Sewing machine

Abstract

To perform favorable sewing by properly pressing an object to be sewn without hindering conveyance of the object to be sewn by a conveyor belt.SOLUTION: A sewing machine includes: a belt feeding mechanism 80 for performing feeding of an object to be sewn C by a conveyor belt 81 which comes into contact with respect to the object C to be sewn on a needle plate 11 from above; a lower pressing member 31A protruding / retracting from an opening of the needle plate 11 by the vertical movement synchronized with a sewing needle 24; an upper pressing member 71 provided opposing to the lower pressing member 31A at the height generating a gap where the object C to be sewn passes with respect to an upper surface of the needle plate 11; and a lifting operation mechanism 30 for imparting a lifting operation for lifting the lower pressing member 31A synchronously with the lowering of the sewing needle 24 to the lower pressing member 31A.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a sewing machine that uses a belt feed. [Background technology]

[0002] Conventional sewing machines feed the fabric by clamping it between the fabric presser foot and the feed dog. For various reasons, such as the risk of scratches or indentations occurring depending on the material of the item being sewn, the risk of the feed dog bouncing up the fabric presser foot when feeding at high speeds reducing the accuracy of the feed amount, and the risk of vibrations being generated by the feed dog, consideration has been given in recent years to transporting the item being sewn using a conveyor belt (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-141276 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a sewing workpiece is transported by a transport belt, if a cloth presser that holds down the sewing workpiece while applying pressure from above as in the conventional case is used, the transport of the belt is hindered. On the other hand, without the presser foot, as shown in FIG. 12, when the sewing needle N enters the needle hole H, the workpiece C may be pulled into the needle hole H, causing the workpiece to interfere with the shuttle mechanism below the needle plate P, making it impossible to continue sewing.

[0005] An object of the present invention is to perform good sewing in a sewing machine in which a workpiece is transported by a transport belt. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a sewing machine comprising: a belt feed mechanism for feeding the workpiece by a conveyor belt that contacts the workpiece on the needle plate from above; a lower presser member that appears and disappears through an opening in the needle plate by vertical movement in synchronization with the sewing needle; an upper presser member provided opposite the lower presser member with a gap provided between the upper surface of the needle plate; a lifting mechanism for lifting the lower presser member in synchronism with the lowering of the sewing needle to press down the workpiece; The present invention is characterized by comprising: Effect of the Invention

[0007] According to the present invention, it is possible to properly press the workpiece and perform good sewing without interfering with the transport of the workpiece by the transport belt. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing the overall configuration of a sewing machine according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a perspective view showing the internal configuration of a sewing machine bed portion. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 4 is a left side view of the pressing mechanism as viewed from the face portion side. [Figure 7] FIG. 4 is a perspective view showing a configuration around the needle plate of the belt feed mechanism. [Figure 8] FIG. [Figure 9] FIG. 13 is a right side view of the configuration around the needle drop position when the lower presser member is lowered. [Figure 10] FIG. 13 is a right side view of the configuration around the needle drop position when the lower presser member is raised. [Figure 11] 13 is a diagram showing the trajectory of the up and down movement of the lower presser member and the trajectory of the up and down movement of the sewing needle during one rotation of the upper shaft. [Figure 12] 13 is an explanatory diagram illustrating the pulling of a sewing material into a needle hole, which occurs when there is no cloth presser. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Overall configuration of the embodiment] A sewing machine according to an embodiment of the present invention will be described in detail below. In this embodiment, a so-called zigzag sewing machine that performs needle oscillation is exemplified as the sewing machine. This sewing machine can selectively transport the sewing material using a feed dog or a transport belt.

[0010] Fig. 1 is a block diagram showing the overall configuration of the sewing machine 100, and Fig. 2 is a perspective view showing the configuration inside a sewing machine bed portion, which will be described later. In the following description, the direction in which the sewing workpiece C (see Fig. 9) is fed during sewing is referred to as the front-to-rear direction, the horizontal direction perpendicular to the front-to-rear direction is referred to as the left-to-right direction, and the direction perpendicular to the front-to-rear and left-to-right directions is referred to as the up-to-down direction. In addition, the downstream side in the feeding direction is referred to as the "front", the opposite side as the "rear", the left hand side when facing forward is referred to as the "left", and the right hand side is referred to as the "right".

[0011] As shown in Figures 1 and 2, the sewing machine 100 is equipped with a needle up and down movement mechanism 20 that moves the sewing needle 24 up and down using a sewing machine motor 23 as a drive source, a needle swing mechanism 26 that moves the sewing needle 24 left and right, a main feed device 30 that feeds the workpiece C on the needle plate 11 in accordance with the up and down movement of the sewing needle 24, a presser mechanism 70 that raises and lowers an upper presser member 71, a belt feed mechanism 80 that feeds the workpiece C by a conveyor belt 81 that contacts the workpiece C on the needle plate 11 from above, a sewing machine frame 110 that supports each of the above components, and a control device 90 that controls each of the above components. The sewing machine 100 is equipped with various components such as a shuttle mechanism, a thread take-up mechanism, a thread tensioner, a thread cutter, etc., which are included in a typical zigzag stitch sewing machine, but as these are well known, a description thereof will be omitted.

[0012] In the sewing machine 100, the belt feed mechanism 80 is detachable from the sewing machine frame 110. That is, in the sewing machine 100, when the workpiece C is fed by the conveyor belt 81 of the belt feed mechanism 80, the belt feed mechanism 80 can be attached to the sewing machine frame 110, and when the workpiece C is fed by the feed dog 31 of the main feed device 30, the belt feed mechanism 80 can be detached from the sewing machine frame 110. It is also possible to feed the workpiece C by the feed dog 31 of the main feed device 30 while the belt feed mechanism 80 is still attached. In this case, the belt may be retracted upward.

