sewing machine

Abstract

Sewing machine (100), including: a needle vertical movement mechanism which moves a needle bar up and down; a sewing machine motor (16) which drives the needle vertical movement mechanism as a drive source; a transporter holder (32) which holds a transporter (31) which transports a workpiece on a needle plate; a horizontal transport mechanism which receives a driving force from the sewing machine motor (16) and transmits a horizontal back-and-forth movement to the feed dog support (32); and a vertical transport mechanism which imparts a vertical back-and-forth movement to the transporter holder (32), wherein the horizontal transport mechanism includes a transport adjustment motor (57) which changes and adjusts the division of the horizontal reciprocating movement by the sewing machine motor (16) with respect to the feed dog support (32), the vertical transport mechanism comprises a vertical transport motor (66) which provides the vertical reciprocating movement with respect to the transporter support (32) as a drive source, the sewing machine (100) includes a control device (90) which controls the feed adjustment motor (57) and the vertical feed motor (66) in order to cause the feed dog (31) to transport the workpiece, the control device (90) controls the vertical transport motor (66) in such a way that the feed dog (31) performs a circular movement along a predetermined path in synchronization with a rotation angle of a main shaft which is rotatably driven by the sewing machine motor (16), and controls the vertical transport motor (66) in such a way that a path of the feed dog (31) in a transport section is corrected according to a rotation speed of the main shaft.

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a sewing machine which performs a transport adjustment. State of the art

[0002] A sewing machine which transports a fabric clamped between a presser foot and a feed dog typically uses a transport mechanism which employs a feed dog that is mechanically linked to a main shaft (see JP 2013 - 146 326 A).

[0003] A fabric feed drive device for a sewing machine is known from JP S56-91790 A. A fabric feed device for a sewing machine is described in JP H04-156883 A. A sewing machine is disclosed in JP 2015-150361 A. A feed device for a sewing machine is known from JP 2006-141547 A. Summary

[0004] In a sewing machine that uses a feed mechanism where the fabric is clamped between a presser foot and a feed dog, increasing the sewing speed also increases the speed of the feed dog's rotation. At this point, there is a risk that the feed dog will strike the presser foot forcefully, causing the presser foot to bounce and reducing the presser foot pressure.

[0005] In this case, raising the feed dog to a higher position reduces the gap between the feed dog and the presser foot, thus compensating for a reduction in presser foot pressure. However, at low sewing speeds, the presser foot pressure is unnecessarily increased.

[0006] In a conventional transport mechanism that uses a conveyor mechanically linked to a main shaft, it is difficult to change the height of the conveyor during the rotation of the main shaft; therefore, it is difficult to maintain a press foot pressure that is correct at both high and low speeds.

[0007] One object of the present invention is to modify a transport path in such a way that the height of a conveyor is increased according to the speed of a main shaft. (1) To solve the above-mentioned problem, a sewing machine according to the present invention comprises: a needle vertical movement mechanism which moves a needle bar up and down; a sewing machine motor which drives the needle vertical movement mechanism as a drive source; a feed dog support which holds a feed dog which transports a workpiece on a needle plate; a horizontal feed mechanism which receives a drive force from the sewing machine motor and transmits a horizontal reciprocating motion to the feed dog support; and a vertical feed mechanism which imparts a vertical reciprocating motion to the feed dog support. The horizontal feed mechanism comprises a feed adjustment motor which changes and adjusts the division of the horizontal reciprocating motion by the sewing machine motor with respect to the feed dog support.The vertical feed mechanism comprises a vertical feed motor, which provides the vertical reciprocating motion relative to the feed dog bracket as a drive source. The sewing machine includes a control unit that controls the feed adjustment motor and the vertical feed motor to cause the feed dog to transport the workpiece. The control unit controls the vertical feed motor such that the feed dog performs a circular motion along a predetermined path in synchronization with the rotation angle of a main shaft, which is driven to rotate by the sewing machine motor. It also controls the vertical feed motor such that the feed dog's path is corrected within a transport section according to the rotational speed of the main shaft. (2) In the sewing machine according to (1), the control device controls the vertical feed motor in such a way that in a transport section, a path of the feeder takes up a higher position when the main shaft rotates at a higher rotational speed than a path of the feeder when the main shaft rotates at a lower rotational speed. (3) In the sewing machine according to (1) or (2), the vertical feed mechanism comprises: a first connecting element which is connected to an output shaft of the vertical feed motor to perform a rotational movement; a second connecting element with a first end region which is connected to a rotatable end of the first connecting element; a third connecting element with a first end region which is connected to a second end region of the second connecting element; and a rotating shaft which is connected to a second end of the third connecting element and is held by a sewing machine frame.The control device controls the vertical transport motor to perform forward and backward reciprocating rotations within an angular range which does not reach an output shaft angle where the first connecting link and the second connecting link are aligned in the same straight line to extend to their maximum extent, such that the control device subjects the third connecting link to reciprocating rotation and that the control device subjects the conveyor bracket to vertical reciprocating movement. (4) In the sewing machine according to (3), the first connecting link and the second connecting link in the vertical feed mechanism are at an angle of 90° when the output shaft angle of the vertical feed motor is 0°. The control device controls the vertical feed motor to perform forward and reverse reciprocating rotations within an angular range in which the output shaft angle of the vertical feed mechanism is ±10°.

