CN110093723B

CN110093723B - Sewing machine

Info

Publication number: CN110093723B
Application number: CN201910099246.1A
Authority: CN
Inventors: 中野元就; 竹村徹
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 2018-01-31
Filing date: 2019-01-31
Publication date: 2021-12-10
Anticipated expiration: 2039-01-31
Also published as: CN110093723A; JP2019130121A

Abstract

The invention relates to a sewing machine, which is easy to optimize the pressure of pressing cloth with a presser foot. The sewing machine is provided with a needle plate, a cloth feeding tooth, a pressure lever, a presser foot, an elastic component and a cloth pressing motor. The cloth is loaded on the needle plate by an operator. The cloth feeding teeth can convey the cloth on the needle plate. The presser foot can press the cloth from above. The elastic member can apply force to the presser foot. The cloth pressing motor can move the pressing rod up and down and change the elastic deformation of the elastic component. When the cloth is not fed to the feed dog, that is, when the cloth is not fed, the CPU of the sewing machine controls the cloth pressing motor to set the pressure of the presser foot to a predetermined pressure, that is, an initial pressure. The elastic deformation amount of the elastic member becomes a predetermined amount of initial deformation. In the case of cloth feeding, the CPU controls the cloth pressing motor to make the pressure of the presser foot greater than the initial pressure.

Description

Sewing machine

Technical Field

The present invention relates to a sewing machine.

Background

A sewing machine for pressing a cloth with a presser foot is known. A sewing machine disclosed in japanese patent application laid-open No. 2017, 192474, includes a needle plate, a presser bar, a presser foot, a lower bar hoop, a pressing spring, a sleeve, and a cloth pressing motor. The needle plate can carry cloth. The pressing rod extends in the vertical direction above the needle plate. The presser foot is arranged at the lower end part of the pressure rod and can clamp cloth between the presser foot and the needle plate. The lower side rod hoop is fixed on the pressure bar above the pressure foot. The pushing spring is spiral, the pressure rod is inserted in the pushing spring, and the pushing spring is contacted with the lower side rod hoop from the upper part. The sleeve is provided to the press rod so as to be movable up and down, and a pressing spring is interposed between the sleeve and the lower rod hoop. The cloth pressing motor can enable the sleeve to move up and down. When the sleeve moves up and down, the elastic deformation of the pressing spring is increased or decreased, so that the pressure of the presser foot on the cloth is increased or decreased. The sewing machine can set the pressure of the presser foot, and the sewing machine enables the pressure of the presser foot to be the set pressure by controlling the cloth pressing motor.

The appropriate pressure varies according to the sewing condition of the cloth. However, the sewing machine does not set the pressure according to the sewing condition. Therefore, the pressure at the time of sewing may become inappropriate.

Disclosure of Invention

The invention aims to provide a sewing machine which is easy to optimize the pressure of pressing cloth by a presser foot.

The sewing machine of claim 1 comprises: a needle plate capable of placing a fabric; a cloth feeding table supporting cloth feeding teeth capable of conveying the cloth placed on the needle plate; a cloth feeding mechanism capable of driving the cloth feeding table and conveying the cloth by the cloth feeding teeth; a presser foot capable of pressing the cloth from above; a pressing rod extending in the vertical direction, the lower end of the pressing rod being fixed with the presser foot; an elastic member provided above the presser foot, the elastic member applying a pressing force to the presser foot to press the fabric in a state where the presser foot is at a contact position where the presser foot contacts the fabric placed on the needle plate from above; a cloth pressing motor capable of moving the pressing rod up and down and changing the elastic deformation amount of the elastic member; and a cloth pressing control unit that controls the pressure of the presser foot at the contact position by controlling the cloth pressing motor, wherein the elastic member has an initial deformation amount that is the elastic deformation amount capable of realizing a predetermined pressure, that is, an initial pressure, and the cloth pressing control unit controls the cloth pressing motor so that the elastic deformation amount is different between a time of cloth feeding when the cloth feeding mechanism conveys the cloth and a time of stopping the cloth feeding when the cloth feeding mechanism does not convey the cloth. The sewing machine can change the pressure to make the pressure different between the time of feeding cloth and the time of stopping feeding cloth. Since the force received by the presser foot from the feed dog varies between when feeding and when stopping feeding, the sewing conditions at the time of feeding and when stopping feeding are different. Therefore, the sewing machine can appropriately control the pressure according to the sewing condition.

In the sewing machine according to claim 2, the cloth pressing control unit may control the cloth pressing motor so that the elastic deformation amount becomes the initial deformation amount when the cloth feeding is stopped, and the cloth pressing control unit may control the cloth pressing motor so that the elastic deformation amount becomes larger than the initial deformation amount when the cloth feeding is stopped. The pressure at the time of feeding the cloth is larger than the initial pressure at the time of stopping feeding the cloth, and therefore, the sewing machine can suppress the deviation of the cloth which may occur at the time of performing the sewing operation.

The sewing machine according to claim 3 may further include a presser foot height detecting unit capable of detecting a vertical position of the presser foot with respect to the needle plate, wherein the cloth pressing control unit may control the cloth pressing motor to increase the elastic deformation amount of the elastic member when the vertical position of the presser foot detected by the presser foot height detecting unit is greater than a predetermined value. When the cloth is thick and heavy, the pressure is insufficient, and the cloth may be displaced during sewing. When the height of the presser foot is larger than the specified value, the sewing machine increases the pressure by increasing the elastic deformation amount of the elastic component. Therefore, even under the condition that the cloth is thick and heavy, the sewing machine can prevent the cloth from shifting in the sewing process.

In the sewing machine according to claim 4, the cloth pressing control unit may include: a first cloth pressing control unit that controls the cloth pressing motor to maintain the current elastic deformation amount of the elastic member or reduce the elastic deformation amount when the vertical position of the presser foot detected by the presser foot height detection unit is greater than a predetermined value; and a second cloth pressing control unit that controls the cloth pressing motor by the second cloth pressing control unit after the cloth pressing motor is controlled by the first cloth pressing control unit, so that the elastic deformation amount of the elastic member is increased. The sewing machine can prevent the pressure from rising sharply when the step part of the cloth enters between the presser foot and the needle plate. Therefore, the sewing machine can easily optimize the pressure of pressing the cloth with the presser foot.

In the sewing machine according to claim 5, the cloth feeding mechanism may include: a horizontal transport mechanism having a horizontal transport shaft connected to the cloth feeding table, the horizontal transport mechanism moving the cloth feeding table in a horizontal direction by rotating the horizontal transport shaft; and an up-down conveying mechanism having an up-down conveying shaft extending in parallel with the horizontal conveying shaft and connected to the cloth feeding table, the up-down conveying mechanism rotating the up-down conveying shaft in synchronization with the horizontal conveying mechanism to move the cloth feeding table up and down, the sewing machine including: an upper and lower conveyance shaft angle detection unit for detecting an upper and lower conveyance shaft angle that is a rotation angle phase of the upper and lower conveyance shafts; and a cloth feeding timing determining section for determining whether the cloth is fed based on a detection result of the vertical feed shaft angle detecting section, wherein the cloth pressing control section controls the cloth pressing motor in accordance with the determination result of the cloth feeding timing determining section. The result of the determination as to whether or not the cloth is fed by the cloth feeding timing determining section is obtained based on the detection result of the up-down conveying shaft angle detecting section, which has a correlation with the up-down position of the cloth feeding tooth. That is, the sewing machine determines whether the cloth is fed or not according to the vertical position of the cloth feeding tooth, and changes the pressure of the presser foot. Therefore, the sewing machine can appropriately judge whether the cloth feeding is carried out or stopped, thereby optimizing the pressure of pressing the cloth by the presser foot.

The sewing machine according to claim 6 may further include: a sewing mechanism capable of sewing the cloth pressed by the presser foot; a drive unit capable of driving the cloth feeding mechanism and the sewing mechanism; a sewing control unit capable of controlling the driving of the driving unit; and a cloth feed information acquiring unit capable of acquiring cloth feed information indicating a cloth feed amount, which is an amount of the cloth to be fed by the cloth feed teeth, wherein the sewing control unit controls the driving unit to feed the cloth in accordance with the cloth feed amount indicated by the cloth feed information acquired by the cloth feed information acquiring unit, and the cloth pressing control unit controls the cloth pressing motor in accordance with the cloth feed amount. Since the pressure varies according to the cloth feeding amount, the sewing machine can optimize the pressure for pressing the cloth with the presser foot.

The sewing machine according to claim 7 may further include a trajectory information acquiring unit capable of acquiring trajectory information indicating a swing trajectory of the feed dog, the swing trajectory of the feed dog being different between different trajectories at least one of a start timing and an end timing of the movement of the feed dog in the horizontal direction during the vertical movement of the feed dog, the sewing control unit may control the driving unit to drive the feed dog in accordance with the swing trajectory of the feed dog indicated by the trajectory information acquired by the trajectory information acquiring unit, and the cloth pressing control unit may control the cloth pressing motor in accordance with the trajectory information acquired by the trajectory information acquiring unit. The sewing machine can optimize the pressure of pressing the cloth by the presser foot by changing the pressure of the presser foot according to the swing track of the cloth feeding tooth.

