CN107881658B

CN107881658B - Sewing machine and sewing machine control method

Info

Publication number: CN107881658B
Application number: CN201710899669.2A
Authority: CN
Inventors: 竹村徹
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 2016-09-30
Filing date: 2017-09-28
Publication date: 2020-04-14
Anticipated expiration: 2037-09-28
Also published as: CN107881658A; JP2018051147A

Abstract

The present invention relates to a sewing machine and a control method of the sewing machine which automatically change the pressing force with which the presser foot presses the cloth according to the cloth feed amount. The sewing machine has a feed dog, a feed motor, a presser foot, and a presser foot motor. The feed teeth swing back and forth under the drive of the feed motor. The amount of movement of the cloth feed teeth to move the cloth in the front-rear direction, that is, the cloth feed amount, changes according to the drive of the cloth feed motor. The presser foot is in contact with the fabric from the upper side. The pressing force applied to the fabric by the presser foot changes according to the drive of the presser foot motor. The CPU acquires sewing information. The sewing information stores the feed amount and the pressing force so that the feed amount and the pressing force are associated with the stitch number. The CPU controls the driving of the main motor and the feed motor based on the acquired sewing information, and executes sewing. The CPU executes sewing with the feed amount and pressing force indicated by the sewing information. Therefore, the sewing machine changes the pressing force according to the feed amount of the sewing information.

Description

Sewing machine and control method of sewing machine

Technical Field

The invention relates to a sewing machine and a control method of the sewing machine.

Background

A sewing machine capable of adjusting a pressing force for pressing a cloth and a cloth feed amount for feeding the cloth is known. The sewing machine disclosed in japanese patent laid-open No. 2003-326027 has a bed portion, a spring, a presser foot, a feed dog, and a feed adjusting motor. The operator places the cloth on the bed. The spring applies force to the presser foot downwards. The presser foot presses the cloth on the base part from above under the action of the force of the spring. The pressing force of the presser foot on the cloth changes according to the biasing force of the spring. The cloth feeding teeth convey the cloth through reciprocating swing. The conveying adjusting motor changes the cloth feeding amount by changing the swing amount of the cloth feeding teeth.

When the pressing force applied to the fabric is changed or when the pressing force applied to the fabric is constant but the fabric feeding amount is changed, the degree of tightness of the upper thread to the fabric is changed. When the operator wants to perform sewing with a predetermined degree of tightness, the sewing machine preferably applies a pressing force corresponding to the feed amount to the cloth by the presser foot. In the sewing machine, the operator manually changes the biasing force of the spring, thereby changing the pressing force of the presser foot. However, if the operator changes the biasing force of the spring every time the sewing machine changes the cloth feed amount, the work of the operator may become complicated.

Disclosure of Invention

The invention aims to provide a sewing machine and a control method of the sewing machine, which automatically changes the pressing force of a presser foot pressing cloth according to the cloth feeding amount.

The sewing machine of claim 1 comprises: a needle plate having a cloth feed sprocket hole and capable of placing a cloth thereon; a cloth feeding tooth capable of protruding from or retreating into the cloth feeding tooth hole by swinging; a cloth feeding mechanism which supports the cloth feeding teeth in a manner that the cloth feeding teeth can swing and can move the cloth in a horizontal direction by the cloth feeding teeth protruding from the cloth feeding tooth holes; a presser foot mechanism having a presser foot contactable with the cloth from a side opposite to the needle plate, the presser foot mechanism being capable of applying a pressing force for pressing the cloth against the needle plate; a sewing mechanism for sewing the cloth contacted with the presser foot; a driving part for driving the cloth feeding mechanism and the sewing mechanism; and a sewing control part for controlling the driving of the driving part, the sewing machine is characterized by comprising: an acquisition unit configured to acquire predetermined cloth feed information indicating a cloth feed amount which is a movement amount of the cloth to be moved in the horizontal direction by the cloth feed teeth; a presser foot motor connected with the presser foot mechanism; and a presser foot control unit capable of changing the pressing force applied by the presser foot mechanism by controlling driving of the presser foot motor, wherein the sewing control unit controls driving of the driving unit based on the predetermined cloth feed information acquired by the acquisition unit, and the presser foot control unit controls driving of the presser foot motor based on the predetermined cloth feed information acquired by the acquisition unit to change the pressing force when the sewing control unit controls driving of the driving unit. The sewing control part conveys the cloth with the cloth feeding amount shown by the preset cloth feeding information acquired by the acquisition part, and the presser foot control part changes the pressing force of the presser foot according to the cloth feeding amount shown by the preset cloth feeding information acquired by the acquisition part. Therefore, the sewing machine can automatically change the pressing force of the presser foot pressing the cloth according to the cloth feeding amount.

In the sewing machine according to claim 2, the acquisition unit may further acquire predetermined pressing information indicating the pressing force corresponding to the feed amount, and the presser foot control unit may control the driving of the presser foot motor based on the predetermined feed information acquired by the acquisition unit so that the pressing force becomes the pressing force indicated by the predetermined pressing information. The sewing control part changes the pressing force of the presser foot in sewing to the pressing force of the preset pressing information corresponding to the preset cloth feeding information acquired by the acquisition part. In the sewing machine, the pressing force of the presser foot is easily set to a settable pressing force. Therefore, the sewing machine can stabilize the sewing action.

In the sewing machine according to claim 3, the acquiring unit may acquire the predetermined pressing information by specifying the pressing information corresponding to the cloth feeding amount indicated by the predetermined cloth feeding information among the plurality of kinds of cloth feeding amounts in an information table including the plurality of kinds of cloth feeding amounts and pressing information indicating the pressing forces corresponding to the plurality of kinds of cloth feeding amounts, respectively. The sewing machine can simplify the control of obtaining the predetermined pressing information.

In the sewing machine according to claim 4, the acquiring unit may acquire reference cloth feed information indicating one of the cloth feed amounts and reference pressing information indicating one of the pressing forces, and acquire the predetermined pressing information based on the reference cloth feed information, the predetermined cloth feed information, and the reference pressing information. The sewing machine can acquire the predetermined pressing information by simple control.

In the sewing machine according to claim 5, the acquiring unit may acquire the predetermined pressing information indicating the pressing force that increases with an increase in the cloth feed amount by multiplying the pressing force indicated by the reference pressing information by a first coefficient. The larger the cloth feed amount is, the larger the pressing force indicated by the predetermined pressing information is. The larger the feed amount is, the larger the degree of change in the degree of tightness of the upper thread with respect to the fabric accompanying the change in the pressing force is. The greater the pressing force, the more moderate the tightness of the upper thread to the fabric becomes. Therefore, the sewing machine is easy to perform sewing with long stitch and mild tightness of the upper thread to the cloth.

In the sewing machine according to claim 6, the acquiring unit may acquire the predetermined pressing information indicating the pressing force that decreases with an increase in the cloth feed amount by dividing the pressing force indicated by the reference pressing information by a second coefficient. The larger the cloth feed amount is, the smaller the pressing force indicated by the predetermined pressing information is. The larger the feed amount is, the larger the degree of change in the degree of tightness of the upper thread with respect to the fabric accompanying the change in the pressing force is. The closer the pressing force is, the firmer the tightness of the upper thread to the fabric becomes. Therefore, even if the length of the stitch is changed, the sewing machine can easily make the tightness degree of the upper thread to the cloth uniform.

In the sewing machine according to claim 7, the predetermined feed information may be set to the feed amount on a stitch-by-stitch basis. The sewing machine can adjust the cloth feeding amount when sewing a stitch. Therefore, the sewing machine can diversify the sewing of the cloth.

