KR100944296B1 - Sewing machine - Google Patents

Abstract

The actuator of the up / down movement change mechanism having a cloth press up / down movement position changing mechanism which can change the movement range of the cloth press moving up and down in synchronization with the sewing operation is changed up and down by an actuator, thereby controlling the sewing of the predetermined immersion from the start of sewing. A cloth pressing control unit for changing the moving range of the cloth pressing downward is provided. The end of the upper thread which extends from the sweat hole of the sewing needle is pushed by the work cloth by the cloth press which moves up and down in the downward movement range, and a frictional resistance is applied. The sewing machine of the present invention can prevent the ejection of the end of the upper thread to the lower side of the processing cloth, and can form the stitch reliably from the first sweat of sewing start by a simple configuration that does not require the upper thread pressing mechanism. Can be.

Sewing machine, cloth pusher, push rod, needle rod, up and down drive, lever swing mechanism

Description

Sewing machine {SEWING MACHINE}

The present invention relates to a sewing machine provided with a cloth pawl vertical drive device for moving the cloth pawl up and down in synchronization with the vertical movement of the sewing needle.

BACKGROUND OF THE INVENTION A sewing machine having a cylindrical cloth stopper that moves up and down in synchronization with the up and down movement of a sewing needle is prevalent.

For example, the sewing machine described in Japanese Patent Application Laid-Open No. 2006-122230 has a vertical drive device for vertically moving a cylindrical cloth stopper. The vertical driving device operates to vertically move the cylindrical cloth stopper in synchronization with the vertical movement of the sewing needle. The lowered fabric presser presses the upper surface of the fabric to surround the outer periphery of the sewing needle, thereby preventing the floating of the fabric. The cloth stopper is raised so as not to interfere with the transfer of the workpiece during the cloth transfer.

In the sewing machine described in Japanese Patent Laid-Open No. 2006-122230, the cloth presser is positioned away from the processing cloth when the sewing needle descends and passes through the processing cloth. This cloth stopper does not hold down the end of the upper thread held by the sewing needle that descends in the first stitch at the start of sewing.

Therefore, the pointed part of the rotary drum which rotates by rotating the loop of an upper thread may tension the edge part of the upper thread with little frictional resistance, and this end part may be extracted to the lower part of a process cloth. If the ejection of the upper thread end occurs, there is a problem that the first stitch can not be formed. The lower thread after the second stitch is entangled at the end of the extracted upper thread a plurality of times, and there is a problem that a bird nest shape occurs on the back side of the processed fabric at the beginning of sewing, and the aesthetics of the sewing product is deteriorated. .

In order to cope with this problem, some sewing machines are provided with an upper thread pressing mechanism for clamping the end portion of the upper thread at the start of sewing to prevent the drawing out of the lower side of the fabric.

The object of the present invention is to reliably prevent the end of the upper thread from being pulled out of the processing cloth at the start of sewing by a simple configuration using a top and bottom drive device of a thousand presses, without separately installing the upper thread pressing mechanism. It is to be able to form a stitch from the first sweat.

The sewing machine according to claim 1 moves up and down in synchronization with a sewing operation by the rotation of the sewing machine motor, and has a cylindrical cloth presser for pressing a working cloth from above, wherein the movement range of the cloth presser is moved up and down by an actuator. The change of the cloth lever up-and-down movement position change mechanism which can be changed, and the cloth press for sewing up the predetermined immersion in the initial stage of sewing is changed below the movement range of the cloth press after sewing the predetermined immersion. And a cloth presser control unit for controlling the actuator such that the time for pressing the fabric cloth is longer than the time for pressing the fabric cloth after sewing the predetermined immersion.

The cloth pawl control unit changes the movement range of the cloth pawl downward until sewing the predetermined number of stitches (for example, three stitches) at the beginning of sewing. The cloth press always presses the work piece on the needle plate, and pushes the end of the upper thread extending from the sweat hole of the sewing needle to the work piece to apply frictional resistance. When the point of the rotary drum bottom of the needle plate extends over the loop of the upper thread, the end of the upper thread to which the frictional resistance is applied is not ejected to the lower side of the fabric. Therefore, the stitch can be surely formed from the first stitch after the start of sewing.

The sewing machine of claim 2 includes: a first link for converting and transmitting rotation of the sewing machine motor; a second link connected with the first link and transmitting a force converted by the first link to the cloth press; And a third link connected to the second link and supporting the second link to the device frame.

