JP2016064096A - Sewing machine and control method of sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sewing machine and a control method of a sewing machine capable of preventing needle breakage by controlling sewing rotational frequency according to cloth thickness.SOLUTION: In a case where a lowering instruction of a presser foot of a cloth presser device is input (S4: YES), a CPU lowers the presser foot by driving a pulse motor for cloth pressing (S5). The CPU starts measuring rotational speed of the pulse motor for cloth pressing (S6). When the presser foot comes into contact with the cloth, change occurs in the rotational speed of the pulse motor for cloth pressing. The CPU detects the time at which the change occurred in the rotational speed, and estimates cloth thickness by referring to a cloth thickness estimation table (S7). When the cloth thickness is equal to or greater than 10 mm (S8: YES), a sewing machine is driven by decreasing the highest rotation number of the sewing machine than usual (S9, S11, S12). Therefore, the sewing machine can prevent a sewing needle from sticking in the cloth in the middle of cloth delivery, and needle breakage and the like can be prevented.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a sewing machine and a method for controlling the sewing machine.

  The tacking sewing machine includes a presser foot device. The presser foot device raises and lowers a presser foot that presses a cloth, which is a sewing object, from above. Patent Document 1 discloses a sewing machine that automatically adjusts the presser foot pressure according to the fabric thickness. The sewing machine includes pressure control means, storage means, and switching control means. When the presser foot is lowered, the pressure control means transmits a command signal for the target lowering position to the motor, feeds back the position of the presser foot detected by the detecting means, and controls the driving of the motor with a normal current. The storage means stores the presser foot switching position. The switching position is a position at which the presser foot lowering control is switched from the position control means to the pressure control means. When the descending presser foot reaches the switching position stored in the storage unit, the switching control unit switches the presser foot lowering control from the position control unit to the pressure control unit.

JP 2010-88493 A

  Regardless of the fabric thickness, the bar-tacking sewing machine controls the sewing rotational speed as set on the operation panel. The sewing rotation speed is the number of needle drops per unit time. The sewing machine described in Patent Document 1 can adjust the presser foot pressure according to the cloth thickness, but if the sewing machine is moved at high speed under conditions where the cloth thickness is thicker than usual, the sewing needle is being fed while the cloth is being fed. May pierce the cloth and break the needle.

  An object of the present invention is to provide a sewing machine and a sewing machine control method that can prevent needle breakage by controlling the number of rotations of sewing in accordance with the cloth thickness.

  The sewing machine according to claim 1 of the present invention is a sewing machine that sews a cloth by moving a sewing needle up and down, a cloth thickness detecting means that detects a cloth thickness that is sewn with the sewing needle, and the cloth thickness detecting means that detects the cloth thickness. Control means for controlling the number of rotations of sewing based on the cloth thickness, wherein the control means makes the maximum value of the number of rotations of sewing slower than a predetermined value when the cloth thickness is equal to or greater than a predetermined thickness. To do. Since the sewing machine controls the sewing speed to an appropriate value in accordance with the thickness of the cloth to be sewn, the sewing needle can be prevented from being stuck in the cloth while the cloth is being fed. Therefore, the sewing machine can prevent needle breakage.

  A sewing machine according to a second aspect of the present invention includes, in addition to the configuration according to the first aspect of the invention, a presser foot that presses the cloth from above, and a cloth presser device that can be moved up and down by the power of a motor. The means moves the presser foot up and down, and detects the speed change of the motor that occurs when the presser foot contacts or separates from the cloth, and the speed change detected by the detection means Based on the cloth thickness, and the control means controls the sewing rotation speed based on the cloth thickness estimated by the estimation means. When the presser foot of the presser device moves downward and contacts the cloth, or moves upward and moves away from the cloth, the load applied to the motor fluctuates. The sewing machine estimates the cloth thickness by reading the load variation, and can sew the cloth at an appropriate sewing rotational speed in accordance with the estimated cloth thickness. Since the sewing machine uses a cloth presser, there is no need to provide a sensor or the like for detecting the cloth thickness. Therefore, the sewing machine can save the manufacturing cost.

  A sewing machine according to a third aspect of the invention includes a bed, a leg column extending upward from the bed, and an upper end of the leg from the bed to the bed. An arm portion extending in parallel, and the cloth presser device is disposed between the bed portion and the arm portion, and is supported by the bed portion on the side of the pedestal portion, and the base end portion. On the other hand, a presser arm having a distal end located on the opposite side of the pedestal, a mounting portion provided at the distal end of the presser arm and capable of mounting the presser foot in a vertically movable state, and the presser A connection portion extending along the arm and connected to the presser arm so as to be swingable in the vertical direction; an end portion engageable with the presser foot attached to the attachment portion; and the end portion with respect to the connection portion And a lever having a protruding portion protruding upward on the opposite side, and the lever is moved downward at the end. A spring that is biased in the direction to be moved, and can be moved up and down by the power of the motor above the projecting portion, and comes into contact with the projecting portion from above from a state of being spaced upward from the projecting portion, and the projecting portion And a pressing member that can swing the lever in a direction in which the end moves upwardly against the biasing force of the spring. When the pressing member is moved upward by the power of the motor from a state in which the protruding portion is pressed downward, the speed change of the motor that occurs when the pressing member moves away from the protruding portion is detected. One detecting means is provided. The presser foot device includes a presser arm, a mounting portion, a lever, a spring, and a pressing plate. Therefore, when the sewing machine moves the pressing plate upward, if the pressing plate is separated from the protruding portion, the urging force of the spring applied to the pressing plate is lost. Since the biasing force of the spring disappears, the motor changes in speed. The sewing machine can estimate the cloth thickness by detecting the speed change.

  According to a fourth aspect of the present invention, in addition to the configuration of the third aspect of the invention, the detection means is configured to use the power of the motor from the state where the pressing member is spaced upward with respect to the protruding portion. When the pressing member is moved downward, second detection means is provided for detecting the speed change of the motor that occurs when the pressing member comes into contact with the protruding portion from above. When the presser foot moves upward in a state where there is a cloth under the presser foot, a speed change occurs in the motor at a timing when the pressing plate is separated from the protruding portion. The sewing machine can estimate the cloth thickness by detecting the speed change.

  A sewing machine according to a fifth aspect of the invention is the sewing machine according to any one of the second to fourth aspects, wherein the detection means is based on an output value of an encoder that detects position information of the motor. The speed change of the motor is detected. Since the output value of the encoder is used, the sewing machine can accurately read the speed change of the motor.