In the sewing machine according to claims 8 and 9, the sewing machine may include a detection unit for detecting the pressing force of the presser foot, and the presser foot control unit may acquire a detection result of the pressing force detected by the detection unit and change the pressing force. The sewing machine can change the pressing force of the presser foot when sewing the cloth with high precision.

The sewing machine of the control method of the sewing machine according to claim 10 comprises: a needle plate having a cloth feed sprocket hole and capable of placing a cloth thereon; a cloth feeding tooth capable of protruding from or retreating into the cloth feeding tooth hole by swinging; a cloth feeding mechanism which supports the cloth feeding teeth in a manner that the cloth feeding teeth can swing and can move the cloth in a horizontal direction by the cloth feeding teeth protruding from the cloth feeding tooth holes; a presser foot mechanism having a presser foot contactable with the cloth from a side opposite to the needle plate, the presser foot mechanism being capable of applying a pressing force for pressing the cloth against the needle plate; a sewing mechanism for sewing the cloth contacted with the presser foot; and a driving section for driving the cloth feeding mechanism and the sewing mechanism, the method for controlling the sewing machine is characterized by comprising: an acquisition step of acquiring predetermined cloth feed information indicating a cloth feed amount which is a movement amount of the cloth to be moved in the horizontal direction by the cloth feed teeth; a sewing control step of controlling the drive of the drive section based on the predetermined cloth feed information acquired in the acquisition step to sew the cloth; and a presser foot control step of controlling a drive of a presser foot motor connected to the presser foot mechanism of the sewing machine to change the pressing force applied by the presser foot mechanism, wherein in the presser foot control step, when the drive of the drive section is controlled in the sewing control step, the drive of the presser foot motor is controlled based on the predetermined cloth feed information acquired in the acquisition step to change the pressing force. With the above configuration, the same effect as that of claim 1 can be obtained.

Drawings

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

Fig. 2 is a left side view of the sewing machine 1.

Fig. 3 is a front view of the inside of the head 5.

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

Fig. 5 is a left side view of the cloth feeding motor 123.

Fig. 6 is a block diagram of an electrical structure of the sewing machine 1.

Fig. 7 is a data configuration diagram of the first information table 301.

Fig. 8 is a data configuration diagram of the second information table 302.

Fig. 9 is a flowchart of the main process.

Fig. 10 is a data configuration diagram of the first setting information 350.

Fig. 11 is a data configuration diagram of the first sewing information 360.

FIG. 12 is an illustration of traces Q1-Q30.

Fig. 13 is a data structure diagram of the second sewing information 370.

Fig. 14 is a left side view of the sewing machine 201.

Fig. 15 is a front view of the inside of the head of the sewing machine 201.

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.

The structure of the sewing machine 1 will be described with reference to fig. 1 and 2. The sewing machine 1 has a bed 2, a column 3, and a arm 4. The base 2 is attached to a table, and the base 2 extends in the left-right direction. The housing part 2 has a needle plate 7 mounted on an upper surface thereof. The operator places the cloth 9 on the bed 2 and the needle plate 7. The needle plate 7 has a needle receiving hole 8 (see fig. 4) and a feed dog hole 14. The pin receiving hole 8 has a circular shape in plan view. The feed sprocket 14 has a long diameter in the front-rear direction, and the feed sprocket 14 is located leftward, rearward, rightward, and forward of the needle accommodating hole 8. The column part 3 extends upward from the right end of the base 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. 6) is fixed to the right portion of the upper surface of the arm portion 4. The operation unit 46 includes operation buttons 47 and a display unit 48. The operator operates the operation buttons 47 while looking at the display unit 48 to input various instructions. In fig. 1, the operation unit 46 is not shown. The arm portion 4 includes an upper shaft 11 and a main motor 31 (see fig. 6) therein. The upper shaft 11 extends in the left-right direction and is connected to the main motor 31 via an upper shaft pulley. The upper shaft belt wheel is fixed at the right end of the upper shaft 11. The arm portion 4 has a head portion 5 at a left end portion. The head 5 protrudes downward from the arm 4 and faces the needle plate 7 from above. The head 5 supports the needle bar 16 in such a manner that the needle bar 16 can move up and down. The lower end of the needle bar 16 protrudes downward from the head 5. The needle bar 16 is connected to the upper shaft 11 by an up-and-down movement mechanism. The needle bar 16 moves up and down above the needle plate 7 in association with the rotation of the upper shaft 11. Needle bar 16 has needle 10 mounted at a lower end thereof. The needle 10 holds the needle thread 6 (see fig. 2) passing through the needle eye. The needle 10 moves up and down together with the needle bar 16. Hereinafter, the upper end of the movable range of the needle 10 is referred to as an upper needle position (see fig. 2), and the lower end of the movable range of the needle 10 is referred to as a lower needle position. The lower end of the needle 10, which is in the needle position, is located above the cloth 9. The lower end of the needle 10 at the needle-down position enters the needle receiving hole 8 of the needle plate 7.

The housing part 2 includes therein a rotating hook, a thread cutting mechanism, and a cloth feeding mechanism 130 (see fig. 4). The rotary shuttle is provided below the needle plate 7 and houses a bobbin around which a lower thread is wound. The rotary hook can be rotated by the power of the main motor 31 and catch the upper thread 6 held by the needle 10 located 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. 6). The movable blade is connected to a tangent electromagnetic element 161. The movable knife moves relative to the fixed knife by the driving of the thread cutting solenoid 161, and the thread cutting mechanism cuts the upper thread 6 and the lower thread.

As shown in fig. 2 and 3, the head 5 includes a sub thread take-up 26, a main thread take-up 27, a thread guide 24, an upstream guide hook 28, a thread take-up lever 23, and a downstream guide hook 29 (see fig. 1) in this order from the upstream side of the feed path of the upper thread 6. The sub clip means 26 is provided at the upper right portion of the front surface of the head 5. The main clamp 27 is provided on the front surface of the head 5 below the sub clamp 26. The sub thread take-up 26 and the main thread take-up 27 apply tension to the upper thread 6, respectively. The sub thread take-up device 26 can suppress the occurrence of the situation where the upper thread 6 from the thread supply source is extracted against the intention of the operator. The main thread tension device 27 can appropriately adjust the tension applied to the upper thread 6 in accordance with the sewing operation of the sewing machine 1. The thread take-up lever 23 is provided on the left of the sub thread take-up 26. The thread take-up lever 23 moves up and down in accordance with the driving of the main motor 31. The thread guide 24 is provided below the thread take-up lever 23. The thread guide section 24 guides the upper thread 6 via the main thread take-up 27 so as to fold the upper thread 6 back toward the thread take-up lever 23. The upstream guide hook 28 is provided above the main yarn gripper 27. The upstream side guide hook 28 guides the upper thread 6 guided by the thread guide portion 24 toward the thread take-up lever 23. The downstream guide hook 29 (see fig. 1) is provided on the left of the upstream guide hook 28. The downstream side guide hook 29 guides the upper thread 6 passing through the thread take-up lever 23 toward the needle bar 16.

The arm portion 4 has a presser foot mechanism 50. The presser foot mechanism 50 has a support member 61, a presser foot motor 32, an upper holder 57, a lower holder 58, a presser foot lever 55, a detection portion 56, and a spring 59. The support member 61 is a plate-like member having an L-shape in front view, and a lower end portion thereof is fixed to an upper surface of the arm portion 4. The presser motor 32 is a pulse motor fixed to the right surface of the upper portion of the support member 61. The output shaft of the presser motor 32 projects leftward from the upper portion of the support member 61. A motor gear 32A is fixed to the output shaft of the presser motor 32. The upper holder 57 is a tube extending in the vertical direction and is fixed to the upper portion of the head 5. The lower holder 58 is a tube extending in the vertical direction and is fixed to the lower portion of the head 5. The lower holder 58 is coaxial with the upper holder 57.

