EP2615199B1

EP2615199B1 - Buttonholing machine

Info

Publication number: EP2615199B1
Application number: EP20130150672
Authority: EP
Inventors: Takashi Sugiyama; Yutaka Hirasawa; Kenji Murai; Wataru Kawaguchi
Original assignee: Juki Corp
Current assignee: Juki Corp
Priority date: 2012-01-10
Filing date: 2013-01-09
Publication date: 2014-10-08
Anticipated expiration: 2033-01-09
Also published as: JP5957227B2; JP2013141482A; EP2615199A1; CN103194860B; CN103194860A

Description

The present invention relates to a buttonholing machine.
A buttonholing machine includes a needle oscillating mechanism configured to cause a needle bar to make a needle oscillating motion, and a thread take-up mechanism configured to take up a needle thread, see by example EP-A-0 887 454 .
As a conventional buttonholing machine, for example, the buttonholing machine "299U" manufactured by Singer Corporation has been known. In this buttonholing machine, as shown in Fig. 10, a lower shaft 202 is rotated by a sewing machine motor 201 and is coupled to a looper mechanism 210. An upper shaft 204 moves a needle bar 209 up and down, and causes the needle bar 209 to make a needle oscillating motion. The rotation of the lower shaft 202 is transmitted to the upper shaft 204 through a vertical shaft 203 perpendicular to the upper shaft 204. The lower shaft 202 and the vertical shaft 203 are coupled by bevel gears 205 and 206, and the vertical shaft 203 and the upper shaft 204 are coupled by bevel gears 207 and 208.
On the other hand, in a buttonholing machine disclosed in JP4702608B2 , an upper shaft and a shaft perpendicular to the upper shaft are coupled by using hypoid gears. That is, as shown in Fig. 9, the buttonholing machine includes an upper shaft 101 having a front end portion providing an up-down movement to a needle bar via a crank rod mechanism 105, and an auxiliary shaft 102 rotating at half the rotation speed of the upper shaft 101. A lower shaft is rotated by a sewing machine motor disposed at the lower portion in the rear of the sewing machine, and the rotation is transmitted from the lower shaft to the upper shaft 101 via a belt mechanism. A hypoid gear 103 fixed to the upper shaft 101 and a hypoid gear 104 fixed to the auxiliary shaft 102 mesh each other to couple the upper shaft 101 and the auxiliary shaft 102 such that the upper shaft 101 and the auxiliary shaft 102 interlock at a rotation ratio of 2:1. The auxiliary shaft 102 has one end providing a back and forth needle oscillating motion to the needle bar via the crank rod mechanism 106, and the other end providing a back and forth oscillating motion of the thread take-up via the crank rod mechanism 107.
Because the buttonholing machines of Figs. 9 and 10 are configured to cause the needle bars to make a needle oscillating motion, two loopers are provided so that the a needle thread can be caught at both sides of the needle oscillation.
In the buttonholing machine shown in Fig. 10, in order to cause the needle to make up-down movement at double the frequency of oscillation of the two loopers, the upper shaft 204 rotates at double the rotation speed of the lower shaft 202. Accordingly, the transmission ratio of the bevel gears 207 and 208 is set such that the rotation speed of the vertical shaft 203 is doubled when transmitting the rotation of the vertical shaft 203 to the upper shaft 204.
However, the up-down movement of the needle bar generates a periodic torque variation, and when the rotation is transmitted from the upstream side to the downstream side of a power transmission path using bevel gears while increasing the rotation speed, operating sound and vibration from the gear mechanism become severe due to the torque variations. This causes loud noise and deteriorates working condition, and also lowers durability of the respective portions due to the vibration.
Further, the vertical shaft 203 is required to have a length to transmit torque from the lower shaft 202 provided below the sewing machine head to the upper shaft 204 provided on the upper side of the sewing machine head. When such a long vertical shaft 203 is used, an extended amount caused by thermal expansion according to a rise in surrounding temperature is large, and the bevel gears mesh with each other in a pressed state, which results in a great torque loss.
In the buttonholing machine shown in Fig. 9, the stability at the time of high-speed rotation of the upper shaft 101 and the auxiliary shaft 102 is improved by use of the hypoid gears 103 and 104 for coupling of the upper shaft 101 and the auxiliary shaft 102 perpendicular to one another. However, because special processing by a dedicated processing machine is required for the manufacture of the hypoid gears 103 and 104, the manufacturing cost of the sewing machine is increased.
An object of the present invention is to provide a buttonholing machine having a structure with low noise and vibration, at a low cost.
According to an aspect of the present invention, a buttonholing machine is provided. The buttonholing machine includes a frame having a bed portion, a vertical drum portion extending upward from the bed portion, and an arm portion extending from the vertical drum portion and above the bed portion, a needle bar holding a sewing needle, a needle up-down moving mechanism provided inside the arm portion to move the needle bar up and down, an upper shaft rotatably provided inside the arm portion and coupled to the needle up-down moving mechanism, a looper mechanism having a pair of loopers and provided inside the bed portion, a lower shaft rotatably provided inside the bed portion and coupled to the looper mechanism, a sewing machine motor coupled to one of the upper shaft and the lower shaft, a transmission mechanism configured to interlock the upper shaft and the lower shaft, and a vertical shaft arranged along an up-down direction so as to be rotatable with respect to the frame. The vertical shaft has an upper portion coupled to the upper shaft via bevel gears and a lower portion coupled to at least one of a thread take-up mechanism and a needle oscillating mechanism. The bevel gears are configured to transmit the rotation of the upper shaft to the vertical shaft such that the rotation speed of the upper shaft is reduced by half.
A bottom end of the vertical shaft may be located higher than a top surface of the bed portion.
The bottom end of the vertical shaft may be located higher than a bottom end of the arm portion.
The lower portion of the vertical shaft may be coupled to the thread take-up mechanism, and a portion of the vertical shaft above the lower portion of the vertical shaft may be coupled to the needle oscillating mechanism.
he needle oscillating mechanism may include a link member coupled to the vertical shaft, a supporting member holding the needle bar to provide an oscillating motion to the needle bar, and a bell crank member having an arm portion coupled to the supporting member and another arm portion coupled to the link member.
The sewing machine motor may be coupled to the upper shaft, and the transmission mechanism may be configured to transmit the rotation of the sewing machine motor to the lower shaft such that the rotation speed of the sewing machine motor is reduced by half.
Because the upper shaft and the vertical shaft are coupled by using the bevel gears, not hypoid gears, manufacturing cost of the sewing machine can be reduced.
The output shaft of the sewing machine motor may be coupled directly to the upper shaft. In this case, it is possible to suppress the occurrence of vibration and noise as compared with the case where torque is applied to the upper shaft via bevel gears.
The vertical shaft may be provided so as not to transmit power to the lower shaft. In this case, there is no need for the vertical shaft to have the length for connecting the lower shaft and the upper shaft. Thus, it is possible to prevent an increase in torque due to thermal expansion of the vertical shaft according to a rise in temperature, which results in a reduction in load on the sewing machine motor.
Further, in the case where the arm portion of the bell crank member of the needle oscillating mechanism is coupled to the vertical shaft at a position above the lower portion of the vertical shaft to which the thread take-up mechanism is coupled, as compared with the case where the arm portion of the bell crank member is coupled to the lower portion of the vertical shaft, it is easier to provide a turning motion to the arm portion from a direction perpendicular to the arm portion, which makes it possible to reduce a load due to the oscillating motion, and achieve the stability of the oscillating motion.
Further, when an eccentric cam configured to provide a reciprocating motion to the bell crank member and a grooved cam configured to provide a movement to the thread take-up mechanism are secured to the vertical shaft, it is possible to further suppress the occurrence of vibration and noise.
Other aspects and advantages of the present invention will be apparent from the following description, drawings, and the claims.
The following description of embodiments of the present invention describes the present invention in greater detail along with the drawings. The drawings include:

Fig. 1:: a side view of a buttonholing machine according to an embodiment of the invention.
Fig. 2:: a perspective view of an internal structure of the buttonholing machine;
Fig. 3:: a plan view of a needle oscillating mechanism;
Fig. 4:: a side view of a thread take-up mechanism;
Fig. 5:: a plan view of the thread take-up mechanism;
Fig. 6:: an explanatory front view of a cloth cutting knife mechanism, illustrating a state in which a hammer has retracted upward;
Fig. 7:: an explanatory diagram of operation of the cloth cutting knife mechanism, illustrating a state in which the hammer has moved down to carry out cutting;
Fig. 8:: an explanatory diagram illustrating an example of the order of stitching in an eyelet buttonhole sewing;
Fig. 9:: a plan view of an internal structure of a conventional buttonholing machine; and
Fig. 10:: a side view of an internal structure of another conventional buttonholing machine.

A buttonholing machine 1 according to an embodiment of the present invention will be described with reference to Figs. 1 to 8. The buttonholing machine 1 is an eyelet buttonholing machine capable of forming an eyelet buttonhole. As shown in Figs. 1 and 2, the buttonholing machine 1 includes a frame 2 (sewing machine frame) having a bed portion 2a with a horizontal and flat top surface 2aa, a vertical drum portion 2b extending upward from the bed portion 2a, and an arm portion 2c extending from the vertical drum portion 2b and above the bed portion 2a. In the following description, the Z-axis direction is the up-down direction, the Y-axis direction is the horizontal direction (longitudinal direction) perpendicular to the Z-axis direction and in which the bed portion 2a and the arm portion 2c extend, and the X-axis direction the horizontal direction perpendicular to the Y-axis direction and the Z-axis direction.
As shown in Fig. 1, the buttonholing machine 1 includes a needle bar 12 holding a sewing needle 11 through which an upper thread is passed, a needle up-down moving mechanism 50 configured to the needle bar 12 up and down, a needle oscillating mechanism 40 configured to oscillate the needle bar 12 to perform needle oscillation, a looper mechanism 60 including loopers to interlace an upper thread and a lower thread, a turning mechanism 20 configured to turn a needle bar turning base 42 of the needle oscillating mechanism 40 and the looper mechanism 60, a sewing machine motor 13 serving as a driving source of sewing operation and fixed to the upper portion of the frame 2, a thread take-up mechanism 70 configured to take up the upper thread from the sewing needle side or feeds out the upper thread from a thread-feeding source side, and a cloth feeding mechanism 80 configured to move a workpiece along the X-Y plane by an optional moving amount to position the workpiece, a cloth cutting knife mechanism 30 configured to form a slit to provide a buttonhole in a cloth (a workpiece), an upper shaft 14 disposed along the Y-axis direction inside the arm portion 2c, a vertical shaft 15 provided together with the upper shaft 14, a lower shaft 16 disposed along the Y-axis direction inside the bed portion 2a, a transmission mechanism 90 configured to transmit torque from the sewing machine motor 13 to the lower shaft 16, and a coupling mechanism 95 configured to transmit torque from the upper shaft 14 to the vertical shaft 15.

Upper Shaft

The upper shaft 14 is supported so as to be rotatable along the Y-axis direction inside the arm portion 2c, and the output shaft of the sewing machine motor 13 is coupled to one end of the upper shaft 14 via a coupling 13a. That is, the upper shaft 14 is connected directly to the sewing machine motor 13 to rotate at the same speed as the output shaft.

Needle Bar

The needle bar 12 is formed into an internally hollow tubular form, and has a structure in which the upper thread is inserted from the top end opening to guide the upper thread through the hollow interior to the sewing needle 11 at its bottom end.