[0008] According to the present invention, it is possible to freely change the height and transport path of a conveyor via software, even when a main shaft is rotating. Thus, it is possible to change the transport path such that, in a transport section, the conveyor is raised to a higher position according to the speed of a main shaft. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view showing the configuration of main components in a bed area of ​​a sewing machine; Fig. Figure 2 is a perspective view of a transport adjustment mechanism; Fig. Figure 3 is a perspective view showing the configuration of a vertical transport mechanism; Fig. Figure 4 is an explanatory operational view of the vertical transport mechanism when the angle of a vertical transport motor is 0°; Fig. Figure 5 is an explanatory operational view of the vertical transport mechanism when the shaft angle of the vertical transport motor is -5°; Fig. Figure 6 is an explanatory operational view of the vertical transport mechanism when the shaft angle of the vertical transport motor is +5°; Fig. 7 is a block diagram showing a control system of a sewing machine; Fig. Figure 8 is a diagram showing a reference form of a transport path at the time of normal transport; Fig. Figure 9 is a diagram showing the relationship between a principal wave angle and the wave angle of the vertical transport motor in reference transport path pattern data obtained by clockwise and counterclockwise rotation; Fig. Figure 10 shows a circular path of the conveyor and is a diagram showing an example where the height of the conveyor is changed when the rotational speed of the main shaft is 3000 rpm; Fig. Figure 11 is a diagram showing the relationship between the main shaft angle and the vertical transport motor shaft angle in transport path pattern data obtained by clockwise and counterclockwise rotation when the main shaft rotation speed is 3000 rpm; Fig. Figure 12 shows the circular path of the conveyor and is a diagram showing an example where the height of the conveyor is changed when the rotational speed of the main shaft is 4000 rpm; and Fig. Figure 13 is a diagram showing the relationship between the main shaft angle and the vertical transport motor shaft angle in transport path pattern data obtained by clockwise and counterclockwise rotation when the main shaft rotation speed is 4000 rpm. DETAILED DESCRIPTION [Overall configuration of the embodiment]

[0009] The following describes a sewing machine according to one embodiment of the present invention.

[0010] Fig. Figure 1 is a perspective view and shows the configuration of main components of a sewing machine 100.

[0011] As in Fig. As shown in Figure 1, the sewing machine 100 comprises a needle vertical movement mechanism (not shown) for moving a sewing needle up and down, a sewing machine motor 16 (see Figure 1). Fig. 7), which serves as a drive source, a main shaft (not shown) which is set in rotation by the sewing machine motor 16, a shuttle 12 for joining an upper thread to a lower thread, a feed mechanism 30 for transporting a fabric, i.e. a workpiece, on a needle plate 11 according to a vertical movement of the sewing needle, a belt mechanism 20 for transmitting a rotational force from the main shaft to a lower shaft 33 of the feed mechanism 30, a thread cutting device 14 (see Fig. 7) for cutting the upper and lower threads, a sewing machine frame (not shown) for holding the above-mentioned components and a 90° control device (see Fig. 7) to control each of the components.

[0012] The sewing machine 100 is a so-called lockstitch sewing machine. Therefore, the sewing machine 100 also includes a thread take-up mechanism, a thread tensioner, a presser foot, etc., which are standard components of a lockstitch sewing machine. Since these components are well-known, their description is omitted.

[0013] The sewing machine frame comprises a bed area, which is located in a lower part of the overall structure of the sewing machine, a vertical stand area, which stands at one end of the bed area in a longitudinal direction of the bed area, and an arm area (not shown), which extends from an upper end of the vertical stand area in the same direction as the bed area.

[0014] In the following description, a horizontal direction parallel to the longitudinal direction of the bed area is referred to as the Y-axis direction, and a horizontal direction perpendicular to the Y-axis direction is referred to as the X-axis direction. A direction perpendicular to both the X-axis and Y-axis directions is referred to as the Z-axis direction. [Configuration of the needle vertical movement mechanism and the belt mechanism]

[0015] The needle vertical movement mechanism comprises: a main shaft, which is arranged in the arm area, is set in rotation by the sewing machine motor 16 and is oriented in the Y-axis direction; a needle bar, which holds the sewing needle at one lower end; and a crank mechanism (not shown), which converts the rotational force of the main shaft into a reciprocating driving force for a vertical reciprocating movement and transmits the reciprocating driving force to the needle bar.

[0016] A belt mechanism 20 comprises a main drive pulley, which is fixedly mounted on the main shaft, a driven pulley 21, which is fixedly mounted on the lower shaft 33 of the transport device 30, and a timing belt 22, which is tensioned between the drive pulley and the driven pulley 21 and wraps around them. The belt mechanism 20 causes the lower shaft 33 to rotate at the same speed as the main shaft.