The presser bar 55 extends in the vertical direction, and a presser foot 53 is attached to the lower end thereof. The presser foot lever 55 has an upper presser bar 51 and a lower presser bar 52. The upper pressure lever 51 is a columnar shape extending in the vertical direction, and has a large diameter portion 51A and a small diameter portion 51B. The large-diameter portion 51A is fitted to the upper holder 57 so as to be movable up and down. The large diameter portion 51A protrudes upward from the head portion 5 behind the motor gear 32A. The large diameter portion 51A has a tooth portion 51C at the front portion of the outer peripheral surface. The tooth portion 51C extends in the vertical direction and meshes with the motor gear 32A. Therefore, the upper pressing lever 51 can be moved up and down by the driving force of the presser motor 32. The small diameter portion 51B extends downward from the lower end of the large diameter portion 51A inside the head 5. The small diameter portion 51B is coaxial with the large diameter portion 51A. The small diameter portion 51B has an outer diameter smaller than that of the large diameter portion 51A. The small diameter portion 51B has a pair of pins 63 near the lower end. The pair of pins 63 protrude from the outer peripheral surface of the small-diameter portion 51B inside the head 5, and are symmetrical to each other with respect to the axis of the upper pressing rod 51.

The lower pressure lever 52 is a cylindrical shape extending in the vertical direction, and is coaxial with the upper pressure lever 51. The lower pressing lever 52 is supported by the lower holder 58 so as to be movable up and down. The lower lever 52 extends downward from the upper lever 51 and protrudes downward from the head 5. The upper end of the lower lever 52 opens upward inside the head 5, and the lower lever 52 is fitted to the upper lever 51 so as to be movable up and down. The push-down lever 52 has a spacer 64 and a pair of engaging holes 66. The spacer 64 is a plate-like member having a thickness in the vertical direction, and is fixed to the upper end of the outer peripheral surface of the lower stem 52. The pair of engagement holes 66 are formed in the outer peripheral surface of the lower press lever 52 below the spacer 64, and have a long diameter in the vertical direction. The pair of pins 63 of the upper press lever 51 are inserted into the pair of engagement holes 66 so as to be movable up and down, respectively. Therefore, the upper pressure lever 51 is engaged with the lower pressure lever 52 so as to be movable up and down with respect to the lower pressure lever 52.

The detection unit 56 is a known load sensor, for example, and the detection unit 56 is fixed to the upper surface of the pad 64. The spring 59 is a coil spring extending in the vertical direction, the presser bar 55 is inserted into the spring 59, and the spring 59 is in contact with the lower end of the large diameter portion 51A and the detection portion 56. Therefore, the spring 59 is coupled to the upper and lower

pressing rods

51 and 52. The spring 59 applies a downward urging force to the lower push rod 52 in accordance with the vertical position of the upper push rod 51. The detection unit 56 detects the urging force of the spring 59.

The lower pressure lever 52 has a lower end 54. A presser foot 53 is mounted to the lower end 54. The presser foot 53 is located above the needle plate 7 and can move up and down integrally with the lower presser bar 52. The presser foot 53 moves up and down between a separation position (see fig. 2) and a contact position (see fig. 3). The presser foot 53 located at the separated position is spaced apart from the cloth 9 above the cloth 9. At this time, the pair of pins 63 of the upper pressure lever 51 contact the upper ends of the pair of engagement holes 66 of the lower pressure lever 52 (see fig. 2). The presser foot 53 at the contact position is in contact with the cloth 9 from the side opposite to the needle plate 7 with respect to the cloth 9. At this time, the relative positions of the pair of pins 63 with respect to the pair of engagement holes 66 change as described later.

The presser foot 53 located at the contact position presses the cloth 9 by the urging force of the spring 59. In other words, the presser foot mechanism 50 can apply a pressing force to the presser foot 53 for pressing the cloth 9. The pressing force applied by the presser foot 53 is greater than 0, and the pressing force is directed downward.

The cloth feeding mechanism 130 is explained with reference to fig. 4. The cloth feeding mechanism 130 includes a cloth feeding table 133, a cloth feeding tooth 13, an up-down conveying mechanism 135, and a horizontal conveying mechanism 125. The cloth feeding table 133 extends substantially parallel to the needle plate 7 and is disposed below the needle plate 7. The feed dog 13 is fixed near the center of the upper surface of the feed table 133. The feed dog 13 corresponds to the feed dog hole 14. The upper end of the cloth feeding tooth 13 is concave-convex. The feed dog 13 is long in the front-rear direction, and the length of the feed dog 13 is smaller than the length 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 horizontal direction parallel to the upper shaft 11. The right end of the upper and lower conveyance shafts 127 is connected to a lower shaft pulley 124. The lower shaft pulley 124 is connected to the upper shaft pulley via a belt passing through the inside of the column part 3. The up-down conveying shaft 127 is rotated by the main motor 31. Therefore, the upper and lower feed shafts 127 and the upper shaft 11 rotate in synchronization with each other. The eccentric portion 151 is provided at the left end of the up-down conveying shaft 127. The eccentric portion 151 is eccentric with respect to the upper and lower conveyance shafts 127. The link member 139 is rotatably provided at the rear end 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. The eccentric portion 151 moves the cloth feeding table 133 up and down via the link member 139 by the rotation of the up-and-down feed shaft 127. In the sewing machine 1, the feed dog 13 and the feed table 133 reciprocate up and down once while the needle bar 16 and the needle 10 reciprocate up and down once. That is, in the sewing machine 1, the up-and-down movement of the needle 10 and the up-and-down movement of the feed dog 13 are synchronized.

The horizontal transport mechanism 125 includes a cloth feed motor 123, a link mechanism portion 140, a horizontal transport shaft 128, a link member 150, and the like. The cloth feeding motor 123 is disposed inside the housing unit 2 and is located at a position to the right of the cloth feeding table 133. The cloth feed motor 123 is a pulse motor and can rotate the drive shaft 136 within a predetermined angular range. The cloth feed motor 123 moves the cloth feed table 133 in the front-rear direction.

The link mechanism portion 140 has an intermediate acting arm 138, a first arm portion 141, and a second arm portion 142. One end of the first arm 141 is attached to the tip end of the drive 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 feed shaft 128 extends in the left-right direction and is rotatably supported by the base 2 at the upper left of the cloth feed motor 123. When the driving shaft 136 is reciprocally rotated, the joint portion of the first arm 141 and the second arm 142 is moved in the front-rear direction. The intermediate working arm 138 swings in the vertical direction about the horizontal conveyance shaft 128.

The horizontal conveyance shaft 128 rotates within a predetermined angular 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 so as to be 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 conveying shaft 128 rotates within a range of a predetermined angle, the cloth feeding table 133 reciprocates in the front-rear direction by the link member 150. When the cloth feeding table 133 is raised, the upper end of the cloth feeding tooth 13 protrudes upward from the cloth feeding tooth hole 14, and the cloth 9 is sandwiched between the cloth feeding tooth 13 and the presser foot 53. The needles 10 do not penetrate the cloth 9 during the period in which the feed dog 13 is located above the needle plate 7.