Needle Up-Down Moving Mechanism

The needle up-down moving mechanism 50 is disposed in the leading end of the arm portion 2c, and is coupled to the upper shaft 14. The needle up-down moving mechanism 50 includes a needle bar crank 51 fixedly attached to the other end of the upper shaft 14, a crank rod 52 having one end coupled so as to be rotatable around the Y-axis at a position of the needle bar crank 51 eccentrically-located from the upper shaft 14, and a needle bar connecting bracket 53 holding the needle bar 12.
The needle bar crank 51 rotates integrally with the upper shaft 14, and the crank rod 52 transmits only a displacement in the Z-axis direction (up-down movement) in a circling movement at the portion coupled to the needle bar crank 51, to the needle bar connecting bracket 53.
The needle bar connecting bracket 53 holds the needle bar 12 so as not to move it along its longitudinal direction while allowing the rotation around the axis line of the needle bar 12 itself. Accordingly, it is possible to transmit the up-down movement from the crank rod 52, to the needle bar 12 while it is possible to allow the needle bar 12 to turn.
Further, a universal joint is interposed in a sleeve 54 supporting the needle bar 12, which is configured to allow the needle oscillation of the needle bar 12, which will be described later.

Vertical Shaft

The vertical shaft 15 is disposed so as to be rotatable at the frame 2, specifically, at the arm portion 2c along the Z-axis direction. The lower portion of the vertical shaft 15 is coupled to the thread take-up mechanism 70, and the portion of the vertical shaft 15 higher than the lower portion of the vertical shaft 15 is coupled to the needle oscillating mechanism 43.
The vertical shaft 15 is supported by a bearing 56 fixed to the arm portion 2c so as to be rotatable inside the arm portion 2c. The top end of the vertical shaft 15 is disposed near the middle of the upper shaft 14 with respect to the longitudinal direction of the upper shaft 14. The axis line of the vertical shaft 15 is perpendicular to the axis line of the upper shaft 14. The vertical shaft 15 has a length with which the bottom end of the vertical shaft 15 is located higher than the top surface of the bed portion 2a, and more preferably, a length with which the bottom end of the vertical shaft 15 is located higher than the lowermost portion of the arm portion 2c, in a state where a sewing machine is assembled.

Coupling Mechanism

The coupling mechanism 95 has a main driving bevel gear 96 fixedly mounted on the upper shaft 14, and a driven bevel gear 97 fixedly mounted on the upper portion of the vertical shaft 15, specifically, to the top end of the vertical shaft 15. The main driving bevel gear 96 and the driven bevel gear 97 are disposed so as to mesh with each other. The driven bevel gear 97 has twice as many gear teeth as the number of gear teeth of the main driving bevel gear 96. Therefore, the main driving bevel gear 96 and the driven bevel gear 97 reduce the rotation speed of the upper shaft 14 by half, to transmit the rotation of the upper shaft 14 to the vertical shaft 15.

Needle Oscillating Mechanism

As shown in Figs. 1 to 3, the needle oscillating mechanism 40 includes a supporting member 41 which is coupled to the intermediate portion in the direction of the axis line of the vertical shaft 15, to support the needle bar 12 so as to be able to move the needle bar 12 up and down, a needle bar turning base 42 which supports the supporting member 41, and is supported so as to be able to turn around the Z-axis at the arm portion 2c, a bell crank member 43 whose one arm portion 43a is coupled to the supporting member 41, an oscillating arm 45 which contains an eccentric cam (not shown) which is provided to the vertical shaft 15, and a link member 44 which couples the oscillating arm 45 and the other arm portion 43b of the bell crank member 43.
The supporting member 41 is structured such that the needle bar 12 is inserted through it, so as to slidably hold the needle bar 12, which does not interfere with the up-down movement of the needle bar 12. An oblique groove directed obliquely upward is formed in the supporting member 41, and a protrusion fitting into the oblique groove is formed on the needle bar turning base 42. Accordingly, when the supporting member 41 is pulled upward, the supporting member 41 moves obliquely upward along the oblique groove. Thereby, causing the bottom end of the needle bar 12 to move along the X-axis direction, and tilting the needle bar 12 by the universal joint of the sleeve 54 supporting the needle bar 12, that performs needle oscillation. That is, an oscillating movement (needle oscillating movement) is given to the needle bar 12 by the up-down movement of the supporting member 41.
The needle bar turning base 42 supports the supporting member 41 so as to be movable obliquely as described above, and turns the supporting member 41 at the same time in turning. With this turning, it is possible to change the direction of the needle oscillation of the needle bar 12, which performs needle oscillation by the supporting member 41, to an optional direction on the X-Y plane.
The bell crank member 43 is supported so as to be able to turn around the X-axis in the arm portion 2c, and includes the arm portion 43a extending substantially along the Y-axis direction, and the arm portion 43b extending upward. The one arm portion 43a is coupled to the supporting member 41 so as to be able to turn around the X-axis and the Z-axis, and the other arm portion 43b is coupled to the other end of the aforementioned link member 44 via a long hole formed along its longitudinal direction.
The respective ends of the link member 44 are coupled to the oscillating arm 45 and the bell crank member 43 via the universal joint.
The oscillating arm 45 has a C-shape in top view, and a holding plate 48 is screw-fixed to the open portion. The oscillating arm 45 and the holding plate 48 form a frame shape, and an eccentric cam (triangular cam) 46 fixed to the intermediate portion in the direction of axis line of the vertical shaft 15 is housed in the frame shape. Further, one end of the oscillating arm 45 is pivotally supported along the Z-axis direction by a support shaft 47 fixed to the sewing machine arm 2. The other end of the oscillating arm 45 is coupled to the one end side of the link member 44 via a universal joint and a fixation screw. These universal joint and fixation screw form a coupling portion 49.
The oscillating arm 45 performs one reciprocating turning motion per rotation of the vertical shaft 15, and the link member 44 performs one reciprocating motion substantially along the Y-axis direction, to turn the bell crank member 43. The bell crank member 43 moves the supporting member 41 up and down at the same frequency as half of the number of rotations of the upper shaft 14 by the above-described turning, to execute needle oscillation. That is, one reciprocating needle oscillation is performed per rotation of the vertical shaft 15.
The other arm portion 43b of the bell crank member 43 is capable of adjusting the coupling position of the link member 44 along its long hole. Due to this position adjusting, it is possible to change and adjust a turning stroke of the bell crank member 43 provided by the link member 44, thereby, adjusting the width of needle oscillation of the needle bar 12.
Further, the other arm portion 43b of the bell crank member 43 and its long hole are formed into a circular arc shape, and even when the coupling position of the link member 44 is changed in a state in which the needle bar 12 is not tilted, the bell crank member 43 is not caused to turn.
The eccentric cam 46 configured to provide a reciprocating motion to the bell crank member 43 via the oscillating arm 45 and the link member 44, and a grooved cam 75 configured to provide a movement to the thread take-up mechanism are secured to the vertical shaft 15. As attaching positions thereof, the eccentric cam 46 is disposed on the upper side and the grooved cam 75 is disposed on the lower side across the bearing 56. With this arrangement, the attaching positions are suitable for the case where the arm portion 43b of the bell crank member 43 extends substantially along the Z-axis direction in a state in which the needle bar 12 is not tilted, and this is coupled to the vertical shaft 15 in a state in which the arm portion 43b of the bell crank member 43 and the link member 44 are perpendicular to one another.
When the link member 44 is perpendicular to the arm portion in the state in which the arm portion 43b extends along the Z-axis direction, it is possible to efficiently perform torque transmission from the vertical shaft 15 to the bell crank member 43.

