the distance between the fulcrum and the first joint portion, the output of the actuator can be made smaller.

[0023] According to a second aspect of the present invention, the second joint portions of the two links are symmetrically arranged with respect to the first joint portion, and the first joint portion has an input portion from which a driving force of the actuator is input. According to this configuration, the link ratio can be set such that the distance between the fulcrum and the second joint portion is made longer in a configuration in which the lengths of the two links are the same, and such that the distance between the fulcrum and the second joint portion is longer than the distance between the fulcrum and the first joint portion. Therefore, the output of the actuator can be made smaller while increasing a radius of rotation of the second joint portion to be larger than conventional.

[0024] According to the cloth opening device of the present invention, the two links are arranged to face each other in the up-down directions, so that the length in the front-rear directions can be easily shortened. Further, the link ratio can be set such that the distance between the fulcrum and the second joint portion is longer than the distance between the fulcrum and the first joint portion, so that the output of the actuator can be made smaller. As a result, advantageous effects such as easy and reliable space-saving can be obtained.

[0025] Other aspects and advantages of the present invention will be apparent from the following description, the drawings and the claims.

[0026] The following description of preferred embodiments of the invention serves to explain the invention in greater detail in conjunction with the drawings. These show:

Fig. 1:

a side view of a buttonholing machine on which a cloth opening device according to an embodiment of the invention is mounted;

Fig. 2:

an perspective view of the cloth opening device;

Fig. 3:

an exploded perspective view of a right cloth opening means of the cloth opening device of Fig. 2;

Fig. 4:

an enlarged perspective view of the cloth opening means of Fig. 3;

Fig. 5:

an enlarged plan view of the cloth opening means of Fig. 3;

Fig. 6:

a schematic view of a closing state of the cloth opening means of Fig. 3;

Fig. 7:

a schematic view an opening state of the cloth opening device of Fig. 3; and

Fig. 8:

a schematic view of a right cloth opening means of a conventional cloth opening device.

[0027] For convenience of description, firstly, a general configuration of a buttonholing machine, on which the cloth opening device is mounted, will be described with reference to Fig. 1.

[0028] A basic configuration of the buttonholing machine is similar to those of conventional buttonholing machines for forming overlock stitches.

[0029] As shown in Fig. 1, the buttonholing machine 1 includes a main body 2 and a bottom cover 3 covering a bottom of the main body 2. The bottom cover 3 is supported on a sewing machine table not shown.

[0030] The main body 2 includes a bed portion 2a having a substantially rectangular box shape, a vertical drum portion 2b protruding upward from a rear portion of the bed portion 2a, and an arm portion 20 extending parallel to the bed portion 2a toward the front from an upper portion of the vertical drum portion 2b. The main body 2 is configured in a substantially U shape as a whole.

[0031] For convenience of description, the respective directions are defined such that, in a state in which the buttonholing machine 1 is placed on a horizontal plane, the up-down directions are directions in which a needle 6 moves, the front-rear directions are directions which are orthogonal to the up-down directions and in which the arm portion 2c extends, and the left-right directions are directions which are orthogonal to both the up-down directions and the front-rear directions. During a buttonholing operation, an operator of the buttonholing machine 1 faces the front side of the buttonholing machine 1.

[0032] On a free end portion (a front portion) of the arm portion 2c, a needle bar 5 is arranged. The needle bar 5 is arranged such that its lower end portion projects toward the bed portion 2a. To the lower end portion of the needle bar 5, a base end portion of the needle 6 is removably attached. A needle bar drive mechanism (not shown) moves the needle bar 5 up and down along the up-down directions, and a needle swinging mechanism (not shown) swings the needle 6 along the left-right directions. The needle bar drive mechanism is driven in linkage with a rotation of a main shaft (an upper shaft) which is arranged rotatably inside the arm portion 2c. The main shaft is driven by a sewing machine motor which is arranged inside the bed portion 2a. The needle swinging mechanism is driven by a driving force of the sewing machine motor.

[0033] In the bed portion 2a, and below the needle bar 5, a looper and various drive mechanisms (not shown) for driving the looper in synchronization with the movement of the needle bar 5.