  According to a sixth aspect of the present invention, there is provided a sewing machine control method comprising: a bed portion; a leg column portion extending upward from the bed portion; and an arm portion extending in parallel to the bed portion from an upper end portion of the leg column portion. , A sewing machine control method for sewing a cloth by moving a sewing needle up and down, based on a cloth thickness detection step for detecting a cloth thickness to be sewn with the sewing needle, and the cloth thickness detected in the cloth thickness detection step, A control step for controlling the number of rotations of sewing, and the sewing machine includes a presser foot that can move the presser foot that presses the cloth from above by a motor power, and the presser foot includes the bed portion. And a presser foot having a base end portion that is disposed between the arm portion and supported by the bed portion on the side of the pedestal portion, and a tip end portion that is located on the opposite side of the pedestal portion with respect to the base end portion. The arm and the tip of the presser arm are provided, and the presser foot is moved up and down. A mounting portion that can be mounted in a state of being able to be mounted, a connection portion that extends along the presser arm and is swingably connected to the presser arm, and can be engaged with the presser foot mounted on the mounting portion. An end portion, a lever having a protruding portion that protrudes upward on the opposite side of the connecting portion, a spring that biases the lever in a direction in which the end portion moves downward, and the protruding portion The upper part is provided so as to be movable up and down by the power of the motor, and comes into contact with the projecting part from above from a state of being spaced upward with respect to the projecting part, and presses the projecting part downward, whereby the lever is A pressing member swingable in a direction in which the end portion moves upward against the urging force of the spring, and the cloth thickness detecting step moves the presser foot up and down, and the presser foot moves to the cloth The speed of the motor that occurs when contacting or moving away from the fabric A detection step of detecting the change, and an estimation step of estimating the cloth thickness based on the speed change detected in the detection step, wherein the pressing member presses the protruding portion downward in the detection step Thus, when the pressing member is moved upward by the power of the motor, the speed change of the motor that occurs when the pressing member separates from the protruding portion is detected. Therefore, the sewing machine can obtain the effect of the third aspect by executing the above control method.

The perspective view of the sewing machine 1. FIG. The right view of the sewing machine 1. FIG. The right side view of the presser foot device 10 (the presser foot lifting mechanism 80 is omitted). FIG. 3 is a front view of the presser foot device 10. FIG. 3 is a plan view of the presser foot device 10 (the presser foot lifting mechanism 80 is omitted). The perspective view of the right presser foot 120. FIG. FIG. 3 is a perspective view of the presser foot device 10. FIG. 2 is a block diagram showing an electrical configuration of the sewing machine 1. The conceptual diagram of the cloth thickness estimation table 541. FIG. The flowchart of a 1st sewing control process. The table | surface which shows the change of the rotational speed of the pulse motor 94 for presser foot at the time of presser foot 12 descent | fall. The table | surface which shows the change of the drive current of the pulse motor 94 for presser foot at the time of presser foot 12 descending. The flowchart of a 2nd sewing control process. The table | surface which shows the change of the rotational speed of the pulse motor 94 for presser foot at the time of presser foot 12 raising. The chart which shows the change of the drive current of the pulse motor 94 for presser foot at the time of presser foot 12 raising. The conceptual diagram of the cloth thickness estimation table 542. FIG.

  Embodiments of the present invention will be described with reference to the drawings. In the following description, the top, bottom, left and right, front and back indicated by arrows in the figure are used.

  The overall structure of the sewing machine 1 will be described with reference to FIGS. The sewing machine 1 is a tacking sewing machine that forms tacking seams on a cloth, and includes a bed portion 2, a pedestal column portion 3, an arm portion 4, and a cloth presser device 10. The bed part 2 is arranged on a table 9 (see FIG. 2). The bed portion 2 extends in the front-rear direction and includes a vertical shuttle 8 and a feed base 37 inside. The bed portion 2 includes a needle plate 29 having a needle hole (not shown) on the upper surface of the front end portion. The pedestal 3 extends upward from the rear side of the bed 2 and includes a sewing machine motor 91 (see FIG. 8) inside. The arm portion 4 extends forward substantially parallel to the bed portion 2 from the upper end of the pedestal portion 3 and includes a sewing machine main shaft (not shown) driven by a sewing machine motor 91 inside. The front end portion 5 of the arm portion 4 projects downward from other portions of the arm portion 4. The front end portion 5 supports the needle bar 6 so as to be movable up and down. The needle bar 6 extends downward from the lower end of the front end portion 5. The sewing needle 7 is detachably attached to the lower end of the needle bar 6 and is driven in the vertical direction together with the needle bar 6 by driving the sewing machine main shaft. The cloth presser device 10 is provided on the upper part of the bed portion 2 and presses the cloth as a sewing object from above.

  The sewing machine 1 includes a thread trimming mechanism (not shown) that cuts the upper thread and the lower thread after the end of sewing inside the bed portion 2. The thread cutting mechanism includes a fixed blade provided below the needle plate 29 and a movable blade movable relative to the fixed blade, and moves the movable blade via a link mechanism (not shown) to cut the thread. .

  The configuration of the presser foot device 10 will be described with reference to FIGS. The presser foot device 10 includes a feed plate 11, a presser arm 13, a mounting portion 14, a right lever 310, a left lever 320, a biasing portion 15, and a presser lifting mechanism 80. As shown in FIGS. 1 to 3, the feed plate 11 is fixed to the upper surface of the feed base 37 disposed inside the bed portion 2. In FIG. 1, the feed plate 11 is omitted. The feed base 37 is movable in the front-rear direction and includes a rack connecting portion 61 (see FIG. 5) at the rear end. The rack connecting portion 61 has a bottomed cylindrical shape with the vertical direction as the axial direction. The lower end portion of the shaft portion 63 is inserted into the hole at the center of the rack connecting portion 61. The upper end portion of the shaft portion 63 is connected to the front end portion of the rack shaft 60 extending in the front-rear direction. The rear part of the rack shaft 60 is located inside the pedestal column part 3 and has a tooth part (not shown). The tooth portion of the rack shaft 60 meshes with a small gear (not shown) fixed to the output shaft of the Y-feed pulse motor 93 (see FIG. 8) inside the pedestal 3.

  When the Y-feed pulse motor 93 is driven, the rack shaft 60 moves in the front-rear direction. The feed table 37 and the feed plate 11 move in the front-rear direction as the rack shaft 60 moves. The feed plate 11 has a through hole (not shown) at the front end. The sewing needle 7 passes through the through hole during sewing and reaches the needle hole of the needle plate 29. The feed base 37 is connected to a swing mechanism (not shown) below the rack connecting portion 61. An X-feed pulse motor 92 (see FIG. 8) inside the bed unit 2 drives the swing mechanism. The feed base 37 and the feed plate 11 can swing in the left-right direction around the shaft portion 63 as the swing mechanism is driven.

  As shown in FIG. 3, the presser arm 13 includes a base end portion 16, an intermediate portion 17, and an inclined portion 18. The base end portion 16 is a portion that extends vertically in front of the pedestal column portion 3 and is fixed to the feed base 37 at the lower end portion. The intermediate portion 17 extends substantially horizontally below the arm portion 4 from the upper end of the base end portion 16 to the front. The inclined portion 18 extends obliquely downward from the front end of the intermediate portion 17. The front end of the inclined portion 18 fixes the mounting portion 14 integrally.