Thread Take-Up Mechanism

In Figs. 4 and 5, the thread take-up mechanism 70 coupled to the lower portion of the vertical shaft 15, specifically, to the vicinity of the bottom end of the vertical shaft 15 is provided between a thread tensioner 17 and a needle bar side thread guide 18 which are located on the upstream side of the upper thread path, and produces a change of the thread path length to the upper thread U fed from a thread feeding source, to perform thread fastening for forming a stitch and thread feeding-out from the thread feeding source.
The thread take-up mechanism 70 includes a pair of thread guides 71 and 72 which are fixedly mounted on the thread path for the upper thread in the top surface of the arm portion 2c, an arm member 73 which has an insertion portion 73a through which the upper thread U is inserted, in its turning end, a turning pivot 74 along the Z-axis direction, that pivotally supports the arm member 73, the grooved cam 75 which is fixedly mounted on the lower portion of the vertical shaft 15, and a driven arm 76 which has a cam roller 76a fitting into the cam groove 75a of the grooved cam 75.
The cam groove 75a is formed so as to make a circuit surround the vertical shaft 15 in the top surface of the grooved cam 75. Due to the cam roller 76a fitting into the cam groove 75a, the turning end of the driven arm 76 fixedly mounted on the turning pivot 74 adjacent to the vertical shaft 15 turns according to the shape of the cam groove 75a, to turn the arm member 73 as well through the turning pivot 74 in the same way as the driven arm 76. The phase of the cam groove 75a of the grooved cam 75 is adjusted such that a section in which the distance from the vertical shaft 15 is increased matches the timing at which the upper thread is to be taken up.
The thread guides 71 and 72 have insertion holes through which the upper thread is inserted, and these insertion holes of the thread guides 71 and 72 are formed on the same straight line along the Y-axis direction.
The arm member 73 is attached to the turning pivot 74 such that the insertion portion 73a at the turning end thereof makes reciprocating movement substantially along the X-axis direction between the thread guides 71 and 72 in a state in which the arm member 73 is directed substantially in the Y-axis direction. When the upper thread U is inserted through the thread guide 71, the insertion portion 73a, and the thread guide 72 in this order, and the arm member 73 makes a turning motion, the thread path length between the thread guides 71 and 72 is fluctuated, to perform feeding-out and taking-up of the upper thread U according to the fluctuating range.
The insertion portion 73a of the arm member 73 is adjusted so as to make a reciprocating motion within the range on only one side in the X-axis direction with respect to the straight line connecting the thread guides 71 and 72, but not to make a reciprocating motion over the straight line connecting the thread guides 71 and 72.
Further, the arm member 73 includes a screw 77 for fastening-fixation with respect to the turning pivot 74 on the base end side, and is capable of adjusting its orientation around the turning pivot 74 by loosening of fastening. In this case, because the angular range of the reciprocating turning of the arm member 73 is determined according to the cam shape of the grooved cam 75, even when the arm member 73 is adjusted in angle with respect to the turning pivot 74, a difference between the minimum thread feeding-out amount and the maximum thread feeding-out amount is not fluctuated. However, it is possible to adjust the minimum thread feeding-out amount and the maximum thread feeding-out amount of the upper thread U by the above-described angular adjustment.
The portion of the needle bar side thread guide 18 through which the upper thread U is inserted is configured as a separate member, and its position is vertically adjustable.

Transmission Mechanism

The transmission mechanism 90 includes a main driving sprocket 91 provided on the output shaft of the sewing machine motor 13, a driven sprocket 92 provided to one end of the lower shaft 16, a timing belt 93 bridged between these sprockets 91 and 92, and a tension roller 94 which applies tension to the timing belt 93.
The ratio of effective diameters of the main driving sprocket 91 and the driven sprocket 92 is 1:2, and torque is transmitted from the sewing machine motor 13 to the lower shaft 16 at half the rotation speed.