[0013] [Sewing machine frame] The sewing machine frame 110 includes a sewing machine bed portion 101 located at the bottom of the entire sewing machine 100, a vertical body portion 102 standing upward at one longitudinal end of the sewing machine bed portion 101, and a sewing machine arm portion 103 extending from the upper end of the vertical body portion 102 in the same direction as the sewing machine bed portion 101 (see FIG. 5). The sewing machine bed portion 101 and the sewing machine arm portion 103 extend in the left-right direction. The needle drop position is located near the left end (the end on the face side) of the sewing machine bed 101, and a needle plate 11 is provided on the upper surface thereof.

[0014] [Needle vertical movement mechanism] The needle up-down movement mechanism 20 is disposed inside the sewing machine arm portion 103, and includes an upper shaft that is rotated by the sewing machine motor 23 and disposed along the left-right direction, a needle bar 25 (see FIG. 7) that holds the sewing needle 24 at its lower end, and a crank mechanism (not shown) that converts the rotational force of the upper shaft into a reciprocating drive force for up-down movement and transmits it to the needle bar 25. Since the needle up-down movement mechanism 20 has a cyclical configuration, illustrations of parts other than the sewing machine motor 23 are omitted.

[0015] 2, the needle up-down movement mechanism 20 is provided with a belt mechanism for transmitting the torque of the sewing machine motor 23 to the lower shaft 33 of the main feed device 30. This belt mechanism has a driving pulley (not shown) fixedly mounted on the upper shaft described above, a driven pulley 21 fixedly mounted on the lower shaft 33, and a timing belt 22 stretched between the driving pulley and the driven pulley 21. This belt mechanism causes the lower shaft 33 to rotate synchronously with the upper shaft at the same speed. In addition, instead of the belt mechanism, the rotational force may be transmitted from the upper shaft to the lower shaft 33 by a gear transmission mechanism consisting of a vertical shaft and a bevel gear.

[0016] [Needle swing mechanism] The needle swing mechanism 26 has a needle swing motor 27 which serves as a drive source for swinging the needle, a needle bar support frame which supports the needle bar 25 so that it can move up and down, an arm member which is rotated by the needle swing motor 27, and a link member which connects the arm member and the needle bar support frame. Since the needle swing mechanism 26 has a cyclic configuration, components other than the needle swing motor 27 are omitted from the illustration.

[0017] The arm member is connected to the output shaft of the needle swing motor 27 so that the rotating end portion of the arm member rotates in the left-right direction. The left-right rotational movement of the rotating end portion of the arm member is imparted to the needle bar support frame via the link member, so that the needle bar support frame can move freely in the left-right direction. The needle swing motor 27 can arbitrarily control the rotation angle of the output shaft and the operation timing, so that it is possible to impart a needle swing motion to the needle bar support frame with a target needle swing amount at the timing of needle release. Furthermore, the above-mentioned needle up / down movement mechanism 20 imparts up and down movement to the needle bar holder connected to the needle bar 25 via a sliding shaft along the left-right direction, so that even when the needle swings along the left-right direction, smooth up and down movement can be imparted to the needle bar 25.

[0018] [Main feed device] FIG. 3 is a front view of the main feed device 30. As shown in Figures 2 and 3, the main feed device 30 is equipped with a feed dog 31 that appears and disappears from below in the opening of the needle plate 11 to feed the sewn material C in a predetermined direction, a feed table 32 that holds the feed dog 31, a horizontal feed mechanism 40 that receives power from the sewing machine motor 23 and transmits a reciprocating motion in the front-to-back direction (horizontal direction) to the feed table 32, and a vertical feed mechanism 60 that imparts a reciprocating motion in the up-down direction to the feed table 32.

[0019] [Main feed device: horizontal feed mechanism] The horizontal feed mechanism 40 includes a feed adjustment mechanism 50 which adjusts the stroke of the reciprocating motion in the front-to-rear direction relative to the feed table 32, a crank rod 41 which extracts reciprocating motion along the front-to-rear direction from the lower shaft 33, a horizontal feed shaft 42 to which reciprocating motion is imparted from the crank rod 41 via the feed adjustment mechanism 50, and a horizontal feed arm 43 which converts the reciprocating rotational force of the horizontal feed shaft 42 into reciprocating driving force in the feed direction and transmits it to the feed table 32.

[0020] One end of the crank rod 41 rotatably holds an eccentric cam (not shown) fixed to the lower shaft 33, and the other end is connected to the feed adjustment mechanism 50. The crank rod 41 is disposed so that its longitudinal direction is generally along the front-rear direction. When the lower shaft 33 aligned in the left-right direction is driven to rotate fully, the other end of the crank rod 41 reciprocates along its length with a stroke twice the amount of eccentricity due to the eccentric cam. The reciprocating motion of the crank rod 41 is transmitted as a reciprocating rotation force to the horizontal feed shaft 42 aligned in the left-right direction via the feed adjustment mechanism 50. The rotating end of the horizontal feed arm 43 provided on the horizontal feed shaft 42 rotates back and forth, and the feed base 32 is given a back and forth reciprocating motion.

[0021] [Main feed device: feed adjustment mechanism] FIG. 4 is a perspective view of the feed adjustment mechanism 50. As shown in FIG. 2 and 4, the feed adjustment mechanism 50 includes a swing arm 51 fixed to the horizontal feed shaft 42 and extending radially outward around the horizontal feed shaft 42, a pair of first link bodies 53 connecting the other end of the crank rod 41 and the swing arm 51, a pair of second link bodies 54 for guiding the direction of reciprocating motion of the other end of the crank rod 41 in any one of a combination of the front-rear direction and the up-down direction, a feed adjustment body 55 for determining the direction guided by the second link bodies 54, a support shaft 52 that rotates integrally with the feed adjustment body 55, an input arm 56 fixed to the support shaft 52 and extending radially outward around the support shaft 52, a feed adjustment motor 57 for rotating the feed adjustment body 55 to adjust the amount of reciprocating motion in the front-rear direction (horizontal direction) transmitted from the lower shaft 33 to the feed table 32, and two transmission links 58, 59 for transmitting rotational force from the output shaft of the feed adjustment motor 57 to the input arm 56.