  As shown in FIG. 5, the base end portion 16 includes a pair of left and right support portions 35 on the back side of the lower end portion. The support part 35 has a bottomed cylindrical shape with the vertical direction as the axial direction. The rack connecting portion 61 of the feed base 37 is located between the pair of support portions 35. Since the presser arm 13 is connected to the rack shaft 60 via the shaft portion 63 of the feed base 37, the presser arm 13 moves in the front-rear direction together with the feed base 37 as the rack shaft 60 moves. Since the presser arm 13 is also connected to the swing mechanism via the shaft portion 63, the presser arm 13 can swing in the left-right direction around the shaft portion 63.

  The mounting portion 14 is a portion where the presser foot 12 is mounted. The presser foot 12 includes a right presser foot 120 and a left presser foot 130. As shown in FIG. 6, the right presser foot 120 includes a support plate portion 121, a leg portion 122, and a presser portion 123. The support plate 121 has a substantially vertically long rectangular shape when viewed from the front, and has a circular engagement hole 124 at the top. The diameter of the engagement hole 124 is substantially equal to the vertical length of the front end 421 of the right lever 310 described later. The leg portion 122 is narrower than the support plate portion 121, extends downward from the lower end portion of the support plate portion 121, bends forward, and further extends obliquely downward in the front direction. The presser portion 123 extends forward from the lower end portion of the leg portion 122.

  As shown in FIGS. 4 and 5, the left presser foot 130 includes a support plate portion 131 having an engagement hole 134, a leg portion 132, and a presser portion 133, and has a bilaterally symmetric shape with the right presser foot 120. The presser portion 123 and the presser portion 133 have a rectangular frame shape in plan view when they are arranged side by side.

  As shown in FIGS. 3 to 5, the mounting portion 14 includes a mounting member 20 that is integrally fixed to the front end of the inclined portion 18, and three mounting plates 250 that are fixed to the mounting member 20. The mounting member 20 includes a pair of left and right engaging portions 201 (see FIG. 3) on the front side. Each engaging portion 201 is a groove extending in the vertical direction opened at the upper end of the mounting member 20. The operator attaches the right presser foot 120 and the left presser foot 130 to the mounting member 20 by inserting the support plate portion 121 and the support plate portion 131 into the engaging portion 201 from above. The right presser foot 120 and the left presser foot 130 can move up and down along the engaging portion 201.

  The mounting plate 250 is a plate that holds the presser foot 12 engaged with the engaging portion 201 so that the presser foot 12 does not come forward. The mounting plate 250 is a plate-like member having a vertically long rectangular shape when viewed from the front, and has two through holes (not shown) for the screws 22 in the upper part and the lower part. The three mounting plates 250 are fixed to the mounting member 20 with two screws 22 on the right side of the right engaging portion 201, between the left and right engaging portions 201, and on the left side of the left engaging portion 201, respectively. The left-right width of the gap between the left and center mounting plates 250 is smaller than the left-right width of the left engagement portion 201. The lateral width of the gap between the center and the right mounting plate 250 is smaller than the lateral width of the right engagement portion 201.

  Each of the right lever 310 and the left lever 320 is a member extending in the front-rear direction along the intermediate portion 17 and the inclined portion 18 of the presser arm 13 and has a bilaterally symmetric shape. The support shaft 301 is inserted in the left-right direction at the center portion in the front-rear direction of the intermediate portion 17. The right end portion and the left end portion of the support shaft 301 protrude from the intermediate portion 17 to the right and left, respectively. The right end portion of the support shaft 301 supports the substantially central portion of the right lever 310 in the front-rear direction so as to be swingable. The left end portion of the support shaft 301 supports the substantially central portion of the left lever 320 in the front-rear direction so as to be swingable.

  The right lever 310 includes a front portion 311 extending forward from the support shaft 301 and a rear portion 312 extending rearward from the support shaft 301. The left lever 320 includes a front portion 321 extending forward from the support shaft 301 and a rear portion 322 extending rearward from the support shaft 301. The front end 421 of the right lever 310 engages with the engagement hole 124 of the right presser foot 120. The front end 422 of the left lever 320 engages with the engagement hole 134 of the left presser foot 130.

  The rear end portion 316 of the right lever 310 and the rear end portion 326 of the left lever 320 are connected to the pair of urging portions 15. Each urging portion 15 includes a guide shaft 34 that is movable in the vertical direction, and a compression coil spring 32 that is mounted around the guide shaft 34. The rear end 316 and the rear end 326 are rotatably connected to the upper end of the guide shaft 34, respectively. The lower end portion of the guide shaft 34 is inserted into the support portion 35 of the base end portion 16. The compression coil spring 32 biases the rear end 316 of the right lever 310 and the rear end 326 of the left lever 320 upward. That is, the compression coil spring 32 urges the right lever 310 and the left lever 320 in the direction in which the front end 421 and the front end 422 move downward.

  When the later-described pressing plate 90 does not act on the right lever 310 and the left lever 320, the front end portion 421 and the front end portion 422 are in the lowest position by the urging force of the compression coil spring 32. The lowermost positions of the front end portion 421 and the front end portion 422 correspond to positions where the lower surfaces of the presser portion 123 and the presser portion 133 are in contact with the upper surface of the feed plate 11 when the presser foot 12 is attached. The rear part 312 of the right lever 310 and the rear part 322 of the left lever 320 are inclined obliquely downward in the front direction.

  Each of the right lever 310 and the left lever 320 has a configuration for changing the position in the front-rear direction with respect to the presser arm 13. Although illustration is omitted, each of the right lever 310 and the left lever 320 has a long hole extending in the front-rear direction at the center and a screw hole in front of the long hole. The support shaft 301 is inserted through the elongated hole. The horizontally-long rectangular positioning plate 44 has a long hole 47 that is long in the horizontal direction, and has a round hole that is substantially equal to the diameter of the support shaft 301 next to the long hole 47.

  The operator changes the positions of the right lever 310 and the left lever 320 with respect to the support shaft 301 along the elongated hole. The operator arranges a pair of positioning plates 44 on the right and left surfaces of the right lever 310 and the left lever 320, fits the support shaft 301 into the round hole, and inserts the set screw 43 from the right and left of the elongated hole 47. Screw into the screw hole. The operator can change the front-rear direction positions of the right lever 310 and the left lever 320 with respect to the presser arm 13 by the above-described method, and can attach and detach the right presser foot 120 and the left presser foot 130 to and from the mounting portion 14.

  The right lever 310 includes a right attachment portion 313 at the rear portion 312. The right mounting portion 313 is detachable from the right protruding portion 315. The right attachment portion 313 has a through hole that penetrates the rear portion 312 left and right. The through hole is a vertically long slot. The right protrusion 315 is a vertically long rectangular plate member with rounded corners, and has screw holes. The operator aligns the screw hole of the right projecting portion 315 with the left side (presser arm 13 side) of the through hole of the right mounting portion 313. The operator fixes the right protruding portion 315 to the right mounting portion 313 by tightening the set screw 317 from the right side.