Looper Mechanism

The looper mechanism 60 is disposed in the upper portion of the bed portion 2a and on the lower side of the cloth feeding mechanism 80 which will be described later. This looper mechanism 60 is supported so as to be rotatable around the rotation center line which is the same as the turning center line of the needle bar 12 by the bed portion 2a, and the upper portion thereof includes a left looper and a left spreader for interlacing the lower thread with the upper thread, to perform double chainstitch, and a right looper and a right spreader for performing single-thread chainstitch. The looper mechanism 60 is supplied with power for operating these respective loopers and respective spreaders from the lower shaft 16. The lower shaft 16 rotates at half the rotation speed of the upper shaft 14 as described above. However, because the left looper and the left spreader, and the right looper and the right spreader respectively operate alternately per rotation of the lower shaft 16, it is possible to respectively execute double chainstitch and single thread chainstitch with respect to the sewing needle 11 that makes up-down movement at double the frequency of the loopers.
That is, with respect to the left looper and the left spreader and the right looper and the right spreader, during sewing, the left looper and the left spreader perform double chainstitch with respect to inner needle stitch points of the needle bar 12, and the right looper and the right spreader perform single thread chainstitch with respect to outer needle stitch points of the needle bar 12.

Turning Mechanism

The turning mechanism 20 includes a turning motor 21 which is disposed in the bed portion 2a, a main driving sprocket 22 which is provided to the output shaft of the turning motor 21, a transmission shaft 25 equipped with sprockets 23 and 24 up and down, a timing belt 26 which transmits the rotation of the turning motor 21 to a sprocket (not shown) provided in the looper mechanism 60 and the sprocket 23, a sprocket 27 which is provided to the needle bar turning base 42, and a timing belt 28 which is bridged between the sprockets 24 and 27. With this configuration, the turning motion is transmitted from the turning motor 21 to the looper mechanism 60 and the needle bar 12 in the same phase. Accordingly, the turning mechanism 20 provides the turning motion such that the direction of the needle oscillation of the needle bar 12 and the direction in which the right and left loopers and spreaders are arranged are always the same.

Cloth Feeding Mechanism

The cloth feeding mechanism 80 includes a placing base 81 having a placing plane for a workpiece, which is parallel to the X-Y plane, an X-axis motor 82 serving as a cloth-moving motor that moves the placed workpiece in the X-axis direction, a Y-axis motor 83 serving as a cloth-moving motor that moves the placed workpiece in the Y-axis direction, a well-known power transmission mechanism which converts rotary driving force of the respective motors 82 and 83 into linear motion driving force along the X-axis direction and the Y-axis direction, to apply the force to the workpiece.