[0022] One end of the first link body 53 is connected to the other end of the crank rod 41 so as to be rotatable about an axis extending in the left-right direction. The other end of the first link body 53 is connected to the swing end of the swing arm 51 so as to be rotatable about an axis extending in the left-right direction. One end of the second link body 54 is connected to one end of the first link body 53 and to the other end of the crank rod 41 so as to be rotatable about an axis extending in the left-right direction. The other end of the second link body 54 is connected to a rotating end of the feed adjustment body 55 so as to be rotatable about an axis extending in the left-right direction. The feed adjusting body 55 has a support shaft 52 fixedly mounted on its base end along the left-right direction, and the support shaft 52 is supported within the sewing machine frame so as to be rotatable about an axis along the left-right direction.

[0023] When the feed adjusting body 55 is rotated so that the longitudinal directions of the first link body 53 and the second link body 54 coincide with each other, that is, the link bodies 53, 54 exactly overlap, the feed adjusting mechanism 50 is in a state where the driving force of the crank rod 41 is not transmitted to the swing arm 51. At this time, since no reciprocating rotational motion is transmitted to the horizontal feed shaft 42, the reciprocating stroke in the front-rear direction of the feed table 32 is 0, that is, the stitching pitch is 0. The rotation angle of the feed adjusting body 55 at which the link bodies 53, 54 overlap in this manner is defined as the "neutral angle of the feed adjusting body 55."

[0024] When the feed adjustment body 55 is rotated in one direction from the neutral angle, a reciprocating swing motion is imparted to the swing arm 51 side in accordance with the amount of rotation angle, thereby making it possible to increase the stitch pitch in the forward feed (feed to the front) direction. In addition, when the feed adjustment body 55 is rotated in the opposite direction from the neutral angle, a reciprocating swing motion can be imparted to the swing arm 51 side according to the amount of rotation angle. In this case, the phase is inverted and transmitted, thereby making it possible to increase the stitch pitch in the reverse feed direction (feed to the rear).

[0025] The feed adjusting motor 57 is disposed with its output shaft facing left and right on the right end side within the sewing machine bed portion 101. The aforementioned transmission link 58 has its one end fixedly mounted to the output shaft of the feed adjusting motor 57 with its longitudinal direction facing roughly in the front-to-rear direction. Therefore, the other end of the transmission link 58 rotates up and down when driven by the feed adjusting motor 57. The transmission link 59 has a longitudinal direction that is generally aligned in the vertical direction, and its lower end is connected to the other end of the transmission link 58 so as to be rotatable about an axis that is aligned in the horizontal direction. Therefore, when the feed adjustment motor 57 is driven, the transmission link 59 moves up and down as a whole. The input arm 56 is fixedly mounted on the support shaft 52 and extends from the support shaft 52 generally in the front-to-rear direction, with its extended end connected to the upper end of a transmission link 59 so as to be rotatable around an axis along the left-to-right direction. As a result, when the feed adjusting motor 57 is driven, the feed adjusting body 55 can be rotated via the transmission links 58 and 59 and the input arm 56 .

[0026] The horizontal feed shaft 42 is supported rotatably in the left-right direction within the sewing machine bed portion 101, and is disposed in front of the lower shaft 33. A reciprocating rotation force is applied to the right end of the horizontal feed shaft 42 from the lower shaft 33 via the above-mentioned feed adjustment mechanism 50, and a reciprocating motion in the front-rear direction is transmitted from the left end of the horizontal feed shaft 42 to the feed table 32 via the horizontal feed arm 43.

[0027] The horizontal feed arm 43 has a lower end fixedly connected to the left end of the horizontal feed shaft 42 and an upper end connected to the feed table 32 . Therefore, the horizontal feed arm 43 can reciprocate the feed table 32 in the front-to-rear direction by driving the sewing machine motor 23. In addition, the feed adjustment motor 57 is a stepping motor, and can arbitrarily control the stroke and phase of the reciprocating movement of the feed table 32 in the front-to-rear direction.

[0028] The feed table 32 is disposed below the needle plate 11, with its rear end connected to the vertical feed mechanism 60 and its front end connected to the horizontal feed arm 43. In addition, a feed dog 31 is provided on the upper part of the feed table 32 at a central position in the front-rear direction. The rear end of the feed table 32 receives a vertical reciprocating motion from the vertical feed mechanism 60, and the front end receives a front-rear reciprocating motion from the horizontal feed arm 43 at the same cycle as the vertical reciprocating motion. The vertical and front-rear reciprocating motions are combined to impart an elliptical motion to the feed dog 31 along a plane perpendicular to the left-right direction. When the feed dog 31 moves in the upper region of the elliptical motion locus, the tip of the feed dog 31 protrudes upward from the opening of the needle plate 11, making it possible to feed the sewing workpiece C.

[0029] The feed dog 31 has an upper end portion that comes into contact with the sewing workpiece C from below, and mainly functions to feed the sewing workpiece C forward. For this reason, sawtooth tips that are sharp upward and inclined forward are formed in a row in the front and rear at the upper end portion of the feed dog 31.

[0030] In addition, the feed adjustment mechanism is not limited to the configuration described above in which the reciprocating motion direction of the other end of the first link body 53 is guided in a predetermined direction by the second link body 54 and the feed adjustment body 55 to adjust the forward / rearward stroke of the feed dog 31. The feed adjustment mechanism may utilize any configuration capable of adjusting the stroke and phase of the feed dog 31 in the front-rear direction. For example, a link member may be used to connect the crank rod 41 and the swing arm 51, and a square piece serving as a slide member may be attached to the link member so as to be rotatable about an axis along the left-right direction. A feed adjuster having a guide groove for guiding the square piece so that it can reciprocate may be rotated about an axis along the left-right direction to arbitrarily adjust the stroke and phase of the reciprocating motion occurring at the end of the link member on the swing arm 51 side.