In the sewing machine according to

claim

8 or 9, the sewing mechanism may include a face thread adjusting mechanism having a tension plate capable of applying tension to a face thread, the face thread adjusting mechanism being capable of adjusting the tension of the face thread, the sewing machine may include a tension information acquiring unit capable of acquiring tension information indicating the tension of the face thread, the sewing control unit may adjust the tension of the face thread by using the face thread adjusting mechanism so that the tension of the face thread becomes the tension indicated by the tension information acquired by the tension information acquiring unit, and the cloth pressing control unit may control the cloth pressing motor in accordance with the tension information acquired by the tension information acquiring unit. The sewing machine can optimize the pressure of pressing the cloth by the presser foot by changing the pressure according to the tension of the upper thread.

The sewing machine according to claim 10 may further include: a clamping member connected to the press rod in a vertically movable manner, the clamping member being in contact with the elastic member above the elastic member; a first rotating member that is rotatable in an axial direction that is a predetermined direction orthogonal to the vertical direction by a driving force of the cloth pressing motor; and a second rotating member that is provided so as to be rotatable about the predetermined direction as an axial direction, the second rotating member being connected to the clamping member, and the second rotating member transmitting motion so as to convert rotation of the first rotating member into vertical motion of the clamping member. When the first rotating member rotates under the driving force of the cloth pressing motor, the second rotating member rotates, and the elastic deformation amount of the elastic member changes. The driving force of the cloth pressing motor is not directly transmitted to the clamping component, therefore, the sewing machine can restrain the clamping component from being damaged.

The sewing machine according to claim 11 may further include a link extending in a direction orthogonal to the vertical direction and the predetermined direction, the link being rotatably connected to the first rotating member and the second rotating member, respectively. Since the link links the first rotating member and the second rotating member, the cloth pressing motor can be disposed at a position remote from the presser bar. Therefore, according to the sewing machine of the present invention, other members can be arranged around the presser bar.

Drawings

Fig. 1 is a front view of the sewing machine 1.

Fig. 2 is a sectional view of the thread tension device 221.

Fig. 3 is a perspective view of the cloth pressing mechanism 70.

Fig. 4 is a perspective view of the cloth feeding mechanism 130.

Fig. 5 is an enlarged perspective view of the needle plate 7 and its vicinity.

Fig. 6 is a left side view of the swing locus 101 and the swing locus 401.

Fig. 7 is an electrical block diagram of the sewing machine 1.

Fig. 8 is a flowchart of the main process.

Fig. 9 is a data structure diagram of the first information 111.

Fig. 10 is a data structure diagram of the sewing information 122.

Fig. 11 is a rear view of the cloth pressing mechanism 70 with the presser foot 71 in the spaced position.

Fig. 12 is a rear view of the cloth pressing mechanism 70 with the presser foot 71 in the contact position.

Fig. 13 is a flowchart of a stitch forming process.

Fig. 14 is a flowchart of the cloth feeding process.

Fig. 15 is a rear view of the cloth pressing mechanism 70 with the thick cloth portion 9B between the presser foot 71 and the needle plate 7.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the left and right, front and back, and up and down shown by arrows in the drawings are used.

Referring to fig. 1, the structure of the sewing machine 1 is explained. The sewing machine 1 has a bed 2, a column 3, and a arm 4. The housing part 2 is fitted at an opening of the table, extending in the left-right direction. A needle plate 7 is mounted on the upper surface of the bed portion 2. A cloth 9 (see fig. 3) is placed on the upper surface of the bed 2 and the needle plate 7 by an operator. The needle plate 7 has a needle receiving hole 8 (see fig. 5) and a feed dog hole 14 (see fig. 5). The pin receiving hole 8 is circular in plan view. The feed sprocket 14 has a major diameter in the front-rear direction, and the feed sprocket 14 is located at the left, rear, right, and front of the needle accommodating hole 8, respectively. The column part 3 extends upward from the right end of the seat part 2. The arm portion 4 extends leftward from the upper end of the column portion 3 and faces the upper surface of the base portion 2. An operation portion 46 (see fig. 7) is fixed to a right portion of the upper surface of the arm portion 4. The operation unit 46 includes an operation knob 47 and a display unit 48. The operator can input various instructions by operating the operation knob 47 while looking at the display unit 48.

The arm portion 4 includes an upper shaft 11 and a main motor 31 (see fig. 7) therein. The upper shaft 11 extends in the left-right direction. The right end of the upper shaft 11 is connected to the main motor 31 via an upper shaft pulley. The arm portion 4 has a nose portion 5 at a left end portion. The nose portion 5 protrudes downward from the arm portion 4, and faces the needle plate 7 from above. The head unit 5 supports the needle bar so that the needle bar can move up and down. The needle bar protrudes downward from the head portion 5. The needle bar is connected to the upper shaft 11 by means of an up-and-down movement mechanism. The needle bar can move up and down above the needle plate 7 along with the rotation of the upper shaft 11. The needle is assembled at the lower end of the needle rod. The needle holds the upper thread worn in the needle eye thereof. The needle moves up and down together with the needle bar. The sewing machine 1 supplies an upper thread to the eye of a needle by a thread tension device 221, which will be described later, provided in the head portion 5. Hereinafter, the upper end of the needle movable range is referred to as an upper needle position, and the lower end of the needle movable range is referred to as a lower needle position. The lower end of the needle in the needle-up position is above the cloth 9. The lower end of the needle in the needle-down position enters the needle receiving opening 8 of the needle board 7.

The housing part 2 has a rotating hook and a thread cutting mechanism inside. The rotary hook is provided below the needle plate 7, and accommodates therein a bobbin around which a lower thread is wound. The rotary hook is rotated by obtaining the power of the main motor 31, and the rotary hook can catch the needle thread held by the needle in the vicinity of the needle-lower position. The thread cutting mechanism includes a fixed blade, a movable blade, and a thread cutting electromagnetic element 161 (see fig. 7). The movable blade is connected to a tangent electromagnetic element 161. When the thread cutting electromagnetic element 161 is driven, the movable knife is moved relative to the fixed knife, and the upper thread and the lower thread are cut by the thread cutting mechanism.

The sewing machine 1 has a control device 30 (see fig. 7) below the table. The controller 30 is connected to a foot pedal 37 (see fig. 7). The operator presses the pedal 37 toward the toe side to input a sewing start instruction for the cloth 9 to the sewing machine 1. The operator can operate the pedal 37 to the toe side or the heel side. The control device 30 controls the operation of the sewing machine 1 in accordance with the operation direction and the operation amount of the pedal 37.

Referring to fig. 2, the yarn trapper 221 is explained. The thread tension device 221 has an upper thread adjusting mechanism 222, a thread tension electromagnetic member 231, an intermediate lever 240 and a driving lever 245. The upper thread adjusting mechanism 222 is provided at the front part of the arm part 4. The thread tension solenoid 231 is fixed to the rear of the arm portion 4. The intermediate lever 240 and the driving lever 245 are provided inside the arm portion 4 so as to be movable in the front-rear direction, and can transmit the driving force of the thread tension solenoid 231 to the pressing tension plate 223 of the upper thread adjusting mechanism 222.

The upper thread adjusting mechanism 222 has a thread tension base 225, a thread tension shaft 226, a pressing thread tension plate 223, a pressed thread tension plate 224 and a fixing nut 227. The wire clamping base 225 has a substantially cylindrical shape, is inserted into a cylindrical fixing hole 228 formed in the front portion of the arm portion 4, and is fixed to the arm portion 4 by a screw 229. The yarn trap shaft 226 is provided to penetrate the yarn trap base 225 in the front-rear direction and to protrude forward of the yarn trap base 225. The pressure clamp 223 and the pressure clamp 224 are both annular, are located forward of the arm 4, have a clamp shaft 226 inserted therethrough, and are arranged in this order from the rear. A fixing nut 227 is fastened to the front end of the clamp shaft 226 to restrict the forward movement of the pressure clamp 223 and the pressure clamp 224. The driving rod 245 is provided inside the grip shaft 226 in a manner capable of moving back and forth. When the driving lever 245 moves forward, the front end of the driving lever 245 comes into contact with the rear side surface of the pressing jaw 223. When sewing, the upper thread passes between the pressing clamp 223 and the pressing clamp 224. The pressing clamp 223 and the pressed clamp 224 can apply tension to the upper thread by clamping the upper thread.