  The left lever 320 has the same configuration as the right lever 310. That is, the rear portion 322 includes a left attachment portion 323. The left attachment portion 323 has a through hole that penetrates the rear portion 312 left and right. The left protrusion 325 has the same configuration as the right protrusion 315. The operator aligns the screw hole of the left projecting portion 325 with the right side (presser arm 13 side) of the through hole of the left mounting portion 323. The operator fixes the left protruding portion 325 to the left mounting portion 323 by tightening the set screw 327 from the left side.

  As shown in FIG. 7, the presser foot lifting mechanism 80 includes a presser foot pulse motor 94, a drive gear 82, a cam gear 83, a drive lever 84, a link 85, a presser foot lift lever 86, a shaft portion 87, a support rod 88, and a press plate 90. Prepare.

  The presser foot pulse motor 94 is disposed inside the pedestal 3. The drive gear 82 is fixed to the output shaft of the presser foot pulse motor 94 and meshes with the cam gear 83. The cam gear 83 is connected to the drive lever 84 via a cam. The drive lever 84 is connected to the link 85. The link 85 is connected to one end of a V-shaped presser lifting lever 86 that can rotate around a shaft portion 87. The other end of the presser lifting lever 86 is connected to a support bar 88 that extends in the vertical direction and is supported so as to be movable up and down. The rectangular plate-shaped pressing plate 90 is fixed to the lower end of the support bar 88 in such a posture that the lower surface, which is a flat surface, extends in the horizontal direction. The initial position of the pressing plate 90 is above the right lever 310 and the left lever 320 and at a position where it does not come into contact with the right protruding portion 315 and the left protruding portion 325. The pressing plate 90 is a portion that presses the right protruding portion 315 attached to the right lever 310 and the left protruding portion 325 attached to the left lever 320 from above.

  The sewing machine 1 includes a control box (not shown) storing a control device 50 (see FIG. 8) and a foot pedal 23 (see FIG. 8, omitted in FIG. 1) below the table 9. The foot pedal 23 is a pedal that an operator operates with his / her foot, and is an operation unit capable of inputting various instructions to the control device 50. The foot pedal 23 includes a first switch 24 and a second switch 25 (see FIG. 8, hereinafter referred to as a first SW 24 and a second SW 25) inside, and has a two-step depression position. In the state where the foot pedal 23 is not depressed, both the first SW 24 and the second SW 25 are off. When the first step is depressed, the first SW 24 is turned on, and when the second step is depressed, the second SW 25 is turned on. Therefore, the control device 50 detects the depression position of the foot pedal 23 based on on / off of the first SW 24 and the second SW 25. For example, the operator can input an instruction to raise or lower the presser foot 12 of the presser foot device 10 from the foot pedal 23. When an instruction to raise or lower the presser foot 12 is input, the controller 50 drives the presser foot pulse motor 94 to control the operation of the presser foot lifting mechanism 80.

  When the presser foot pulse motor 94 is driven forward, the cam gear 83 meshing with the drive gear 82 rotates in the opposite direction to the drive gear 82. The rotation of the cam gear 83 is transmitted to the presser lift lever 86 via the drive lever 84 and the link 85. The connection end of the presser lifting lever 86 with the link 85 rotates backward about the shaft portion 87 and moves the support bar 88 downward. The pressing plate 90 moves downward together with the support bar 88. When the cloth presser pulse motor 94 is driven in reverse, the drive gear 82, the cam gear 83, the drive lever 84, the link 85, and the presser lifting lever 86 operate in the reverse direction. The connection end of the presser lifting lever 86 with the link 85 rotates forward about the shaft portion 87 and moves the support bar 88 upward. The pressing plate 90 moves upward together with the support bar 88.

  The electrical configuration of the sewing machine 1 will be described with reference to FIG. The control device 50 of the sewing machine 1 includes a microcomputer including a CPU 51, a ROM 52, a RAM 53, and a non-volatile memory 54, an input interface 56 and an output interface 57 connected to the microcomputer via a data bus, and driving circuits 71 to 74. Have. The CPU 51 controls the overall operation of the sewing machine 1. The ROM 52 includes a first sewing control program for executing a first sewing control process (see FIG. 10) described later, a second sewing control program for executing a second sewing control process (see FIG. 13) described later, and various types. The sewing pattern and the like of the tacking seam are stored in advance. The sewing pattern is coordinate data in which needle drop points are determined in order. The needle drop point is a predetermined position on the cloth where the sewing needle 7 is stuck when the sewing needle 7 moves downward together with the needle bar 6. The RAM 53 temporarily stores various information generated during the execution of various processes. The nonvolatile memory 54 stores a cloth thickness estimation table 541 (see FIG. 9) described later.

  The drive circuits 71 to 74 are connected to the output interface 57, respectively. The drive circuit 71 is connected to the sewing machine motor 91 and drives the sewing machine motor 91 based on a control command from the CPU 51. The drive circuit 72 is connected to the X-feed pulse motor 92 and drives the X-feed pulse motor 92 based on a control command from the CPU 51. The drive circuit 73 is connected to the Y-feed pulse motor 93 and drives the Y-feed pulse motor 93 based on the control command of the CPU 51. The drive circuit 74 is connected to the presser foot pulse motor 94 and drives the presser foot pulse motor 94 based on a control command of the CPU 51.

  The power switch 77, the first SW 24 and the second SW 25 of the foot pedal 23, the encoders 91A to 94A, the operation panel 98, and the like are connected to the input interface 56, respectively. The power switch 77 activates and terminates the sewing machine 1. The encoder 91 </ b> A is connected to the sewing machine motor 91 and inputs information on the rotational position and rotational speed of the sewing machine motor 91 to the input interface 56. The encoder 92 </ b> A is connected to the X-feed pulse motor 92 and inputs pulse information to be output corresponding to the rotation direction, rotation position, and rotation speed of the X-feed pulse motor 92 to the input interface 56. The encoder 93 </ b> A is connected to the Y-feed pulse motor 93 and inputs pulse information to be output corresponding to the rotation direction, rotation position, and rotation speed of the Y-feed pulse motor 93 to the input interface 56. The encoder 94 </ b> A is connected to the presser foot pulse motor 94, and inputs to the input interface 56 pulse information output corresponding to the rotation direction, rotational position, and rotational speed of the presser foot pulse motor 94. The operation panel 98 can input various settings such as a sewing pattern, a horizontal magnification, a vertical magnification, a sewing speed, a presser foot lift amount, and a counter.

  The cloth thickness estimation table 541 will be described with reference to FIG. The cloth thickness estimation table 541 stores the cloth thickness estimated based on the timing when the presser foot 12 of the cloth presser device 10 is lowered and the presser foot 12 contacts the cloth. As will be described later, the sewing machine 1 according to the present embodiment measures the time t at which the speed change has occurred in the presser foot pulse motor 94 after the presser foot 12 starts to descend. The cloth thickness estimation table 541 stores the cloth thickness as 10 mm or more when the time t is less than or equal to the predetermined value α and the cloth thickness as less than 10 mm when the time t is greater than α. That the time t is less than or equal to α means that the time t at which the speed change has occurred is earlier than the predetermined value α. The time t being greater than α means that the time t at which the speed change has occurred is later than the predetermined value α.