The sewing machine 1 synchronously drives the main motor 31 and the cloth feed motor 123 during execution of sewing. The feed dog 13 swings together with the feed table 133. Therefore, the feed dog 13 protrudes from the feed dog hole 14 or recedes into the feed dog hole 14. When the feed motor 123 is driven during a period in which the upper ends of the feed dogs 13 are positioned above the needle plate 7, the cloth 9 moves in the front-rear direction. When the cloth feeding table 133 descends, the upper ends of the cloth feeding dogs 13 descend below the needle plate 7. Therefore, even if the cloth feeding teeth 13 move in the front-rear direction, the cloth 9 does not move. During the period in which the feed dog 13 is located below the needle plate 7, the needle 10 penetrates into the cloth 9. The sewing machine 1 synchronously drives the main motor 31 and the cloth feed motor 123 to form stitches Q1 to Q30 (see fig. 12) on the cloth 9.

As shown in fig. 5, the drive shaft 136 of the cloth feeding motor 123 reciprocates at a specific rotational position as an intermediate position. The specific rotational position is a rotational position of the drive shaft 136 when the first arm portion 141 extends obliquely rearward and upward from the drive shaft 136. The drive shaft 136 of fig. 5 is in a particular rotational position. The drive shaft 136 reciprocates within a range in which the first arm portion 141 is inclined with respect to both the up-down direction and the front-rear direction. When the drive shaft 136 is located at the specific rotational position, the feed dog 13 is located at the center in the front-rear direction of the swing range. When the drive shaft 136 is located at one end of the rotation range, the feed dog 13 is located at the front end of the swing range, and when the drive shaft 136 is located at the other end of the rotation range, the feed dog 13 is located at the rear end of the swing range. When the cloth feeding motor 123 reciprocates the drive shaft 136 once, the cloth feeding teeth 13 reciprocate once in the front-rear direction. While the output shaft of the main motor 31 rotates once, the cloth feeding motor 123 reciprocates the drive shaft 136 once.

In the present embodiment, the sewing machine 1 changes the feed amount by changing the rotational width of the drive shaft 136 (i.e., the angle θ in fig. 5). The cloth feed amount is a moving amount by which the cloth 9 is moved in the front-rear direction by the cloth feed teeth 13 protruding from the cloth feed sprocket holes 14. The cloth feeding mechanism 130 of this example changes the cloth feeding amount in a range of 0.1mm to 5mm in units of 0.1 mm.

Hereinafter, the upper shaft 11, the needle bar 16, the rotary hook, the thread take-up lever 23, and the cloth feeding mechanism 130 will be collectively referred to as a sewing mechanism 15 (see fig. 1). The sewing mechanism 15 sews the cloth 9 pressed by a presser foot 53 described later.

The sewing machine 1 has a control device 30 (see fig. 6) below the table. The control device 30 is connected to a pedal 36 (see fig. 6) of a step type. The operator presses the pedal 36 to input a sewing start instruction to start sewing the cloth 9 to the sewing machine 1. The operator can operate the pedal 36 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 36. The controller 30 increases the rotation speed of the output shaft of the main motor 31 and increases the sewing speed of the sewing machine 1 as the operator steps on the pedal 36 toward the toe side. When the operator steps back the pedal 36 to the heel side, the control device 30 drives the thread cutting solenoid 161 of the thread cutting mechanism.

Referring to fig. 6, an electrical structure of the sewing machine 1 is explained. The control device 30 has a CPU 41. The CPU41 controls the operation of the sewing machine 1. The CPU41 is connected to a ROM42, a RAM43, a storage device 44, and an I/O interface (hereinafter referred to as I/O) 45. The ROM42 stores programs and the like for executing various processes such as a main process (see fig. 9) described later. The RAM43 temporarily stores various values when executing a program. The RAM43 stores the cumulative number of pins n. The cumulative needle count n is the number of needles accumulated from the start of sewing. The storage device 44 is non-volatile. The storage device 44 stores a first information table 301 and a second information table 302.

As shown in fig. 7 and 8, the first information table 301 and the second information table 302 each store the cloth feeding information and the pressing information so that the cloth feeding information and the pressing information are associated with each other. The feed information indicates a plurality of feed amounts. For example, the feed information indicates a range of a continuous feed amount of 0.1mm to 1mm, 19 types of feed amounts increasing per 0.1mm in 1.1mm to 2.9mm, and a range of a continuous feed amount of 3mm to 5 mm. The range of the continuous cloth feeding amount of 0.1mm to 1mm and the range of the continuous cloth feeding amount of 3mm to 5mm both include a plurality of cloth feeding amounts. The pressing information indicates the pressing force by a percentage based on a predetermined value. The predetermined value is, for example, 5N. For example, the press information 80% represents 4N. The pressing force information in this example indicates a plurality of kinds of pressing forces that change in stages in the range of 80% to 125%. In the first information table 301, the pressing force increases as the cloth feed amount increases. In the second information table 302, the pressing force decreases as the cloth feed amount increases.

The I/O45 is connected to the drive circuits 81 to 85. The CPU41 controls the driving of the driving circuit 81 to drive the main motor 31. The CPU41 controls the driving of the driving circuit 82 to drive the presser foot motor 32. The CPU41 controls the driving of the driving circuit 83 to drive the cloth feeding motor 123. The CPU41 controls the driving of the driving circuit 84, and displays various information on the display unit 48 of the operation unit 46. The CPU41 controls the drive of the drive circuit 85 to drive the tangent electromagnetic element 161. The sewing machine 1 includes a main encoder 71, a presser foot encoder 72, and a cloth feed encoder 73. The main encoder 71 can detect the rotational angle phase and the rotational speed of the output shaft of the main motor 31. Therefore, the main encoder 71 can detect the vertical position of the needle 10. The main encoder 71 outputs the detection result to the CPU41 via the I/O45. The presser foot encoder 72 can detect the rotational angle phase and the rotational speed of the output shaft of the presser foot motor 32. Therefore, the presser foot encoder 72 can detect the vertical position of the upper pressing lever 51. The presser foot encoder 72 outputs the detection result to the CPU41 via the I/O45. The cloth feed encoder 73 can detect the rotation angle phase and the rotation speed of the drive shaft 136 of the cloth feed motor 123. The cloth feed encoder 73 outputs the detection result to the CPU41 via the I/O45.

The I/O45 is connected to the operation button 47, the pedal 36, and the detection unit 56. The operation buttons 47 detect various instructions input by an input operation of the operator. The CPU41 acquires the detection result of the operation button 47. The various instructions include setting instructions of sewing modes. The sewing patterns include a first sewing pattern and a second sewing pattern. In the first sewing mode, the pressing force increases as the cloth feed amount increases. In the second sewing mode, the pressing force is reduced as the cloth feeding amount is increased. The CPU41 acquires the operation direction and the operation amount of the pedal 36. The detector 56 detects the pressing force of the presser foot 53, which is the biasing force of the spring 59. The CPU41 acquires information indicating the pressing force by acquiring the detection result of the detection unit 56.

Referring to fig. 2 and 3, the outline of the movement of the presser foot 53 between the separation position and the contact position will be described. When the presser motor 32 is driven in a state where the presser foot 53 is located at the separated position, the upper presser bar 51 and the lower presser bar 52 integrally move downward. The presser foot 53 moves downward from the separated position in accordance with the movement of the presser bar 52. After the presser foot 53 moves to the contact position, the lower presser bar 52 and the presser foot 53 become unable to move downward. The presser foot motor 32 is further driven. The upper pressing lever 51 moves downward relative to the lower pressing lever 52 and the presser foot 53. The pair of pins 63 are spaced downward from the upper ends of the pair of engaging holes 66. As the upper pressure lever 51 moves downward relative to the lower pressure lever 52, the larger diameter portion 51A moves downward, and the elastic deformation amount of the spring 59 increases. Therefore, the pressing force increases. The elastic deformation amount of the spring 59 changes in accordance with the driving amount of the presser motor 32.