A mechanism for moving the cloth stopper up and down is configured by a link mechanism including a first link, a second link, and a third link. The first link, the second link, and the third link may operate by absorbing the change of the cloth pawl vertical movement position.

The sewing machine of Claim 3 is equipped with the thread take-up position detector which detects the up-and-down movement position of the thread take-up which discharge | releases the said upper thread, The said cloth presser control part is until the thread take-up control part is sewed until the predetermined submersion is sewn. And when the thread take-up position detector detects that it has reached, the actuator is controlled to be spaced apart from the top surface of the fabric cloth by changing the vertical movement range of the fabric press upward.

The cloth pawl control unit changes the moving range of the cloth pawl upward when the thread take-up is in the vicinity of the highest value even until the predetermined water is sewn. The cloth stopper is positioned away from the upper surface of the fabric and does not interfere with the transfer movement of the fabric. During the movement of the workpiece fabric, the thread take-up descends so that the end of the upper yarn is not pulled out below the workpiece cloth without tensioning the upper yarn.

The sewing machine of claim 4 controls the cloth transfer mechanism to transfer the workpiece cloth when the thread take-up position detector detects that the thread take-up has reached the uppermost value. A cloth transfer control unit is further provided.

The cloth transfer control unit transfers and moves the processed cloth when the thread take-up reaches the highest value. The transfer movement occurs in a state where the cloth stopper is moved upward, and can be surely executed even in a short transfer period.

The sewing machine of Claim 5 memorizes the sewing start speed until it sews the said predetermined immersion, and the normal sewing speed after finishing sewing of the said predetermined immersion, and the said normal sewing speed is faster than the said sewing start speed. And a sewing speed control section for controlling the sewing machine motor so as to switch from the sewing start speed to the normal sewing speed after sewing of the predetermined immersion from the beginning of sewing, after sewing the predetermined immersion.

The sewing speed control unit sews predetermined immersion from the beginning of sewing, and then switches from the sewing start speed to the normal sewing speed. The sewing start speed is usually slower than the sewing speed, and the period of the feed movement of the work cloth becomes longer. Therefore, even when the transfer amount is large, the transfer can be reliably performed. Before and after the conveyance period, it can change without delaying the moving range of a thousand presses.

According to the present invention, the end of the upper thread is ejected to the lower side of the processing cloth at the start of sewing, by a simple configuration using the upper and lower driving devices of the fabric press without first installing the upper thread pressing mechanism. Stitches can be formed from sweat.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail with reference to drawings which show preferable embodiment.

As shown in Fig. 1, the sewing machine 1 includes a bed 2, a leg column 3, and an arm 4. The leg pillar 3 is provided so that it may rise vertically upward at the rear end (back left upper part in FIG. 1) of the bed 2. The arm 4 is provided to extend forward from the upper end of the leg post 3. Inside the arm 4, the main shaft 5 which rotates by the drive of the sewing machine motor 63 (refer FIG. 12) is arrange | positioned in the front-back direction. As shown in Fig. 1 and Fig. 2, the needle rod 8 and the push rod 7 are provided at the front end of the arm 4. The sewing needle 9 is detachably attached to the lower end of the needle bar 8 protruding downward of the arm 4. The cloth stopper 6 is fixed to the lower end of the pressing rod 7 protruding downward of the arm 4.

The cloth pawl vertical drive device 10 for moving the cloth pawl 6 up and down will be described with reference to FIGS. 1 to 6.

The cloth presser vertical drive device 10 includes a lever rocking mechanism 11, a cloth presser vertical movement mechanism 12, and a cloth presser vertical movement position changing mechanism 13. The lever swing mechanism 11 swings the first lever 24 by the rotation of the main shaft 5. The cloth pawl vertical movement mechanism 12 moves the cloth pawl 6 up and down by swinging the tip of the first lever 24. The cloth pawl vertical movement position changing mechanism 13 changes the vertical movement range of the cloth pawl 6 by the cloth pawl vertical movement mechanism 12.

As shown in FIG. 6, the lever rocking mechanism 11 is provided with the eccentric cam 20, the annular member 21, the rotating shaft 22, and the lever member 23. As shown in FIG. The eccentric cam 20 is provided near the front end of the main shaft 5. The annular member 21 has the annular part 21b fitted to the eccentric cam 20, and the arm part 21a which protrudes from the outer periphery of the annular part 21b.