[0031] [Main feed device: vertical feed mechanism] As shown in Figures 2 and 3, the vertical feed mechanism 60 includes a vertical feed motor 66 which serves as a drive source for the vertical reciprocating motion relative to the feed table 32, a first link 61 which is connected to the output shaft of the vertical feed motor 66 and rotates, a second link 62 having one end connected to the rotating end of the first link 61, a third link 63 having one end connected to the other end of the second link 62, a rotating shaft 67 which is connected to the other end of the third link 63 and is rotatably supported on the sewing machine frame, a fourth link 64 which is connected to the third link 63 via the rotating shaft 67, and a fifth link 65 which has one end connected to the rotating end of the fourth link 64 and the other end connected to one end of the feed table 32.

[0032] The vertical feed motor 66 is disposed with its output shaft directed in the left-right direction. The first link 61 has a rotating end facing upward, and a base end fixedly supported by the output shaft of a vertical feed motor 66 . The third link 63 has a rotating end facing downward and a base end supported by the rear end of a rotating shaft 67 that extends in the left-right direction. The rotating end of the first link 61 and the rotating end of the third link 63 are connected to one end and the other end of the second link 62 respectively so as to be rotatable about axes extending in the left-right direction.

[0033] The fourth link 64 is aligned roughly in the front-rear direction, and its base end is pivotally supported by the front end of the rotating shaft 67 . The fifth link 65 is generally aligned in the up-down direction, and its lower end is connected to the rotating end of the fourth link 64 so as to be rotatable about an axis along the left-right direction. In addition, the upper end of the fifth link 65 is connected to the rear end of the feed table 32 so as to be rotatable about an axis along the left-right direction.

[0034] The up and down feed mechanism 60 has a reference position in which the rotating end of the first link 61 faces vertically upward, and when the rotating end rotates forward or backward within a predetermined angle range, it can raise or lower the rear end of the feed table 32 via the first link 61 to the fifth link 65. The vertical feed motor 66 is a stepping motor, the amount of rotation of which can be arbitrarily controlled, and the forward and reverse directions can also be arbitrarily switched.

[0035] The operations of the feed adjustment motor 57 and the vertical feed motor 66 are both controlled by a control device 90. The control device 90 controls the up / down feed motor 66 to move the feed table 32 up and down in synchronization with the rotation of the sewing machine motor 23, thereby causing the feed dog 31 held by the feed table 32 to move circularly within a plane perpendicular to the left-right direction, thereby enabling the feeding operation of the workpiece C to be performed. Furthermore, the control device 90 can arbitrarily adjust the stroke of the forward and backward movement of the feed dog 31 caused by the feed adjustment motor 57 and the stroke of the up and down movement of the feed dog 31 caused by the up and down feed motor 66, so that the workpiece C on the needle plate 11 can be fed at any feed pitch in either the forward or backward direction. In addition, the control device 90 can set the stroke of the forward and backward movement of the feed dog 31 by the feed adjustment motor 57 and the stroke of the up and down movement of the feed dog 31 by the up and down feed motor 66 to zero individually, so that, for example, the feed dog 31 can only move up and down without moving forward and backward. Furthermore, the feed dog 31 can be held at any height.

[0036] The above-described configuration of the vertical feed mechanism 60 is just one example, and any configuration can be used that can arbitrarily adjust the stroke and phase of the vertical reciprocating motion of the feed table 32 by using an actuator that can arbitrarily control the amount of operation of a motor or the like.

[0037] [Press mechanism] Fig. 5 is a side view of the presser mechanism 70, with a part of the sewing machine frame 110 indicated by a two-dot chain line, so as to clarify the arrangement within the sewing machine frame 110. Fig. 6 is a left side view of the presser mechanism 70, as viewed from the face side. As shown in these figures, the presser mechanism 70 comprises an upper presser member 71 that presses down the workpiece C from above, a presser bar 72 that holds the upper presser member 71 at its lower end, a presser motor 73 that serves as the driving source for raising and lowering the upper presser member 71, a transmission mechanism 74 that transmits the raising and lowering motion from the presser motor 73 to the presser bar 72 and the upper presser member 71, a presser spring 75 that applies a pressing pressure against the workpiece C to the upper presser member 71 via the presser bar 72, and a presser height detection unit 76 that detects the height of the upper presser member 71.

[0038] The upper pressing member 71 is a so-called boat-shaped pressing member having a smooth bottom surface and an upwardly curved rear end portion. The presser bar 72 is disposed at two positions, one above and one below, inside the sewing machine arm portion 103 in the vicinity of the needle bar 25 and aligned in the vertical direction, and is supported by metal bearings 721, 721 so as to be vertically movable. Between the upper metal bearing 721 and the lower metal bearing 721 of the pressing bar 72, an upper bar holder 722 and a lower bar holder 723 are fixedly mounted by being clamped.

[0039] A sleeve 725 capable of sliding up and down relative to the pressure bar 72 is provided below the upper bar holder 722, and a coil-shaped pressure spring 75 is provided between the sleeve 725 and the lower bar holder 723 with the pressure bar 72 inserted.

[0040] The sleeve 725 is a cylindrical body into which the presser bar 72 can be inserted, and is actuated by the presser motor 73 via the transmission mechanism 74 to move up and down, so that the sleeve 725 can be positioned at any desired height. For example, when the sleeve 725 is lowered by the presser motor 73, the lower presser spring 75 is compressed, and the elastic force of the compressed presser spring 75 is applied to the upper presser member 71 via the lower bar bracket 723. At this time, by arbitrarily positioning the height of the sleeve 725, the presser spring 75 can be compressed to an arbitrary compression amount, and the pressing pressure of the upper presser member 71 on the sewing workpiece C can be arbitrarily adjusted. In addition, when the sleeve 725 is raised by the presser motor 73, the sleeve 725 abuts against the upper bar holder 722, and the presser bar 72 is raised via the upper bar holder 722, thereby moving the upper presser member 71 to any height above the needle plate 11.

[0041] In addition, the presser bar 72 is set to a length that allows its upper end to protrude from the top of the sewing machine arm portion 103 even when the upper presser member 71 is lowered to the top surface of the needle plate 11, and the upper end is equipped with a knob member 724 for being grasped by hand to pull up the upper presser member 71.