[0017] Alternatively, the transmission of the rotational force from the main shaft to the lower shaft 33 can be carried out via a gear transmission mechanism consisting of a vertical shaft and a bevel gear drive, instead of via the belt mechanism. [Transport equipment]

[0018] As in Fig. As shown in Figure 1, the transport device 30 comprises a feed dog 31, which partially emerges from an opening in a stitch plate 11 to transport a fabric in a predetermined direction, a feed dog holder 32 which holds the feed dog 31, a horizontal transport mechanism 40 which receives a drive force from the sewing machine motor 16 and transmits a back-and-forth movement in the X-axis direction (the horizontal direction) to the feed dog holder 32, and a vertical transport mechanism 60B which imparts a vertical back-and-forth movement to the feed dog holder 32. [Horizontal transport mechanism]

[0019] The horizontal transport mechanism 40 comprises a transport adjustment mechanism 50 for adjusting the stroke of a reciprocating movement in the X-axis direction with respect to the conveyor bracket 32, a connecting rod 41 for transferring the reciprocating movement in the X-axis direction from the lower shaft 33, a horizontal transport shaft 42, to which a reciprocating rotation is imparted by the connecting rod 41 via the transport adjustment mechanism 50, and a horizontal transport arm 43 for converting the reciprocating rotational driving force of the horizontal transport shaft 42 into a reciprocating driving force, which is exerted in a transport direction, and for transmitting the reciprocating driving force to the conveyor bracket 32.

[0020] The connecting rod 41 has a first end that rotatably holds an eccentric cam body (not shown) fixedly mounted on the lower shaft 33, and a second end that is connected to the transport adjustment mechanism 50. The connecting rod 41 is arranged such that its longitudinal direction essentially coincides with the X-axis direction. Thus, when the lower shaft 33 completes a full revolution, the second end of the connecting rod 41 performs a reciprocating motion in its longitudinal direction with a stroke that is twice the eccentricity of the eccentric cam body. The reciprocating motion of the connecting rod 41 is transmitted as a reciprocating rotational force via the transport adjustment mechanism 50 to the horizontal transport shaft 42.

[0021] As in Fig. As shown in Figure 2, the transport adjustment mechanism 50 comprises: a swing arm 51, which is fixedly mounted on the horizontal shaft 42 and extends outwards in a radial direction of the horizontal transport shaft 42; a pair of first connecting link bodies for connecting the second end of the connecting rod 41 and the swing arm 51; a pair of second connecting link bodies 54 for guiding the direction of the reciprocating movement of the second end of the connecting rod 41 in a specific direction; a transport adjustment body 55 for determining the direction of the reciprocating movement, which is guided by the second connecting link bodies 54; a support shaft 52, which rotates together with the rotation of the transport adjustment body 55; an input arm 56, which is fixedly mounted on the support shaft 52 and extends outwards in a radial direction of the support shaft 52;a transport adjustment motor 57, which rotates the transport adjustment body 55 to adjust the amount of a back-and-forth movement in the X-axis direction (the horizontal direction), which is transmitted from the lower shaft 33 to the conveyor bracket 32; and two transmission connecting elements 58 and 59, which transmit a rotational force from an output shaft of the transport adjustment motor 57 to the input arm 56.

[0022] A first end of the first connecting link body 53 is connected to the second end of the connecting rod 41, and a second end of the first connecting link body 53 is connected to a swing end of the swing arm 51. Both the first and second ends of the first connecting link body 53 are connected so as to be rotatable about the Y-axis direction.

[0023] A first end of the second connecting link body 54 and the first end of the first connecting link body 53 are connected to the second end of the crank rod 41, and a second end of the second connecting link body 54 is connected to a rotatable end of the transport adjusting body 55. The first and second ends of the second connecting link body 54 are connected so as to rotate about the Y-axis direction.

[0024] The support shaft 52 extending in the Y-axis direction is fixed to a base area of ​​the transport adjustment body 55, and the support shaft 52 is mounted within the sewing machine frame so as to be rotatable around the Y-axis.

[0025] The rotatable end of the transport adjusting body 55 is rotatably connected to the second end of the second connecting link body 54 about the Y-axis. With respect to the transport adjusting mechanism 50, when the transport adjusting body 55 is rotated, the longitudinal direction of the first connecting link body 53 coincides with the longitudinal direction of the second connecting link body 54, i.e., when the connecting link bodies 53 and 54 are superimposed, making it impossible to transmit the driving force of the crank rod 41 to the swing arm 51. At this point, because the reciprocating rotational movement is not transmitted to the horizontal transport shaft 42, the stroke of the reciprocating movement of the feed dog support 32 in the X-axis direction is zero, i.e., the stitch pitch is zero.Thus, the rotation angle of the transport adjusting body 55, at which the connecting element bodies 53 and 54 overlap, is defined as the "neutral angle of the transport adjusting body 55".

[0026] If this transport adjusting body 55 is rotated in one direction starting from the neutral angle, the swing arm 51 can be given a back-and-forth oscillating movement according to a rotation angle amount, thereby increasing the sewing pitch in a forward transport direction.

[0027] Conversely, if the transport adjusting body 55 is rotated backwards from the neutral angle, the swing arm 51 can also be given a back-and-forth oscillating motion corresponding to the rotation angle. In this case, however, the phase of the oscillating motion is reversed, and the reversed phase of the oscillating motion is transmitted to the swing arm 51, thereby increasing the stitch pitch in a reverse transport direction.

[0028] The transport adjustment motor 57 is arranged in an end region of the bed area in the Y-axis direction, with its output shaft oriented in the Y-axis direction. A first end of the transmission link 58 is fixedly mounted to the output shaft of the transport adjustment motor 57, with the longitudinal direction of the transmission link 58 being oriented essentially in the X-axis direction. Thus, when the transport adjustment motor 57 is driven for operation, a second end of the transmission link 58 is rotated up and down.