Cloth Cutting Knife Mechanism

Fig. 6 is an explanatory diagram of operation of the cloth cutting knife mechanism 30 showing a state in which a cloth cutting hammer 32 retreats upward (initial position), and Fig. 7 is an explanatory diagram of operation of the cloth cutting knife mechanism 30 showing a state in which the hammer 32 comes down to carry out cutting (cloth cutting position).
As shown in Fig. 6, the cloth cutting knife mechanism 30 includes a cloth cutting knife 31 which is fixedly mounted on the bed portion 2a such that its cutting edge is directed upward on the top surface of the bed portion 2a, the hammer 32 which is pressed against the cloth cutting knife 31 from above to form a slit serving as a buttonhole in a workpiece cloth between the hammer 32 and the cloth cutting knife 31, a cloth cutting arm 33 serving as a first lever member which holds the hammer 32 with its one end, and is supported so as to be able to turn to the frame 2, an air cylinder 34 (a linear actuator) serving as a driving source for cloth cutting motion, an input arm 35 serving as a second lever member whose one end is coupled to the output shaft 34a, that makes forward and backward motion of the air cylinder 34, a link member 36 which couples the input arm 35 and the cloth cutting arm 33 so as to be capable of interlocking, and a first sensor 145 and a second sensor 144 which are supported by a supporting member 2d fixed to the frame 2, that detect an operating condition of the cloth cutting knife mechanism 30.
The cutting edge of the cloth cutting knife 31 has a drop-shaped eyelet portion for eyelet buttonholing and a linear straight portion, so that the cloth cutting knife 31 is capable of forming both eyelet buttonholes and straight buttonholes.
The opposed surface of the hammer 32 with respect to the cloth cutting knife 31 is formed smoothly. The hammer 32 is pressed against the opposed surface of the cloth cutting knife 31, to form a buttonhole in a cloth interposed between the cloth cutting knife 31 and the hammer 32.
The cloth cutting arm 33 extends substantially along the Y-axis direction inside the frame 2, and a first support shaft 142 along the X-axis direction is provided in the vicinity of the intermediate portion in the longitudinal direction. The first support shaft 142 is fixed to the frame 2, to support the cloth cutting arm 33 so as to be able to turn it. As described above, the hammer 32 is attached and fixed to the one end (leading end side) of the cloth cutting arm 33 so as to face downward. Further, a first coupling pin 137 is fixed to the other end (rear end side) of the cloth cutting arm 33. One end of the link member 36 is coupled to the first coupling pin 137 so as to be able to turn around the X-axis, and the power of turning of the cloth cutting arm 33 is input thereto. That is, the cloth cutting arm 33 has a lever structure in which the one end holding the hammer 32 is the point of action, the other end to which turning force is input is the point of effort, and the first support shaft 142 located therebetween is the fulcrum.
The cloth cutting arm 33 is set such that the length from the first support shaft 142 to the coupling position (the first coupling pin 137) with the link member 36 is longer than the length from the first support shaft 142 to the hammer 32 in order to increase the pressurizing force from the hammer side.
In addition, a tension spring 33b always biasing in a direction in which the hammer 32 retreats upward, is provided together with this cloth cutting arm 33.
The input arm 35 includes a base portion 35c, and first and second arm portion 35a and 35b, each extending from the base portion 35c toward the hammer (in a direction from the second support shaft 143 toward the hammer). The input arm 35 extends substantially along the Y-axis direction inside the frame 2. The input arm 35 is supported so as to be able to turn by the second support shaft 143, which is inserted through the base y portion 35c. The second support shaft 143 is fixed to the frame 2. The input arm 35 includes the first arm portion 35a extending from the second support shaft 143 toward the hammer, and the second arm portion 35b extending longer than the first arm portion 35a from the second support shaft 143 toward the hammer.
A second coupling pin 138 is provided to one end side (the hammer side) of the first arm portion 35a.
Further, a third coupling pin 139 is provided to one end side (the hammer side) of the second arm portion 35b.
The link member 36 is a plate-like member, extending substantially along the Z-axis direction in the frame 2, and a long hole 36a is formed on the upper side. The first coupling pin 137 provided on the rear end side of the cloth cutting arm 33 is inserted through the long hole 36a of the link member 36. Further, the other end side of the link member 36 is coupled to the first arm portion 35a via the second coupling pin 138. The link member 36 couples the end of the cloth cutting arm, which is on the opposite side of the hammer of the cloth cutting arm, and extended one end of the first arm portion 35a.
Further, the air cylinder 34 (a linear actuator) has a main body portion and a plunger 34a (an output shaft). The plunger 34a is supported by the main body portion so as to be able to move forward and backward to the lower side. Further, the top end portion (main body portion) of the air cylinder 34 is supported by the frame 2 so as to be able to turn around the X-axis.
Further, this air cylinder 34 is disposed to be adjacent to the cloth cutting arm 33 along the X-axis direction when viewed from above, and when these are viewed from the X-axis direction, the air cylinder 34 is disposed to intersect with the cloth cutting arm 33. That is, the cloth cutting arm 33 and the air cylinder 34 are disposed so as to intersect with one another when viewed from the direction along the first support shaft (the X-axis direction).
A holding member 140 in which a female screw is formed in the up-down direction is disposed under the plunger 34a. The holding member 140 is screw-fixed to the plunger 34a of the air cylinder 34. The holding member 140 is coupled to the leading end side (one end side) of the second arm portion 35b via the third coupling pin 139 disposed in the X-axis direction. The air cylinder 34 is supported by the frame 2, and the plunger 34a is coupled to the extended one end side of the second arm portion 35b. As a result, the air cylinder 34 is disposed on the cloth cutting arm side and the cloth cutting knife side with respect to the second support shaft 143.
Further, a detection plate 141 is fixed to the holding member 140 with an adjusting screw. The detection plate 141 is supported by the plunger 34a of the air cylinder 34, and when the air cylinder 34 is driven, the detection plate 141 also moves forward and backward along with the plunger 34a.
Further, the first sensor 145 and the second sensor 144 are disposed on the movement locus of the detection plate 141. The first sensor 145 and the second sensor 144 are supported by the supporting member 2d fixed to the frame 2, and the second sensor 144 is located above the first sensor 145.
By driving of the air cylinder 34, the hammer 32 moves between the initial position at which the hammer 32 retreats upward, and the cloth cutting position at which cloth cutting is performed. At this time, the first sensor 145 detects that the hammer 32 is located at the initial position via the detection plate 141. Further, the second sensor 144 detects that the hammer 32 is located at the intermediate position between the initial position and the cloth cutting position via the detection plate 141.
As described above, the input arm 35 has a lever structure in which the second arm portion 35b becomes the point of effort at which the power of turning is input from the air cylinder 34, the second support shaft 143 becomes the fulcrum of turning, and the second coupling pin 138 of the first arm portion 35a coupled to the link member 36 becomes the point of action at which the power of turning is input to the cloth cutting arm 33.
This input arm 35 is set such that the length from the second support shaft 143 to the coupling position with the air cylinder 34 is longer than the length from the second support shaft 143 to the link member 36 in order to increase the turning force toward the cloth cutting arm 33 side.
As shown in Figs. 2 and 7, the air cylinder 34 is disposed on the cloth cutting arm side with respect to the second support shaft 143. Thereby, it is possible to dispose the air cylinder 34 within the range of the total length in the Y-axis direction of the cloth cutting arm 33. Accordingly, with respect to the cloth cutting knife mechanism 30, as compared with the case where the air cylinder 34 is disposed outside of the range of the total length in the Y-axis direction of the cloth cutting arm 33, it is possible to reduce the occupied space of the cloth cutting knife mechanism 30 inside the sewing machine.
Further, the cloth cutting knife mechanism 30 includes the first sensor 145 that detects that the hammer 32 fixed to the leading end side of the cloth cutting arm 33 is located at the initial position at which the hammer 32 retreats upward, and the second sensor 144 that detects an intermediate position between the initial position and the cloth cutting position. Accordingly, because it is possible to reliably detect the turning condition of the hammer 32, the safety is further improved.