The rotating shaft 22 is supported by the machine frame F (refer FIG. 1) toward the front-back direction on the front side of the annular member 21. As shown in FIG. The upper end of the lever member 23 is fixed to the rear end of the rotating shaft 22. The upper end of the first lever 24 is fixed to the front end of the rotating shaft 22.

As shown in Fig. 6, the lever member 23 is provided with an arc hole 23a having an arc shape of radius R around the center of the eccentric cam 20. As shown in Figs. The tip portion of the arm portion 21a extending from the annular member 21 to the left side is connected to the arc hole 23a by the pin 25. The connection position of the arm part 21a can be changed by moving the pin 25 in the length range of the circular arc hole 23a.

When starting a sewing operation, the main shaft 5 rotates in a predetermined direction (clockwise view from the front). The eccentric cam 20 rotates by the rotation of the main shaft 5, and the annular member 21 reciprocates by the eccentric part of the eccentric cam 20 to the left-right direction. By the movement of the annular member 21, the lever member 23 connected to the arm portion 21a swings around the rotation shaft 22 within the angle range indicated by the arrow in FIG. The swing of the lever member 23 is transmitted to the first lever 24 connected by the rotation shaft 22, and the first lever 24 also swings as shown in FIG. The swing angles of the lever member 23 and the first lever 24 can be adjusted by moving the pin 25 in the arc hole 23a provided in the lever member 23.

The cloth pusher up-and-down movement mechanism 12 which moves the cloth presser 6 up and down by rocking of the 1st lever 24 is demonstrated.

As shown in Fig. 1, Fig. 3, Fig. 4, and Fig. 7, the cloth pawl vertical movement mechanism 12 includes a first link 30, a second link 31, and a third link 32. Figs. The first link 30 is arranged laterally. The left end of the first link 30 is connected to the lower end of the first lever 24. The second link 31 is an L-shaped link having the vertical link portion 31a and the horizontal link portion 31b integrally. The upper end of the longitudinal link portion 31a is connected to the right end of the first link 30.

As shown in Figs. 3, 4 and 7, the left end of the lateral link portion 31b is connected to the push rod gripper 34 by the connecting link 33 in the vertical direction. The pressing rod gripper 34 is fixed to the middle portion of the pressing rod 7.

The cloth pawl 6 provided at the lower end of the pressing rod 7 has a cylindrical pressing portion 6a as shown in FIG. The sewing needle 9 passes through the center portion of the pressing portion 6a. The upper thread 15 extending from the sweat hole of the sewing needle 9 can also be connected to the stitch of the working cloth W (see FIG. 2) through the inside of the pressing portion 6a.

The third link 32 is disposed in the horizontal orientation so as to overlap the front portion of the lateral link portion 31b of the second link 31. The right end of the third link 32 is connected to the intersection of the longitudinal link portion 31a and the lateral link portion 31b of the second link 31. The left end of the third link 32 is connected to a support (not shown) provided in the device frame F.

As shown in FIG. 5, the 3rd link 32 has the spring support part 32a in the back side of the 2nd link 31. As shown in FIG. The spring bearing portion 32a exerts downward force by the spring force of the compression coil spring 35 attached to the outer side of the pressing rod 7. The inclination angle of the third link 32 with respect to the horizontal direction is set by the third link 32 against the spring force of the compression coil spring 35 by the operation of the cloth lever vertical movement position change mechanism 13 described later. You can change it by pushing. By changing the inclination angle of the third link 32, the height position of the cloth tab 6 can also be changed.

The 1st, 2nd, 3rd links 30-32 become a parallel link at the time of the sewing stop in which the needle bar 8 is slightly lower than the highest value. As shown in FIGS. 7 and 8, the connection point between the first lever 24 and the first link 30 is P1, and the connection point between the first link 30 and the second link 31 is P2 and the second link. When the connection point between the 31 and the third link 32 is P3, and the connection point between the third link 32 and the device frame F is P4, the sides P1-P2 and the sides P4-P3 are parallel to each other, and the sides P2 -P3 and the sides P1-P4 are parallel.

As the main shaft 5 rotates, the first lever 24 swings as described above. The swing of the first lever 24 is transmitted to the second link 31 by the first link 30. As shown in Fig. 7, the second link 31 swings around the connection point P3 with the third link 32, and the end of the horizontal link portion 31b moves up and down. The pressing rod 7 and the cloth press 6 which are connected by the connecting link 33 and the pressing rod holding | gripping tool 34 to the edge part of the horizontal link part 31b move up and down. The needle bar 8 and the sewing needle 9 also move up and down by the rotation of the main shaft 5. Therefore, the vertical movement of the cloth stopper 6 occurs in synchronization with the vertical movement of the sewing needle 9. The reference position of the vertical movement range of the cloth pressing 6 can be changed by the cloth pressing vertical movement position changing mechanism 13. The reference position of the up-and-down movement range of the cloth pressing piece 6 represents the substantially upper end of the up-and-down moving range of the cloth pressing piece 6.