  When the presser foot 12 is lowered, the pressing plate 90 is lifted, and when the presser foot 12 comes into contact with the cloth, the presser foot 12 moves away from the right protruding portion 315 and the left protruding portion 325. That is, the thicker the cloth that the presser foot 12 presses, the earlier the timing at which the right protruding portion 315 and the left protruding portion 325 are separated from the lower surface of the pressing plate 90. Therefore, the shorter the time that the pressing plate 90 starts to rise and the distance from the right protrusion 315 and the left protrusion 325 is, the thicker the cloth. The predetermined value α may be set to a time when a speed change occurs in the cloth presser pulse motor 94 when a cloth having a thickness of 10 mm is set on the bed 2 and the presser foot 12 is lowered.

  The first sewing control process will be described with reference to FIGS. When the operator presses the power switch 77 (see FIG. 8) provided below the table 9 to activate the sewing machine 1, the CPU 51 reads the first sewing control program from the ROM 52 and executes this processing. The operator depresses the foot pedal 23 to the second step in order to input an instruction for detecting the origin. The CPU 51 determines whether there is an origin detection instruction (S1). If there is no origin detection instruction (S1: NO), the CPU 51 returns to S1 and waits. When there is an origin detection instruction (S1: YES), the CPU 51 performs origin detection (S2), and then raises the presser foot 12 by performing the following operations (S3).

  As shown in FIG. 7, the CPU 51 starts normal rotation driving of the presser foot pulse motor 94. The pressing plate 90 starts to descend from the initial position. The lower surface of the pressing plate 90 is in contact with the right protrusion 315 and the left protrusion 325 simultaneously (see FIG. 4). The pressing plate 90 further descends and presses the right protruding portion 315 and the left protruding portion 325 downward. The right lever 310 swings around the support shaft 301 against the urging force of the compression coil spring 32. The front end 421 of the right lever 310 starts to move upward. Since the front end portion 421 engages with the engagement hole 124, the right presser foot 120 starts to rise together with the front end portion 421. Similarly to the right lever 310, the left lever 320 swings about the support shaft 301 against the urging force of the compression coil spring 32. The front end 422 of the left lever 320 starts to move upward. Since the front end portion 422 is engaged with the engagement hole 134, the left presser foot 130 starts to rise together with the front end portion 422. As the pressing plate 90 is further lowered, the right presser foot 120 and the left presser foot 130 continue to move upward. The CPU 51 stops driving the presser foot pulse motor 94 when both the front end portion 421 and the front end portion 422 reach the uppermost position.

  The operator sets the cloth to be sewn between the feed plate 11 and the presser foot 12 and depresses the foot pedal 23 to the first step in order to input a lowering instruction of the presser foot 12. As shown in FIG. 10, the CPU 51 determines whether or not there is an instruction to lower the presser foot 12 (S4). If there is no lowering instruction (S4: NO), the CPU 51 returns to S4 and waits. When there is a lowering instruction (S4: YES), the CPU 51 lowers the presser foot 12 by performing the following operation (S5).

  As shown in FIG. 7, the CPU 51 starts reverse rotation driving of the presser foot pulse motor 94. The pressing plate 90 starts to rise. As the pressing plate 90 moves up, the right lever 310 and the left lever 320 swing with the support shaft 301 as a fulcrum by the urging force of the compression coil spring 32, respectively. As the front end 421 and the front end 422 move downward, the right presser foot 120 and the left presser foot 130 descend. The CPU 51 starts measuring the rotational speed of the presser foot pulse motor 94 based on the pulse information from the encoder 94A simultaneously with the start of reverse rotation drive of the presser foot pulse motor 94 (S6). Based on the pulse information from the encoder 94A, the CPU 51 calculates the rotational speed (r / min), for example, by measuring the pulse time of one cycle and the number of output pulses per cycle. The CPU 51 sequentially stores the calculated rotation speed in the RAM 53.

  While the presser foot 12 is away from the cloth, the lower surface of the pressing plate 90 is in contact with the right protruding portion 315 and the left protruding portion 325. Therefore, the urging force of the compression coil spring 32 is applied to the pressing plate 90. As shown in FIG. 11, the presser foot pulse motor 94 maintains a constant rotational speed so that the presser foot 12 descends at a constant speed. At the moment (time t1) when the presser foot 12 that is descending comes into contact with the cloth, the lower surface of the pressing plate 90 is separated from the right protruding portion 315 and the left protruding portion 325, so the urging force applied to the pressing plate 90 is instantaneously lost. At this time, the load applied to the presser foot pulse motor 94 disappears all at once, so that the rotational speed of the presser foot pulse motor 94 that has been maintained constant increases momentarily. However, since the presser foot pulse motor 94 tries to maintain a constant rotational speed, it immediately returns to the original rotational speed.

  Here, a change in current for driving the presser foot pulse motor 94 when the presser foot 12 is lowered will be described. As shown in FIG. 12, at the start of reverse driving of the presser foot pulse motor 94, the drive circuit 74 outputs a constant current to the presser foot pulse motor 94. Therefore, since the presser foot pulse motor 94 rotates at a constant rotational speed (see FIG. 11), the pressing plate 90 rises at a constant speed, and the presser foot 12 descends at a constant speed. At the moment (time t1) when the presser foot 12 that is descending comes into contact with the cloth, the load applied to the cloth presser pulse motor 94 disappears all at once as described above, so the drive circuit 74 outputs to the presser foot pulse motor 94. The current to be reduced also decreases at a stretch. The time t1 when the current changes is the same as the time t1 when the rotation speed of the presser foot pulse motor 94 changes. Thereafter, since the current is kept constant at the lowered level, the pressing plate 90 continues to rise at a constant speed.

  The CPU 51 stops driving the cloth presser pulse motor 94 when the pressing plate 90 reaches the initial position. The lowering of the presser foot 12 is completed, and the cloth is pressed by the presser foot 12. The CPU 51 detects the time t1 at which the rotational speed has increased instantaneously from the rotational speed history information recorded in the RAM 53 (see FIG. 11). The time t1 is an elapsed time from the start of reverse driving of the presser foot pulse motor 94 in order to lower the presser foot 12. As shown in FIG. 10, the CPU 51 estimates the cloth thickness corresponding to the time t1 based on the cloth thickness estimation table 541 (S7). In the example shown in FIG. 11, the time t1 when the speed change has occurred is a timing earlier than the predetermined value α, so that the cloth thickness can be estimated to be 10 mm or more. On the contrary, when the time t1 has passed the predetermined value α, the cloth thickness can be estimated to be less than 10 mm. The CPU 51 stores the estimated cloth thickness in the RAM 53.

  CPU51 judges whether the cloth thickness memorize | stored in RAM53 is 10 mm or more (S8). When the cloth thickness is less than 10 mm (S8: NO), the CPU 51 sets the maximum rotational speed of the sewing machine motor 91 to the normal 3,200 r / min (S10). The maximum rotational speed is the maximum value of the rotational speed of the sewing machine motor 91 that is permitted during sewing. On the other hand, when the estimated cloth thickness is 10 mm or more (S8: YES), since the cloth thickness is larger than usual, the CPU 51 sets the maximum rotational speed of the sewing machine motor 91 to 2,000 r / min (S9). That is, under the condition that the cloth thickness is thicker than usual, the CPU 51 sets the maximum number of revolutions of the sewing machine motor 91 to be lower than usual.