The trapping solenoid 231 is a proportional solenoid, and by supplying a drive voltage thereto, the intermediate lever 240 connected to the output shaft 232 can be moved forward. In the sewing machine 1, the pressure applied to the clamp 223 can be changed by changing the driving voltage supplied to the thread clamping solenoid 231. The tension applied to the upper thread by the pressing tension plate 223 and the pressing tension plate 224 is changed according to the driving voltage supplied to the thread tension electromagnetic element 231, and therefore, the upper thread adjusting mechanism 222 can adjust the tension of the upper thread.

The intermediate lever 240 extends forward from the output shaft 232 of the wire clamping solenoid 231. The intermediate rod 240 penetrates the large-diameter hole 234 and the small-diameter hole 235 formed in the arm portion 4. The large-diameter hole 234 is provided on the rear side in the arm 4. The small-diameter hole portion 235 communicates with the large-diameter hole portion 234 on the front side of the large-diameter hole portion 234, and the diameter of the small-diameter hole portion 235 is smaller than that of the large-diameter hole portion 234. The intermediate lever 240 has a flange portion 241 at a portion located in the large-diameter hole portion 234. The gasket 237 is disposed at a step portion 236 connecting the large-diameter hole portion 234 and the small-diameter hole portion 235. A compression coil spring 243 is attached between the spacer 237 and the flange portion 241 of the intermediate lever 240. The compression coil spring 243 biases the intermediate lever 240 rearward via the flange portion 241. When the intermediate lever 240 moves forward, the front end of the intermediate lever 240 comes into contact with the rear end of the driving lever 245.

When the wire clamping electromagnetic element 231 is in the non-driving state, the intermediate lever 240 is in the non-operating position by the urging force of the compression coil spring 243. At this time, the front end of the intermediate lever 240 and the rear end of the driving lever 245 do not contact each other. Therefore, a forward force is not applied to the pressing clamps 223. Therefore, the thread tension device 221 does not impart tension to the upper thread passing between the pressing clamp 223 and the pressed clamp 224.

Referring to fig. 1 and 3, the cloth pressing mechanism 70 is explained. The cloth pressing mechanism 70 has a cloth pressing motor 73, a first rotating member 741, a link 749, a second rotating member 742, a pressing lever 72, an elastic member 75, a clamping member 725, a presser foot 71, and a height detecting portion 76. The cloth pressing motor 73 is provided at the right portion inside the arm portion 4, and is driven to rotate in the forward and reverse directions. An output shaft of the cloth pressing motor 73 protrudes forward, and a gear 73A is fixed to a front end portion of the output shaft. The first rotating member 741 has a substantially fan shape in front view, and is supported by the first shaft portion 751 so as to be rotatable about the first shaft portion 751. The first shaft portion 751 is fixed inside the arm portion 4 and extends in the front-rear direction. The first rotating member 741 has a tooth 741A and an arm 741B. A tooth section 741A is formed on the outer periphery of the first rotating member 741, and meshes with the gear 73A. The arm section 741B is provided on the left side of the tooth section 741A and protrudes downward to the left. The first rotating member 741 rotates about the first shaft portion 751 by the driving force of the cloth pressing motor 73. The link 749 extends in the left-right direction. The right end of the link 749 is rotatably connected to the arm portion 741B via the link 749, and the left end of the link 749 is rotatably connected to the second rotating member 742 via the link 749. The second rotating member 742 has a substantially L-shape in a rear view, and the bent portion of the second rotating member 742 is rotatably supported by the second shaft portion 752 so that the second rotating member 742 can rotate. The second shaft portion 752 is fixed inside the nose portion 5 and extends in the front-rear direction. The second rotating member 742 has an arm 742A and an arm 742B. The arm 742A projects upward from the bent portion of the second rotating member 742, and the arm 742B projects leftward from the bent portion. The distal end portion of the arm 742A is connected to the left end portion of the link 749 so that the arm 742A can rotate. When the link 749 reciprocates in accordance with the rotation of the first rotating member 741, the second rotating member 742 rotates about the second shaft portion 752.

The pressing rod 72 extends in the up-down direction, and is inserted in a pair of bearings 721. A pair of bearings 721 are fixed inside the nose part 5 in a vertically aligned manner, and support the pressing rod 72 in such a manner that the pressing rod 72 can move up and down. The upper end of the pressing rod 72 protrudes upward from the head 5, and the lower end of the pressing rod 72 protrudes downward from the head 5. An upper bar anchor 722 and a lower bar anchor 723 are fixed to the strut 72. The upper and

lower pole hoops

722 and 723 are arranged in the up-down direction between the pair of bearings 721. The elastic member 75 is a coil spring, which is located between the upper bar anchor 722 and the lower bar anchor 723, and the press bar 72 is inserted in the elastic member 75. The elastic member 75 is in contact with the lower pole ear 723.

The holding member 725 is cylindrical with its vertical direction as the axial direction, and is located between the elastic member 75 and the upper bar anchor 722, and the press bar 72 is inserted into the holding member 725. The lower end of the clamping member 725 abuts the upper end of the resilient member 75. The clamping member 725 is movable up and down along the presser bar 72. The clamping member 725 has a protrusion 725A and a protrusion 725B. The protruding portion 725A protrudes rearward from the upper end of the clamping member 725, and the protruding portion 725B protrudes rearward from the lower end of the clamping member 725. The square block 748 is provided at the tip end portion of the arm 742B, and is fitted between the protruding portion 725A and the protruding portion 725B so as to be slidable left and right. Therefore, the clamping member 725 is connected to the distal end portion of the arm 742B via the square block 748. Therefore, when the second rotating member 742 rotates, the clamping member 725 moves up and down. When the clamping member 725 pushes up the upper bar hoop 722, the pressing rod 72 is raised, and when the clamping member 725 presses down the lower bar hoop 723 via the elastic member 75, the pressing rod 72 is lowered.

The presser foot 71 is fixed to the lower end of the pressing rod 72. The presser foot 71 is vertically movable between a spaced position (see fig. 11) and a contact position (see fig. 12) by moving vertically integrally with the presser bar 72. The separated position is a vertical position where the presser foot 71 is separated upward from the cloth 9 placed on the needle plate 7. The contact position is a vertical position at which the presser foot 71 contacts the cloth 9 placed on the needle plate 7 from above. When the clamp member 725 moves up and down with the presser foot 71 in the contact position, the force applied to the presser foot 71 by the elastic member 75 changes. Therefore, the pressure of the presser foot 71 against the cloth 9 changes.

The height detector 76 includes a detector 762 and a subject 761. The detection unit 762 is, for example, an optical sensor, and is fixed inside the head unit 5. The detection unit 762 includes a plurality of light receiving elements arranged in the vertical direction. The output of each light receiving element changes according to the difference in light intensity. The subject 761 is fixed to the lower bar hoop 723 and can block the light receiving element at the same vertical position as the subject 761 among the plurality of light receiving elements. Therefore, the height detection unit 76 can detect the vertical position of the subject 761 with respect to the needle plate 7 (i.e., the vertical position of the lower bar hoop 723 and the presser foot 71 with respect to the needle plate 7).

As shown in fig. 3, the cloth 9 of the present embodiment has a normal thickness portion 9A and a thick cloth portion 9B. The thickness of the thick portion 9A is normally smaller than a predetermined thickness, and the thickness of the thick cloth portion 9B is larger than a predetermined thickness. The connecting portion between the thick portion 9A and the thick cloth portion 9B is normally a step portion 9C.

Referring to fig. 4 and 5, the cloth feeding mechanism 130 will be described. The cloth feeding mechanism 130 includes a cloth feeding table 133, an up-down conveying mechanism 135, and a horizontal conveying mechanism 125. The cloth feeding table 133 is disposed below the needle plate 7 substantially in parallel with the needle plate 7. The cloth feeding tooth 13 is fixed near the center of the upper surface of the cloth feeding table 133, and is long in the front-rear direction. The feed dog 13 is arranged to correspond to the position of the feed dog hole 14.

The up-down conveying mechanism 135 has an up-down conveying shaft 127, an eccentric portion 151, and a link member 139. The vertical transport shaft 127 is rotatably supported by the base 2 and extends in the left-right direction. A lower shaft pulley 124 is fixed to a right end of the upper and lower conveyance shaft 127. The lower shaft pulley 124 is connected to the upper shaft pulley by a belt. The up-down conveying shaft 127 is rotated by the main motor 31. Therefore, the upper and lower conveying shafts 127 and 11 can be rotated in synchronization with each other. The eccentric portion 151 is provided at the left end portion of the up-down conveying shaft 127. The eccentric portion 151 is eccentric with respect to the axial center of the upper and lower conveyance shafts 127. The link member 139 is rotatably provided at the rear end portion of the cloth feeding table 133. The link member 139 holds the eccentric portion 151 in a manner that the eccentric portion 151 can rotate. When the up-and-down feed shaft 127 rotates, the eccentric portion 151 moves the cloth feeding table 133 up and down via the link member 139. In the sewing machine 1, the feed dog 13 and the feed table 133 reciprocate once up and down while the needle bar and the needle reciprocate once up and down.