[0034] In the buttonholing machine 1, a cloth cutting device 8 for forming a slit such as an eyelet buttonhole or a closed buttonhole in a workpiece is arranged. The cloth cutting device 8 includes a cloth cutting knife 9 (a movable knife) which is arranged the arm portion 2c so as to be movable in the up-down directions, and a knife receiver 10 (a fixed knife) which is fixed to the bed portion 2a (see Fig. 2) via a knife receiving base (not shown). In some cases, the cloth cutting knife 9 is arranged on the bed portion 2a or on the vertical drum portion 2b. In a state in which the workpiece is arranged between the cloth cutting knife 9 and the knife receiver 10, a knife drive mechanism (not shown) moves the cloth cutting knife 9 toward the knife receiver 10 such that the cloth cutting knife 9 is brought into contact with the knife receiver 10, whereby a part of the workpiece sandwiched between the cloth cutting knife 9 and the knife receiver 10 is pressure-cut, and a slit penetrating through the workpiece in the thickness direction is formed. The upper end of the knife receiver 10 is arranged at substantially the same height as that of the upper surfaces of a pair of left and right cloth receiving plates 22.

[0035] On the upper surface portion of the bed portion 2a, a feed base 11 on which the workpiece is placed is arranged. On the upper surface portion of the feed base 11, the pair of left and right cloth receiving plates 22 (Fig. 2) of a cloth opening device 21 is arranged. Above the pair of cloth receiving plates 22, cloth pressers 13 are arranged, respectively. Presser drive mechanisms 14 moves the respective cloth pressers 13 are toward and away from the cloth receiving plates 22. The cloth presser 13 and the presser drive mechanism 14 are also provided in pairs.

[0036] The presser drive mechanism 14 includes a presser drive arm 15 having the cloth presser 13 on the distal end portion. The presser drive arm 15 is rotatable around a presser support pin 16 which is horizontally arranged on the rear end portion of the cloth receiving plate 22 such that its axial direction is directed in the left-right directions. The presser drive arm 15 is rotated by a driving force of an actuator (not shown) which is arranged inside the feed base 11. The feed base 11 is disposed below the cloth receiving plate 22. In accordance with the rotation of the presser drive arm 15, the cloth presser 13 is brought into contact with or separated from the cloth receiving plate 22. Thus, when the workpiece is placed on the cloth receiving plate 22, the workpiece can be held between the cloth receiving plate 22 and the cloth presser 13. The cloth presser 13 is supported on the cloth receiving plate 22. Thus, when the cloth receiving plate 22 is moved, the cloth presser 13 moves together with the cloth receiving plate 22.

[0037] The feed base 11 has a low-profile rectangular box shape as a whole, and an upper portion thereof is formed with an opening extending is the front-rear directions between the pair of cloth pressers 13. The feed base 11 is moved horizontally in the front-rear directions and the left-right directions by a feed mechanism (not shown).

[0038] In other words, the workpiece is pressed and held between by the cloth pressers 13 and the cloth receiving plates 22 on the feed base 11. In this state, a slit is opened by the cloth opening device 21, and the feed base 11 is moved in accordance with the shape of the slit to form overlock stitches along the circumference of the slit.

[0039] A material of the workpiece to be processed by the buttonholing machine 1 may be a cloth, a leather, etc.

[0040] Other components of the buttonholing machine 1 are similar to those of conventional buttonholing machines, so that detailed description thereof will be omitted.

[0041] Hereinafter, the cloth opening device 21 will be described in detail with reference to Fig. 2 to Fig. 5.

[0042] As shown in Fig. 2, the cloth opening device 21 includes the pair of cloth receiving plates 22 and a pair of cloth opening means 23.

[0043] Each of cloth receiving plates 22 (the reference numeral 22 is the general reference number of the left cloth receiving plate 22L and the right cloth receiving plate 22R) has a rectangular shape extending in the front-rear directions as a whole. The cloth receiving plates 22 are arranged on the feed base 11 to face each other in the left-right directions on opposite sides of a moving path of the cloth cutting knife 9 (hereinafter, referred to as the moving path). More specifically, the cloth receiving plates 22 are arranged bilaterally symmetrical with respect to the moving path, on the left and right sides of the knife receiver 10.

[0044] The pair of cloth opening means 23 (the reference numeral 23 is the general reference number of the left cloth opening means 23L and the right cloth opening means 23R) are also arranged bilaterally symmetrical so as to face each other in the left-right directions across the moving path. When the pair of cloth receiving plates 22 is moved in the left-right directions so as to separate away from the moving path, the workpiece that is held by the pair of cloth receiving plates 22 is pulled (stretched) in the left and right directions, whereby a slit formed in a workpiece by the cloth cutting knife 9 is opened.