Sewing Operation

In addition, when the upper shaft 14 is rotated by driving of the sewing machine motor 13, the needle up-down moving mechanism 50 is interlocked with the upper shaft 14, to move up and down the needle bar 12 throughout all the sections K1 to K7 during sewing. The vertical shaft 15 coupled to the upper shaft 14 is reduced in speed by the main driving bevel gear 96 and the driven bevel gear 97, to rotate. Thereby, performing so-called needle oscillation, that is, the needle oscillating mechanism 40 interlocked with the vertical shaft 15 oscillates the needle bar 12 in a predetermined direction of the needle oscillation such that the sewing needle 11 form stitches alternately at outer stitch point positions and at inner stitch point positions which are respectively away from and close to the eyelet serving as a buttonhole, and the arm member 73 (a thread take-up) interlocked with the vertical shaft 15 makes a thread-taking motion.
The buttonholing machine 1 includes a control device configured to control the respective sections, and the control device stores a sewing program for sequentially executing the control for each of the sections K1 to K7 shown in Fig. 8, and executes sewing based on this program.
To form the buttonhole stitches shown in Fig. 8 by the buttonholing machine 1 having the configuration described above, first, a start switch is turned on by an operator of the sewing machine, whereby bar tack stitch is executed in the section K1. That is, while the control device drives the sewing machine motor 13 to form stitches by the needle oscillation of a predetermined width, the control device drives the Y-axis motor 83 to carry out the stitches forward at set pitches. Then, the control device drives the X-axis motor 82 position a stitch point at the stitch start position in the straight section of the eyelet.
K2 is a section for sewing the straight portion of the eyelet, and the control device drives the sewing machine motor 13 and the Y-axis motor 83 to execute the straight stitch in the direction of forward movement.
K3 is a section for sewing the oblique shape of the drop-shaped portion of the eyelet, and while the control device drives the sewing machine motor 13 to make stitches by the needle oscillation, the control device executes the motion control of carrying the needle 11 obliquely forward by the cooperation of the Y-axis motor 83 and the X-axis motor 82.
K4 is a section for sewing the semicircular arc shape of the drop-shaped portion of the eyelet, and while the control device drives the sewing machine motor 13 to make stitches by the needle oscillation, the control device drives the turning motor 21 to gradually rotate the direction of the needle oscillation 180 degrees, even after the control device executes the motion control of carrying out positioning so as to make stitch points along the margins of the eyelet by the cooperation of the Y-axis motor 83 and the X-axis motor 82.
K5 is a section for sewing another oblique shape of the drop-shaped portion of the eyelet, and while the control device drives the sewing machine motor 13 to make stitches by the needle oscillation, the control device executes the motion control of carrying the needle 11 obliquely backward by the cooperation of the Y-axis motor 83 and the X-axis motor 82.
K6 is a section for sewing another straight portion of the eyelet, and the control device drives the sewing machine motor 13 and the Y-axis motor 83 to execute the straight stitch in the direction of backward movement.
K7 is a section for executing another bar tack stitch, and while the control device drives the sewing machine motor 13 to make stitches by the needle oscillation of a predetermined width, the control device drives the Y-axis motor 83 to carry out the stitch backward, and further, the control device drives the X-axis motor 82 to move the stitch to the center, and the formation of the seam is terminated.
Moreover, when the formation of the seam is terminated, the control device drives the Y-axis motor 83 to move the stitched portion of the cloth to a position directly below the hammer 32.
Then, as shown in Fig. 7, the hammer 32 is made to come down with respect to the cloth cutting knife mechanism 30 in the state of Fig. 6 by bringing the air cylinder 34 into operation. Thereby, the control device confirms the execution of the cloth cutting according to an output from the sensor 37, and after the passage of a predetermined time, the control device cancels the operation of the air cylinder 34 to return the hammer 32 upward. Thereby, completing the cloth cutting operation, and completing the buttonhole sewing work.
s Further, provided that the control device controls the cloth feeding mechanism to start cloth feeding when detecting the intermediate position when the cloth cutting arm 33 moves from the cloth cutting position to the initial position after the cloth cutting process is terminated, it is possible to shorten a cycle time while assuring the safety.
According to the above-described buttonholing machine 1, the coupling mechanism 95 reduces by half the rotation speed of the upper shaft 14 by the main driving bevel gear 96 and the driven bevel gear 97, to transmit the rotation of the upper shaft 14 to the vertical shaft 15. That is, because hypoid gears are not used, it is possible to reduce the manufacturing cost of the sewing machine.
Moreover, the output shaft of the sewing machine motor 13 is directly coupled to the upper shaft 14, to rotate the upper shaft 14. Therefore, it is possible to suppress the occurrence of vibration and noise as compared with the case where torque is applied to the upper shaft 14, which transmit power to the needle up-down moving mechanism that generates torque variation, via the bevel gears.
Moreover, the vertical shaft 15 does not transmit power to the lower shaft 16, and has the length which does not reach the top surface of the bed portion 2a. That is, there is no need for the vertical shaft 15 to have the length reaching the lower shaft 16 from the upper shaft 14. Thereby, it is possible to prevent an increase in torque due to thermal expansion of the vertical shaft 15 according to a rise in temperature, which reduces the load on the sewing machine motor 13.
Further, the arm portion 43b of the bell crank member 43 is coupled to the vertical shaft 15 at a position higher than the lower portion of the vertical shaft 15 to which the thread take-up mechanism 70 is coupled. Therefore, as compared with the case where the arm portion 43b of the bell crank member 43 is coupled to the lower portion of the vertical shaft 15, it is easier to provide a turning motion to the arm portion 43b from a direction perpendicular to the arm portion 43b, which makes it possible to reduce a load due to the oscillating motion, and achieve the stability of the oscillating motion.
Further, with respect to the cloth cutting knife mechanism 30, it is possible to reduce the occupied space in the sewing machine according to the layout of the cloth cutting arm 33, the input arm 35, the link member 36, and the air cylinder 34. Therefore, it is possible to avoid the necessity of downsizing the respective members in the cloth cutting knife mechanism 30, and there is no need to shorten the cloth cutting arm 33. Therefore, there is no need to fold even a workpiece with a long depth, and it is possible to prevent damage of the workpiece as well.
Further, because it is possible to elongate the cloth cutting arm 33 and the input arm 35, it is possible to sufficiently increase power from the air cylinder 34, and it is possible to apply intensive pressurizing force to the hammer 32, to perform more reliable cutting operation.
Further, because it is possible to elongate the cloth cutting arm 33 and the input arm 35, it is possible to sufficiently increase an input from the air cylinder 34 side, thereby it is possible to achieve reduction in load applied to the turning pivots 33a and 35a of the cloth cutting arm 33 and the input arm 35.
Further, the air cylinder 34 is disposed on the cloth cutting arm 33 side, that is, on the upper side of the input arm 35. That is, because the cloth cutting arm 33, the link member 36, and the air cylinder 34 are all located above the input arm 35, it is possible to achieve downsizing of the cloth cutting knife mechanism 30 in a direction perpendicular to the longitudinal direction of the input arm 35 (substantially in the Z-axis direction).
Further, because of the configuration in which the turning pivot 35a of the input arm 35 is located on the side opposite to the coupling position with the air cylinder 34 across the coupling position with the link member 36, the point of effort and the point of action of the input arm 35 are to be disposed on the same side of the fulcrum. As compared with the lever member in which the point of effort and the point of action are disposed so as to sandwich the fulcrum therebetween, it is possible to shorten the total length thereof, and therefore, it is easy to widely secure the space in the back of the hammer 32, which makes it possible to perform sewing of a larger workpiece.
The cloth cutting knife 31 and the hammer 32 in the cloth cutting knife mechanism 30 may be disposed inversely. That is, the cloth cutting knife 31 may be mounted on the cloth cutting arm 33, and the hammer 32 may be fixedly mounted on the top surface of the bed portion 2a.
Further, in the description of the operation of the sewing machine 1, the case where the cloth cutting is executed after the formation of the seam is shown as an example. However, the formation of the seam may be carried out after the cloth cutting is carried out.
According to the above-described embodiment, the buttonholing machine includes the needle up-down moving mechanism 50 which moves the needle bar up and down that holds a sewing needle, the sewing machine motor 13 which is fixed to the upper portion of the frame 2, the upper shaft 14 which has the one end side coupled to the sewing machine motor, and the other end coupled to the needle up-down moving mechanism, the looper mechanism 60 which has the pair of loopers for interlacing a lower thread with an upper thread, the lower shaft 16 which transmits power for bringing the pair of loopers of the looper mechanism into operation, the vertical shaft 15 which is supported so as to be able to turn to the frame 2, and is disposed along the up-down direction, the needle oscillating mechanism 40 which is supplied with driving force from the vertical shaft, to oscillate the needle bar, and the coupling mechanism 95 having the bevel gears 96 and 97 which are mounted on both of the upper shaft and the vertical shaft, to mesh with each other. The output shaft of the sewing machine motor is coupled to the upper shaft. The rotation at half the rotation speed of the upper shaft is transmitted from the upper shaft to the vertical shaft.
The vertical shaft does not transmit power to the lower shaft, and has the length which does not reach the top surface of the bed portion.
The buttonholing machine includes the thread take-up mechanism 70 having the thread take-up which is supplied with power from the vertical shaft 15, to take up the upper thread periodically. The needle oscillating mechanism 40 includes the supporting member 41 which moves the needle bar up and down to provide an oscillating motion to the needle bar, and the bell crank member 43 which has the arm portion 43a coupled to the supporting member 41, and the arm portion 43b coupled to the link member 44. The bell crank member 43 is coupled to the vertical shaft 15 at a position higher than the lower portion of the vertical shaft 15 to which the thread take-up mechanism 70 is coupled.
The eccentric cam 46 that provides a reciprocating motion to the bell crank member 43 via the oscillating arm 45, and the grooved cam 75 that provides movement to the thread take-up mechanism are secured to the vertical shaft 15.
The buttonholing machine includes the transmission mechanism 90 which reduces by half the rotation speed of the sewing machine motor 13, to transmit the rotation of the sewing machine motor 13 to the lower shaft.