[0029] The lower end of the transmission link 59 is connected to the second end of the transmission link 58 so that it can be rotated about the Y-axis in a state where its longitudinal direction is essentially oriented in the Z-axis direction. Thus, when the transport adjustment motor 57 is driven into operation, the transmission link 59 as a whole performs a vertical movement.

[0030] The input arm 56 is fixedly mounted on the support shaft 52 and extends from the support shaft 52 essentially in the X-axis direction. A distal end of the extension of the input arm 56 is rotatably connected to an upper end of the transmission connecting element 59 to allow rotation about the Y-axis.

[0031] Consequently, when the transport adjustment motor 57 is driven, the transport adjustment body 55 can be rotated via the transmission connecting elements 58 and 59 and the input arm 56.

[0032] The horizontal transport shaft 42 is rotatably mounted in the bed area and oriented in the Y-axis direction. Furthermore, the horizontal transport shaft 42 extends downstream (left side in) Fig. 1) the lower shaft 33 is arranged in a material transport direction. From the lower shaft 33, a reciprocating rotational force is applied to a first end of the horizontal transport shaft 42, which is an end close to the vertical stand area, via the transport adjustment mechanism 50 described above, and the reciprocating movement in the X-axis direction is transmitted from the second end of the horizontal transport shaft 42 via the horizontal transport arm 43 to the feed dog holder 32.

[0033] A base area of ​​the horizontal transport arm 43 is rigidly connected to an end of the horizontal transport shaft 42, which is an end near the needle plate 11, and a vibrating end of the horizontal transport arm 43 is connected to the feed dog holder 32 in a state in which the vibrating end is an upper end of the horizontal transport arm 43.

[0034] Thus, the horizontal feed arm 43 of the feed dog bracket 32 ​​can be driven back and forth in the X-axis direction when the sewing machine motor 16 is powered for operation. Furthermore, the stroke of the back-and-forth movement of the feed dog bracket 32 ​​in the X-axis direction can be freely adjusted by controlling the feed adjustment motor 57 of the feed adjustment mechanism 50.

[0035] The feed dog support 32 is located below the needle plate 11. One end of the feed dog support 32, which is in the direction of fabric transport (X-axis direction), is connected to the vertical feed mechanism 60B, and a second end of the feed dog support 32 is connected to the horizontal feed arm 43. Furthermore, the feed dog 31 is installed above the feed dog support 32 and fixed at a position located in the middle of the longitudinal direction of the feed dog support 32.

[0036] Thus, the first end of the feed dog support 32 is subjected to a reciprocating driving force acting in the vertical direction, and the second end of the feed dog support 32 is subjected to a reciprocating driving force acting in the transport direction in the same cycle. Since these reciprocating driving forces add up, the feed dog support 32 performs an elliptical movement in an XZ plane. The feed dog 31 also performs an elliptical movement along with the feed dog support 32. At this point, as the feed dog support 32 moves along an upper part of the path of the elliptical movement, the tip of the feed dog 31 partially protrudes upwards through the opening of the needle plate 11, thereby transporting the fabric. [Vertical transport mechanism]

[0037] Fig. Figure 3 is a perspective view of the vertical transport mechanism 60B and Fig. Figures 4 to 6 show explanatory operational views of the Vertical Transport Mechanism 60B.

[0038] The vertical transport mechanism 60B comprises a vertical transport motor 66, which serves as a drive source for the reciprocating movement in the vertical direction (the Z-axis direction) imparted to the feed dog support 32; a first connecting link 61B, which is connected to an output shaft of the vertical transport motor 66 to perform a rotational movement; a second connecting link 62B with a first end connected to a rotatable end of the first connecting link 61B; a third connecting link 63B with a first end connected to a second end of the second connecting link 62B; a rotational shaft 67, which is connected to a second end of the third connecting link 63B and is fixed in position within the sewing machine frame; and a fourth connecting link 64, which is connected to the third connecting link 63B via the rotational shaft 67.and a fifth connecting link 65 with a first end which is connected to a rotatable end of the fourth connecting link 64, and with a second end which is connected to the first end of the conveyor bracket 32.

[0039] Instead of the vertical transport mechanism 60B described above, the use of a structure with a motor, an eccentric cam body and a connecting link or a structure with a motor and a rack and pinion drive is also easily conceivable.

[0040] The vertical transport motor 66 is located at an end of the bed area near the needle plate 11 in the Y-axis direction. That is, the vertical transport motor 66 is spaced apart from the transport adjustment motor 57 of the transport adjustment mechanism 50, as described above.

[0041] Both motors 57 and 66 require a large installation space. However, since the motors 57 and 66 are spaced apart longitudinally within the bed area, the space between the motors 57 and 66 can be used as installation space for a solenoid, which serves as a drive source for a thread cutting device 14 and, like the motors, also requires a large installation space.

[0042] Furthermore, the vertical transport motor 66 is arranged such that its output shaft is oriented in the Y-axis direction.

[0043] Furthermore, the vertical transport motor 66 has the same specifications and performance as the transport adjustment motor 57. The vertical transport motor 66 can be identical to the transport adjustment motor 57 in terms of model and type.

[0044] In this configuration, the motors and their peripherals can be shared, making it possible to reduce costs and increase maintenance efficiency.