The horizontal transport mechanism 125 has a cloth feed motor 123, a link mechanism portion 140, a horizontal transport shaft 128, and a link member 150. The cloth feeding motor 123 is disposed inside the bed unit 2 and to the right of the cloth feeding table 133. The cloth feed motor 123 is a pulse motor that can rotate the drive shaft 136 within a predetermined rotational range. The cloth feed motor 123 can move the cloth feed table 133 forward and backward.

The link mechanism portion 140 has a first arm portion 141, a second arm portion 142, and an intermediate action arm 138. One end of the first arm 141 is mounted on the top end of the driving shaft 136. The first arm portion 141 is orthogonal to the drive shaft 136. The other end of the first arm 141 is connected to one end of the second arm 142 such that the first arm 141 is rotatable. The other end of the second arm portion 142 is connected to the rear end of the intermediate acting arm 138 so that the second arm portion 142 can rotate. The front end of the intermediate acting arm 138 is fixed to the right end side of the horizontal conveyance shaft 128. The horizontal transport shaft 128 extends in the left-right direction in parallel with the vertical transport shaft 127, and the horizontal transport shaft 128 is rotatably supported by the base 2 on the left of the feed motor 123. When the drive shaft 136 rotates, the joint between the first arm 141 and the second arm 142 is moved back and forth, and the intermediate acting arm 138 is swung up and down about the horizontal conveyance shaft 128.

The horizontal feed shaft 128 is rotatable within a predetermined rotation range in association with the swing of the intermediate acting arm 138. The lower end of the link member 150 is fixed to the left end of the horizontal transfer shaft 128 such that the link member 150 is orthogonal to the horizontal transfer shaft 128. The upper end of the link member 150 is connected to the front end of the cloth feeding table 133 so that the link member 150 can rotate. When the horizontal transport shaft 128 rotates within a predetermined rotation range, the cloth feeding table 133 moves back and forth by means of the link member 150. When the feed table 133 is raised, the upper ends of the feed dogs 13 are caused to protrude from the feed dog holes 14 to above the needle plate 7. The needle does not penetrate the cloth 9 while the upper end of the feed dog 13 is above the needle plate 7.

The sewing machine 1 drives the main motor 31 and the cloth feed motor 123 synchronously during execution of sewing. The feed dog 13 swings together with the feed table 133. Therefore, the feed dog 13 can protrude from the feed dog hole 14 or sink into the feed dog hole 14. When the feed motor 123 is driven while the upper end of the feed dog 13 is above the needle plate 7, the cloth 9 is moved backward. When the cloth feeding table 133 is lowered, the upper ends of the cloth feeding teeth 13 are positioned below the needle plate 7. Therefore, the cloth 9 is not moved even if the cloth feeding teeth 13 move back and forth. The needle forms a stitch on the cloth 9 while the feed dog 13 is below the needle plate 7. Hereinafter, the timing of swinging the feed dog 13 when the feed dog 13 protrudes from the feed dog hole 14 and moves backward is referred to as "feed", and the timing of swinging the feed dog 13 when it is not feed is referred to as "feed stop". The timing of the cloth 9 being conveyed by the cloth conveying teeth 13 is the timing when the cloth 9 is not conveyed by the cloth conveying teeth 13 when the cloth conveying is stopped.

The cloth feeding motor 123 reciprocates the drive shaft 136 at a specific rotational position as an intermediate position. The specific rotation position is a position to which the drive shaft 136 is rotated when the first arm portion 141 extends obliquely upward rearward from the drive shaft 136. When the cloth feeding motor 123 reciprocates the drive shaft 136 once, the cloth feeding teeth 13 reciprocate once in the front-rear direction. In the sewing machine 1, the feed amount can be changed by adjusting the rotational width of the drive shaft 136 to adjust the amount of forward and backward movement of the feed dog 13. The cloth feed amount is an amount of feeding the cloth 9 backward by the cloth feed dog 13.

Referring to fig. 6, the swing locus of the feed dog 13 is explained. The upper surface of the needle plate 7 is illustrated by a two-dot chain line in fig. 6. The cloth feeding motor 123 can change the reciprocation start timing and the reciprocation end timing of the drive shaft 136 during the rotation of the output shaft of the main motor 31. That is, the sewing machine 1 can change the timing to start and the timing to end the cloth feeding. The cloth feed start timing is a start timing at which the cloth feed table 133 operates backward while the cloth feed table 133 operates in the up-down direction, and the cloth feed end timing is an end timing at which the cloth feed table 133 operates backward while the cloth feed table 133 operates in the up-down direction. The sewing machine 1 can change the swing locus of the feed dog 13 by changing the feed start timing and the feed end timing.

The cloth feeding table 133 of the present embodiment can draw either one of the swing locus 101 and the swing locus 401. The direction of oscillation of the feed dog 13 in the case of the oscillation trajectory 101 is indicated by arrow 104, and the direction of oscillation of the feed dog 13 in the case of the oscillation trajectory 401 is indicated by arrow 404. When the feed dog 13 swings along the trajectory 401A and the trajectory 402B extending in the vertical direction out of the swing trajectories 401, the main motor 31 is driven and the feed motor 123 is not driven. A point on the swing path 101 which is above the needle plate 7 and is the center in the front-rear direction is a point 107. A point above the needle plate 7 and at the center in the front-rear direction on the swing path 401 is a point 407. In the present embodiment, the swing start positions of the feed dog 13 are the point 107 and the point 407.

The cloth feed start timing in the case of the swing locus 401 is later than the cloth feed start timing in the case of the swing locus 101, and the cloth feed end timing in the case of the swing locus 401 is earlier than the cloth feed end timing in the case of the swing locus 101. Therefore, when the feed dog 13 draws the swing locus 401, the feed table 133 starts the backward movement after the feed dog 13 rises sufficiently. Therefore, when the sewing machine 1 is to sew the thick cloth portion 9B, it is preferable that the feed dog 13 draws the swing locus 401. The operator can select either one of the swing locus 101 and the swing locus 401 in accordance with the thickness of the cloth 9. Fig. 6 illustrates the swing locus 101 and the swing locus 401 on the premise that the cloth feed amount is the same, but the sewing machine 1 can change the cloth feed amount according to the swing locus 101 and the swing locus 401.

Referring to fig. 7, an electrical structure of the sewing machine 1 is explained. The control device 30 has a CPU 91. The CPU91 controls the operation of the sewing machine 1. The CPU91 is connected to a ROM92, a RAM93, a storage device 94, and an input/output interface (hereinafter referred to as an input/output section) 95. The ROM92 stores programs and the like for executing various processes such as a main process (see fig. 8) described later. The RAM93 is used to temporarily store various values when a program is executed. The storage device 94 is nonvolatile, and stores a flag of a specific property, that is, a specific flag.

The storage device 94 stores basic information. The basic information is an information table obtained by associating the needle number with the pressure of the presser foot 71. The number of needles is numbered from the first needle to the Nth needle, and N is an integer of 2 or more. That is, the basic information includes N pressures of the presser foot 71. Hereinafter, the number of any of the first to nth needles is referred to as the number of needles N, and the pressure of the presser foot 71 corresponding to the nth needle is F_n。

The storage device 94 stores first reference angle information and second reference angle information. The first reference angle information and the second reference angle information are information tables each obtained by associating an upper shaft angle, which is a rotational angle phase of the upper shaft 11, with a cloth feeding shaft angle, which is a rotational angle phase of the drive shaft 136 of the cloth feeding motor 123. The first reference angle information is an information table in which: the CPU91 calculates and acquires the feed shaft angle when the feed dog 13 swings along the swing locus 101 by a predetermined feed amount, based on the information table. The second reference angle information is an information table in which: the CPU91 calculates and acquires the feed shaft angle when the feed dog 13 swings along the swing locus 401 by a predetermined feed amount, based on the information table. The upper axis angle stored in the first reference angle information and the second reference angle information is, for example, 0 ° to 359 °. The feed axis angle stored in the first reference angle information and the second reference angle information is an angle in a predetermined range such as 20 ° to 50 °, for example. The CPU91 can acquire the feed shaft angle corresponding to the feed amount and the swing locus 101 by referring to the first reference angle information, and the CPU91 can acquire the feed shaft angle corresponding to the feed amount and the swing locus 401 by referring to the second reference angle information.