When the presser motor 32 is driven in the direction opposite to the direction in which the presser foot 53 is lowered, the upper pressing lever 51 moves upward. After the pair of pins 63 contact the upper ends of the pair of engagement holes 66, the upper pressing lever 51 moves upward integrally with the lower pressing lever 52 and the presser foot 53. Therefore, the presser foot 53 moves from the contact position to the separation position.

The outline of the sewing operation of the sewing mechanism 15 will be described with reference to fig. 2 to 4. The presser foot 53 presses the cloth 9 from the side opposite to the needle plate 7 at the contact position. The needle 10 is in the over-the-needle position. The sewing mechanism 15 is operated by driving the main motor 31 and the cloth feed motor 123. After the needle 10 moves from the needle-up position to the needle-down position and pierces the cloth 9, the rotary hook catches the upper thread 6 held by the needle 10 and interweaves the upper thread 6 with the lower thread. The needle 10 is retreated upward from the fabric 9. At this time, the cloth feed motor 123 rotates the drive shaft 136 about the specific rotational position, and the cloth feed dog 13 projects from the cloth feed sprocket hole 14 and feeds the cloth 9 backward. The thread take-up lever 23 moves upward in accordance with the movement of the needle 10 to the needle-up position, and lifts the upper thread 6 interlaced with the lower thread up to the needle plate 7. The needle thread 6 is bent backward between the needle receiving hole 8 and the needle 10. The sewing machine 1 forms stitches Q1 to Q30 (see fig. 12) on the fabric 9. The sewing mechanism 15 sews the cloth 9 by repeating the above operations of the upper shaft 11, the needle 10, the rotary hook, the thread take-up lever 23, and the cloth feeding mechanism 130.

The main processing is described with reference to fig. 9 to 13. In the main processing, the sewing machine 1 sews the fabric 9 by changing the feed amount and the pressing force in accordance with sewing information set by an operator, which will be described later. Before the main process is started, the presser foot 53 is located at the separating position, and the needle 10 is located at the needle-up position (see fig. 2). In this state, the operator places the cloth 9 on the bed 2 and the needle plate 7, and inserts the upper thread 6 through the eye of the needle 10. The length of the end of the needle thread 6 passing through the needle eye is dimension M of fig. 2. When the operator operates the operation button 47 to turn on the power of the sewing machine 1, the CPU41 reads out a program for executing the main processing from the ROM42, and starts the processing.

The CPU41 acquires setting information based on the detection result of the operation button 47 (S11). The setting information associates the needle count information with the predetermined cloth feed information. The needle number information indicates a needle number for sewing the fabric 9. The predetermined feed information indicates a feed amount corresponding to the number of stitches of the number of stitches information. For example, the operator inputs setting instructions of the needle count information and the predetermined cloth feed information to the operation button 47. The information on the number of stitches can be set in units of one stitch. The feed amount of the predetermined feed information can be set in units of 0.1mm by the operation of the operator in correspondence with the number of needles of the needle count information. Therefore, the operator can freely set the number of needles sewing the fabric 9 and the feed amount in the process of inputting the setting instruction of the setting information.

Fig. 10 illustrates first setting information 350 as an example of the setting information. The operator sets the feed amount of the 1 st needle to 0.7mm, the feed amounts of the 2 nd to 3 rd needles to 1.2mm, the feed amounts of the 4 th to 14 th needles to 2.5mm, and the feed amounts of the 15 th to 30 th needles to 3.2 mm. Accordingly, the CPU41 acquires the first setting information 350 for 30 pins (S11). Hereinafter, the maximum number of pins of the setting information is referred to as the total number of pins. In the first setting information 350, the total number of pins is 30 pins.

As shown in fig. 9, the CPU41 acquires any one of the first sewing mode and the second sewing mode (S13). For example, when the operator inputs the instruction of selecting the first sewing mode to the operation button 47, the CPU41 acquires the first sewing mode (S13). The CPU41 acquires sewing information based on the setting information acquired in S11 and the information table corresponding to the sewing pattern acquired in S13 (S15). The sewing information is an information table in which predetermined pressing information and the needle count information of the setting information are also associated with each other. The predetermined pressing information indicates a pressing force applied to the cloth 9 by the presser foot mechanism 50 during execution of sewing by the sewing machine 1.

Fig. 11 shows first sewing information 360 as an example of the sewing information. The first sewing information 360 is an information table in which the predetermined pressing information is associated with the needle count information and the predetermined cloth feeding information of the first setting information 350 (see fig. 10). The predetermined pressing information is represented by a percentage based on a predetermined value, for example. For example, when the operator selects the first sewing mode (S13), the CPU41 acquires the first information table 301. The CPU41 specifies the feed information corresponding to the predetermined feed information of the first setting information 350 among the feed information of the first information table 301 for each number of needles indicated by the number-of-needles information. The CPU41 acquires predetermined pressing information by determining a pressing force corresponding to the feed amount indicated by the determined feed information. For example, the feed amount of the 1 st needle of the first setting information 350 is 0.7mm, which corresponds to 0.1mm to 1mm of the feed information of the first information table 301. Therefore, the CPU41 specifies the pressing force corresponding to 0.1mm to 1mm of the cloth feeding information of the first information table 301, that is, 80% (i.e., 4N). The CPU41 acquires the determined pressing force, that is, 80%, as the predetermined pressing information corresponding to the 1 st needle of the needle count information (S15). The CPU41 acquires 84% as the predetermined pressing information corresponding to the 2 nd to 3 rd needles, 112.5% as the predetermined pressing information corresponding to the 4 th to 14 th needles, and 125% as the predetermined pressing information corresponding to the 15 th to 30 th needles in the same process (S15). Accordingly, the CPU41 acquires the first sewing information 360 (S15).

As shown in fig. 9, the CPU41 determines that there is no input of a foot down instruction based on the detection result of the operation button 47 (S17). When the operator does not input the presser foot lowering instruction to the operation button 47 (S17: no), the CPU41 determines whether or not the instruction to turn off the power supply of the sewing machine 1 is input based on the detection result of the operation button 47 (S19). When the operator operates the operation button 47 and inputs an instruction to turn off the power supply of the sewing machine 1 (yes in S19), the CPU41 ends the main process and turns off the power supply of the sewing machine 1. When the operator does not input an instruction to turn off the power supply of the sewing machine 1 to the operation button 47 (S19: no), the CPU41 shifts the process to S17.

When the presser foot lowering instruction is inputted to the operation button 47 by the operator (yes in S17), the CPU41 controls the driving of the presser foot motor 32 to move the presser foot 53 from the separated position to the contact position (S21). For example, the CPU41 controls the driving of the presser foot motor 32 so that the pressing force becomes 1N (S21). After the CPU41 sets the cumulative number of pins n stored in the RAM43 to 1 (S23), it determines whether or not the pedal 36 is depressed (S25).

When the operator depresses the pedal 36 (S25: YES), the CPU41 controls the drive of the presser foot motor 32 so that the pressing force becomes Pn (S31). Pn is a pressing force corresponding to the needle number corresponding to the cumulative needle number n in the sewing information. For example, the predetermined pressing information corresponding to the needle number 1 of the first sewing information 360 is 80%. The CPU41 changes the pressing force from 1N to 4N (i.e., 80% of 5N) by acquiring the detection result of the detection unit 56 and controlling the driving of the presser foot motor 32 (S31). When the pressing force Pn becomes the pressing force indicated by the predetermined pressing information of the first sewing information 360, the CPU41 controls the driving of the presser foot motor 32 to maintain the vertical position of the upper pressing lever 51 (S31). Therefore, the CPU41 maintains the pressing force (S31).