The cloth lever vertical movement position changing mechanism 13 will be described. As shown in FIG. 1, the drive part case 40 is provided in the inside of the leg post 3. As shown in FIG. Inside the drive part case 40, the camshaft 41 which has the cam body 42 is rotatably supported as shown in FIG. The camshaft 41 and the cam body 42 are rotated by the drive of the cloth lever up-down movement position change motor 43 (refer FIG. 1) provided in the outer side of the drive part case 40. FIG. The cloth stopper up-down movement position change motor 43 is a stepping motor, and the rotation position can be changed with high precision according to the number of drive pulses. The cam surface of the cam body 42 is set so that the cloth press 6 may become high in proportion to the number of drive pulses driving the cloth press vertical movement position change motor 43. The cloth stopper vertical movement position change motor 43 corresponds to the actuator of claim 1.

In the drive part case 40, the substantially L-shaped lever 45 is supported by the support shaft 44 above the cam shaft 41. The camshaft 41 and the support shaft 44 are parallel. The lower end of the lever 45 is provided with a driven wheel 46 which rotates in contact with the outer circumference of the cam body 42. The rear end of the connecting rod 47 is connected to the upper end of the lever 45. The connecting rod 47 extends forward in the arm 4 as shown in FIG. 1. The front end of the connecting rod 47 is connected to one end of the support lever 48. The support lever 48 is rotatably supported by the apparatus frame F. As shown in FIG. As shown in Fig. 5, the front end portion 48a of the support lever 48 extending forward is in contact with the spring support portion 32a of the third link 32 from below.

When the camshaft 41 and the cam body 42 are rotated forward by the drive of the cloth lever up-down movement position change motor 43, the connecting rod 47 moves back. By this movement, the support lever 48 swings clockwise in FIG. The front end portion 48a of the support lever 48 is raised to push up the third link 32 upward against the spring force of the compression coil spring 35. 7 shows a state in which the third link 32 is pushed up. At this time, the connection point P3 of the 3rd link 32 and the 2nd link 31 moves upward, and pulls up the cloth press 6. The up-and-down movement of the cloth stopper 6 occurs in a predetermined range in which the position of the cloth stopper 6 shown by the solid line in FIG. 7 is the upper end (upper position). The reference position of the up-and-down movement range of the cloth pressing 6 is the position of the cloth pressing 6 shown by the solid line in FIG.

When the camshaft 41 and the cam body 42 are reversely rotated by the drive of the cloth stopper up-down movement position change motor 43, the connecting rod 47 moves forward. By this movement, the support lever 48 swings in the counterclockwise direction in FIG. The front end 48a of the support lever 48 is lowered. The third link 32 is pushed down by the spring force of the compression coil spring (35). 8 shows a state in which the third link 32 is lowered. At this time, the connection point P3 of the 3rd link 32 and the 2nd link 31 moves downward, and pushes down the cloth press 6. The up-and-down movement of the cloth stopper 6 occurs in a predetermined range in which the position of the cloth stopper 6 indicated by the solid line in FIG. 8 is the upper end (lower position).

As shown in Fig. 8, even if the reference position of the up / down movement range of the cloth tab 6 is set to the needle plate 2a, the needle plate 2a prevents the movement of the cloth tab 6, so that the substrate 2a. The cloth stopper 6 does not move lower than). When the needle plate 2a does not block the movement of the cloth stopper 6, the second link 31 rotates with the connection point P3 as a supporting point. The cloth stopper 6 moves up and down by the rotation of the second link 31.

When the needle plate 2a prevents the movement of the cloth stopper 6, the second link 31 cannot rotate with the connection point P3 as a supporting point. In this case, the second link 31 is rotated by using the connection point of the connection link 33 and the second link 31 (lateral link 31b) as a supporting point. Rotation of the 2nd link 31 which makes the connection point of the connection link 33 and the 2nd link 31 (lateral link 31b) a support point moves the connection point P3 up and down.