  Subsequently, the operator depresses the foot pedal 23 to the second step in order to input a sewing instruction. The CPU 51 determines whether there is a sewing instruction (S11). If there is no sewing instruction (S11: NO), the CPU 51 returns to S11 and stands by. When there is a sewing instruction (S11: YES), the CPU 51 drives the sewing machine motor 91 at the maximum number of revolutions set in S9 or S10, and sews the cloth with the sewing pattern of the tacking seam selected on the operation panel 98 ( S12). As described above, the sewing machine 1 is set so that the maximum rotational speed of the sewing machine 1 is lower than usual under the condition that the cloth thickness is thicker than usual. Therefore, the sewing machine 1 can prevent needle breakage and the like since the sewing needle 7 does not pierce the cloth while the feed plate 11 is operating during sewing.

  The CPU 51 determines whether or not the sewing pattern has been sewn (S13). When sewing is in progress (S13: NO), the CPU 51 stands by. When the sewing is completed (S13: YES), the CPU 51 drives the thread trimming mechanism to cut the upper thread and the lower thread, then raises the presser foot 12 (S14), and returns the process to S4. When the operator presses the power switch 77 (see FIG. 8) to end the sewing machine 1, this process ends.

  As described above, the sewing machine 1 of the present embodiment sews the cloth by moving the sewing needle 7 up and down. The sewing machine 1 detects the thickness of the cloth to be sewn. If the detected cloth thickness is 10 mm or more, the sewing machine 1 executes sewing with the maximum rotational speed of the sewing machine motor 91 slower than the normal 3,200 r / min. Since the sewing machine 1 controls the sewing rotation speed to an appropriate value in accordance with the thickness of the cloth to be sewn, the sewing needle 7 can be prevented from being stuck in the cloth while the cloth is being fed. Therefore, the sewing machine 1 can prevent needle breakage.

  The sewing machine 1 of the above embodiment further includes a presser foot device 10. The presser foot device 10 can move the presser foot 12 that presses the cloth from above with the power of the presser foot pulse motor 94. When the descending presser foot 12 comes into contact with the cloth, or when the ascending presser foot 12 leaves the cloth, the load applied to the cloth presser pulse motor 94 varies. The sewing machine 1 estimates the cloth thickness by reading the load fluctuation, and can sew the cloth at an appropriate sewing rotational speed in accordance with the estimated cloth thickness. Since the sewing machine 1 uses the cloth presser device 10, it is not necessary to provide a sensor or the like for detecting the cloth thickness, so that the manufacturing cost can be saved.

  The presser foot device 10 of the above embodiment includes the structure shown in FIG. When the pressing plate 90 of the presser foot device 10 is moved upward to lower the presser foot 12, the lower surface of the pressing plate 90 is separated from the right protruding portion 315 and the left protruding portion 325. At that time, the urging force of the compression coil spring 32 applied to the pressing plate 90 disappears all at once, so that the rotation speed of the cloth presser pulse motor 94 changes. Therefore, the sewing machine 1 can easily estimate the cloth thickness by detecting the change in the rotational speed generated in the cloth presser pulse motor 94 and based on the detected timing.

  In the above embodiment, since the change in speed of the presser pulse motor 94 is detected based on the output value of the encoder 94A that detects the position information of the presser foot pulse motor 94, the change in speed generated in the presser foot pulse motor 94 is detected. It can be detected accurately and promptly.

  The present invention can be variously modified in addition to the above embodiment. The sewing machine 1 is a tacking sewing machine that forms tacking stitches on a cloth, but is not limited to the tacking sewing machine and may be other sewing machines.

  In the first sewing control process shown in FIG. 10, the CPU 51 of the above embodiment detects a speed change that occurs in the presser foot pulse motor 94 when the presser foot 12 is raised, and at the time t when the speed change occurs. Based on this, the maximum rotational speed of the sewing machine 1 is controlled. For example, the CPU 51 may detect a speed change that occurs in the presser foot pulse motor 94 when the presser foot 12 is raised by executing the second sewing control process shown in FIG.

  The second sewing control process shown in FIG. 13 will be described. Since the second sewing control process is merely a modification of the first sewing control process, the description will focus on the deformed portion. Common processing steps are simply described with the same reference numerals. When the operator presses the power switch 77 to start the sewing machine 1, the CPU 51 reads the second sewing control program from the ROM 52 and executes this processing.

  When the operator steps on the foot pedal 23 to the first step (S1: YES), the CPU 51 executes the origin detection process (S2) and raises the presser foot 12 (S3). The operator sets a cloth under the presser foot 12 and depresses the foot pedal 23 to the first step (S4: YES). The CPU 51 lowers the presser foot 12 (S5). The presser foot 12 presses the cloth.

  In order to raise the presser foot 12 again and detect the cloth thickness, the operator depresses the foot pedal 23 to the first step again. The CPU 51 determines whether there is an instruction to raise the presser foot 12 (S21). If there is no upward instruction (S21: NO), the CPU 51 returns to S21 and waits. When there is an upward instruction (S21: YES), the CPU 51 raises the presser foot 12 (S22). As described above, when the presser foot 12 is raised, the CPU 51 starts normal rotation driving of the presser foot pulse motor 94. The pressing plate 90 starts to descend. The CPU 51 starts measuring the rotational speed of the presser foot pulse motor 94 based on the pulse information from the encoder 94A simultaneously with the start of forward rotation of the presser foot pulse motor 94 (S23). The CPU 51 sequentially stores the calculated rotation speed in the RAM 53.

  While the presser foot 12 is in contact with the cloth, the lower surface of the pressing plate 90 is separated from the right protruding portion 315 and the left protruding portion 325. Therefore, the urging force of the compression coil spring 32 is not applied to the pressing plate 90. As shown in FIG. 14, the presser foot pulse motor 94 maintains a constant rotational speed so that the presser foot 12 rises at a constant speed. At the moment when the presser foot 12 that has been lifted is separated from the cloth (time t2), the lower surface of the pressing plate 90 comes into contact with the right protruding portion 315 and the left protruding portion 325, so that an urging force is instantaneously applied to the pressing plate 90. At this time, since a load is applied to the presser foot pulse motor 94 at a stretch, the rotational speed of the presser foot pulse motor 94 which has been maintained constant until then is instantaneously reduced. However, since the presser foot pulse motor 94 tries to maintain a constant rotational speed, it immediately returns to the original rotational speed.