Claims

A buttonholing machine (1) comprising:
a frame (2) having a bed portion (2a), a vertical drum portion (2b) extending upward from the bed portion (2a), and an arm portion (2c) extending from the vertical drum portion (2b) and above the bed portion (2a);

a needle bar (12) holding a sewing needle (11);

a needle up-down moving mechanism (50) provided inside the arm portion (2c) to move the needle bar (12) up and down;

an upper shaft (14) rotatably provided inside the arm portion (2c) and coupled to the needle up-down moving mechanism (50);

a looper mechanism (60) having a pair of loopers and provided inside the bed portion (2a);

a lower shaft (16) rotatably provided inside the bed portion (2a) and coupled to the looper mechanism (60);

a sewing machine motor (13) coupled to one of the upper shaft (14) and the lower shaft (16);

a transmission mechanism (90) configured to interlock the upper shaft (14) and the lower shaft (16); and

a vertical shaft (15) arranged along an up-down direction (Z) so as to be rotatable with respect to the frame (2),

characterized in that the vertical shaft (15) has an upper portion coupled to the upper shaft (14) via bevel gears (96, 97) and a lower portion coupled to at least one of a thread take-up mechanism (70) and a needle oscillating mechanism (40), and

the bevel gears (96, 97) are configured to transmit the rotation of the upper shaft (14) to the vertical shaft (15) such that the rotation speed of the upper shaft (14) is reduced by half.
The buttonholing machine (1) according to claim 1, wherein a bottom end of the vertical shaft (15) is located higher than a top surface (2aa) of the bed portion (2a).
The buttonholing machine (1) according to claim 1, wherein the bottom end of the vertical shaft (15) is located higher than a bottom end of the arm portion (2c).
The buttonholing machine (1) according to any one of claims 1 to 3, wherein the lower portion of the vertical shaft (15) is coupled to the thread take-up mechanism (70), and a portion of the vertical shaft (15) above the lower portion of the vertical shaft (15) is coupled to the needle oscillating mechanism (40).
The buttonholing machine (1) according to claim 4, wherein the needle oscillating mechanism (40) comprises:
a link member (44) coupled to the vertical shaft (15);

a supporting member (41) holding the needle bar (12) to provide an oscillating motion to the needle bar (12); and

a bell crank (43) member having an arm portion (43a) coupled to the supporting member and another arm portion (43b) coupled to the link member (44).
The buttonholing machine (1) according to any one of claims 1 to 5, wherein
the sewing machine motor (13) is coupled to the upper shaft (14), and
the transmission mechanism (90) is configured to transmit the rotation of the sewing machine motor (13) to the lower shaft (16) such that the rotation speed of the sewing machine motor (13) is reduced by half.