As shown in FIG. 9, the up-and-down movement of the cloth presser 6 which makes an upper value (position of the cloth presser 6 shown by a solid line in FIG. 7) to the upper end is the needle plate 2a of the upper surface of the bed 2. As shown in FIG. Occurs in a range that does not contact. The position where the cloth stopper 6 is located at the bottom is set so as to be spaced apart from the upper surface of the needle plate 2a by a suitable length (5 mm to 10 mm) by a change in the rotation amount of the cloth stopper up-down moving position changing motor 43. do.

The vertical movement of the cloth tab 6 having the lower value (the position of the cloth tab 6 shown by the solid line in Fig. 8) as the upper side occurs in the range below the needle plate 2a as shown in Fig. 10. . The movement range shown in FIG. 10 has shown the movement range in the case where obstacles, such as the needle plate 2a, do not exist. The cloth stopper 6 moving this range always presses the work cloth W on the needle plate 2a.

In Fig. 10, the first link 30, the second link 31, and the third link 32 attempt to move the cloth stopper 6 from the lower position downward, but the needle plate 2a is the cloth stopper 6 ) To prevent movement. The force for moving the cloth stopper 6 can be absorbed by the first link 30, the second link 31, and the third link 32. The cloth stopper 6 remains in contact with the needle plate 2a, and only the first link 30, the second link 31, and the third link 32 operate. Fig. 11 shows a state in which the lower end of the cloth press 6 is set as shown in Fig. 10, and the cloth press 6 is moved to the bottom end. Compared with FIG. 8, it can be seen that the states of the first link 30, the second link 31, and the third link 32 are different.

The control system of the sewing machine 1 will be described with reference to FIG.

The control device 50 (corresponding to the cloth pressing control unit, the sewing speed control unit, and the cloth conveying control unit) has an input interface 51, a CPU 52, a ROM 53, a RAM 54, and an output interface 55. A computer and drive circuits 56 to 59 are provided. The stepping pedal 60, the operation panel 61, and the rotation position detection sensor 62 are connected to the input interface 51.

The stepping pedal 60 is stepped by an operator to indicate the start and end of sewing. The operation panel 61 is operated by an operator to set sewing conditions. The rotation position detection sensor 62 detects the rotation position of the main shaft 5. Since the detected rotation position of the main shaft 5 corresponds to the position of the thread take-up 14 (refer FIG. 2), the rotation position detection sensor 62 corresponds to a thread take-up position detector.

The output interface 55 includes a drive circuit 56 for driving the sewing machine motor 63, a drive circuit 57 for driving the cloth lever up-down movement position changing motor 43, and an X-axis drive motor 64. The drive circuit 58 for driving () and the drive circuit 59 for driving the Y-axis drive motor 65 are connected.

The sewing machine motor 63 drives the main shaft 5 as described above. The cloth stopper up / down movement position change motor 43 changes the up / down movement range of the cloth stopper 6 upward or downward. The X-axis drive motor 64 operates the X feed mechanism 66. The Y-axis drive motor 65 operates the Y feed mechanism 67. The X conveyance mechanism 66 and the Y conveyance mechanism 67 constitute a cloth conveyance mechanism for conveying and moving the processing cloth W in the left-right direction (X direction) and the front-rear direction (Y direction).

The ROM 53 (corresponding to the storage unit) stores sewing data for forming various stitches. The ROM 53 also stores a control program for the thousand push operation control described later. The ROM 53 also stores data of the number of drive pulses of the cloth tap vertical movement position change motor 43 used for the cloth tap operation control. The data of the driving pulse number includes the evacuation pulse number for evacuating the cloth tab 6 to the evacuation position (see Figs. 2 and 5) spaced about 20 mm above the needle plate 2a while the sewing is stopped. Doing. The data of the drive pulse number includes the number of sewing pulses for moving the cloth presser 6 up and down on the basis of the above-described upper value (see FIGS. 9 and 15) during sewing, and the cloth presser at the start of sewing ( It also includes the number of pulses for pressing the yarn to move 6) up and down based on the above-described lower values (Figs. 10 and 14).

The ROM 53 also stores the rotational speed of the sewing machine motor 63 at the beginning of sewing and normal sewing. The rotational speed at the beginning of sewing is 400 rpm, for example. The rotation speed (normal sewing speed) at the time of normal sewing is 2000 rpm, for example, and is higher than the rotation speed at the time of sewing initial stage.

The control operation performed by the control device 50 will be described with reference to the flowchart in FIG. In the figure, reference symbol Si (i = 11, 12, 13, ...) is a step number indicating an operation step of the CPU 52. FIG.