[0045] Because the cloth opening means 23 are configured and arranged bilaterally symmetrical on the feed base 11, the right cloth opening means 23R will be mainly described hereinafter, and detailed description of the left cloth opening means 23L will be omitted.

[0046] As shown in Fig. 3 to Fig. 5, the right cloth opening means 23R includes an upper link 25, and a lower link 26 which is arranged below the upper link 25. The upper link 25 and the lower link 26 have flat plate shapes extending in the front-rear directions, and are arranged by directing the thickness directions of these links in the up-down directions. The upper link 25 and the lower link 26 are arranged to overlap vertically in a state in which they are shifted from each other in the front-rear directions such that the front end of the upper link 25 is positioned forward of the front end of the lower link 26, and the rear end of the lower link 26 is positioned rearward of the rear end of the upper link 25. The upper link 25 and the lower link 26 are arranged to face each other in the up-down directions such that a base end portion of one of the links 25, 26 is closer to a free end portion of the other of the links 25, 26 than to a base end portion of the other of the links 25, 26.

[0047] The front end portion of the upper link 25 is the base end portion which does not overlap the front end portion of the lower link 26. In this base end portion, an upper link support hole 27 penetrating in the thickness direction is formed. By inserting a shoulder screw 28 into the upper link support hole 27 from above and screwing the tip end of the shoulder screw 28 into the feed base 11, the upper link 25 is supported rotatably around the shoulder screw 28 along the horizontal plane. In other words, the upper link 25 is provided with a fulcrum 25F at the base end portion arranged on the front side so that the base end portion is supported by the feed base 11 and the free end portion is rotatable.

[0048] A shoulder screw has a columnar step portion arranged on the head side and a screw portion which is arranged at the center of the tip end of the step portion and has a diameter smaller than the step portion. The step portion of the shoulder screw 28 is fitted in the upper link support hole 27, and the screw portion is screwed into the feed base 11.

[0049] On the free end portion arranged on the rear side of the upper link 25, a plate support pin 29 is provided to project upward, and the tip end portion of the plate support pin 29 is rotatably fitted in and joined to a rear side plate joint hole 30 as a plate joint hole provided on the rear side of the cloth receiving plate 22R.

[0050] At an intermediate portion in the longitudinal direction of the upper link 25, a support hole 31 penetrating in the thickness direction is formed. On the front side of the upper link 25, a slot 32 extending in the left-right directions is formed.

[0051] The rear end of the lower link 26 is defined as a base end portion which does not overlap the rear end of the upper link 25, and in this base end portion, a lower link support hole 33 penetrating in the thickness direction is formed. By inserting a shoulder screw 34 into the lower link support hole 33 from above and screwing the tip end of the shoulder screw 34 into the feed base 11, the lower link 26 is supported rotatably around the shoulder screw 34 along the horizontal plane. In other words, the lower link 26 is provided with a fulcrum 26F at the base end portion arranged on the rear side so that the base end portion is supported by the feed base 11 and the free end portion is rotatable.

[0052] The shoulder screw 34 is has a similar configuration as the shoulder screw 28, and the step portion of the shoulder screw 34 is fitted in the lower link support hole 33 and the screw portion is screwed into the feed base 11.

[0053] On the free end portion arranged on the front side of the lower link 26, a plate support pin 35 is provided so as to project upward, and the tip end portion of the plate support pin 35 passes through a slot 32 formed in the upper link 25 and is rotatably fitted in and joined to a front plate joint hole 36 as a plate joint hole provided on the front side of the right cloth receiving plate 22R. The lower end of the plate support pin 35 is provided so as to project downward of the lower link 26. The size and shape of the slot 32 are set such that, when the cloth receiving plate 22R moves in the left-right directions, the plate support pin 35 does not interfere with it.

[0054] At a substantially intermediate portion in the longitudinal direction of the lower link 26, a slot 37 extending in the front-rear directions is formed toward the front side, and in this slot 37, a square piece 38 having a square planar shape is arranged movably in the front-rear directions. At the central portion of the square piece 38, a through hole 38a penetrating in the up-down directions is formed.