  Here, a change in current for driving the presser foot pulse motor 94 when the presser foot 12 is raised will be described. As shown in FIG. 15, at the start of normal rotation driving of the presser foot pulse motor 94, the drive circuit 74 outputs a constant current to the presser foot pulse motor 94. Therefore, since the presser foot pulse motor 94 rotates at a constant rotational speed (see FIG. 14), the pressing plate 90 descends at a constant speed, and the presser foot 12 rises at a constant speed. At the moment (time t2) when the lifting presser foot 12 leaves the cloth, as described above, the lower surface of the pressing plate 90 comes into contact with the right protruding portion 315 and the left protruding portion 325. Take it. Therefore, the current output from the drive circuit 74 to the presser foot pulse motor 94 also increases at a stretch. Thereafter, since the current is kept constant at the increased level, the pressing plate 90 continues to descend at a constant speed, and the presser foot 12 also rises at a constant speed. The CPU 51 stops driving the presser foot pulse motor 94 when both the front end portion 421 and the front end portion 422 reach the uppermost position.

  When the lifting of the presser foot 12 is completed, the CPU 51 detects the time t2 (see FIG. 14) when the rotation speed is instantaneously reduced from the rotation speed history information recorded in the RAM 53. The time t2 is an elapsed time from the start of reverse rotation driving of the presser foot pulse motor 94 in order to raise the presser foot 12. Next, the CPU 51 estimates the cloth thickness corresponding to the time t2 based on the cloth thickness estimation table 542 shown in FIG. 16 (S24). The cloth thickness estimation table 542 is stored in the nonvolatile memory 54 (see FIG. 8). The cloth thickness estimation table 542 stores the cloth thickness estimated based on the timing when the presser foot 12 of the presser foot 10 is raised and the presser foot 12 is separated from the cloth. The sewing machine 1 measures the time t when the speed change occurs in the presser foot pulse motor 94 after the presser foot 12 starts to rise. The cloth thickness estimation table 542 stores the cloth thickness as less than 10 mm when the time t is less than β and the cloth thickness as 10 mm or more when the time t is equal to or greater than β, based on the predetermined value β.

  Here, the relation between the time t2 and the cloth thickness in the cloth thickness estimation table 542 shown in FIG. 16 is different from the relation between the time t1 and the cloth thickness in the cloth thickness estimation table 541 shown in FIG. That is, when the presser foot 12 is raised, the presser plate 90 is lowered, and the presser foot 12 is separated from the cloth when it comes into contact with the right protruding portion 315 and the left protruding portion 325. In the presser foot device 10 of the present embodiment, the thicker the fabric that the presser foot 12 presses, the lower the height positions of the right protruding portion 315 and the left protruding portion 325. Therefore, the longer the time from when the pressing plate 90 starts to descend and until it contacts the right protrusion 315 and the left protrusion 325, the thicker the cloth. The predetermined value β may be a time when the speed change occurs in the presser foot pulse motor 94 when the presser foot 12 is lifted from the state where the presser foot 12 holds the cloth having a thickness of 10 mm. In the example shown in FIG. 14, the time t2 when the speed change has occurred is a timing faster than the predetermined value β, so the CPU 51 can estimate the fabric thickness to be less than 10 mm.

  The CPU 51 stores the estimated cloth thickness in the RAM 53. CPU51 judges whether the cloth thickness memorize | stored in RAM53 is 10 mm or more (S25). When the fabric thickness stored in the RAM 53 is less than 10 mm (S25: NO), the CPU 51 sets the maximum rotational speed of the sewing machine motor 91 to 3,200 r / min, similarly to the first sewing control process (S27). On the other hand, when the estimated cloth thickness is 10 mm or more (S25: YES), the CPU 51 sets the maximum rotational speed of the sewing machine motor 91 to 2,000 r / min (S26).

  Next, the operator depresses the foot pedal 23 to the first step again in order to input a lowering instruction of the presser foot 12. The CPU 51 determines whether or not there is an instruction to lower the presser foot 12 (S28). If there is no lowering instruction, the CPU 51 returns to S28 and waits. When the lowering instruction is input (S28: YES), the CPU 51 lowers the presser foot 12 (S29). The presser foot 12 is in a state of pressing the cloth. Subsequently, the operator depresses the foot pedal 23 to the second step in order to input a sewing instruction. In response to the input of the sewing instruction (S11: YES), the CPU 51 drives the sewing machine motor 91 at the maximum rotational speed set in S26 or S27, and sews the cloth with the sewing pattern selected on the operation panel 98 (S12). When the sewing is completed (S13: YES), the CPU 51 drives the thread trimming mechanism to cut the upper thread and the lower thread, then raises the presser foot 12 (S14), and returns the process to S4. When the operator presses the power switch 77 (see FIG. 8) to end the sewing machine 1, this process ends.

  As described above, the CPU 51 executes the second sewing control process shown in FIG. 11 to detect the speed change generated in the presser foot pulse motor 94 when the presser foot 12 is raised, and the timing at which the speed change occurs. The fabric thickness can be estimated based on Therefore, the sewing machine 1 can automatically set the maximum rotational speed of the sewing machine 1 according to the thickness of the cloth to be sewn, as in the above embodiment.

  The present embodiment can be variously modified in addition to this. The CPU 51 of the above embodiment estimates the cloth thickness when the presser foot 12 is lowered by executing the first sewing control process. For example, the timing at which the cloth thickness is estimated on the operation panel 98 is lowered. It may be possible to freely select whether to perform at times or at times of ascent. When the operator selects to perform when the presser foot 12 is lowered, the CPU 51 executes the first sewing control process. When the operator selects to perform when the presser foot 12 is raised, the CPU 51 executes the second sewing control process. That's fine. The timing for estimating the cloth thickness may be executed both when the presser foot 12 is lowered and when it is raised. In this case, the CPU 51 may execute the processes of S6 to S10 of the first sewing control process between the processes of S5 and S21 in the second sewing control process.

  Further, in the sewing machine 1 of the above embodiment, the foot pedal 23 has the first SW 24 and the second SW 25 inside, and has a two-step depression position, but the first SW 24 and the second SW 25 are respectively provided inside. A foot pedal may be provided. In this case, each of the two foot pedals only needs to have a one-step depression position.

  The sewing machine 1 of the above embodiment detects the cloth thickness using the cloth presser device 10 and controls the sewing rotational speed in accordance with the detected cloth thickness. However, there are other methods for detecting the cloth thickness. The method may be used. For example, the cloth thickness may be estimated by detecting the height of the presser foot 12 from the feed plate 11 or the feed base 37 with a sensor or the like.

  The sewing machine 1 of the above embodiment detects the time t1 when the speed change occurs in the cloth presser pulse motor 94, and compares the time t1 with a predetermined value α to determine whether the cloth thickness is 10 mm or more. For example, the cloth thickness may be estimated more finely by providing a plurality of predetermined values. Further, the sewing machine 1 of the above embodiment controls the sewing rotation speed by one of two types depending on whether the cloth thickness is 10 mm or more, but it is appropriate for the cloth thickness by estimating the cloth thickness more finely. The sewing rotation speed may be set more finely.