The control device 50 starts the control operation when the power of the sewing machine 1 is turned on. The control apparatus 50 drives the cloth presser vertical movement position change motor 43 forward rotation by the number of pulses for retraction, and raises the cloth presser 6 to a retracted position (S11). As shown in Fig. 2, the thread take-up machine 14 is at the highest level when the sewing press 6 is in the retracted position.

The control apparatus 50 waits until there is an input of a sewing start command (S12). The operator arranges the work cloth W on the bed 2, and operates the stepping pedal 60 to instruct the start of sewing. When there is an input of a sewing start instruction by stepping on the stepping pedal 60 (S12: YES), the control device 50 drives the sewing machine motor 63 at a low speed at the start of sewing (S13). At the same time, the control device 50 sets the initial value "0" to the count value N of the submerged counter (S14).

The control apparatus 50 lowers the cloth press 6 to a lower value (upper thread pressing position) (S15). The lowering to the upper thread pressing position is realized by reverse rotation of the cloth pressing device vertically moving position changing motor 43 by the above-described driving pulse of the thread pressing pulse number. The cloth stopper 6 lowered to the upper thread pressing position exerts a pressure on the work cloth W on the needle plate 2a. The cloth stopper 6 also pushes the end of the upper thread 15 extending from the sweat hole of the sewing needle 9 onto the work cloth W.

The control apparatus 50 determines whether the thread take-up 14 reached the highest value (S16). When it is determined that the thread take-up 14 has reached the highest value (S16: YES), the control device 50 raises the cloth pressing 6 to the upper value (sewing height position) (S17). When it is determined that the thread take-up 14 has not reached the highest value (S16: No), the control device 50 waits until the highest value is reached. The determination of the position of the thread take-up 14 is performed based on the detection signal of the rotation position detection sensor 62. The rise to the sewing height position is realized by forward rotation of the cloth lever vertical movement position changing motor 43 by the above-described driving pulse of the sewing pulse number.

The control apparatus 50 determines whether the conveyance of the process cloth W is complete | finished (S18). When it determines with the conveyance of the processing cloth W being complete | finished (S18: Yes), the control apparatus 50 checks the immersion count value N (S19). The end of the conveyance of the workpiece | work cloth W can be determined by the stop of the X-axis drive motor 64 and the Y-axis drive motor 65, for example. The stop of the X-axis drive motor 64 and the Y-axis drive motor 65 can be determined from the detection result of the rotation detector provided in each. In the block diagram of the control system shown in FIG. 11, illustration of the rotation detector of the X-axis drive motor 64 and the Y-axis drive motor 65 is abbreviate | omitted.

When the immersion count value N is a predetermined value (for example, three stitches) or smaller than the predetermined value (S19: YES), the control device 50 increases the count value N by "1" (S20). ), The process proceeds to S15.

By the above operation, about three stitches after the start of sewing, the cloth stopper 6 is lowered to the upper thread pressing position, and the upper thread 15 is pushed onto the processing cloth W. Therefore, friction occurs between the end of the upper thread 15 and the work cloth W, so that the end of the top thread 15 is not pulled out below the work cloth W. The cloth stopper 6 rises to the sewing height position for a period during which the conveyance of the processing cloth W is executed after the thread take-up 14 reaches the highest value. Therefore, the cloth stopper 6 does not disturb the conveyance of the processing cloth W. The thread take-up 14 is descending from the uppermost level during the transfer of the workpiece cloth W, and the upper thread 15 is in a relaxed state. Therefore, the edge part of the upper thread 15 is not pulled out below the process cloth W by the tension of the upper thread 15 during conveyance.

When the immersion count value N is larger than the predetermined value (S19: No), the control device 50 drives the sewing machine motor 63 at a high speed (set speed) at the time of normal sewing (S21). This drive continues until there is an input of a sewing end command. When there is an input of a sewing end command (S22: YES), the control apparatus 50 transfers a process to S11, raises the cloth press 6 to a retracted position, and waits.

After the fourth stitch by the above operation, the cloth stopper 6 moves up and down the highway in synchronization with the sewing needle 9 at the sewing height position. The entanglement of the upper thread 15 and the lower thread (not shown) reliably occurs, and stitches can be formed in order until the end of sewing. The cloth stopper 6 presses the processing cloth W from above when the sewing needle 9 rises. The vertical movement range of the cloth tab 6 is located above the upper surface of the needle plate 2a, and does not impede the conveyance of the processing cloth W.