As shown in fig. 9, 11, and 12, the CPU41 controls the driving of the main motor 31 and the cloth feed motor 123 to carry out the sewing of the nth needle while feeding the cloth 9 at Ln (S33). Ln is the feed amount of the predetermined feed information corresponding to the needle number corresponding to the cumulative needle number n in the sewing information. For example, when the cumulative needle count n is 1, the predetermined cloth feeding information corresponding to the 1 st needle of the needle count number of the first sewing information 360 is 0.7 mm. Therefore, Ln is 0.7 mm. In a state where the presser foot 53 presses the cloth 9 with a pressing force of 80%, the CPU41 performs sewing of the 1 st needle while conveying the cloth 9 with a cloth feeding amount of 0.7mm (S33). Thus, the sewing machine 1 forms a stitch Q1 on the cloth 9. The length of trace Q1 became 0.7 mm. The CPU41 acquires the detection results of the main encoder 71 and the feed encoder 73 and controls the driving of the main motor 31 and the feed motor 123.

The CPU41 determines whether sewing is finished (S35). The CPU41 determines whether sewing is finished by determining whether the accumulated needle count n matches the full needle count. When the cumulative number of pins n is smaller than the total number of pins (NO in S35), the CPU41 adds 1 to the cumulative number of pins n (S37) and shifts the process to S25. The CPU41 repeatedly executes S25, S31 to S37 until the cumulative needle number n matches the full needle number (S35: YES). The CPU41 controls the drive of the presser foot motor 32 for each needle to change Pn to the pressing force indicated by the preset pressing information of the sewing information (S31), and simultaneously executes the sewing from the 2 nd needle to the 30 th needle (S31 to S37). Stitches Q2-Q30 formed on the cloth 9 are in accordance with the cloth feeding amount indicated by the predetermined cloth feeding information of the sewing information. For example, the length of the traces Q2, Q3 is 1.2mm, and the length of the traces Q15-Q30 is 3.2 mm.

When the cumulative needle count n matches the total needle count (S35: YES), the CPU41 stops the driving of the main motor 31 and the cloth feed motor 123, stops the sewing operation, and drives the thread cutting solenoid 161 to cut the side thread 6 and the lower thread (S39). At this time, the CPU41 overwrites the cumulative number of pins n stored in the RAM43 with 1 (S39). The CPU41 shifts the process to S25.

When the operator does not depress the pedal 36 in S25 (no in S25), the CPU41 determines whether or not the pedal 36 is depressed (S26). When the operator steps back on the pedal 36 (S26: YES), the CPU41 shifts the process to S39. The CPU41 drives the thread cutting solenoid 161 to cut the cut thread 6 and the bobbin thread so that the cumulative needle count n becomes 1 (S39). When the operator does not step back on the pedal 36 (S26: NO), the CPU41 judges whether or not there is an instruction to turn off the power supply of the sewing machine 1 (S27). S27 is the same processing as S19. When the operator does not input an instruction to turn off the power supply of the sewing machine 1 to the operation button 47 (S27: no), the CPU41 shifts the process to S25. When the operator inputs an instruction to turn off the power supply of the sewing machine 1 to the operation button 47 (S27: yes), the CPU41 controls the driving of the presser foot motor 32 to move the presser foot 53 from the contact position to the separation position (S29). The CPU41 ends the main process and cuts off the power of the sewing machine 1. The operator can take out the sewn cloth 9 from the sewing machine 1.

In the main process, the operator can input an instruction to select the second sewing mode to the operation button 47 (S13). At this time, the CPU41 acquires the second information table 302. The CPU41 specifies the feed information corresponding to the predetermined feed information of the first setting information 350 among the feed information indicating the plurality of kinds of feed amounts in the second information table 302 for each of the number of needles indicated by the number-of-needles information. The CPU41 acquires predetermined pressing information by determining a pressing force corresponding to the feed amount indicated by the determined feed information. As shown in fig. 13, the CPU41 acquires second sewing information 370 as an example of the sewing information, instead of the first sewing information 360 (S15). The second sewing information 370 is an information table in which the predetermined pressing information is associated with the needle count information and the predetermined cloth feeding information of the first setting information 350 (see fig. 10). In the second sewing information 370, the pressing force of the 1 st needle is 125% (i.e., 6.25N), the pressing forces of the 2 nd to 3 rd needles are 120%, the pressing forces of the 4 th to 14 th needles are 90%, and the pressing forces of the 15 th to 30 th needles are 80%. The CPU41 repeats the operations S25, S31-S37, thereby executing the sewing of the 1 st to 30 th needles based on the second sewing information 370. The lengths of stitches Q1 to Q30 (see fig. 12) formed in the cloth 9 are the same as those in the case where the first sewing mode is selected.

As described above, the CPU41 feeds the cloth 9 at the feed amount indicated by the predetermined feed information of the sewing information acquired in S15 and sews the cloth 9(S33) until the cumulative needle count n matches the full needle count (S35: yes). The CPU41 changes the pressing force according to the cloth feeding amount indicated by the preset cloth feeding information of the sewing information (S31). Therefore, the sewing machine 1 can automatically change the pressing force applied to the cloth 9 by the presser foot 53 according to the cloth feeding amount.

The CPU41 acquires predetermined pressing information by acquiring sewing information (S15), and controls the driving of the presser foot motor 32 based on the acquired predetermined cloth feeding information (S31). The pressing force applied by the presser foot 53 becomes a pressing force indicated by the predetermined pressing information. The CPU41 is not easy to execute the drive control of the presser foot motor 32 such that the pressing force exceeds the specification of the sewing machine 1. That is, the CPU41 can easily set the pressing force within the specification of the sewing machine 1. Therefore, the sewing machine 1 can stabilize the sewing operation.

The CPU41 acquires any one of the first information table 301 and the second information table 302 (S13), and determines the pressing information corresponding to the feed amount of the setting information from the feed amount of the acquired information table. Therefore, the CPU41 acquires predetermined press information (S15). Therefore, the sewing machine 1 can simplify the control of acquiring the predetermined pressing information.

The CPU41 acquires sewing information including predetermined pressing information set in units of one stitch (S15). The sewing machine 1 can adjust the amount of cloth feed every time a stitch is made. Therefore, the sewing machine 1 can diversify the sewing of the cloth 9.

The CPU41 obtains the detection result of the detection section 56 and sets the pressing force Pn to the pressing force indicated by the predetermined pressing information (S31). Therefore, the sewing machine 1 can change the pressing force applied to the cloth 9 during sewing with high accuracy.

In the above description, the main motor 31 and the cloth feeding motor 123 are examples of the driving means of the present invention. The first information table 301 and the second information table 302 are examples of the information table of the present invention.

The CPU41 executing S33 is an example of the sewing control unit of the present invention. The CPU41 executing S15 exemplifies the acquisition unit of the present invention. The CPU41 executing S31 is an example of the presser foot control unit of the present invention. S33 is an example of the sewing control process of the present invention. S15 is an example of the acquisition step of the present invention. S31 is an example of the presser foot control step of the present invention.