[0055] Below the lower link 26, an input link 39 having a flat plate shape extending in the left-right directions is arranged while the thickness direction of the input link 39 is directed in the up-down directions. On the left end side of the upper surface of the input link 39, a joint pin 39a is provided so as to project upward, and the tip end portion of this joint pin 39a passes through a through hole 38a of the square piece 38 and is rotatably fitted in a support hole 31 of the upper link 25.

[0056] Therefore, the upper link 25 and the lower link 26 are joined by the joint pin 39a, and the upper link 25 and the lower link 26 are joined to the input link 39. Thus, by joining the upper link 25 and the lower link 26 by the joint pin 39a, the upper link 25 and the lower link 26 are configured and arranged such that the base end portions are supported by the feed base 11 and the free end portions are swingable.

[0057] At the right end of the input link 39, a link through hole 39b penetrating in the thickness direction is formed. Below the input link 39, a bell crank 40 is arranged while its thickness direction is directed in the up-down directions. The bell crank 40 is has a substantially L shape in a plan view. The bell crank 40 has a short plate portion 40a arranged to extend in the front-rear directions and a long plate portion 40b extending rightward from the front side of the right side surface of the short plate portion 40a. On the rear side of the upper surface of the short plate portion 40a, a driven pin 40c is provided so as to project upward, and this driven pin 40c is rotatably fitted in the link through hole 39b. In other words, the bell crank 40 and the input link 39 are joined via the driven pin 40c.

[0058] A substantially intermediate portion of the long plate portion 40b of the bell crank 40 is rotatably supported by a crank support pin 41 attached to the feed base 11. To the right end of the long plate portion 40b of the bell crank 40, the front end of a joint plate 42 extending in the front-rear directions is joined rotatably along the horizontal plane by a shoulder screw 43, and the rear end of the joint plate 42 is joined to a knuckle joint 45 attached to an output shaft 44a of the air cylinder 44 as an actuator, rotatably along the horizontal plane by an attaching screw 46. The air cylinder 44 is attached to the feed base 11 along the front-rear directions by setting the output shaft 44a forward.

[0059] Therefore, on the upper link 25 and the lower link 26, a link joining point 47 as a first joint portion joining the two links is provided between the base end portion and the free end portion, and at the link joining point 47, an input point 48 as an input portion for inputting a driving force by the air cylinder 44 is provided. The link joining point 47 is also a point 49 at which a force is applied to the upper link 25 and the lower link 26, and this point 49 is arranged inward of the fulcrums 25F, 26F and the plate joining points 25C, 26C as second joint portions of the links 25, 26. Further, the upper link 25 and the lower link 26 are provided with plate joining points 25C, 26C as second joint portions, respectively, to be used for joining with the cloth receiving plate 22, on the free end sides of the link joining point 47. In other words, on the upper link 25 and the lower link 26, the fulcrums 25F, 26F and the plate joining points 25C, 26C are arranged via the link joining point 47. Further, the plate joining point 25C of the upper link 25 and the plate joining point 26C of the lower link 26 are arranged symmetrically via the link joining point 47.

[0060] The upper link 25 is configured such that, as shown in Fig. 3, the ratio of the distance 25La between the fulcrum 25F (the center of the shoulder screw 28) and the plate joining point 25C (the center of the plate support pin 29) to the distance 25Lb between the fulcrum 25F and the link joining point 47 (the center of the joining point 39a), as a link ratio (a lever ratio), becomes 2:1. Similar to the upper link 25, the lower link 26 is also configured such that the ratio of the distance 26La between the fulcrum 26F (center of the shoulder screw 34) and the plate joining point 26C (center of the plate support pin 35) to the distance 26Lb between the fulcrum 26F and the link joining point 47, as a link ratio of the lower link 26, becomes 2:1.

[0061] The moving amount (a rotation angle) of the plate support pin 29 and the moving amount (a rotation angle) of the plate support pin 35 are set to be equal to each other.

[0062] The link ratio of the distance 25La (26La) to the distance 25Lb (2Lb) is not limited to 2:1, and may be set to any ratio as long as the distance 25La (26La) is longer than the distance 25Lb (2Lb). The distance 25La (26La) can be set in accordance with requirements such as the design concept.