[0042] The presser motor 73 is supported by a plate-shaped bracket 731 at the upper inside portion of the upright body portion 102 with its output shaft facing in the front-rear direction. The presser motor 73 is a stepping motor, and can be positioned at any shaft angle in predetermined small angle units.

[0043] The transmission mechanism 74 includes a driving gear 741 fixedly mounted on the output shaft of the presser motor 73, a substantially sector-shaped driven gear 742, a bell crank-shaped link member 745 having two bifurcated rotating arms 746, 747, and a connecting rod 749 connecting the driven gear 742 and the link member 745.

[0044] The driving gear 741 is a spur gear and meshes with the driven gear 742 . The driven gear 742 is a sector-shaped gear supported rotatably around an axis along the front-rear direction within the sewing machine frame 110, and teeth that mesh with the main gear 741 are formed only on the arc-shaped portion of the driven gear 742. The teeth of the driven gear 742 have a larger effective diameter than those of the main gear 741, and the rotation input from the main gear 741 is transmitted at a greatly reduced speed. Further, the driven gear 742 includes an arm 743 extending in the direction of the radius of rotation, and the arm 743 is connected to one end of a connecting rod 749 so as to be rotatable about an axis along the front-rear direction. When the driven gear 742 receives torque from the driving gear 741 and rotates, it applies a movement motion to the one end of the connecting rod 749 generally along the left-right direction. The connecting rod 749 is arranged within the sewing machine arm portion 103 in a state that is generally aligned in the front-to-rear direction, and its left end is connected to one of the pivot arms 746 of the link member 745 so as to be rotatable around an axis that is aligned in the front-to-rear direction.

[0045] The link member 745 has one rotating arm 746 facing generally upward and the other rotating arm 747 facing generally leftward, and is supported within the sewing machine frame 110 so as to be rotatable about an axis along the front-to-rear direction. The other rotating arm 747 is connected to the sleeve 725 via a square piece 748. The square piece 748 is connected to the rotating arm 747 so as to be rotatable about an axis along the front-to-rear direction, and is formed in a rectangular parallelepiped shape. The sleeve 725 supports the square piece 748 by sandwiching it from above and below, and allows the square piece 748 to move in the left-to-right direction. As a result, when the link member 745 performs a rotational movement, the rotating arm 747 rotates vertically, and transmits the vertical movement to the sleeve 725 via the square piece 748 .

[0046] The height detection unit 76 is mainly composed of a detection object 761 supported by the lower rod support 723 and a height sensor 762 consisting of a line sensor that optically detects the height of the detection object 761. The object to be detected 761 is supported by the lower bar support 723 and therefore moves up and down together with the upper pressing member 71 and the pressing bar 72 . The height sensor 762 has light receiving elements arranged along the Z-axis direction, and is capable of detecting the height of the upper end of the object to be detected 761 by being shielded by the object to be detected 761 . The height detection unit 76 may have any configuration capable of detecting the height of the upper presser member 71. For example, the height detection unit 76 may detect the height of the upper presser member 71 by a magnetic sensor.

[0047] [Belt feed mechanism] FIG. 7 is a perspective view showing the configuration of the belt feed mechanism 80 around the needle plate 11, and FIG. 8 is a rear view seen from the rear. The belt feed mechanism 80 includes a conveyor belt 81, a plurality of guide rollers 821, 822 that form the conveying path of the conveyor belt 81, a conveyor motor 83 that conveys the conveyor belt 81, a support member 84 that supports the guide rollers 821, 822 above the needle plate 11, and a lifting mechanism (not shown) that supports the support member 84 so that it can be raised and lowered.

[0048] The support member 84 is disposed in the vicinity of the upper side of the needle plate 11 and to the left of the upper presser member 71. The support member 84 supports guide rollers 821, 822 individually on the front and rear sides across the needle hole 111 of the needle plate 11. The guide rollers 821, 822 are supported so as to be rotatable about an axis in the left-right direction. One end of the endless circular conveyor belt 81 is wound around a belt pulley of a conveyor motor 83 (not shown in FIG. 7) above the front side of the support member 84. The other end of the conveyor belt 81 passes through a guide roller 821 on the front side of the support member 84 and is wound around a guide roller 822 on the rear side.

[0049] The lifting mechanism supports the support member 84 so that it can be switched between a conveying height at which the lower surface of the conveyor belt 81 passing under the guide rollers 821, 822 of the support member 84 leaves a slight gap with respect to the upper surface of the needle plate 11, and a retracted height at which the lower surface of the conveyor belt 81 is significantly separated from the upper surface of the needle plate 11. The conveying height may be set to a lower position. For example, the conveying height may be set to a height at which the lower surface of the conveyor belt 81 abuts against the upper surface of the needle plate 11 with a constant pressure. The retracted height is a height that does not interfere with setting or removing the workpiece C on the needle plate 11. The switching of the support member 84 between the retracted height and the transport height by the lifting mechanism may be performed by an operating member such as a manual lever, or by an actuator such as a motor, a solenoid, or an air cylinder.

[0050] The conveying motor 83 is, for example, a stepping motor, and the amount of rotation can be arbitrarily controlled, and the forward and reverse directions can also be arbitrarily switched. The transport motor 83 feeds the transport belt 81 intermittently in synchronization with the up and down movement of the needle bar 25, and can transport the material C by a target feed pitch during the period when the sewing needle 24 has passed above the material C to be sewn.

[0051] [Sewing machine control system] As shown in FIG. 1, the control device 90 of the sewing machine 100 includes a ROM (Read Only Memory) 92 in which programs for controlling the operation of each part of the sewing machine 100 are stored, a RAM (Random Access Memory) 93 which serves as a working area for calculation processing, a rewritable non-volatile data memory 94 as a storage means for storing various setting data and the like, and a CPU (Central Processing Unit) 91 which executes the programs in the ROM 92.