The present invention is not limited to the above embodiments. The sewing machine 1 may have a structure having a plurality of needles 10. The sewing machine 1 may not have the detection unit 56. For example, the sewing machine 1 may acquire information indicating the pressing force based on the detection result of the presser foot encoder 72. In this case, the presser foot encoder 72 is an example of the detection unit of the present invention.

In the above embodiment, when the cumulative needle count n matches the total needle count (yes in S35), the CPU41 may not stop driving the main motor 31 and the cloth feeding motor 123. For example, while the operator is depressing the pedal 36 (S25: yes), the CPU41 may repeatedly execute S25, S31 to S37 based on the sewing information. That is, the process of S35 may be omitted. At this time, when the operator steps back on the pedal 36 (no in S25, yes in S26), the CPU41 may stop the driving of the main motor 31 and the cloth feeding motor 123 to stop the sewing operation. After the last stitch (30 th stitch in the case of the first sewing information 360) of the sewing information acquired in S15, the CPU41 may continue the sewing operation based on the predetermined feed information and the predetermined pressing information of the last stitch.

Instead of the percentage based on the predetermined value, the pressing force indicated by the pressing information in the first information table 301 and the second information table 302 may be a numerical value in units of N, for example, or may be a rotational angle phase of the output shaft of the presser foot motor 32. The rotational angle phase of the output shaft of the presser motor 32 changes in accordance with the driving amount of the presser motor 32. The CPU41 can control the pressing force by acquiring the detection result of the presser foot encoder 72. Instead of the numerical values in mm, the feed amounts indicated by the feed information in the first information table 301 and the second information table 302 may be percentages based on a predetermined value, or may be rotational angle phases indicating the rotational amplitudes of the output shafts of the feed motors 123, for example.

The storage device 44 may store two values of 95% and 100% instead of the first information table 301 and the second information table 302. The CPU41 judges whether or not it is necessary to change the cloth feed amount in the next sewing after the one-stitch sewing is performed (S33). When the CPU41 determines that it is necessary to change the cloth feed amount, the pressing force is changed from one of 95% and 100% to the other before the next sewing is performed. For example, even if the sewing machine 1 feeds the cloth 9 by the same feed amount in the 1 st needle and the 4 th needle, the pressing forces of the 1 st needle and the 4 th needle may not be matched with each other. Therefore, 95% and 100% of the information stored in the storage device 44 do not correspond to the cloth feed amount. In this case, the sewing machine 1 capable of automatically changing the pressing force according to the change of the cloth feeding amount can be realized.

The storage device 44 may store equations (a) to (C) instead of the first information table 301 and the second information table 302.

Pn＝P'×K… (A)

Pn＝P'/K… (B)

K＝1+(Ln-L')/L'… (C)

P' in the formulae (a) and (B) is reference pressing information indicating one pressing force. P' is for example 5N, constant. L' in the formula (C) is reference feed information indicating one feed amount. L' is, for example, 2.0mm and is constant. K is a coefficient varying according to the difference between Ln and L 'and the ratio of Ln to L'. The coefficient K increases the more Ln increases. The expression (a) is an expression obtained by multiplying P' as the reference pressing information by a coefficient K. The formula (a) is a formula corresponding to the first sewing pattern. The expression (B) is an expression obtained by dividing P' as the reference pressing information by the coefficient K. The formula (B) is a formula corresponding to the second sewing mode. The operator inputs a setting instruction of the setting information (S11) and selects the first sewing mode (S13). When the operator selects the first sewing mode, the CPU41 acquires predetermined pressing information based on the expressions (a) and (C) (S15). Specifically, the CPU41 substitutes Ln with 0.7mm, which is the feed amount corresponding to the 1 st needle of the first setting information 350, and acquires K equal to 0.35. The CPU41 substitutes K in 0.35 for formula (a) to obtain Pn in 1.75. Therefore, the CPU41 acquires 1.75N as the predetermined pressing information corresponding to the needle number 1 of the sewing information (S15). The CPU41 acquires the predetermined pressing information corresponding to the needle numbers 2-3, 4-14, 15-30 by executing the same processing. Therefore, the CPU41 acquires sewing information (S15). The predetermined pressing information of the sewing information in the first sewing mode indicates a pressing force that increases with an increase in Ln.

In the above-described modification, the CPU41 acquires Pn as the predetermined press information based on L 'as the reference cloth feeding information, P' as the reference press information, and Ln as the predetermined cloth feeding information. Accordingly, the sewing machine 1 can acquire Pn as the predetermined pressing information by a simple control in accordance with the cloth feeding amount Ln input by the operator. When the operator selects the first sewing mode (S13), the CPU41 acquires Pn as predetermined pressing information based on the expressions (a) and (C) (S15). The more Ln as the scheduled cloth feeding information increases, the more Pn as the scheduled press information increases. The larger Ln, the greater the degree of change in the degree of tightness of the upper thread 6 with respect to the fabric 9 accompanying the change in Pn. The greater Pn, the more moderate the tightness of the upper thread 6 with respect to the fabric 9. Therefore, when the operator selects the first sewing mode, the sewing machine 1 can easily perform sewing with long stitches and a gentle tightness degree of the upper thread 6 with respect to the fabric 9. When the operator selects the second sewing mode (S13), the CPU41 acquires Pn as predetermined pressing information based on equations (B) and (C) (S15). The more Ln increases, the more Pn decreases. The larger Ln, the greater the degree of change in the degree of tightness of the upper thread 6 with respect to the fabric 9 accompanying the change in Pn. The lower Pn, the firmer the tightness of the upper thread 6 to the cloth 9. Therefore, when the operator selects the second sewing mode, the sewing machine 1 can easily make the tightness of the upper thread 6 with respect to the fabric 9 uniform even if the length of the stitch is changed. In the above modification, the coefficient K is an example of the first coefficient and the second coefficient of the present invention. In addition, the storage device 44 may store, for example, the formula (a ') or the formula (C') instead of the formula (a) or the formula (C), respectively.

Pn＝P'×K'+C1… (A')

K'＝1+(Ln-L')/C2… (C')

C1 and C2 are constants, respectively. K 'is a coefficient varying only in accordance with the difference between Ln and L'. K 'may be a coefficient that varies only in accordance with the ratio of Ln to L', and detailed description thereof will be omitted.

The cloth feeding mechanism 130 is not limited to the above embodiment. The horizontal conveyance mechanism 125 of the cloth feeding mechanism 130 may not include the cloth feeding motor 123. In this case, the horizontal conveyance mechanism includes a link mechanism portion, a horizontal conveyance shaft 128, and a link member 150. The link mechanism portion is a well-known mechanism having an eccentric wheel, a lever, and a switching mechanism. The eccentric wheel is provided on the upper and lower conveying shafts 127 and is eccentric from the axial center of the upper and lower conveying shafts 127. One end of the rod in the extending direction is connected with the eccentric wheel, and the other end is connected with the switching mechanism. The switching mechanism is coupled to the lever and the horizontal transport shaft 128. The rotation of the vertical feed shaft 127 drives the switching mechanism by the action of the eccentric in the extending direction by the lever, and the reciprocating rotation of the horizontal feed shaft 128 is achieved by the switching mechanism. The switching mechanism is connected with the conveying amount adjusting mechanism. The conveying amount adjusting mechanism is used to adjust the amount of rotation of the horizontal conveying shaft 128 under the drive of the switching mechanism. When the rotation amount of the horizontal conveying shaft 128 is changed, the cloth feeding amount of the cloth feeding teeth 13 is changed. In this case, the horizontal conveyance mechanism may adjust the rotation amount of the horizontal conveyance shaft 128 by the conveyance amount adjustment mechanism driven by the switching mechanism by using a motor. The conveyance amount adjustment mechanism changes the rotation amount of the horizontal conveyance shaft 128 in accordance with the driving of the motor. Therefore, the feed amount varies.