[0063] Below the cloth receiving plate 22, an opening side stopper 51 for restricting a maximum position on the opening side to which the right cloth receiving plate 22 moves rightward and a closing side stopper 52 for restricting a maximum position on the closing side to which the right cloth receiving plate moves leftward are arranged. The stoppers 51 and 52 are attached to the feed base 11 while their positions in the left-right directions are adjustable.

[0064] The opening side stopper 51 of the present embodiment is arranged so that the tip end face thereof positioned on the left side can be brought into contact with and separated from the right side surface on the free end side of the upper link 25, and by bringing the tip end face of the opening side stopper 51 into contact with the right side surface on the free end side of the upper link 25, the opening position which is the maximum rightward movement position of the right cloth receiving plate 22 is restricted. The closing side stopper 52 is arranged such that a slot 52a extending in the left-right directions can be brought into contact with and separated from the lower end portion of the plate support pin 35 of the lower link 26, and by bringing the lower end of the plate support pin 35 inserted in the slot 52a into contact with the right end of the slot 52a, the closing position which is the maximum leftward movement position of the right cloth receiving plate 22 is restricted.

[0065] Next, operations of the cloth opening device 21 having the configuration described above will be described with reference to Fig. 6 and Fig. 7.

[0066] As shown in Fig. 6, in a closed state in which the cloth receiving plate 22R is positioned at a closing position closest to the moving path (a standby state), the output shaft 44a of the air cylinder 44 is held at a withdrawn position at which the output shaft 44a is contracted, and the links 25, 26 overlap in the up-down directions. In Fig. 6, the links 25, 26 vertically overlapping each other are shown by being shifted laterally from each other.

[0067] When the air cylinder 44 is driven from the closed state and the output shaft 44a is elongated, the output shaft 44a advances forward and the bell crank 40 rotates clockwise in Fig. 6 around the crank support pin 41, and in accordance with this clockwise rotation of the bell crank 40, the input link 39 moves rightward. Then, in accordance with the rightward movement of the input link 39, the link joining point 47 moves rightward, and in linkage with this rightward movement of the link joining point 47, the upper link 25 rotates clockwise in Fig. 6 along the horizontal plane around the fulcrum 25F, and in synchronization with this rotation of the upper link 25, the lower link 26 rotates counterclockwise along the horizontal plane around the fulcrum 26F. In accordance with the rotations of the links 25, 26, the plate joining points 25C, 26C move rightward and the cloth receiving plate 22R moves rightward so as to separate from the moving path.

[0068] The upper link 25 is configured such that the link ratio as a ratio of the distance 25La to the distance 25Lb becomes 2:1, and the lower link 26 is also configured such that the link ratio as a ratio of the distance 26La to the distance 26Lb becomes 2:1. Thus, the moving amounts of the plate joining points 25C, 26C as a rightward moving amount of the cloth receiving plate 22 becomes twice as large as the moving amount of the link joining point 47.

[0069] Therefore, the output of the air cylinder 44 necessary for moving the cloth receiving plate 22 becomes 1/2. Accordingly, the air cylinder 44 can be easily downsized.

[0070] When the cloth receiving plate 22R moves rightward and reaches the opening position most separated from the predetermined moving path, it enters an opened state (an actuation finished state). This opened state of the close opening device 21 is shown in Fig. 7.

[0071] The left cloth receiving plate 22L moves leftward similarly. Therefore, the slit in the workpiece held on the pair of left and right cloth receiving plates 22 is opened. To close the slit in the workpiece, the left and right cloth opening means 23 are actuated in reverse, that is, the output shaft 44a of the air cylinder 44 is withdrawn.

[0072] In the closed state, the plate support pin 35 comes into contact with the left end of the slot 52a of the closing side stopper 52, and the tip end face of the opening side stopper 51 separates from the right side surface on the free end side of the upper link 25. Further, in the opened state, the tip end face of the opening side stopper 51 comes into contact with the right side surface on the free end side of the upper link 25, and the plate support pin 35 moves rightward and separates from the left and right ends of the slot 52a of the closing side stopper 52.

[0073] Thus, according to the cloth opening device 21 of the present embodiment, two links, that is, the upper link 25 and the lower link 26 are arranged to face each other in the up-down directions, so that in comparison with the conventional configuration (see Fig. 8) in which the first link 104 and the second link 105 are joined to extend in the front-rear directions, the length in the front-rear directions can be easily shortened.