  The sewing machine 1 of the above embodiment detects the time t1 when the speed change occurs in the cloth presser pulse motor 94, and compares the time t1 with a predetermined value α to determine whether the cloth thickness is 10 mm or more. As estimated, for example, when the presser foot 12 descends or rises, the time t1 and t2 of the change that occurs in the current that drives the presser foot pulse motor 94 may be detected (see FIGS. 12 and 15). . The sewing machine 1 can also estimate the cloth thickness in this method.

  Further, the sewing machine 1 of the above embodiment may display the result of estimating the cloth thickness, for example, on a display unit provided on the operation panel 98.

  7, the presser arm 13 corresponds to the presser arm of the present invention, the mounting portion 14 corresponds to the mounting portion of the present invention, and the rear end portions 316 and 326 of the present invention. The right protruding portion 315 and the left protruding portion 325 correspond to the protruding portion of the present invention, the front end portions 421 and 422 correspond to the end portions of the present invention, and the right lever 310 and the left lever 320 are the main connecting portions. The compression coil spring 32 corresponds to the spring of the present invention, the presser foot pulse motor 94 corresponds to the motor of the present invention, the pressing plate 90 corresponds to the pressing member of the present invention, and the encoder 94A corresponds to the lever of the present invention. This corresponds to the encoder of the present invention. The maximum rotational speed of the sewing machine motor 91 corresponds to the maximum value of the sewing rotational speed of the present invention. The CPU 51 that executes the processes of S5 and S6 in FIG. 10 corresponds to the first detection means of the present invention, and the CPU 51 that executes the process of S7 corresponds to the estimation means of the present invention and executes the processes of S9, S10, and S12. The CPU 51 that corresponds to the control means of the present invention. The CPU 51 that executes the processes of S22 and S23 in FIG. 13 corresponds to a second detection unit.

  Each processing step of S5 and S6 in FIG. 10 corresponds to the first detection step of the present invention, the processing step of S7 corresponds to the estimation step of the present invention, and each processing step of S9, S10, and S12 is the present invention. This corresponds to the control step. Each processing step of S22 and S23 in FIG. 13 corresponds to a second detection step.

DESCRIPTION OF SYMBOLS 1 Sewing machine 2 Bed part 3 Leg column part 4 Arm part 7 Sewing needle 10 Material presser 12 Presser foot 13 Presser arm 14 Attaching part 32 Compression coil spring 51 CPU
90 pressure plate 94 cloth presser pulse motor 94A encoder 310 right lever 320 left lever 316, 326 rear end 315 right protrusion 325 left protrusion 421, 422 front end

Claims (6)

In sewing machines that sew cloth by moving the sewing needle up and down,
Cloth thickness detecting means for detecting the cloth thickness to be sewn with the sewing needle;
Control means for controlling the number of rotations of sewing based on the cloth thickness detected by the cloth thickness detecting means;
The control means includes
The sewing machine characterized in that when the cloth thickness is equal to or greater than a predetermined thickness, the maximum value of the sewing rotational speed is made slower than the predetermined value. The sewing machine according to claim 1, wherein
The presser foot that presses the cloth from above is provided with a presser device that can be moved up and down by the power of a motor,
The cloth thickness detecting means includes
Detecting means for moving the presser foot up and down and detecting a change in speed of the motor that occurs when the presser foot comes into contact with or separates from the cloth;
An estimation means for estimating the cloth thickness based on the speed change detected by the detection means;
The control means includes
A sewing machine that controls the sewing rotational speed based on the cloth thickness estimated by the estimating means. The sewing machine according to claim 2, wherein
A bed portion, a pedestal portion extending upward from the bed portion, and an arm portion extending in parallel to the bed portion from an upper end portion of the pedestal portion,
The presser foot device is
A proximal end portion disposed between the bed portion and the arm portion and supported by the bed portion on the side of the pedestal portion, and a distal end portion located on the opposite side of the pedestal portion with respect to the proximal end portion A presser arm having
A mounting portion that is provided at the distal end of the presser arm and can be mounted in a state in which the presser foot can move up and down;
A connection portion extending along the presser arm and connected to the presser arm so as to be swingable in the vertical direction, an end portion engageable with the presser foot attached to the attachment portion, and the connection portion with respect to the connection portion A lever having a protrusion protruding upward on the opposite side of the end;
A spring that biases the lever in a direction in which the end moves downward;
Above the protrusion, it can be moved up and down by the power of the motor, and comes into contact with the protrusion from above from a state separated upward from the protrusion, and presses the protrusion downward, A pressing member capable of swinging the lever in a direction in which the end moves upward against the biasing force of the spring;
The detection means includes
The speed of the motor generated when the pressing member moves away from the protruding portion when the pressing member is moved upward by the power of the motor from the state where the pressing member presses the protruding portion downward. A sewing machine comprising first detection means for detecting a change. The sewing machine according to claim 3, wherein
The detection means includes
When the pressing member is moved downward with the power of the motor from a state where the pressing member is spaced upward with respect to the protruding portion, the pressing member is generated when the pressing member contacts the protruding portion from above. A sewing machine comprising second detection means for detecting the speed change of the motor. The sewing machine according to any one of claims 2 to 4,
The detection means includes
A sewing machine that detects the speed change of the motor based on an output value of an encoder that detects position information of the motor. A sewing machine comprising: a bed portion; a pedestal portion extending upward from the bed portion; and an arm portion extending in parallel to the bed portion from an upper end portion of the pedestal portion, and sewing a cloth by moving a sewing needle up and down. A control method,
A cloth thickness detection step of detecting a cloth thickness to be sewn with the sewing needle;
A control process for controlling the number of rotations of sewing based on the cloth thickness detected in the cloth thickness detection process,
The sewing machine includes a presser foot device that can move the presser foot that presses the cloth from above by using the power of a motor.
The presser foot device is
A proximal end portion disposed between the bed portion and the arm portion and supported by the bed portion on the side of the pedestal portion, and a distal end portion located on the opposite side of the pedestal portion with respect to the proximal end portion A presser arm having
A mounting portion that is provided at the distal end of the presser arm and can be mounted in a state in which the presser foot can be moved up and down;
A connection portion extending along the presser arm and connected to the presser arm so as to be swingable in the vertical direction, an end portion engageable with the presser foot attached to the attachment portion, and the connection portion with respect to the connection portion A lever having a protrusion protruding upward on the opposite side of the end;
A spring that biases the lever in a direction in which the end moves downward;
Above the protrusion, it can be moved up and down by the power of the motor, and comes into contact with the protrusion from above from a state separated upward from the protrusion, and presses the protrusion downward, A pressing member capable of swinging the lever in a direction in which the end moves upward against the biasing force of the spring;
The cloth thickness detection step includes
A detection step of detecting a speed change of the motor that occurs when the presser foot is moved up and down, and the presser foot contacts or separates from the cloth;
An estimation step of estimating the cloth thickness based on the speed change detected in the detection step;
In the detection step,
The speed of the motor generated when the pressing member moves away from the protruding portion when the pressing member is moved upward by the power of the motor from the state where the pressing member presses the protruding portion downward. A method for controlling a sewing machine, characterized by detecting a change.

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