The cloth feeding motor 123 of the cloth feeding mechanism 130 may move the cloth feeding table 133 in the vertical direction instead of moving the cloth feeding table 133 in the front-rear direction. In this case, the vertical transport mechanism may include the cloth feeding motor 123, the link mechanism portion, the vertical transport shaft 127, and the link member. The horizontal conveyance mechanism may be configured such that a lower shaft pulley is provided on the horizontal conveyance shaft 128, and the lower shaft pulley is connected to the upper shaft pulley via a belt. That is, in this sewing machine, the feed dog 13 and the feed table 133 reciprocate once in the front-rear direction while the needle bar 16 and the needle 10 reciprocate once up and down. That is, in this sewing machine, the vertical movement of the needle 10 and the horizontal movement of the feed dog 13 are mechanically synchronized.

The cloth feeding mechanism 130 may include a cloth feeding motor 123 for moving the cloth feeding table 133 in the front-rear direction and a cloth feeding motor for moving the cloth feeding table 133 in the up-down direction.

A sewing machine 201 as a modification of the sewing machine 1 will be described with reference to fig. 14 and 15. In the following description, the same members as those of the sewing machine 1 are shown by the same reference numerals in the drawings, and the description thereof is omitted. The arm 4 of the sewing machine 201 has a presser foot mechanism 250. Unlike the presser foot mechanism 50 of the above embodiment, the presser foot mechanism 250 does not include the spring 59 and the detecting portion 56. The presser bar 155 of the presser mechanism 250 has an up-pressing lever 51 and a down-pressing lever 152. The push-down lever 152 is different from the push-down lever 52 of the above embodiment in that it has a pair of engagement holes 166 instead of the pair of engagement holes 66. The pair of engagement holes 166 are formed in the outer peripheral surface of the lower press lever 152 below the spacer 64, respectively, and have a diameter slightly larger than the pair of pins 63. Therefore, the upper pressure lever 51 and the lower pressure lever 152 are engaged with each other and can move up and down substantially integrally. The presser bar 155 may be a column-shaped member integrally molded without the upper and lower presser bars 51 and 152. In this case, the pair of engagement holes 166, the pair of pins 63, and the spacer 64 may not be provided.

When the presser foot 53 is located at the contact position, the presser foot motor 32 of the sewing machine 201 applies a downward driving force to the presser foot 53 to apply a pressing force to the presser foot 53. Therefore, the pressing force can be changed by controlling the current flowing to the presser motor 32.

Claims

1. A sewing machine (1, 201) comprising:

a needle plate (7) having a cloth feed sprocket hole (14) and capable of placing a cloth (9) thereon;

a feed dog (13) which can protrude from or retreat into the feed dog hole;

a cloth feeding mechanism (130) which supports the cloth feeding teeth and can move the cloth in a horizontal direction by the cloth feeding teeth protruding from the cloth feeding tooth holes;

a presser foot mechanism (50, 250) having a presser foot (53) capable of contacting the cloth from the side opposite to the needle plate and capable of applying a pressing force for pressing the presser foot against the needle plate;

a sewing mechanism (15) for sewing the cloth contacted with the presser foot;

a drive unit (31, 123) for driving the cloth feeding mechanism and the sewing mechanism; and

a sewing control part (41) for controlling the driving of the driving part,

the sewing machine is characterized in that:

an acquisition unit configured to acquire predetermined cloth feed information indicating a cloth feed amount which is a movement amount of the cloth to be moved in the horizontal direction by the cloth feed teeth;

a presser foot motor (32) connected to the presser foot mechanism; and

a presser foot control section capable of changing the pressing force applied by the presser foot mechanism by controlling the driving of the presser foot motor,

the sewing control part controls the driving of the driving part based on the preset cloth feeding information acquired by the acquisition part,

the presser foot control section controls the driving of the presser foot motor based on the predetermined cloth feeding information acquired by the acquisition section to change the pressing force when the sewing control section controls the driving of the driving section.

2. The sewing machine of claim 1,

the acquisition section may further be capable of acquiring predetermined pressing information indicating the pressing force corresponding to the cloth feed amount,

the presser foot control unit controls the drive of the presser foot motor based on the predetermined cloth feeding information acquired by the acquisition unit so that the pressing force becomes the pressing force indicated by the predetermined pressing information.

3. The sewing machine of claim 2,

the acquisition unit acquires the predetermined pressing information by specifying the pressing information corresponding to the cloth feed amount indicated by the predetermined cloth feed information among the plurality of cloth feed amounts in information tables (301, 302) including a plurality of kinds of cloth feed amounts and pressing information indicating the pressing force corresponding to each of the plurality of kinds of cloth feed amounts.

4. The sewing machine of claim 2,

the acquisition unit acquires reference cloth feeding information indicating one cloth feeding amount and reference pressing information indicating one pressing force, and acquires the predetermined pressing information based on the reference cloth feeding information, the predetermined cloth feeding information, and the reference pressing information.

5. The sewing machine of claim 4,

the acquiring unit acquires the predetermined pressing information indicating the pressing force that increases with an increase in the cloth feed amount by multiplying the pressing force indicated by the reference pressing information by a first coefficient that varies in accordance with the reference cloth feed information and the predetermined cloth feed information and increases as the predetermined cloth feed information increases.

6. The sewing machine of claim 4,

the acquiring unit acquires the predetermined pressing information indicating the pressing force that decreases with an increase in the cloth feed amount by dividing the pressing force indicated by the reference pressing information by a second coefficient that varies in accordance with the reference cloth feed information and the predetermined cloth feed information and increases as the predetermined cloth feed information increases.

7. Sewing machine as in any of claims 1 to 6,

the predetermined feed information sets the feed amount in units of one stitch.

8. Sewing machine as in any of claims 1 to 6,

the sewing machine is provided with a detection part (56) for detecting the pressing force of the presser foot,

the presser foot control unit obtains a detection result of the pressing force detected by the detection unit and changes the pressing force.

9. The sewing machine of claim 7,

10. A control method of a sewing machine (1, 201) comprises: a needle plate (7) having a cloth feed sprocket hole (14) and capable of placing a cloth (9) thereon; a feed dog (13) which can protrude from or retreat into the feed dog hole; a cloth feeding mechanism (130) which supports the cloth feeding teeth and can move the cloth in a horizontal direction by the cloth feeding teeth protruding from the cloth feeding tooth holes; a presser foot mechanism (50, 250) having a presser foot (53) capable of contacting the cloth from the side opposite to the needle plate and capable of applying a pressing force for pressing the presser foot against the needle plate; a sewing mechanism for sewing the cloth contacted with the presser foot; and a driving part (31, 123) for driving the cloth feeding mechanism and the sewing mechanism,

the control method of the sewing machine is characterized by comprising the following steps:

an acquisition step of acquiring predetermined cloth feed information indicating a cloth feed amount which is a movement amount of the cloth to be moved in the horizontal direction by the cloth feed teeth;

a sewing control step of controlling the drive of the drive section based on the predetermined cloth feed information acquired in the acquisition step to sew the cloth; and

a presser foot control step of controlling a drive of a presser foot motor connected to the presser foot mechanism of the sewing machine to change the pressing force applied by the presser foot mechanism,

in the presser foot control step, when the drive of the drive section is controlled in the sewing control step, the drive of the presser foot motor is controlled based on the predetermined cloth feed information acquired in the acquisition step, and the pressing force is changed.