JP2004216018A - Needle plate of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently secure the remaining length of a needle thread in a sewing needle after thread cutting and to surely perform thread cutting. <P>SOLUTION: The needle plate 20 of a sewing machine is provided with a thread cutter 110 for cutting the needle thread, and a shuttle mechanism 103 provided under the thread cutter 110 for passing a bobbin thread through a loop of the needle thread. Besides, the thread cutter 110 is equipped with a moving scalpel 111 for forward movement of a reciprocating and turning action along with an approximately horizontal direction to sort the needle thread to be the upstream side of the shuttle mechanism 103 and for backward movement to carry a needle thread U1 which is on the downstream side of the shuttle mechanism 103, to a cutting position, and a thread hauling member 112 for locking the needle thread U1 selected by the moving scalpel 111 to be located on the upstream side. The needle plate 20 of the sewing machine is then equipped with a needle hole 23 where a sewing needle 15 is inserted and on its lower side surface, a thread guide groove 24 is provided approximately along with the same direction from a terminal portion of the needle hole 23 on the side of a reciprocating direction F of the moving scalpel 11. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a needle plate of a sewing machine, and more particularly to a needle plate used for a sewing machine having a thread cutting device.
[0002]
[Prior art]
A conventional sewing machine including the thread cutting device 110 will be described. As shown in FIG. 7, the sewing machine includes a needle plate having a needle hole 102 into which a sewing needle 101 is inserted, a thread cutting device 110 provided below the needle plate, and for cutting an upper thread and a lower thread. A hook mechanism 103 is provided below the thread cutting device 110 and allows the lower thread to pass through the loop formed by the upper thread.
At the time of sewing, the upper thread U is supplied from an upper thread supply source located above a sewing machine (not shown) by applying an adjustable frictional force to the feed of the upper thread U to apply tension and a predetermined thread tension (not shown). The needle reaches the sewing needle via a balance (not shown) that pulls up the upper thread U at a timing, and further passes through the threading hole of the sewing needle to reach the fabric. On the other hand, the bobbin thread D is fed out from a bobbin (not shown) located inside the shuttle mechanism 103, and reaches from the needle hole 102 to the cloth above the needle plate. The upper thread and the lower thread are entangled by the vertical movement of the sewing needle and the cooperation of the shuttle mechanism to form a seam on the fabric.
[0003]
As shown in FIG. 9, the thread cutting device 110 includes a moving knife 111 that reciprocates and rotates, and a thread pulling member 112 that locks an upper thread carried by rotating the moving knife 111 in the forward movement direction. And a fixed knife 113 for cutting the upper thread and the lower thread carried by the rotation of the moving knife 111 in the backward movement direction (for example, see Patent Document 1).
The portion from the needle 101 of the upper thread to the shuttle mechanism 103 is referred to as an upstream portion U1, and the portion from the shuttle mechanism 103 to the fabric is referred to as a downstream portion U2. The moving knife 111 locks the upstream portion U1 of the upper thread to the thread pick-up member 112 by the forward movement, and carries the downstream portion of the upper thread and the lower thread D to the fixed knife by the backward movement.
[0004]
The cutting operation of the upper thread after completion of sewing will be described with reference to FIGS. 7 and 8 described above. At the time of sewing, the upper thread loop captured by the shuttle mechanism 103 is moved through the intermediate shuttle of the shuttle mechanism. Since the lower thread is fed from the inner hook, the lower thread is inserted into the upper thread loop by passing through the inner hook. The cutting operation of the upper thread is started from the middle of the operation of the shuttle mechanism.
That is, when almost half of the inner hook is passed through the upper thread loop, the upstream portion U1 of the upper thread is located on one surface side with respect to the inner hook, and the downstream portion U2 of the upper thread and the lower thread D Is located on the other surface side with respect to the inner hook (FIG. 7A).
The moving knife 111 operates on the upper yarns U1, U2 and the lower yarn D arranged as described above, and rotates in the forward movement direction (clockwise direction in FIG. 7). The upper yarns U1 and U2 and the lower yarn D are selected by the pointed portion 111c directed to the side, and only the upper yarn U1 is captured by the concave portion 111a and transported in the forward movement direction (FIG. 7B). Further, the moving knife 111 carries the upper thread U1 to the thread picker 112, and locks the upper thread U1 to the thread picker 112 (FIG. 7C).