[0045] The base area of ​​the first connecting element 61B, which serves as a center of rotation, is firmly held by the output shaft of the vertical transport motor 66.

[0046] On the other hand, the third connecting element 63B is held firmly by the rotating shaft 67, the second end of which is rotatably held by a frame of the bed area.

[0047] The rotatable end of the first connecting element 61B and the rotatable end of the third connecting element 63B are rotatably connected to the first end and the second end of the second connecting element 62B about the Y-axis.

[0048] As in Fig. As shown in Figure 4, the lengths of the connecting elements one to three, 61B to 63B, are set such that the second connecting element 62B is essentially parallel to the X-axis direction in a state in which the first connecting element 61B is essentially parallel to the Z-axis direction, wherein its rotatable end is an upper end, and in a state in which the third connecting element 63B is essentially parallel to the Z-axis direction, wherein its rotatable end is an upper end.

[0049] Accordingly, the first connecting element 61B and the second connecting element 62B form an angle of 90° (a right angle) when the angle of the output shaft of the vertical transport motor 66 is set to a shaft angle of 0°, as shown in Fig. 4 is shown. This state is referred to as the "origin point" of a strand of connecting links, which consists of connecting links one to three, 61B to 63B.

[0050] At the wave angle designated as "origin point", the height of the transporter 31 is identical to the height of the upper surface of the needle plate 11.

[0051] On the other hand, as in Fig. As shown in Figure 5, the transporter 31 is raised to be higher than the upper surface of the needle plate 11 when the vertical transport motor 66 is driven to rotate in the reverse direction (counterclockwise) from the shaft angle, i.e., the origin point. Conversely, as shown in Fig. As shown in Figure 6, the transporter 31 is lowered to lie below a lower surface of the needle plate 11 when the vertical transport motor 66 is driven to rotate in a forward direction (clockwise).

[0052] In the sewing machine 100, the control device 90 performs an operational control such that, for each transport operation of the feed dog 31, the vertical transport motor 66 performs a single forward and backward rotation within an angular range (for example, origin ±10°) which does not reach an output wave angle at which the first connecting element 61B and the second connecting element 62B are aligned in a straight line to extend to their maximum extent.

[0053] Since the string of connecting links, consisting of the first to third connecting links 61B to 63B, maintains the rotary motion of the vertical feed motor 66 and the impingement of the feed dog support 32 with the vertical movement at an identical frequency, the stroke of the reciprocating motion is relatively small compared to a case in which the reciprocating motion for the horizontal feed is imparted by a separate motor independent of the sewing machine motor 16. Therefore, excellent tracking performance is achieved at high-speed sewing.Since the vertical transport motor 66 is driven to a rotational movement within a range which includes an axial angle in which the angle between the first connecting element 61B and the second connecting element 62B is a right angle, it is particularly possible to reduce the stroke of the reciprocating movement and thereby further improve the tracking performance of keeping pace with the high-speed sewing operation.

[0054] Furthermore, since the base area of ​​the fourth connecting element 64 is not fixed to the rotating shaft 67 in a state in which the fourth connecting element 64 is substantially oriented in the X-axis direction, the fourth connecting element 64 rotates together with the third connecting element 63B.

[0055] With the fifth connecting link 65 oriented essentially in the Z-axis direction, the first end of the fifth connecting link 65 is connected to the rotatable end of the fourth connecting link 64, and the second end of the fifth connecting link 65 is connected to the first end of the conveyor bracket 32. Therefore, the vertical movement via the fifth connecting link 65 can be transmitted to the conveyor bracket 32 ​​by the rotation of the fourth connecting link 64. [Thread cutting device]

[0056] The thread cutting device 14 comprises a fixed knife and a movable knife, which are arranged between the feed dog 31 and the shuttle 12, a cam body provided on the lower shaft 33, a cam body roller which engages with the cam body to cause the movable knife to perform a cutting operation, and a solenoid for engaging the cam body roller with the cam body. The solenoid operates under the control of the control device 90, and in response to the operation of the solenoid, the cam body roller engages with the cam body and thereby transmits a reciprocating motion to the movable knife, causing the movable knife to perform a cutting operation. In this way, the movable knife, in conjunction with the fixed knife, cuts an upper thread and a lower thread. [Sewing machine control system]

[0057] A control system of the sewing machine 100 is shown in the block diagram of Fig. 7 shown. As in Fig. As shown in Figure 7, the sewing machine 100 comprises the control unit 90, which performs operational control for each component of the sewing machine. The control unit 90 is connected to the sewing machine motor 16, the feed adjustment motor 57, and the vertical feed motor 66 via respective motor drive circuits 16a, 56a, and 66a.

[0058] The sewing machine motor 16 is equipped with an encoder 161, which detects a rotational speed. The encoder 161 is also connected to the control unit 90 via a motor drive circuit 16a.

[0059] The thread cutting device 14 is also connected to the control device 90 and thus the solenoid, which is driven to operation during a thread cutting operation, is controlled by the control device 90.

[0060] The control unit 90 comprises a CPU 91, a ROM 92, a RAM 93 and an EEPROM 94 (EEPROM is a registered trademark) and performs various types of operational controls, which are described below.