[0052] The CPU 91 is connected to the sewing machine motor 23 of the needle up-down movement mechanism 20 through a drive circuit (not shown). The sewing machine motor 23 is provided with an encoder (not shown), and the CPU 91 can detect the upper shaft angle from the encoder. The CPU 91 controls the operation of the sewing machine motor 23 based on the detection by the encoder.

[0053] The CPU 91 is also connected to the needle swing motor 27 of the needle swing mechanism 26 through a drive circuit (not shown) to control the needle swing width and operation timing. The needle swing motor 27 may also be provided with an encoder, and the needle swing motor 27 may be controlled based on the detection by the encoder.

[0054] The CPU 91 is also connected to the feed adjustment motor 57 of the feed adjustment mechanism 50 of the main feed device 30 through a drive circuit (not shown) and controls the amount of movement (sewing pitch) in the front-rear direction of the feed dog 31. The feed adjustment motor 57 may also be provided with an encoder, and the feed adjustment motor 57 may be controlled based on the detection by the encoder. The CPU 91 is also connected to the vertical feed motor 66 of the vertical feed mechanism 60 of the main feed device 30 through a drive circuit (not shown), and controls the vertical movement amount and movement timing of the feed dog 31. The vertical feed motor 66 may also be provided with an encoder, and the vertical feed motor 66 may be controlled based on the detection by the encoder.

[0055] The CPU 91 is also connected to the presser motor 73 of the presser mechanism 70 through a drive circuit (not shown) to control the height and presser pressure of the upper presser member 71 . Furthermore, the CPU 91 is connected to a height sensor 762 via an interface (not shown), and controls the height and pressure of the upper presser member 71 more appropriately based on the detection by the height sensor 762.

[0056] The CPU 91 is also connected to the conveying motor 83 of the belt feed mechanism 80 through a drive circuit (not shown) and controls the movement amount (stitching pitch) and movement timing of the conveying belt 81 in the forward and backward directions. The conveying motor 83 may also be provided with an encoder, and the conveying motor 83 may be controlled based on the detection by the encoder.

[0057] The CPU 91 is also connected to a pedal 95 with which the operator inputs the start and end of the sewing operation, the operation speed, whether or not thread cutting is to be performed, and the like. The CPU 91 is also connected to an operation panel 96 that functions as a display unit that displays various information to an operator and as an input unit through which the operator makes various inputs.

[0058] [Sewing operation by feeding the feed dog] As previously mentioned, the main feed device 30 and the belt feed mechanism 80 are selectively used. When feeding the workpiece C using the main feed device 30, the CPU 91 of the control device 90 first drives the feed adjustment motor 57 of the main feed device 30 to adjust the shaft angle of the feed adjustment body 55 so that the feed pitch becomes the one set via the operation panel 96. When the pedal 95 is depressed to start driving the sewing machine motor 23, the CPU 91 monitors the upper shaft angle. At this time, the CPU 91 drives the needle swing motor 27 of the needle swing mechanism 26 in a specified upper shaft angle section in which the sewing needle 24 has left the workpiece C and is staying above, to move the needle bar 25 to the left or right so as to achieve the needle swing width set by the operation panel 96. Furthermore, the CPU 91 drives the vertical feed motor 66 of the vertical feed mechanism 60 in synchronization with the periodic change in the upper shaft angle, and imparts a vertical motion to the feed table 32 so that the feed dog 31 revolves along a preset trajectory. By repeating the above-mentioned operation control in synchronization with the rotation of the sewing machine motor 23, it is possible to perform zigzag stitching while feeding the workpiece C at a stitching pitch set by the feed dog 31 while swinging the needle left and right.

[0059] [Sewing operation by conveyor belt feeding] Next, the sewing operation performed by the conveyor belt 81 of the belt feed mechanism 80 will be described. When the conveyor belt 81 feeds the workpiece C on the needle plate 11, the feeding of the workpiece C is hindered when the upper presser member 71 is applying pressure. For this reason, the upper presser member 71 cannot apply pressure. On the other hand, if the sewing needle 24 is pierced without the upper presser member 71 pressing down on the workpiece C, the workpiece C is not restrained and may be drawn into the needle hole 111 by the descending sewing needle 24, as in the case of the workpiece C2 in Fig. 8, and may interfere with the point of the shuttle (not shown) or the like, damaging the workpiece or causing poor sewing.

[0060] Therefore, when a sewing operation is performed by feeding the conveyor belt 81, the workpiece C is pressed down by the lower presser member 31A. 9 and 10 are right side views of the configuration around the needle drop position. The lower presser member 31A is attached to the feed table 32 in place of the feed dog 31 of the main feed device 30. In this case, the main feed device 30 functions as a lifting mechanism that imparts a lifting action to the lower presser member 31A to lift the lower presser member 31A in synchronization with the descent of the sewing needle 24. The lower presser member 31A, like the feed dog 31, has sawtooth tips formed on its upper end in a line in the front-to-rear direction, and the tips of the teeth appear and disappear from openings formed in the needle plate 11 to hold down the sewn workpiece C. However, since the lower presser member 31A does not have a feeding function, the tips of the teeth point straight up and are not inclined forward like the feed dog 31. The tips of the teeth may also be rounded.

[0061] The sewing operation performed by the belt feed mechanism 80 using the lower presser member 31A to feed the conveyor belt 81 will now be described. As described above, when the upper presser member 71 applies pressure to the workpiece C from above, the belt feed is hindered. Therefore, when the belt is fed, the CPU 91 controls the presser motor 73 of the presser mechanism 70 in advance to maintain the height of the workpiece C relative to the upper surface of the needle plate 11 so as to create a gap through which the workpiece C can pass. It is preferable that the gap is approximately the same as the thickness of the workpiece C or slightly larger. Also, when the thickness of the workpiece C is unknown, the width of the gap may be set based on the general thickness of the workpiece C. This places the bottom surface of the upper presser member 71 in opposition to the teeth of the lower presser member 31A with a gap therebetween.