The input/output unit 95 is connected to the drive circuits 81 to 86. The CPU91 can send a control signal to the drive circuit 81 to control the main motor 31. Therefore, the CPU91 can control the vertical position of the needle bar, the vertical position of the feed dog 13, and the like. The CPU91 can send a control signal to the drive circuit 82 to control the cloth feed motor 123. Therefore, the CPU91 can control the front-rear direction position of the feed dog 13. Hereinafter, the main motor 31 and the cloth pressing motor 73 will be collectively referred to as a driving unit 105. The CPU91 can send a control signal to the drive circuit 83 to control the cloth pressing motor 73. Therefore, the CPU91 can control the vertical position of the presser foot 71 and the amount of elastic deformation of the elastic member 75. The CPU91 can send a control signal to the drive circuit 84 to display various information on the display unit 48 of the operation unit 46. The CPU91 can send a control signal to the drive circuit 85 to control the tangent electromagnet element 161. The CPU91 can send a control signal to the drive circuit 86 to control the wire trap electromagnetic element 231. Therefore, the CPU91 can control the tension applied to the upper thread by the upper thread adjusting mechanism 222.

The main motor 31 is connected to the main encoder 41, the cloth feed motor 123 is connected to the cloth feed encoder 42, and the cloth pressing motor 73 is connected to the cloth pressing encoder 43. The main encoder 41 can detect the rotational angle phase of the output shaft of the main motor 31. Therefore, the main encoder 41 can detect the upper shaft angle. By causing the main encoder 41 to output the detection result to the CPU91 via the input/output unit 95, the CPU91 can acquire the upper shaft angle. The rotational angle phase of the upper and lower conveyance shafts 127, i.e., the upper and lower conveyance shaft angles, is in one-to-one relationship with the upper shaft angle. The vertical feed axis angle is related to the vertical position of the feed dog 13. Therefore, the CPU91 can acquire the up-down conveying shaft angle by acquiring the up-shaft angle based on the detection result of the main encoder 41. The feed encoder 42 is capable of detecting the feed shaft angle. By causing the cloth feeding encoder 42 to output the detection result to the CPU91 via the input/output unit 95, the CPU91 can acquire the front-rear direction position of the cloth feeding dog 13. The cloth pressing encoder 43 can detect the rotational angle phase of the output shaft of the cloth pressing motor 73. By causing the cloth pressing encoder 43 to output the detection result to the CPU91 via the input/output unit 95, the CPU91 can be caused to acquire the vertical position of the clamping member 725.

The input/output unit 95 is connected to the operation knob 47, the pedal 37, and the height detection unit 76. The CPU91 can acquire various instructions input by the operator using the operation buttons 47. The CPU91 can acquire the operation direction and the operation amount for the pedal 37. The CPU91 can acquire the elastic deformation amount of the elastic member 75 based on the detection results of the height detecting section 76 and the cloth pressing encoder 43. Therefore, the CPU91 can control the pressure of the presser foot 71 against the cloth 9 when in the contact position by controlling the cloth pressing motor 73 based on the detection results of the height detecting section 76 and the cloth pressing encoder 43.

Referring to fig. 1 to 5, an outline of the sewing operation of the sewing machine 1 will be described. Hereinafter, the upper shaft 11, the needle bar, the rotary hook, the thread take-up lever, and the cloth feeding mechanism 130 will be collectively referred to as a sewing mechanism 40. The presser foot 71 presses the cloth 9 from the side opposite to the side where the needle plate 7 is located at the contact position. The needle is in the needle-up position before the drive section 105 is driven. When the driving part 105 is driven, the sewing mechanism 40 is driven. At the same time, the thread tension solenoid 231 is driven at a prescribed driving voltage, and the pressing tension 223 clamps the upper thread between it and the pressing tension 224. The upper thread adjusting mechanism 222 applies a predetermined tension to the upper thread. After the needle moves from the needle-up position to the needle-down position and pierces the cloth 9, the rotating shuttle catches the upper thread held by the needle and interlaces the upper thread with the lower thread. The needle is pulled upward out of the cloth 9. At this time, the cloth feed motor 123 reciprocally rotates the drive shaft 136 about the specific rotational position, so that the cloth feed dog 13 protrudes from the cloth feed dog hole 14 and feeds the cloth 9 backward by a predetermined cloth feed amount. The thread take-up lever moves upward in accordance with the movement of the needle to the needle-up position, and lifts the upper thread interlaced with the lower thread to the needle plate 7. The sewing mechanism 40 sequentially forms stitches on the cloth 9.

The main process is described with reference to fig. 8 to 15. Before the main process starts, the presser foot 71 is in the spaced position (see fig. 11). Before the main process is started, the normal thickness portion 9A is located below the presser foot 71, and the step portion 9C and the thick cloth portion 9B are located in front of the normal thickness portion 9A. When the operator turns on the power of the sewing machine 1, the CPU91 reads out the program from the ROM92 and starts the main process.

As shown in fig. 8 to 10, the CPU91 acquires initial pressure information indicating an initial pressure (S11). Specifically, the initial pressure information is acquired by the CPU91 by the operator selecting a desired initial pressure from a plurality of initial pressures displayed on the display unit 48 of the operation unit 46. The initial pressure is a prescribed pressure of the presser foot 71. The elastic deformation amount of the elastic member 75 when the pressing force of the presser foot 71 is the initial pressing force is the initial deformation amount, and has a correlation with the dimension L1 in fig. 12. In the present embodiment, the sewing machine 1 controls the cloth pressing motor 73 so that the pressure becomes the initial pressure when stopping the cloth feeding.

The CPU91 acquires feed information indicating the feed amount (S13), acquires tension information indicating the tension of the upper thread (S15), and acquires trajectory information indicating either one of the swing trajectory 101 and the swing trajectory 401 (S17). In the present embodiment, the feed amount indicated by the feed information changes depending on the number of stitches, and the tension indicated by the tension information and the swing trajectory indicated by the trajectory information are constant regardless of the number of stitches. The operator operates the operation knob 47 to input instructions for selecting the feed information, desired tension information, and swing trajectory 401 for each number of needles. When the operator inputs the swing locus 401, the CPU91 is caused to acquire locus information indicating the swing locus 401.

The CPU91 acquires the first information 111 (refer to fig. 9) (S19). The first information 111 is an information table in which the feed amount indicated by the feed information acquired at S13 and a predetermined pressure, which is a pressure calculated based on basic information or the like, are associated with the needle number. M in the first information 111₁、M₂、M₃、···、M_n、···M_NThe feed amount indicated by the feed information acquired in S13. G in the first information 111₁、G₂、G₃、···、G_n、···G_NIs at a given pressure. Predetermined pressure G_nIs determined by the formula (1).

G_n＝F_n+(M_n/M₀)×α+(T/T₀)×β+(S/S₀)×γ+(E/E₀) X delta. formula (1)

T in the formula (1) is the tension indicated by the tension information acquired in S15. S is a numerical value indicating the cloth feeding start timing on the swing trajectory indicated by the trajectory information acquired in S17, and is correlated with the dimension H1 in fig. 6. E is a numerical value indicating the timing of the end of the cloth feeding on the swing trajectory indicated by the trajectory information acquired in S17, and is correlated with the size H2. S₀A predetermined value indicating a timing of starting cloth feeding in the swing locus, E₀The predetermined value is a predetermined value indicating the timing of the end of the cloth feeding in the swing locus. M₀、T₀The values are predetermined values, and α, β, γ, and δ are predetermined coefficients. The CPU91 obtains each through S13-S17 based on the basic informationThe seed information and equation (1) to obtain the first information 111.

The CPU91 acquires the sewing information 122 (see fig. 10) (S21). The sewing information 122 is an information table in which the cloth feed amount and the cloth feed pressure indicated in the first information 111, that is, the cloth feed pressure, are associated with the needle number. P in the sewing information 122₁、P₂、P₃、···、P_n、···、P_NThe pressure during cloth feeding. The pressure at the time of cloth feeding is G contained in the first information 111₁、G₂、G₃、···、G_n、···、G_NThe given pressure of (b) that is smaller than the initial pressure obtained by S11 is replaced with the pressure obtained by the initial pressure. In the present embodiment, only G is assumed₁And G₂Less than P representing the initial pressure₀When the cloth is fed, the pressure P_nIs determined by the formula (2) and the formula (3).

P_n＝P₀(n ═ 1, 2) · formula (2)

P_n＝G_n(3. ltoreq. N. ltoreq. N) · formula (3)

The CPU91 acquires the sewing information 122 based on the first information 111 acquired through S19, equation (2), and equation (3). In this embodiment, P in the formula (3)_nGreater than P₀。

The CPU91 acquires angle information (S22). The angle information is an information table in which the upper shaft angle and the cloth feed shaft angle are associated with each other in the case where the cloth feed dog 13 is swung in accordance with the swing locus indicated by the locus information acquired in S17 on the basis of the cloth feed amount indicated by the cloth feed information acquired in S13. The CPU91 acquires the angle information based on the feed amount indicated by the feed information acquired at S13, the second reference angle information stored in the storage device 94, and a predetermined equation.