[0061] Furthermore, an operating input unit 96 for entering selections, executions and set values ​​for various types of operational controls with regard to the transport device 30 described below is connected to the control device 90 via an interface unit 97. [Operational control of the transport device (path pattern reference form)]

[0062] In the sewing machine 100, the path of the circular movement of the feed dog 31 can be freely changed by controlling the vertical transport motor 66, since the vertical feed motor 66 causes a vertical back-and-forth movement of the feed dog 31 independently of the sewing machine motor 16.

[0063] Fig. Figure 8 shows a path of a reference shape during normal transport. Fig. Figure 8 indicates the horizontal axis as the position of the feed dog 31 in the X-axis direction, and the vertical axis as the position of the feed dog 31 in the Z-axis direction. The left side of the horizontal axis is the downstream side in the transport direction, and position zero on the horizontal axis designates a stitch position. Furthermore, position zero on the vertical axis is the height of the upper surface of the stitch plate 11 (this also applies to the ones described later). Fig. 10 and Fig. 12).

[0064] The path of the reference form is an elliptical path that is essentially symmetrical with respect to the upper surface of the needle plate 11 on both the top and bottom sides. The area of ​​the angle of the main shaft (main shaft angle) in which the tooth tip (the upper end) of the feed dog 31 is positioned to be higher than the upper surface of the needle plate 11 is defined as the 'feed section'.

[0065] The control unit 90 stores path pattern data in the EEPROM 94, in which the shaft angle of the vertical transport motor 66 for positioning the conveyor 31 at each position of points arranged on the elliptical path is recorded in conjunction with the angle of the main shaft.

[0066] Since the wave angle of the feed adjustment motor 57 determines the width (sewing pitch) of the elliptical path, when setting the sewing pitch via the operating input unit 96, the wave angle of the feed adjustment motor 57, at which the sewing pitch becomes a set value, is maintained while the feed dog performs a circular movement.

[0067] During the sewing process, the control unit 90 reads the path pattern data and loads it into RAM 93, monitors the output of the encoder 161, and initiates a circular movement of the transporter 31 along the path of the vertical transport motor 66. Fig. 8 to be carried out by positioning the vertical transport motor 66 at the shaft angle specified in the path pattern data, each time the angle of the main shaft reaches a predetermined angle.

[0068] Fig. Figure 9 shows the relationship between the angle of the shaft (vertical axis) of the vertical transport motor 66 and the angle of the main shaft (horizontal axis), which is obtained using the path of the reference shape.

[0069] As in Fig. Figure 9 shows the change in the shaft angle of the vertical transport motor 66 in the Fig. The reference shape path pattern shown in Figure 8 is a sine curve of approximately 2π.

[0070] Since the conveyor performs a single back-and-forth movement in a vertical direction when the vertical transport motor 66 performs a single back-and-forth rotation in the forward and reverse directions, there is no need to prepare two types of data: path pattern data obtained by clockwise rotation and path pattern data obtained by counterclockwise rotation. That is, only one type of path pattern data is managed. [Change in carrier height]

[0071] As described above, the driving force for the vertical movement of the feed dog 31 of the sewing machine 100 is not obtained - as is conventional - by mechanically connecting the feed dog 31 to the main shaft, but by an actuator which is prepared for the vertical movement of the feed dog 31, i.e. by the vertical transport motor 66, which in one embodiment is provided as a pulse motor.

[0072] The sewing machine motor 16 for rotating the main shaft and the vertical feed motor 66 are jointly controlled by the CPU 91, and information about the rotational speed of the main shaft can be used to control the actuator provided for the vertical movement of the feed dog.

[0073] In this configuration, the height of the conveyor 31 can also be changed independently during the rotation of the main shaft.

[0074] Here, as in Fig. Figure 7 shows the sewing speed, i.e. the rotational speed, of the main shaft on the basis of the amount of pressure applied by a sewing machine pedal 101 or the rotational speed of the sewing machine motor 16 detected by the encoder 161. [Operational control of the transport system]

[0075] The path of the conveyor, when the rotational speed of the main shaft is 2000 rpm, is similar to that in Fig. 8. Path of the reference shape shown, which is obtained during normal transport.

[0076] At low speeds, a hopping event, in which the conveyor violently collides with the press foot and the press foot hops, does not occur. Therefore, it is not necessary to correct the path of the reference form.

[0077] The control unit 90 stores the path pattern data in the EEPROM 94, in which the shaft angle of the vertical transport motor 66 for positioning the conveyor 31 at each position of points arranged on an elliptical path is recorded in conjunction with the angle of the main shaft.

[0078] If it is determined that the rotational speed of the main shaft is low (for example, 0 to 2500 rpm), the control device 90 performs a control such that the vertical transport motor 66 is positioned at a predetermined angle, as specified in the path pattern data, each time the angle of the main shaft reaches a predetermined angle.

[0079] Furthermore: since the relationship between the shaft angle (vertical axis) of the vertical transport motor 66 and the angle of the harmonic (horizontal axis) is similar to that in the case of the reference form, the relationship is as in Fig. 9 shown.

[0080] Fig. Figure 10 shows a modified feed dog path when the main shaft rotation speed is 3000 rpm. As the feed dog moves along this path, the height of the feed dog tooth tip 31 in the transport section is higher than that in the path of the reference form. For example, when the feed dog 31 performs a circular motion along this path, the fact that the feed dog tooth tip 31 passes a position higher than the path of the reference form can reduce the gap between the presser foot and the feed dog, despite the occurrence of presser foot hopping with increasing main shaft rotation speed, and sewing can be performed satisfactorily while maintaining appropriate presser foot pressure.