The operation of the cloth pawl vertical drive device 10 will be described with reference to FIG. 16 which shows the state of the operation of the thread take-up 14, the sewing needle 9, and the cloth pawl 6.

In the sewing atmosphere shown in FIG. 2, the cloth tab 6 is in a retracted position spaced apart by about 20 mm above the needle plate 2a. Thread take-up 14 is at the top. The worker can start sewing by operating the stepping pedal 60, and the sewing machine motor 63 starts to rotate at a low speed at time t0 in FIG. The cloth stopper 6 descends to the upper thread pressing position shown in FIG. The cloth stopper 6 lowered to the upper thread pressing position moves up and down in the range shown in FIG. 10 to apply pressure to the work cloth W and the upper thread 15.

The cloth stopper 6 ascends to the sewing height position shown in Fig. 15 at the time t1 in Fig. 16 when the thread take-up reaches the highest value. The cloth stopper 6 that has risen to the sewing height position moves up and down in the range shown in FIG. 9 and does not contact the work cloth W. In this state, the processing cloth W can be moved. Meanwhile, the thread take-up 14 is descending through the highest value and does not tension the upper thread 15. Therefore, the end of the upper thread 15 does not go out below the processing cloth W. As shown in FIG. The upper thread 15 required for the transfer of the processing cloth W may be drawn out from the thread take-up 14 and supplied without resistance.

The cloth stopper 6 is lowered to the upper thread pressing position at the time point t2 in Fig. 16 just before the sewing needle 9 is inserted into the processing cloth W. The cloth stopper 6 lowered to the upper thread pressing position exerts pressure on the work cloth W and the upper thread 15 which have finished the transfer. A frictional force is generated between the upper thread 15 and the work cloth W, so that the end of the top yarn 15 does not come out below the work cloth W. Therefore, the stitch can be reliably formed by entanglement with the lower thread from the first stitch after the start of sewing. The above operation is repeated from the start of sewing until sewing for a predetermined number of stitches (three stitches) is formed.

The sewing machine motor 63 rotates at a low speed (for example, 400 rpm) until the sewing of the predetermined immersion is finished. The conveyance period of the processing cloth W becomes long, and the cloth stopper 6 can move without delay before and after a conveyance period. The cloth stopper up / down movement position change mechanism 13 can perform the change of the up / down movement position of the cloth stopper 6 by simple control which drives and stops the cloth stopper up / down movement position change motor 43.

The cloth stopper 6 ascends to the sewing height position at the time point t3 in FIG. 16 to start sewing the fourth sweat. The cloth stopper 6 after this time point t3 maintains the sewing height position even after the time point t4 in FIG. 16 in which the transfer of the processing cloth W is completed. The cloth stopper 6 at the sewing height position moves up and down in the range shown in FIG. The cloth pawls 6 at the lowest positions face each other with a small gap therebetween. During normal sewing after the time point t3, the cloth stopper 6 can press the work cloth W when the sewing needle 9 is raised without disturbing the transfer of the work cloth W.

The modified form which partially changed embodiment described above is demonstrated.

1) The rotation speed of the sewing machine motor 63 at the start of sewing is not limited to 400 rpm shown in the embodiment. This rotation speed can be made into the appropriate rotation speed lower than the rotation speed at the time of normal sewing.

2) The operation of the cloth stopper 6 for pressing the upper thread 15 at the start of sewing can be performed during any predetermined immersion after the start of sewing.

3) The structure of the cloth pusher up-and-down movement position change mechanism 13 is not limited to the structure shown in embodiment, and is used to change the up-and-down movement range of the cloth presser 6 by the cloth pusher up-and-down movement position change motor 43. FIG. The mechanism of another structure can be employ | adopted. As the actuator for changing the vertical movement range of the cloth stopper 6, for example, an air cylinder, a solenoid, or a servomotor may be used.

4) The thread take-up position detector which detects the position of the thread take-up 14 is not limited to the rotation position detection sensor 62 which detects the rotation position of the main shaft 5. For example, the sensor which detects the position of the needle bar 8 which moves up and down can be employ | adopted as a thread take-up position detector.

5) The press part 6a of the cloth stopper 6 may be a cylinder which is not cylindrical but has a shape such as a quadrangle or a triangle.

6) The reference position of the vertical movement range of the cloth press 6 may be the lower end of the vertical movement range of the cloth press 6. When the reference position of the up / down movement range of the cloth press 6 is set to the lower end of the up and down movement range of the cloth press 6, the drive when the number of drive pulses of the cloth presser up and down movement position change motor 43 is set to the upper end The number of driving pulses for the vertical movement range may be added to the number of pulses.