As shown in fig. 8, 11, and 12, the CPU91 determines whether a presser foot lowering instruction for moving the presser foot 71 to the contact position is detected (S23). When the CPU91 determines that the presser foot down instruction has not been input by the operator using the operation knob 47 (S23: no), the CPU91 determines whether or not an end instruction for ending the main processing has been detected (S25). When the CPU91 determines that the operator has input an end instruction using the operation knob 47 (S25: yes), the CPU91 turns off the power supply of the sewing machine 1 to end the main process. When the CPU91 determines that the operator has not input an end instruction using the operation knob 47 (S25: no), the CPU91 shifts the process to S23.

When the CPU91 determines that the presser foot lowering instruction is input by the operator using the operation knob 47 (S23: yes), the CPU91 controls the feed motor 73 to be driven to move the presser foot 71 from the spaced position to the contact position (S27). The second rotating member 742 rotates clockwise in the rear view, and moves the holding member 725 downward. The clamp member 725 biases the lower bar anchor 723 downward via the elastic member 75, and moves the presser foot 71 downward together with the presser bar 72. Therefore, the presser foot 71 can be moved to the contact position. In the present embodiment, the CPU91 controls the cloth pressing motor 73 to continue the downward movement of the clamping member 725, thereby setting the elastic deformation amount of the elastic member 75 to the initial deformation amount (see fig. 12). The pressing force of the presser foot 71 becomes the initial pressing force (S27). The CPU91 initializes the pin number n stored in the RAM93 to 1 (S29).

The CPU91 determines whether the pedal 37 has been depressed toward the toe side (S31). When the CPU91 determines that the operator has not depressed the pedal 37 toward the toe side (S31: no), the CPU91 determines whether the pedal 37 has been depressed toward the heel side (S33). When the CPU91 determines that the operator has stepped back the pedal 37 to the heel side (S33: yes), the CPU91 shifts the process to S39. When the CPU91 determines that the operator has not stepped back the pedal 37 to the heel side (S33: no), the CPU91 determines whether or not an end instruction is detected (S35). When the CPU91 determines that the operator has not input an end instruction using the operation knob 47 (S35: no), the CPU91 shifts the process to S31. When the CPU91 determines that the operator has depressed the pedal 37 toward the toe side (S31: yes), the CPU91 performs stitch forming processing (S40).

Referring to fig. 13, the trace forming process is explained. The CPU91 starts driving of the driving section 105 and the wire-clamping electromagnetic element 231 (S41). The needle bar starts to move up and down, and the cloth feeding tooth 13 starts to swing. The feed dog 13 swings at a point 407 (see fig. 6) as a swing start position. The CPU91 drives the wire clamping electromagnetic element 231 with a drive voltage corresponding to the tension indicated by the tension information acquired in S15. Therefore, the tension of the upper thread becomes the tension shown by the tension information acquired at S15.

The CPU91 determines whether or not the portion of the cloth 9 between the presser foot 71 and the needle plate 7 is the thick cloth portion 9B by acquiring the detection result of the height detecting section 76 (S42). When the CPU91 determines that the vertical position of the presser foot 71 indicated by the detection result of the height detecting unit 76 does not exceed the predetermined height (S42: no), the CPU91 sets the specific flag in the storage device 94 to 0 (S43).

The CPU91 determines whether or not the fabric feeding is performed based on the detection result of the main encoder 41 (S44). The CPU91 specifies the upper axis angle corresponding to the cloth feeding based on the angle information acquired in S22. When the vertical axis angle indicated by the detection result of the main encoder 41 is the vertical axis angle corresponding to the time of cloth feeding, the CPU91 determines that the time is the time of cloth feeding. When the CPU91 judges that the cloth feeding is performed (S44: YES), the CPU91 controls the cloth pressing motor 73 so that the pressure of the presser foot 71 is P₁(initial pressure in this embodiment) (S53). The CPU91 executes the feeding process (S50).

The cloth feeding process is described with reference to fig. 14. The CPU91 acquires the upper axis angle by acquiring the detection result of the main encoder 41 (S81). The CPU91 acquires a target feed shaft angle based on the angle information acquired through S22 and the upper shaft angle acquired through S81 (S83). The CPU91 controls the cloth feeding motor 123 based on the detection result of the cloth feeding encoder 42 so that the cloth feeding shaft angle becomes the target cloth feeding shaft angle (S85). The CPU91 ends the cloth feeding process and returns to the stitch forming process (see fig. 13).

As shown in fig. 13, the CPU91 determines whether or not the sewing of the nth needle is completed based on the detection result of the main encoder 41 (S51). The CPU91 acquires the upper shaft angle based on the detection result of the main encoder 41, and determines whether or not the sewing of the nth needle is finished based on the acquired upper shaft angle. When the CPU91 determines that the sewing of the first needle has not ended (S51: no), the CPU91 shifts the process to S42. The CPU91 repeatedly executes S42 to S51. The sewing machine 1 maintains the pressure of the presser foot 71 at P₁(S53), the feed dog 13 swings (S50), and the needle bar moves downward. Thus, the sewing mechanism 40 performs the sewing of the first needle. The cloth feeding teeth 13 protruding from the cloth feeding sprocket hole 14 urge the presser foot 71 upward via the cloth 9 to bounceThe elastic member 75 elastically receives a force applied to the presser foot 71 by the feed dog 13.

When the CPU91 judges that the cloth feeding is stopped (S44: NO), the CPU91 controls the cloth pressing motor 73 so that the pressure of the presser foot 71 is P₀(S49). The CPU91 executes the feeding process (S50). The CPU91 repeatedly executes S42 to S51, whereby the sewing mechanism 40 forms a stitch on the fabric 9.

When the CPU91 determines that the sewing of the first needle is completed (S51: yes), the CPU91 determines whether or not the sewing indicated by the sewing information 122 is completed based on the needle number n and the detection result of the main encoder 41 (S55). When the CPU91 determines that sewing is not completed (S55: no), the CPU91 increments the needle number n by 1(S57) and shifts the process to S42. The CPU91 repeatedly executes S42 to S57, whereby the cloth feeding mechanism 130 feeds the cloth 9 backward, the sewing mechanism 40 forms stitches on the cloth 9 one by one, and the cloth pressing mechanism 70 adjusts the pressure. For example, when the second needle is sewn, the cloth pressing motor 73 maintains the pressure at the initial pressure at the time of stopping the cloth feeding and at the time of cloth feeding (S49, S53). When the third needle is fed, the CPU91 sets the elastic deformation amount of the elastic member 75 to be larger than the initial deformation amount and sets the pressure to P₃(S53)。

A case will be described where the step 9C of the cloth 9 enters between the needle plate 7 and the presser foot 71 when the CPU91 repeatedly executes S42 to S57. When the step portion 9C of the cloth 9 enters between the needle plate 7 and the presser foot 71, the presser foot 71 is moved upward together with the presser bar 72. Therefore, the vertical position of the presser foot 71 indicated by the height detecting unit 76 exceeds the predetermined height (S42: YES). The CPU91 refers to the storage device 94 and determines whether or not the specific flag is 0 (S59). When the CPU91 determines that the specific flag is 0 (S59: yes), the CPU91 overwrites the specific flag stored in the storage device 94 with 1 and acquires the reference upper axis angle based on the detection result of the main encoder 41 (S60). The reference upper axial angle is an upper axial angle when the CPU91 determines that the portion of the cloth 9 between the presser foot 71 and the needle plate 7 is the thick cloth portion 9B in S42.

The CPU91 determines whether or not the cloth is fed (S61). The process of S61 is the same as the process of S44. In the cloth feeding (S61: YES), the step part 9C enters between the needle plate 7 and the presser foot 71. The CPU91 shifts the process to S63.

The CPU91 determines whether the needle count is the second needle or subsequent needle count and whether the specific cumulative upper axial angle is equal to or smaller than a predetermined angle based on the needle count number n and the detection result of the main encoder 41 (S63). The specific cumulative upper shaft angle is a cumulative rotation angle obtained by rotating the upper shaft 11 from the reference upper shaft angle. The predetermined angle is a preset angle. Immediately after the step portion 9C enters between the presser foot 71 and the needle plate 7, the specific cumulative upper axial angle is smaller than the predetermined angle. Therefore, the CPU91 determines that the specific cumulative upper shaft angle is equal to or smaller than the predetermined angle (S63: YES). The CPU91 controls the cloth pressing motor 73 to move the clamping member 725 upward (arrow J in fig. 15) to set the pressure P_n-B (S65). B is a positive predetermined value. Therefore, the sewing machine 1 can suppress a sudden rise in the pressure of the presser foot 71 immediately after the step portion 9C enters between the needle plate 7 and the presser foot 71. The CPU91 proceeds to S50 and the feed dog 13 moves the step 9C of the cloth 9 backward. When S59 is executed next, since the specific flag is 1 (S59: no), the CPU91 shifts the process to S61. The CPU91 repeatedly executes these steps in the order of S42, S59, S61, S63, S65. The specific cumulative upper shaft angle obtained at S63 increases to a value close to the predetermined angle.