Thereafter, the state in which the inner shuttle passes through the upper thread loop is completed, the moving direction of the moving knife 111 is switched in the backward movement direction, and the upper thread U2 and the lower thread are moved by the concave portion 111b provided in the backward movement direction of the moving knife 111. D is captured (FIG. 8A). At this point, the upper thread is released from the tension applied state by the thread tension, and the lower thread is in a low tension state from the beginning.
Then, the upper thread U2 and the lower thread D are sandwiched between the fixed knife 113 and the moving knife 111 provided at the destination in the backward movement direction, and these are cut (FIG. 8B).
In FIGS. 7 and 8, the interval between the upper threads U1 and U2 is shown apart from the actual one for clarity of explanation, but these are actually Closer.
[0005]
[Patent Document 1]
JP-A-10-258196 (FIG. 5)
[0006]
[Problems to be solved by the invention]
However, in the above-mentioned conventional example, when the upstream portion U1 of the upper thread is selected by the moving knife 111 of the thread cutting device 110, the upper thread is removed depending on the hole width of the needle hole 102 located above the thread cutting device 110. In some cases, U1 could not be selected because of the swing in the hole width direction and the position was not stable, or the U1 could not be engaged with the thread pulling member 112 because it fell off the forward-direction recessed portion 111a of the moving knife 111.
The thread take-up member 112 is provided to increase the length of the upper thread remaining on the sewing needle 101 after cutting, and when the upper thread is not locked, the remaining length of the sewing needle 101 becomes extremely short. Then, at the time of the next sewing, the upper thread is detached from the sewing needle, and a sewing error is likely to occur.
[0007]
In order to prevent this, a method of arranging the thread pulling member 112 closer to the needle drop position O or forming the depth d of the concave portion 111a provided on the forward movement direction side of the moving knife 111 is considered. However, in the former case, there is a problem that the remaining length of the upper thread of the sewing needle 101 is shortened after all.
[0008]
In the latter case, the moving knife 111 has to be additionally rotated in the forward direction by the depth d of the concave portion 111a. There is a problem that the size of the H.110 increases.
The thread cutting device 110 has a function of selecting only the upper thread U1 from the upper thread U1, U2, and the lower thread D arranged along the axial direction of the shuttle shaft of the shuttle mechanism (hereinafter, referred to as the shuttle shaft direction). The turning direction of the moving knife 111 needs to be along the direction orthogonal to the hook shaft direction. On the other hand, the hook mechanism is generally branched from the drive motor of the sewing needle 101 and is supplied with power. Often along the length of the bed.
In this case, if the thread cutting device is enlarged in the rotation direction of the moving knife, the sewing machine bed is enlarged in a direction (width direction) orthogonal to the longitudinal direction. In such a case, in the case of a sewing machine having a small width of the sewing machine bed, such as a cylinder bed sewing machine having a small-diameter cylindrical tip at the tip of the sewing machine bed, in particular, it is not possible to adopt a method of making the concave portion of the moving knife deep. However, the thread end length remaining on the sewing needle could not be sufficiently secured. Therefore, the problem that the upper thread comes off from the sewing needle after cutting cannot be solved.
[0009]
Further, another problem of the conventional example will be described with reference to FIG. FIG. 10 is an explanatory view of the state of FIG. 8B as viewed from a direction along the shuttle shaft. Although the above-described operation explanatory diagrams 7 and 8 show the vertical intervals of each component widely for the sake of simplicity of illustration, actually, as shown in FIG. 10, each component is arranged close to each other. .
According to FIG. 10, the upper thread U is remarkably bent everywhere with respect to each configuration, and as a result, sliding friction is generated everywhere and the upper thread cannot be sufficiently pulled out from the supply side of the upper thread. There has been an inconvenience that the remaining length of the upper thread in the later sewing needle 101 cannot be sufficiently secured.