As apparent from the above detailed description, in the sewing machine according to the present invention, the cloth pressing control unit operates while sewing the predetermined immersion in the initial stage of sewing, and moves up and down in synchronization with the sewing operation by the rotation of the sewing machine motor. Change the movement range of the cloth press downward. The cloth stopper pushes the end of the upper thread extending from the stitch hole of the sewing needle to the upper surface of the fabric. The end of the upper thread is not drawn out to the lower side of the fabric by frictional resistance by pushing, so that the stitch can be surely formed from the first sweat after the start of sewing.

1 is a perspective view of a sewing machine of the present invention.

Fig. 2 is a front view of the sewing machine at the time of sewing wait.

Figure 3 is a perspective view of a cloth stopper up and down drive device.

4 is a perspective view of an essential part of a cloth pawl vertical drive.

Fig. 5 is a right side view of the cloth presser vertical drive device.

6 is a front view of the rocking mechanism.

Fig. 7 is a front view of the cloth pawl up and down mechanism in which the cloth pawls are upper teeth;

Fig. 8 is a front view of the cloth pawl vertical movement mechanism when the cloth pawl is at the lower position.

Fig. 9 is a diagram showing the vertical movement trajectory of the cloth tab at the time of sewing.

Fig. 10 is a diagram showing the vertical movement trajectory of the cloth press when the lower value is set on the needle plate (with and without needle plate).

Fig. 11 is a front view of the sewing machine when the lower end of the cloth press is set as shown in Fig. 10 to move the cloth press to the lowest end;

12 is a block diagram of a control system of a sewing machine

Fig. 13 is a flowchart of cloth stopper operation control.

Figure 14 is a front view of the sewing machine when the cloth presser is in the upper thread pressing position.

Figure 15 is a front view of the sewing machine when the cloth stopper is in the sewing height position.

Fig. 16 is a time chart showing the action of thread take-up, needle and cloth tap.

<Explanation of symbols for the main parts of the drawings>

1: sewing machine

4: arm

6: cloth press

7: push rod

8: saliva rod

10: vertical drive

11: lever rocking mechanism

20: eccentric cam

21: annular member

22: rotating shaft

23: lever member

63: sewing machine motor

Claims (5)

In the sewing machine provided with the cylindrical cloth presser which moves up and down in synchronization with the sewing operation by the rotation of a sewing machine motor, and presses a process cloth from the upper side, A cloth presser vertical movement position changing mechanism capable of changing the movement range of the cloth presser up and down by an actuator, The movement range of the cloth press until sewing the predetermined immersion in the initial stage of sewing is changed below the movement range of the cloth press after sewing the predetermined immersion, and the time when the cloth press presses the processed fabric. And a cloth presser control unit for controlling the actuator such that the cloth presser is longer than the time for pressing the processed cloth after sewing the predetermined immersion. The apparatus of claim 1, further comprising: a first link for converting and transmitting rotation of the sewing machine motor; a second link connected with the first link and transmitting a force converted by the first link to the cloth press; And a third link connected to the second link and supporting the second link to the device frame. The thread take-up position detector according to claim 1, further comprising: a thread take-up position detector for detecting a vertical movement position of the thread take-up that discharges the upper thread; The cloth pawl control unit changes the moving range of the cloth pawl upwards when the thread take-up position detector detects that the thread take-up has reached the vicinity of the highest value, until the predetermined immersion is sewn. Sewing machine characterized in that for controlling the actuator to space the cloth presser from the upper surface of the. 4. The cloth conveying mechanism according to claim 3, further comprising a cloth conveying mechanism for conveying and moving said processed cloth, and said cloth conveying mechanism for conveying and moving said processed cloth when said thread take-up position detector detects that said thread take-up has reached the uppermost value. Sewing machine characterized in that it further comprises a cloth transfer control unit for controlling the. The sewing start speed | rate until the sewing of the said predetermined immersion, and the normal sewing speed after finishing sewing of the said predetermined immersion are memorized, and the said normal sewing in any one of Claims 1-4. The speed further includes a storage unit for storing a speed faster than the sewing start speed, and a sewing speed control unit for controlling the sewing machine motor to switch from the sewing start speed to the normal sewing speed after sewing of the predetermined immersion from the beginning of sewing. Characterized by a sewing machine.

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