[0062] Next, the CPU 91 drives the feed adjusting motor 57 of the main feed device 30 to adjust the shaft angle of the feed adjusting body 55 so that the feed pitch becomes zero. When the pedal 95 is depressed to start driving the sewing machine motor 23, the CPU 91 monitors the upper shaft angle. The control of the needle swing mechanism 26 is the same as that in the case where feeding is performed by the feed dog 31.

[0063] Then, CPU 91 drives vertical feed motor 66 of vertical feed mechanism 60 in synchronization with the periodic change in the upper shaft angle, and controls lower presser member 31A to move up and down at a preset timing. 11 is a diagram showing a locus L1 of the up and down movement of the lower presser member 31A and a locus L2 of the up and down movement of the sewing needle 24 during one rotation of the upper shaft. The horizontal axis indicates the upper shaft angle, with the top dead center of the sewing needle 24 being set at 0°. The dotted section in the diagram (a section of approximately 120° to 240° in upper shaft angle) indicates the period during which the sewing needle 24 pierces the workpiece C on the needle plate 11. In response to the above-described behavior of the sewing needle 24, the CPU 91 controls the vertical feed motor 66 so that the lower presser member 31A moves up and down as follows. That is, as shown in Fig. 9, the lower presser member 31A maintains a standby height where the tip of the teeth is lower than the upper surface of the needle plate 11, and starts to rise from an upper shaft angle of about 45° before the sewing needle 24 reaches the workpiece C. Then, in the range of 120° to 240°, which is almost the same as the period during which the sewing needle 24 is stuck into the workpiece C, the lower presser member 31A maintains a presser height where the upper end portion generates a constant presser pressure on the bottom of the upper presser member 71, as shown in Fig. 10. Thereafter, the lower presser member 31A starts to descend, and returns to the original standby height at an upper shaft angle of about 300° when the sewing needle 24 has completely come out of the workpiece C, and waits until the next ascent.

[0064] Meanwhile, the CPU 91 drives the conveying motor 83 of the belt feed mechanism 80 in accordance with the periodic change in the upper shaft angle, and intermittently conveys the conveying belt 81 so that the conveying is performed by a preset feed pitch between the upper shaft angles of 300° and 45° at which the lower presser member 31A maintains the standby height. At the same timing, the needle swing motor 27 is driven to execute needle swing at a set width. The needle swing of the needle swing motor 27 alternates between left and right swing directions for each stitch. By repeating the above-mentioned operation control in synchronization with the rotation of the sewing machine motor 23, it is possible to perform zigzag stitching while swinging the needle left and right and feeding the workpiece C at a sewing pitch set by the conveyor belt 81. Also, when the needle drops, the tooth tip of the lower presser member 31A protrudes directly upward from below the needle plate 11 to clamp the workpiece C in cooperation with the upper presser member 71, thereby preventing it from being pulled into the needle hole 111. Furthermore, since the upper presser member 71 maintains a height approaching the workpiece C on the needle plate 11, when the sewing needle 24 rises, it also prevents the workpiece C from being pulled upward, and the sewing needle 24 can be smoothly pulled out of the workpiece C (see workpiece C1 in FIG. 8).

[0065] [Technical Effects of the Invention Embodiments] In the above-mentioned sewing machine 100, the lower presser member 31A rises synchronously with the descent of the sewing needle 24 and presses down the workpiece C in cooperation with the upper presser member 71, so that it is possible to effectively prevent the workpiece C from being drawn into the needle hole 111 by the lowered sewing needle 24. In addition, when the sewing needle 24 rises and leaves the sewn material C, the lower presser member 31A descends, and at that timing the conveyor belt 81 of the belt feed mechanism 80 conveys the sewn material C, so that conveyance is not impeded and the sewn material C can be fed accurately and satisfactorily at the target feed pitch.

[0066] In addition, the sewing machine 100 is capable of replacing the feed dog 31 of the main feed device 30, which functions as a lifting and lowering mechanism, with the lower presser member 31A, and the up-down feed motor 66 which performs the up-down movement can be controlled to a phase which moves the sewing needle 24 up and down in the opposite direction. Therefore, it is possible to effectively prevent the sewing material C from being drawn into the needle hole 111, and to feed the sewing material C accurately and satisfactorily at a target feed pitch. Furthermore, a sewing machine equipped with an existing main feed device 30 can be easily converted into a sewing machine that feeds the sewn material C by the conveyor belt 81. Therefore, the sewing machine 100 can freely select between feeding by the feed dog 31 and feeding by the conveyor belt 81, thereby improving versatility. Furthermore, since the main feed device 30 functions as a lifting and lowering mechanism, there is no need to place both the main feed device 30 and the lifting and lowering mechanism in the area below the needle plate 11, where space is limited. This not only allows the sewing machine 100 to be made more compact, but also makes it possible to achieve the functions of the main feed device 30 and the lifting and lowering mechanism with fewer mechanical resources.

[0067] The sewing machine 100 also includes a presser mechanism 70 that supports the upper presser member 71 in a height-adjustable manner. Therefore, when feeding is performed by the conveyor belt 81, the upper presser member 71 can be adjusted to a height at which it can press the sewn material C in cooperation with the lower presser member 31A without interfering with the belt conveyance. Therefore, a sewing machine equipped with an existing presser mechanism 70 can be easily converted into a sewing machine that feeds the sewn material C by the conveyor belt 81. Therefore, the sewing machine 100 can freely select between feeding by the feed dog 31 and feeding by the conveyor belt 81, and the versatility can be improved.

[0068] In addition, since the sewing machine 100 has a removable belt feed mechanism 80, when feeding using the feed dog 31, the belt feed mechanism 80 can be removed, making it possible to perform good feeding using the feed dog 31. In addition, the belt feed mechanism 80 can be easily added as a retrofit to an existing sewing machine that does not have the belt feed mechanism 80, making it possible to freely select between feeding by the feed dog 31 and feeding by the conveyor belt 81, thereby improving versatility.

[0069] The belt feed mechanism 80 also has a lifting mechanism that supports a support member 84 that supports the conveyor belt 81 on the needle plate 11 so that the support member 84 can move up and down. For this reason, the support member 84 can be retracted upward away from the needle plate 11, and when feeding using the feed dog 31, it is possible to easily switch from a belt feed state to a feed dog feed state without removing the belt feed mechanism 80.