[0010]
In addition, the boundary between the lower surface of the needle plate and the inner surface of the needle hole has not been sufficiently reduced in friction because it is not suitable for the sewing finish because it is inappropriate to make a curved surface having a large radius of curvature. The upper thread locked by the bobbin member receives a high frictional force at the lower end portion of the inner surface of the needle hole, causing a disadvantage that the remaining length of the upper thread in the sewing needle 101 after cutting cannot be sufficiently secured. Was.
[0011]
An object of the present invention is to ensure a sufficient remaining length of the upper thread in the sewing needle after cutting the upper thread by the thread cutting device and to surely perform the thread cutting.
It is another object of the present invention to prevent the size of the thread cutting device from increasing while securing the remaining length of the upper thread of the sewing needle.
[0012]
[Means for Solving the Problems]
The invention according to claim 1 includes a thread cutting device that cuts an upper thread and a lower thread, a shuttle mechanism provided below the thread cutting device and that allows the lower thread to pass through a loop formed by the upper thread. The cutting device sorts the upper thread that is upstream with respect to the shuttle mechanism by forward movement of the reciprocating rotation along a substantially horizontal direction, and cuts the upper thread that is downstream with respect to the shuttle mechanism by backward movement. A needle plate provided on the upper surface of a sewing machine bed of a sewing machine including a moving knife transported to the moving knife and a thread take-up member that locks an upper thread selected upstream of the moving knife, the needle into which a sewing needle is inserted. In addition to the hole, the lower surface is provided with a thread guide groove having a width smaller than that of the needle hole so as to extend substantially in the same direction from the forward end of the moving knife of the needle hole in the same direction. I am taking it.
[0013]
In the above description, “forward movement” refers to a reciprocating rotating knife in one direction, and “reverse” refers to a reciprocating rotating knife in the other direction. Say.
In the above configuration, when the sewing needle is positioned below the needle hole, the shuttle mechanism catches the upper thread and forms a loop. When the upper thread is engaged with the shuttle mechanism, the upper thread upstream and the lower thread downstream of the shuttle mechanism are arranged above the shuttle mechanism. On the other hand, the moving knife of the thread cutting device selects and captures only the upper thread that is on the upstream side with respect to the shuttle by the forward movement, and transports it to the thread picking member.
[0014]
At this time, the upper thread on the upstream side is inclined from the state along the vertical direction toward the forward movement direction of the moving knife, and at the portion that contacts the needle hole, the forward movement is performed at the end of the needle hole on the forward movement direction side. The yarn enters the yarn guide groove formed in the direction.
The thread guide groove may be at least narrower than the width of the needle hole in the same direction. For example, the thread guide groove is desirably as narrow as possible so that the thread can enter and the thread can slide along the groove. .
Then, since the upper thread is transported to the thread pulling member in the state of having entered the thread guide groove in this manner, the occurrence of a state in which the upper thread swings to both sides within the width of the needle hole is effectively suppressed. Further, the state in which the upper thread has entered the thread guide groove is maintained until the cutting is completed, so that the run-up of the upper thread is suppressed continuously even after the state in which the upper thread is locked by the thread pulling member.
For this reason, accidental detachment of the upper thread from the moving knife is effectively suppressed, and the remaining length of the upper thread after cutting at the sewing needle is properly secured.
[0015]
Further, when the upper thread enters the thread guide groove, the inclination angle of the upper thread from the needle hole to the thread pulling member and the degree of bending of the angle formed by the upper thread before and after the thread pulling member are reduced, and the moving knife moves. , The operation of pulling out the upper thread is smoothly performed. Therefore, the upper thread is smoothly fed by the movement of the moving knife, and the remaining length of the upper thread after cutting at the sewing needle is properly secured.
[0016]
A second aspect of the present invention has the same configuration as the first aspect of the present invention, and connects the inner surface of the needle hole and the boundary between the lower surface of the needle plate with a curved surface, and connects the inner surface of the needle hole with the inner surface of the needle hole. The boundary between the thread guide groove and the bottom surface is connected by a curved surface, and the radius of curvature of the curved surface between the inner surface of the needle hole and the bottom surface of the thread guide groove is larger than the curved surface between the inner surface of the needle hole and the lower surface of the needle plate. Is made larger.