[0081] The control unit 90 stores the path pattern data in the EEPROM 94, in which the shaft angle of the vertical transport motor 66 for positioning the conveyor 31 at each position of points arranged on the elliptical path is recorded in conjunction with the angle of the main shaft.

[0082] When the rotational speed of the main shaft is set to 3000 rpm, the control device 90 performs a correction control such that the vertical transport motor 66 is positioned at a shaft angle specified in the path pattern data for 3000 rpm each time the angle of the main shaft reaches a predetermined angle.

[0083] Fig. Figure 11 shows the relationship between the wave angle of the shaft (vertical axis) of the vertical transport motor 66 and the angle of the harmonic (horizontal axis) in the path pattern data, which is obtained by rotating the modified path of Fig. 10 will be obtained. The transporter 31 is driven such that the height of the tip of the transporter 31 becomes higher than that of the path pattern of the reference shape.

[0084] Fig. Figure 12 shows a modified path of the conveyor when the rotational speed of the main shaft is 4000 rpm. In this modified path, the tooth tip of the conveyor 31 is located higher in a transport section than in the path of the conveyor 31 at a rotational speed of 3000 rpm, which is shown in Figure 12. Fig. Figure 10 shows that when the feeder 31 is driven to perform a circular motion along this modified path, the tooth tip of the feeder 31 passing a position higher than that at a rotational speed of 3000 rpm reduces the gap between the presser foot and the feeder, despite an increase in the rotational speed of the main shaft and the occurrence of strong bouncing of the presser foot, and sewing can be carried out satisfactorily while maintaining a suitable presser foot pressure.

[0085] The control unit 90 stores path pattern data in the EEPROM 94, in which the shaft angle of the vertical transport motor 66 for positioning the conveyor 31 at each position of points arranged on the elliptical path is recorded in conjunction with the angle of the main shaft.

[0086] When the rotational speed of the main shaft is set to 4000 rpm, the control device 90 performs a control such that the vertical transport motor 66 is positioned each time the angle of the main shaft reaches a predetermined angle at which the shaft angle specified in the path pattern data for 4000 rpm is positioned.

[0087] Fig. Figure 13 shows the relationship between the wave angle of the shaft (vertical axis) of the vertical transport motor 66 and the angle of the harmonic (horizontal axis) in the path pattern data, which is obtained by rotating the modified path of Fig. 12 will be obtained. The conveyor 31 is driven in such a way that the height of the tip of the conveyor 31 is further increased compared to the pattern for 3000 rpm.

[0088] In this way, the control unit 90 stores the path pattern data in the EEPROM 94, in which the shaft angle of the vertical transport motor 66 for positioning the conveyor 31 is recorded in conjunction with the angle of the main shaft according to the rotational speed of the main shaft.

[0089] When the main shaft rotates at high speed, it is possible to maintain optimal presser foot pressure in a transport section by correcting and raising the height of the conveyor 31 according to the rotational speed, despite the occurrence of the presser foot bouncing as the rotational speed of the main shaft increases.

[0090] Furthermore, because it is not necessary to correct the height of the transporter 31 in the transport section at the time of a low rotational speed of the main shaft, even when a high-speed operation and a low-speed operation of the main shaft are mixed during a sewing process, an optimal presser foot pressure can be maintained. [Effect of the embodiment]

[0091] As described above, in the sewing machine 100 according to the embodiment, the horizontal feed mechanism 40 comprises the feed adjustment motor 57, which changes and adjusts the division of the horizontal reciprocating movement imparted to the feed dog support 32 by the sewing machine motor 16; the vertical feed mechanism 60B comprises the vertical feed motor 66, which serves as a drive source for the vertical reciprocating movement imparted to the feed dog support 32; and the control device 90 is included to control the feed adjustment motor 57 and the vertical feed motor 66, thereby causing the feed dog 31 to transport a workpiece.

[0092] For this reason, because the vertical back-and-forth movement of the feed dog 31 can be adjusted arbitrarily without restriction by the sewing machine motor 16, it is possible to cause the feed dog 31 to move in a circular motion along a variety of different path patterns, as described above.

[0093] Regarding the horizontal reciprocating motion of the feed dog 31, it is also possible to obtain some of the various path patterns described above when using an additional motor independent of the sewing machine motor 16 as the drive source. However, since the reciprocating stroke in the horizontal direction is much greater than the reciprocating stroke in the vertical direction, a motor with lower inertia and higher output power is required. Since the inertia of a motor tends to increase with increasing output power, such a motor with lower inertia and higher output power is practically difficult to obtain. It is therefore essential to reduce the sewing speed and perform the feed operation at a reduced sewing speed.

[0094] On the other hand, because the sewing machine 100, according to the embodiment, uses the sewing machine motor 16 as a drive source for the horizontal reciprocating movement of the feed dog 31 and the vertical feed motor 66 as a drive source for the vertical reciprocating movement of the feed dog 31, it is possible to impart a reciprocating movement in the vertical direction to the feed dog 31 within a narrow reciprocating stroke range. Furthermore, a compact motor, which is readily available and has a low output power, can be used as the vertical feed motor 66. It is also possible to perform the feed with a wider variety of path patterns.