[0070] The sewing machine 100 is also equipped with a needle swing mechanism 26 that moves the sewing needle 24 left and right, but when the needle drops, the workpiece C is held down by the lower presser member 31A and the upper presser member 71, so the effect of the needle swing is suppressed and stable feeding can be performed. This makes it possible to perform zigzag stitching with high sewing quality.

[0071] [others] Above, each embodiment of the present invention has been described. However, the present invention is not limited to the above-mentioned embodiments. For example, in the embodiments, a component integrally formed from a single member may be replaced with a component divided into a plurality of members and connected or fixed to each other. Also, a component formed by connecting a plurality of members may be replaced with a component integrally formed from a single member. In addition, the details shown in the embodiments can be appropriately changed without departing from the spirit of the invention.

[0072] For example, the sewing machine 100 may use the feed dog 31 of the main feed device 30 as the lower presser member as it is without replacing it. Alternatively, the main feed device 30 may be configured to normally use the lower presser member 31A as the feed dog. In this case, the main feed device 30 may be normally equipped with a feed dog having an intermediate form between the feed dog 31 and the lower presser member 31A (for example, a feed dog with a small inclination on the front side), and may be configured to be used both as the lower presser member and as the feed dog. In the case of these configurations, the operation of replacing the feed dogs is not required, and it is possible to switch extremely easily between feeding by the feed dogs and feeding by the conveyor belt.

[0073] In the above embodiment, a sewing machine capable of both feeding by the feed dog and feeding by the conveyor belt has been exemplified, but a sewing machine capable of feeding only by the conveyor belt may be used. In that case, the configuration of the main feed device 30 may be unnecessary. However, it is necessary to provide a configuration for vertically moving the lower presser member 31A.

[0074] In addition, although the needle swing mechanism 26 has been exemplified as being configured to impart a needle swing motion to the needle bar 25 by the needle swing motor 27, it is also possible to adopt a configuration in which, without using the needle swing motor 27, the needle swing motion is extracted from the sewing machine motor 23 by a cam mechanism or the like and the needle swing motion is imparted to the needle bar 25. Furthermore, although a zigzag stitch sewing machine has been exemplified as the sewing machine 100, the sewing machine may have the configuration of a lock stitch sewing machine excluding the needle swing mechanism 26.

[0075] In addition, the feed adjustment mechanism 50 of the main feed device 30 has been exemplified as being configured to adjust the feed pitch by controlling the feed adjustment motor 57, but it may also be configured not to be equipped with the feed adjustment motor 57 and to adjust the feed pitch by manual operation.

[0076] In addition, the vertical feed mechanism 60 of the main feed device 30 is configured to cause the vertical movement of the feed dog 31 and the lower presser member 31A by the vertical feed motor 66, but it may also be configured to cause the vertical movement of the feed dog 31 and the lower presser member 31A by extracting a vertical reciprocating motion from the sewing machine motor 23 using a cam mechanism or the like. In this case, the stroke and phase of the vertical movement may be adjusted using a mechanism capable of changing and adjusting the phase and amplitude, such as the feed adjustment mechanism 50. In that case, the change and adjustment of the phase and amplitude may be performed manually or by a motor.

[0077] In addition, the pressing mechanism 70 has been exemplified as being configured to adjust the height of the upper pressing member 71 by controlling the pressing motor 73, but it may also be configured not to be equipped with the pressing motor 73 and to manually retract the upper pressing member 71 upward or adjust the height. [Explanation of symbols]

[0078] 11 Needle plate 20 Needle vertical movement mechanism 23 Sewing machine motor 24 Sewing Needle 25 Needle bar 26 Needle swing mechanism 27 Needle swing motor 30 Main feed device (lifting mechanism) 31 Feed dog 31A Lower support member 32 Slide 40 Horizontal feed mechanism 50 Feed adjustment mechanism 55 Feed adjustment body 57 Feed adjustment motor 60 Vertical feed mechanism 66 Vertical feed motor 70 Pressing mechanism 71 Upper holding member 73 Presser motor 76 Presser height detector 80 Belt feed mechanism 81 Conveyor belt 83 Transport motor 84 Support member 90 control device 91 CPU 100 ミシン 111 Acupuncture Points C, C1, C2 Sewing material

Claims

1. a belt feed mechanism for feeding the workpiece by a conveyor belt that contacts the workpiece on the needle plate from above; a lower presser member that appears and disappears through an opening in the needle plate by vertical movement in synchronization with the sewing needle; an upper presser member provided opposite the lower presser member with a gap provided between the upper surface of the needle plate; a lifting mechanism for lifting the lower presser member in synchronism with the lowering of the sewing needle to press down the workpiece; A sewing machine comprising:

2. a feed dog that appears and disappears through an opening in the needle plate by a vertical movement synchronized with the sewing needle; the lifting mechanism is capable of changing a phase of the lifting operation of the feed dog, 2. The sewing machine according to claim 1, wherein the lifting mechanism is capable of providing the lifting action by exchanging the feed dog and the lower presser member.

3. a feed dog that appears and disappears through an opening in the needle plate by a vertical movement synchronized with the sewing needle; the lifting mechanism is capable of changing a phase of the lifting operation of the feed dog, 2. The sewing machine according to claim 1, wherein the feed dog functions as the lower pressure member.

4. 2. The sewing machine according to claim 1, further comprising a presser mechanism that supports the upper presser member in a height-adjustable manner.

5. 2. The sewing machine according to claim 1, wherein the belt feed mechanism is detachable from the sewing machine.

6. the belt feed mechanism has a support member that supports the conveyor belt on the needle plate so that the conveyor belt can be conveyed; 2. The sewing machine according to claim 1, wherein the support member is retractable in a direction away from the needle plate.

7. 2. The sewing machine according to claim 1, further comprising a needle swinging mechanism for moving the sewing needle in a direction intersecting a feed direction of the conveyor belt.

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