[0017]
In the above configuration, the same effect as the first aspect of the invention is achieved, and in a state where the upper thread is locked by the thread take-up member, the upper thread enters the thread guide groove. It does not touch the boundary with the lower surface, but comes into contact with the curved surface provided at the boundary between the inner surface of the needle hole having a larger radius of curvature and the bottom of the thread guide groove. The feeding operation is performed smoothly. Therefore, the upper thread is smoothly fed by the movement of the moving knife, and the remaining length of the upper thread after cutting at the sewing needle is properly secured.
In such a case, since the thread guide groove is not arranged so that the upper thread enters during normal sewing, there is no influence on sewing by providing the curved surface having a large radius of curvature as described above.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a perspective view of the cylinder bed sewing machine 10 according to the embodiment of the present invention. The cylinder bed sewing machine 10 includes a sewing machine bed 11 located at a lower portion thereof, a sewing machine body 12 raised from one end of the sewing machine bed 11, and a cylinder bed sewing machine 10 from above the sewing machine body 12. And a sewing machine arm 13 extending along the sewing machine bed 11.
The machine bed 11 is provided with a substantially cylindrical cylinder-shaped portion 14 extending along the longitudinal direction of the machine bed 11 at an end opposite to the machine body 12.
In describing the configuration of the sewing machine 10, a vertical movement direction of a sewing needle 15 described later is defined as a Z-axis direction, and a direction orthogonal to the Z-axis direction and a longitudinal direction of the sewing machine bed 11 and the sewing machine arm 13 is defined as a Y-axis direction. A direction orthogonal to both the Z-axis direction and the Y-axis direction is defined as an X-axis direction.
[0019]
The cylinder bed sewing machine 10 is provided at the distal end of the sewing machine arm 13 and is provided with a sewing needle 15 that is reciprocated in a vertical direction by a sewing machine motor (not shown). An upper thread supply source (not shown) for supplying the upper thread with a predetermined load between the upper thread supply source and the sewing needle 15 to generate a desired resistance to the movement in the feed direction. A balance device for lifting the upper thread by a balance 17 at a predetermined timing between the thread tension device 16 and the sewing needle 15; and a sewing needle provided on the upper surface of the cylinder-shaped portion 14 of the sewing machine bed 11. A needle plate 20 provided with a needle hole 21 through which the distal end of the needle 15 is inserted; a thread cutting device 110 provided in the cylinder-shaped portion 14 below the needle plate 20 to cut the upper thread and the lower thread; , Thread cutting device Provided below, and a shuttle mechanism 103 for inserting the lower thread in a loop by the upper thread.
[0020]
(Hook mechanism)
FIG. 3 is a schematic configuration diagram of the configuration located below the needle plate 20 as viewed from the Y-axis direction. Since the shuttle mechanism 103 has the same configuration as that of the conventional shuttle mechanism described above, in each of the drawings, its overall shape is shown only by a two-dot chain line, and redundant description will be omitted.
The shuttle mechanism 103 is disposed below the thread cutting device 110 in the cylinder-shaped portion 14 and has a bobbin provided therein with a bobbin serving as a lower thread supply source, and is rotatably provided on the outer periphery of the bobbin. An outer hook that captures the upper thread loop and a shuttle shaft to which the driving force of the sewing machine motor is transmitted to rotate the outer hook are provided (all components are not shown). The shuttle shaft is arranged along the Y-axis direction, and the inner shuttle and the outer shuttle are arranged at the end of the cylinder-shaped portion 14 on the same side as the tip end side.
[0021]
The inner hook pulls out the lower thread from the bobbin located inside the inner hook, while the outer hook causes the upper hook loop captured by the sword point to pass through the inner hook by rotating operation. By this operation, a state where the lower thread is inserted through the upper thread loop is formed, and the seam is formed by the subsequent lifting operation of the upper thread by the balance mechanism.