[0095] Furthermore, the sewing division can be set with high reliability, stability and accuracy using a combination of the feed adjustment body 55 and the feed adjustment motor 57, which are conventionally used.

[0096] In particular, the control unit 90 controls the vertical transport motor 66 such that the height of the conveyor 31 in the transport section is higher during high-speed rotation of the main shaft than during low-speed rotation. Therefore, it is possible to change the transport path even during rotation of the main shaft, such that the height of the conveyor 31 is increased according to the speed of the main shaft by arbitrarily changing the height and transport path of the conveyor 31 via software.

[0097] Therefore, even if the press foot starts to bounce during high-speed rotation of the main shaft, optimal press foot pressure can be maintained.

[0098] Furthermore, because it is not necessary to correct the height of the transporter 31 in the transport section when the speed of the main shaft is low, even when a low-speed operation and a high-speed operation of the main shaft are mixed during sewing, an optimal presser foot pressure can be maintained. [Miscellaneous]

[0099] In the embodiment of the invention described above, the lockstitch sewing machine is described by way of example; however, the transport device 30 can be applied to any type of sewing machine which transports the workpiece with a feed dog.

[0100] In the above embodiment of the invention, the case is described by way of example in which the first connecting element 61B is directly attached to and connected with the output shaft of the vertical transport motor 66. However, the output shaft of the vertical transport motor 66 and the first connecting element 61B can also be connected to each other indirectly via a transfer element or a transfer mechanism.

[0101] Furthermore, it is understood that modifications and changes to other specific detailed structures are possible.

[0102] For the control of the height change of the conveyor during high-speed rotation described above, a plurality of path patterns are prepared in advance, in which the height of the conveyor is gradually increased in the upper half of a circular transport path, a suitable path pattern is selected from the pre-prepared path patterns according to the detected rotational speed of the main shaft, and a suitable operational control is executed such that the conveyor 31 performs a circular movement along the selected path pattern.

[0103] Alternatively, a path pattern of a reference shape, as in Fig.As shown in Figure 8, a reference velocity corresponding to this path pattern is determined in advance, and on the basis of a correction value calculated from a velocity difference between the reference rotational velocity and the detected rotational velocity of the main shaft, the height of the transporter can be corrected at any point in the upper half of the circular transport path of the reference path pattern, and the operational control can be carried out such that the transporter 31 performs a circular movement along the corrected path pattern.

Claims

[1] Sewing machine (100), comprising: a needle vertical movement mechanism which moves a needle bar up and down; a sewing machine motor (16) which drives the needle vertical movement mechanism as a drive source; a transporter holder (32) which holds a transporter (31) which transports a workpiece on a needle plate; a horizontal transport mechanism which receives a driving force from the sewing machine motor (16) and transmits a horizontal back-and-forth movement to the feed dog support (32); and a vertical transport mechanism which imparts a vertical back-and-forth movement to the transporter holder (32), wherein the horizontal transport mechanism includes a transport adjustment motor (57) which changes and adjusts the division of the horizontal reciprocating movement by the sewing machine motor (16) with respect to the feed dog support (32), the vertical transport mechanism comprises a vertical transport motor (66) which provides the vertical reciprocating movement with respect to the transporter support (32) as a drive source, the sewing machine (100) includes a control device (90) which controls the feed adjustment motor (57) and the vertical feed motor (66) in order to cause the feed dog (31) to transport the workpiece, the control device (90) controls the vertical transport motor (66) in such a way that the feed dog (31) performs a circular movement along a predetermined path in synchronization with a rotation angle of a main shaft which is rotatably driven by the sewing machine motor (16), and controls the vertical transport motor (66) in such a way that a path of the feed dog (31) in a transport section is corrected according to a rotation speed of the main shaft. [2] Sewing machine according to claim 1, wherein the control device (90) controls the vertical transport motor (66) such that in a transport section, a path of the feeder (31) assumes a higher position when the main shaft rotates at a higher rotational speed than a path of the feeder (31) when the main shaft rotates at a lower rotational speed. [3] Sewing machine according to claim 1 or 2, wherein the vertical transport mechanism comprises: a first connecting element (61B) which is connected to an output shaft of the vertical transport motor (66) to perform a rotational movement; a second connecting element (62B) with a first end area which is connected to a rotatable end of the first connecting element (61B); a third connecting member (63B) with a first end region which is connected to a second end region of the second connecting member (62B); and a rotating shaft which is connected to a second end section (62B) of the third connecting element (63B) and is held by a sewing machine frame, wherein the control device (90) controls the vertical transport motor (66) to perform forward and backward reciprocating rotations within an angular range which does not reach an output shaft angle in which the first connecting member (61B) and the second connecting member (62B) are aligned in the same straight line to extend to their maximum extent, such that the control device (90) subjects the third connecting member (63B) to reciprocating rotation and that the control device (90) subjects the conveyor holder (32) to vertical reciprocating movement. [4] Sewing machine according to claim 3, wherein in the vertical transport mechanism the first connecting element (61B) and the second connecting element (62B) are at an angle of 90° when the output shaft angle of the vertical transport motor (66) is 0°, the control device (90) controls the vertical transport motor (66) to perform forward and backward reciprocating rotations within an angular range in which the output shaft angle of the vertical transport mechanism is ±10°.

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