[0074] According to the cloth opening device 21 of the present embodiment, the fulcrums 25F, 26F are provided on the base end portion sides of the two links, that is, the upper link 25 and the lower link 26, the plate joining points 25C, 26C are provided on the free end sides, and a link joining point 47 which also serves as an input point 48 is provided between the base end portions and the free end portions, that is, inward of the fulcrums 25F, 26F and the plate joining points 25C, 26C, so that the link ratios can be set such that the distances 25La, 26La become longer than the distances 25Lb and 25Lb, and therefore, the output of the air cylinder 44 can be made smaller.

[0075] In other words, according to the cloth opening device 21 of the present embodiment, the output of the air cylinder 44 can be easily and reliably made smaller by changing the link ratios.

[0076] Therefore, according to the cloth opening device 21 of the present embodiment, the space occupied by the cloth opening means 23 arranged on the feed base 11 can be reduced and space-saving can be easily and reliably realized.

[0077] According to the cloth opening device 21 of the present embodiment, the fulcrums 25F, 26F are provided on the base end portion sides of the two links, that is, the upper link 25 and the lower link 26, the plate joining points 25C, 26C are provided on the free end sides, and the link joining point 47 which also serves as an input point 48 is provided between the base end portions and the free end portions, that is, inward of the fulcrums F and the plate joining points C, so that while the lengths of the upper link 25 and the lower link 26 are set to be equal to each other, the link ratios can be set such that the distances 25La, 26La increase and the distances 25La, 26La become longer than the distances 25Lb, 26Lb, so that the rotation radiuses of the plate joining points 25C, 26C can be made larger than conventional. As a result, the displacement in the front-rear directions which occurs when the cloth receiving plates 22 move can be easily and reliably made smaller than conventional.

[0078] Further, according to the cloth opening device 21 of the present embodiment, the space occupied by the cloth opening means 23 arranged on the feed base 11 can be reduced, so that the space which can be assigned to other mechanisms such as the drive mechanisms of the cloth pressers 13 can be increased. As a result, the degree of freedom in design can be improved.

[0079] Further, according to the cloth opening device 21 of the present embodiment, the space occupied by the cloth opening means 23 arranged on the feed base 11 can be reduced, so that the feed base 11 can also be made smaller, and due to a reduction in weight in accordance with the downsizing of the cloth opening means 23, the output of the drive source for driving the feed mechanism which moves the feed base 11 can also be made smaller, and the main body 2 can also be reduced in size and weight.

[0080] While the present invention has been shown and described with reference to A certain embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A cloth opening device (8) for a buttonholing machine (1), the cloth opening device (8) comprising:

a pair of cloth receiving plates (22L, 22R) which are adapted to hold a workpiece on upper surfaces thereof, and are arranged on a feed base (11) to face each other in left-right directions on opposite sides of a moving path of a cloth cutting knife (9); and

a pair of cloth opening means (23L, 23R) which moves the pair of cloth receiving plates (22L, 22R) along the left-right directions such that each of the cloth opening means (23L, 23R) moves a corresponding one of the cloth receiving plates (22L, 22R) toward or away from said moving path to open or to close a slit that is formed in the workpiece by the cloth cutting knife (9),

characterized in that each of the cloth opening means (23L, 23R) comprises two links (25, 26), each of which having a base end portion supported by the feed base (11) and a swingable free end portion, and an actuator (44) which actuates the links (25, 26), the two links (25, 26) are arranged such that longitudinal directions thereof are oriented along front-rear directions which are orthogonal to the left-right directions, and are arranged to face each other in up-down directions such that the base end portion of one of the links (25, 26) is closer to the free end portion of the other of the links (25, 26) than to the base end portion of said other of the links (25, 26), the two links (25, 26) comprise a first joint portion (47) at which the two links (25, 26) are joined, wherein the first joint portion (47) is located between the base end portion and the free end portion of each of the links (25, 26), and each of the two links (25, 26) comprises a second joint portion (25C, 26C) which is joined to the corresponding cloth receiving plate (22L, 22R) and is located between the respective free end and the first joint portion.

2. The cloth opening device (8) according to claim 1, wherein the second joint portions (25C, 26C) of the two links (25, 26) are symmetrically arranged with respect to the first joint portion (47), and the first joint portion (47) comprises an input portion (48) from which a driving force of the actuator (44) is input

Drawing