[0022]
Here, when the inner hook is passed halfway into the loop of the upper thread by the shuttle mechanism 103, the upper thread is turned back across the inner hook. A portion U1 on the upstream side (a side closer to the sewing needle 15) of the upper thread and a portion U2 on the downstream side (a side closer to the seam of the fabric) are arranged along the Y-axis direction. It will be in a lined up state. Then, the downstream upper thread U2 is located at a position closer to the tip end of the cylinder-shaped portion 14 than the upstream upper thread U1. Further, at this time, the lower thread D is also located on the tip side of the cylinder-shaped portion 14 with respect to the upper thread U1 on the upstream side (see FIG. 7A). By utilizing the state in which the upper yarns U1, U2 and the lower yarn D are arranged along the Y-axis direction in this way, the yarn cutting device 110 selects only the upper yarn U1 on the upstream side and performs other cutting. It is possible. In addition, although U1 and U2 are denoted by different symbols for the upper thread, they are connected at the lower part of the shuttle mechanism 103.
[0023]
(Thread cutting device)
The thread trimming device 110 shown in FIGS. 4 and 9 has the same configuration as that of the above-described conventional thread trimming device, and a duplicate description will be omitted.
The thread cutting device 110 is arranged in the cylinder shape portion 14 in the order of the thread picking member 112, the moving knife 111, and the fixed knife 113 along the X-axis direction. The moving knife 111 has a function of selecting the upper thread U1 from the upper thread U1, U2 and the lower thread D arranged in the Y-axis direction by the above-described shuttle mechanism. To rotate. Further, the moving knife 111 is arranged such that its rotating end is on the distal end side of the cylinder-shaped portion 14 and its base end (the rotating center side) is on the sewing machine body 12 side.
[0024]
The concave portion 111a for catching the upper thread U1 of the moving knife 111 is formed at a position slightly closer to the rotation center from the rotating end in the rotating radial direction on the forward movement direction F side of the moving knife 111, and The concave portion 111b for catching the thread U2 and the bobbin thread D is located at the rotation end on the forward movement direction B side of the moving knife 111. This makes it possible to select only the upper thread U1 closest to the rotation center of the moving knife 111 from the upper thread U1, U2 and the lower thread D arranged in the Y-axis direction by rotating in the forward direction. I have.
[0025]
(Needle plate)
FIG. 1A shows a state where the main part of the needle plate 20 is viewed from the X-axis direction (left side in FIG. 3), and FIG. 1B shows the main part of the needle plate 20 in the Y-axis direction (FIG. 1A ) Shows a state viewed from the left), and FIG. 1C shows a state viewed from the Z-axis direction (upper side in FIG. 1A).
The needle plate 20 has a plate-shaped portion 21 disposed above the cylinder-shaped portion 14 along the XY plane, and a columnar portion provided on the lower surface side of the needle drop position of the sewing needle 15 in the plate-shaped portion 21. And a needle hole 23 penetrating these along the Z-axis direction.
The needle hole 23 is formed in a long hole shape along the X-axis direction when viewed from above or below. A thread guide groove 24 is formed on the lower end surface of the protrusion 22 corresponding to the lower surface of the needle plate 20 from the end of the needle hole 23 on the forward movement direction F side of the moving knife 111 in the F direction. Have been.
[0026]
The thread guide groove 24 is formed to penetrate from the inner surface of the end of the needle hole 23 on the forward movement direction F side to the side surface of the protrusion 22. When the moving knife 111 selects the upper thread U1 and pushes and guides the upper thread U1 to the thread pick-up member 112 in the thread cutting operation by the thread cutting device 110, the thread guide groove 24 allows the upper thread U1 to enter and reduces the deflection in the Y-axis direction. It is formed to prevent it.
For this reason, the width of the yarn guide groove 24 in the Y-axis direction is set to be smaller than that of the needle hole 23. It is essential that the width of the thread guide groove 24 in the Y-axis direction is at least smaller than that of the needle hole 23, and from the viewpoint of preventing the upper thread U1 from swinging in the Y-axis direction, the upper thread U1 can enter. Thus, it is desirable to set as narrow as possible within a range that does not hinder sliding inside.