When the CPU91 judges that the specific cumulative upper shaft angle is larger than the predetermined angle (S63: NO), the CPU91 controls the cloth pressing motor 73 to move the holding member 725 downward to set the pressure of the presser foot 71 to P_n+ C (S67). C is a positive predetermined value. The pressure of the presser foot 71 rises. Therefore, the sewing machine 1 can suppress the slippage of the thick cloth portion 9B with respect to the feed dog 13. When the CPU91 repeatedly executes these steps in the order of S42, S59, S61, S63, S67, and S50, the cloth feeding dog 13 feeds the thick cloth portion 9B backward. After the feed is stopped (S61: NO), the CPU91 controls the cloth pressing motor 73 to make the pressure of the presser foot 71 be P₀+ A (S62). A is a positive predetermined value.

After the sewing mechanism 40 finishes sewing the nth needle indicated by the sewing information 122 (S55: yes), the CPU91 ends the driving of the driving unit 105 and the thread tension solenoid 231 (S69), and returns to the main process (see fig. 8).

As shown in fig. 8, the CPU91 drives the thread cutting solenoid 161 to cut the upper thread and the lower thread (S39). The CPU91 shifts the process to S31. When the CPU91 determines that the operator has not operated the pedal 37 (no in S31, no in S33) and determines that the end instruction has been input (yes in S35), the CPU91 controls the presser motor 73 to move the presser foot 71 to the separated position (S37). The CPU91 ends the main process.

With reference to fig. 13, a stitch forming process in a case where the thick cloth portion 9B is located between the presser foot 71 and the needle plate 7 at the start of sewing will be described. Immediately after the start of the stitch forming process, the CPU91 determines that the portion of the cloth 9 between the presser foot 71 and the needle plate 7 is the thick cloth portion 9B (S42: yes). The CPU91 overwrites the specific flag in the storage device 94 with 1 and acquires the reference upper axis angle (S60). Immediately after the start of sewing, the feed dog 13 feeds the thick cloth part 9B backward (S61: yes). At this time, since the sewing is the first needle (S63: NO), the CPU91 sets the pressure to P_n+ C (S67). When the CPU91 repeatedly executes S50, S51, S42, S59, S61, the specific cumulative upper shaft angle becomes larger than the prescribed angle. Therefore, when the cloth feeding mechanism 130 feeds the thick cloth part 9B from the start of sewing, the CPU91 sets the pressure P to P without executing S65_n+C(S67)。

As described above, the sewing machine 1 changes the control of the cloth pressing motor 73 so that the control of the cloth pressing motor 73 is different between the time of stopping the cloth feeding and the time of the cloth feeding (S49, S53). The sewing machine 1 can be changed to a state in which the pressure of the presser foot 71 is maintained at the initial pressure and a state in which the pressure of the presser foot 71 is greater than the initial pressure. The sewing machine 1 can prevent the pressure of the presser foot 71 from rising unnecessarily by elastically receiving the force of the presser foot 71 from the feed dog 13 by a predetermined pressure. Therefore, the sewing machine 1 can easily optimize the pressing force of the presser foot 71 against the cloth 9. The sewing machine 1 can change the pressure so that the pressure is different between the time of feeding the cloth and the time of stopping the feeding of the cloth (S49, S53). Since the force received by the presser foot 71 from the feed dog 13 varies between the time of feeding and the time of stopping feeding, the sewing conditions at the time of feeding and at the time of stopping feeding are different. Therefore, the sewing machine 1 can appropriately control the pressure according to the sewing conditions.

In the sewing of the third needle and thereafter, the CPU91 controls the cloth pressing motor 73 so that the elastic deformation amount of the elastic member 75 becomes the initial deformation amount at the time of stopping the cloth feeding (S49), and controls the cloth pressing motor 73 so that the elastic deformation amount of the elastic member 75 becomes larger than the initial deformation amount at the time of cloth feeding (S53). Since the pressure of the presser foot 71 at the time of feeding the cloth is larger than the initial pressure, which is the pressure of the presser foot 71 at the time of stopping feeding the cloth, the sewing machine 1 can suppress the deviation of the cloth 9 that may occur at the time of performing the sewing operation.

When the cloth 9 is thick and heavy, the pressure of the presser foot 71 is insufficient, and the cloth 9 may be displaced during sewing. When the vertical position of the presser foot 71 is higher than the predetermined height (S42: YES), the sewing machine 1 controls the cloth pressing motor 73 to increase the elastic deformation amount of the elastic member 75 (S62, S67). Therefore, even when the cloth 9 is thick and heavy, the sewing machine 1 can prevent the cloth 9 from being displaced during sewing.

When the step portion 9C enters between the presser foot 71 and the needle plate 7 (yes in S42), the CPU91 controls the cloth pressing motor 73 to reduce the elastic deformation amount of the elastic member 75 (S65), and then controls the cloth pressing motor 73 to increase the elastic deformation amount of the elastic member 75 (S67). Therefore, the sewing machine 1 can suppress a sudden increase in the pressure of the presser foot 71 when the step portion 9C enters between the presser foot and the needle plate. Therefore, the sewing machine 1 can easily optimize the pressing force of the presser foot 71 against the cloth 9.

The upward force applied to the presser foot 71 from the swinging feed dog 13 changes in accordance with the vertical position of the feed dog 13. The CPU91 determines whether or not the cloth is being fed based on the vertical transport shaft angle detected by the main encoder 41 (S44). The CPU91 determines whether the cloth is fed or not based on the detection result of the main encoder 41, which has a correlation with the vertical position of the cloth feeding teeth 13. That is, the sewing machine 1 determines whether the cloth feeding operation is performed or not according to the vertical position of the cloth feeding tooth 13, and changes the pressure of the presser foot 71 so that the pressure of the presser foot 71 is different between the cloth feeding operation and the cloth feeding stop operation (S49, S53). Therefore, the sewing machine 1 can appropriately determine whether to feed the cloth or stop the cloth, and can optimize the pressure of pressing the cloth 9 with the presser foot 71.

Pressure during cloth feedingForce P_nThe feed amount is determined by equation (1) and changes according to the feed amount indicated by the feed information acquired at S13. The sewing machine 1 can optimize the pressure of pressing the cloth 9 with the presser foot 71 by changing the pressure of the presser foot 71 according to the cloth feeding amount.

The cloth feed start timing and the cloth feed end timing change in accordance with the selection of the swing locus 101 and the swing locus 401 by the operator (S17), and the swing locus of the cloth feed dog 13 changes in accordance with the selection. The CPU91 changes the pressure of the presser foot 71 in accordance with the swing trajectory of the feed dog 13 indicated by the trajectory information acquired at S17, thereby optimizing the pressure with which the presser foot 71 presses the cloth 9 in the sewing machine 1.

Pressure P during cloth feeding_nDetermined by equation (1), it changes according to the tension of the upper thread indicated by the tension information acquired at S15. The CPU91 changes the pressure of the presser foot 71 in accordance with the tension of the upper thread indicated by the tension information acquired at S15, thereby optimizing the pressure with which the presser foot 71 presses the fabric 9 in the sewing machine 1.

When the first rotating member 741 is rotated by the driving force of the cloth pressing motor 73, the second rotating member 742 is rotated, and the gripping member 725 moves up and down. Therefore, the amount of elastic deformation of the elastic member 75 varies. The driving force of the cloth pressing motor 73 can be transmitted to the gripping member 725 via the first and second

rotating members

741 and 742. Since the driving force of the cloth presser motor 73 is not directly transmitted to the clamping member 725, the sewing machine 1 can suppress the clamping member 725 from being damaged.

The link 749 is rotatably coupled to the first rotating member 741 and the second rotating member 742, respectively. Since the link 749 extends in the left-right direction, the cloth pressing motor 73 can be disposed to the right of the presser bar 72 and at a position distant from the presser bar 72. Therefore, with the sewing machine 1, other members such as the needle bar can be arranged around the presser bar 72.

In the above description, the main encoder 41 is an example of the vertical conveyance axis angle detection unit according to the present invention. The

pressure applying clamps

223 and 224 are examples of the clamps of the present invention. The track information is an example of the track information of the present invention.

The CPU91 executing S49, S53, S62, S65, and S67 is an example of the cloth pressing control unit of the present invention. The CPU91 when S65 is executed is an example of the first compress control unit of the present invention. The CPU91 when S67 is executed is an example of the second cloth pressing control unit of the present invention. The CPU91 when executing S41 and S50 is an example of the sewing control unit of the present invention. The CPU91 executing S13 is an example of the cloth feeding information acquiring unit of the present invention. The CPU91 executing S17 exemplifies the trajectory information acquisition unit of the present invention. The CPU91 executing S15 is an example of the tension information acquiring unit of the present invention. The CPU91 executing S44 exemplifies the cloth feeding timing determining unit of the present invention.

The present invention is not limited to the above-described embodiments. The pressure of the presser foot 71 at the time of stopping the cloth feeding may be smaller than the pressure of the presser foot 71 at the time of cloth feeding, and may be larger than the initial pressure. Instead of selecting the initial pressure by the operator (S11), a predetermined initial pressure may be stored in the storage device 94 of the sewing machine 1. The first shaft portion 751 and the second shaft portion 752 may extend in the left-right direction. In this case, the link 749 extends in the front-rear direction, and the cloth pressing motor 73 is disposed at a position shifted in the front-rear direction with respect to the presser bar 72. Alternatively, the cloth pressing mechanism 70 may not have the first rotating member 741, the link 749, and the second rotating member 742. In this case, the clamping member 725 may have a rack extending in the vertical direction and meshing with the gear 73A of the cloth pressing motor 73.

The feed dog 13 may draw a swing locus other than the swing locus 101 and the swing locus 401. For example, the front part of the swing locus may coincide with the swing locus 101, and the rear part of the swing locus may coincide with the swing locus 401. The feed start timing of this trajectory is the same as the feed start timing of the swing trajectory 101, and the feed end timing of this trajectory is earlier than the feed end timing of the swing trajectory 101.

The cloth feeding mechanism 130 is not limited to the above embodiment. Instead of having the cloth feeding motor 123 that can move the cloth feeding table 133 forward and backward, the cloth feeding mechanism 130 may have a cloth feeding motor that can move the cloth feeding table 133 up and down. In this case, the cloth feeding motor may be connected to the vertical transport shaft 127 via a link mechanism. A pulley may be fixed to the right end of the horizontal conveyance shaft 128 of the horizontal conveyance mechanism, and the pulley may be connected to the upper shaft pulley via a belt. When the cloth feeding mechanism 130 includes a cloth feeding motor capable of moving the cloth feeding table 133 up and down, the cloth feeding mechanism may include a cloth feeding motor 123 capable of moving the cloth feeding table 133 forward and backward.

With the structure of the cloth feeding mechanism 130 of the above embodiment, when the cloth feeding motor 123 reciprocates the drive shaft 136 once, the cloth feeding teeth 13 reciprocate once in the front-rear direction. The cloth feeding mechanism may be configured to: when the driving shaft 136 reciprocates once, the feed dog 13 reciprocates twice in the front-rear direction. In this case, the following conditions may be satisfied: when the drive shaft 136 is at the specific rotation position, the first arm portion 141 extends upward from the drive shaft 136, and the second arm portion 142 extends upward from the first arm portion 141.

Claims

1. A sewing machine (1) has:

a needle plate (7) on which a cloth (9) can be placed;

a cloth feeding table (133) that supports cloth feeding teeth (13) that can convey the cloth placed on the needle plate;

a cloth feeding mechanism (130) which can drive the cloth feeding table and can convey the cloth by the cloth feeding teeth;

a presser foot (71) capable of pressing the cloth from above;

a pressing rod (72) extending in the vertical direction, the lower end of the pressing rod being fixed with the presser foot;

an elastic member (75) provided above the presser foot, the elastic member applying a pressure to the presser foot to press the fabric in a state where the presser foot is at a contact position where the presser foot contacts the fabric placed on the needle plate from above;

a cloth pressing motor (73) which can move the pressing rod up and down and can change the elastic deformation amount of the elastic component; and

a cloth pressing control section for controlling the pressing force of the presser foot at the contact position by controlling the cloth pressing motor,

the sewing machine is characterized in that the sewing machine is provided with a sewing machine,

the elastic member has an initial deformation amount, which is the elastic deformation amount capable of achieving a predetermined pressure, i.e., an initial pressure,

the cloth pressing control unit controls the cloth pressing motor to make the elastic deformation amount different between the time of cloth feeding and the time of stopping the cloth feeding, wherein the time of cloth feeding refers to the time when the cloth feeding mechanism conveys the cloth, and the time of stopping the cloth feeding refers to the time when the cloth feeding mechanism does not convey the cloth.

2. The sewing machine of claim 1,

the cloth pressing control unit controls the cloth pressing motor so that the elastic deformation amount becomes the initial deformation amount when the cloth feeding is stopped, and controls the cloth pressing motor so that the elastic deformation amount becomes larger than the initial deformation amount when the cloth feeding is stopped.

3. Sewing machine as in claim 1 or 2,

the sewing machine is provided with a presser foot height detection part (76) which can detect the vertical position of the presser foot relative to the needle plate,

the cloth pressing control unit controls the cloth pressing motor to increase the elastic deformation amount of the elastic member when the vertical position of the presser foot detected by the presser foot height detection unit is greater than a predetermined value.

4. The sewing machine of claim 3,

the cloth pressing control part comprises:

a first cloth pressing control unit that controls the cloth pressing motor to maintain the current elastic deformation amount of the elastic member or reduce the elastic deformation amount when the vertical position of the presser foot detected by the presser foot height detection unit is greater than a predetermined value; and

and a second cloth pressing control unit that controls the cloth pressing motor by the second cloth pressing control unit after the cloth pressing motor is controlled by the first cloth pressing control unit, so that the elastic deformation amount of the elastic member is increased.

5. The sewing machine of claim 1,

the cloth feeding mechanism comprises:

a horizontal transport mechanism (125) having a horizontal transport shaft (128) connected to the cloth feeding table, the horizontal transport mechanism moving the cloth feeding table in a horizontal direction by rotating the horizontal transport shaft; and

an up-down conveying mechanism (135) having an up-down conveying shaft (127) extending parallel to the horizontal conveying shaft and connected to the cloth feeding table, the up-down conveying mechanism rotating the up-down conveying shaft in synchronization with the horizontal conveying mechanism to move the cloth feeding table up and down,

the sewing machine has:

a vertical transport shaft angle detection unit (41) for detecting a vertical transport shaft angle, which is a rotational angle phase of the vertical transport shaft; and

a cloth feeding timing determination unit that determines whether or not the cloth is fed based on a detection result of the vertical feed shaft angle detection unit,

the cloth pressing control unit controls the cloth pressing motor in accordance with the determination result of the cloth feeding timing determination unit.

6. Sewing machine as in claim 5,

the sewing machine has:

a sewing mechanism (40) which can sew the cloth pressed by the presser foot;

a drive unit (105) which can drive the cloth feeding mechanism and the sewing mechanism;

a sewing control unit capable of controlling the driving of the driving unit; and

a cloth feed information acquiring unit capable of acquiring cloth feed information indicating a cloth feed amount, which is an amount of the cloth to be fed by the cloth feed teeth,

the sewing control part controls the driving part to convey the cloth according to the cloth feeding amount indicated by the cloth feeding information acquired by the cloth feeding information acquiring part,

the cloth pressing control unit controls the cloth pressing motor in accordance with the cloth feeding amount.

7. The sewing machine of claim 6,

the sewing machine comprises a track information acquisition part which can acquire track information, the track information is information representing the swing track of the cloth feeding teeth, at least one of the starting time and the ending time of the movement of the cloth feeding table to the horizontal direction in the period of the movement of the cloth feeding table to the vertical direction is different in different tracks,

the sewing control part controls the driving part to drive the cloth feeding table according to the swing track of the cloth feeding teeth shown by the track information acquired by the track information acquisition part,

the cloth pressing control unit controls the cloth pressing motor in accordance with the trajectory information acquired by the trajectory information acquisition unit.

8. The sewing machine of claim 6,

the sewing mechanism is provided with a facial thread adjusting mechanism (222) which is provided with thread clamping plates (223, 224) capable of applying tension to facial threads and can adjust the tension of the facial threads,

the sewing machine is provided with a tension information acquisition part which can acquire tension information representing the tension of the upper thread,

the sewing control part adjusts the tension of the upper thread by using the upper thread adjusting mechanism, so that the tension of the upper thread is changed into the tension shown by the tension information acquired by the tension information acquiring part,

the cloth pressing control unit controls the cloth pressing motor in accordance with the tension information acquired by the tension information acquiring unit.

9. The sewing machine of claim 7,

10. The sewing machine of claim 1,

the sewing machine has:

a clamping member (725) connected to the pressure lever so as to be movable up and down, the clamping member being in contact with the elastic member above the elastic member;

a first rotating member (741) that is rotatable in an axial direction that is a predetermined direction orthogonal to the vertical direction by a driving force of the cloth pressing motor; and

and a second rotating member (742) that is provided so as to be rotatable about the predetermined direction as an axial direction, the second rotating member being connected to the gripping member, and the second rotating member transmitting motion so as to convert rotation of the first rotating member into vertical motion of the gripping member.

11. The sewing machine of claim 10,

the sewing machine includes a link (749) extending in a direction orthogonal to the vertical direction and the predetermined direction, and rotatably connected to the first rotating member and the second rotating member, respectively.