[0027]
Further, at the end of the needle hole 23 in the F direction, the needle hole 23 is formed so as to be biased to one side in the Y axis direction (the left side in FIG. 1A). That is, at the time of selecting the upper thread U1 in the thread cutting device 110, the upper thread U1 is located in the same direction in the Y-axis direction among the upper threads U1, U2 and the lower thread D, and among the respective threads, By matching the arrangement of the upper thread U1 with the arrangement of the thread guide groove 24 in the needle hole 23, it is possible to smoothly guide the upper thread U1 into the thread guide groove 24.
[0028]
Further, the boundary between the bottom surface (the bottom surface as a groove, that is, the upper surface in FIGS. 1A and 1B) of the yarn guide groove 24 and the inner surface of the needle hole 23 at the end in the F direction is curved. As shown in FIG. 3, the boundary between the inner surface of the needle hole 23 and the lower end surface of the protrusion 22 is also formed in a curved shape, but the yarn guide groove 24 is larger than the radius of curvature R1 of the curved surface of the lower end of the needle hole 23. The radius of curvature R2 of the boundary curved surface between the pin hole and the needle hole 23 is set to be larger. Since the upper thread U1 slides and moves on the boundary curved surface between the thread guide groove 24 and the needle hole 23, the curvature radius R2 is desirably set to be larger. For example, the radius of curvature R1 is set to 0.3 to 0.4 [mm], and the radius of curvature R2 is set to 2 to 3 [mm].
The curved surface at the lower end portion of the needle hole 23 is set at most within the above range because setting the radius of curvature to a large value affects the finish at the time of sewing, but the thread guide groove 24 is provided with the upper thread when sewing. And since it is provided in a position which does not affect the lower thread, it is possible to set it sufficiently large.
[0029]
(Description of operation of the embodiment)
The thread cutting operation of the cylinder bed sewing machine 10 will be described. Since the thread cutting device 110 performs the same operation as that of the conventional example, it will be described based on FIGS. 3 to 5 with reference to FIGS.
First, at the end of sewing, the operation of passing the upper thread loop captured by the shuttle mechanism 103 through the intermediate shuttle of the shuttle mechanism is performed. When approximately half of the inner hook is passed through the upper thread loop, the upper thread U1, U2 and the lower thread D are arranged along the X-axis direction, and the upper thread U2 and the lower thread D rotate the moving knife 111. The upper thread U1 is disposed slightly away from the center of rotation from the center (FIG. 7A).
[0030]
In the above-described state, the moving knife 111 rotates toward the forward movement direction F, and the concave portion 111a captures only the upper thread U1 (FIG. 7B) and carries the thread to the thread pulling member 112. Thereby, the upper thread U1 is locked by the thread pulling member 112 (FIG. 7C).
In the process of being carried from the capture of the upper thread U1, as shown in FIGS. 4 and 5, the upper thread U1 enters the thread guide groove 24 from the needle hole 23 and is blocked by the side walls on both sides of the thread guide groove 24. As a result, the moving knife 111 is carried to the moving knife 111 in a state where the deflection in the Y-axis direction is prevented, so that accidental detachment of the moving knife 111 from the forward-direction-side concave portion 111a is effectively prevented.
[0031]
Thereafter, the state in which the inner hook passes under the upper thread loop is completed, the moving direction of the moving knife 111 is switched in the backward movement direction B, and the upper thread U2 and the lower thread D are captured by the concave portion 111b of the moving knife 111 (FIG. 8 (A)). At this point, the upper thread is released from the tension applied state by the thread tension, and the upper thread U2 and the lower thread D are transported to the fixed knife 113 by the moving knife 111 to be cut (FIG. 8B).
[0032]
In the process from the start of the backward movement of the moving knife 111 to the cutting, the upper thread U1 receives the tension due to the backward movement of the moving knife 111 because the upper thread U1 is locked by the thread pulling member 112, and is supplied from the yarn supply source. The upper thread is fed, and as shown in FIG. 3, the upper thread is moved downstream while sliding at the start end of the thread guide groove 24 and the thread pulling member 112.
That is, the upper thread U1 comes into contact with the curved surface formed at the boundary with the inner surface of the needle hole 23 in the thread guide groove 24, but the curved surface has a sufficiently large radius of curvature R2. Slides smoothly and does not hinder feeding from the supply source. Therefore, the remaining length of the upper thread of the sewing needle 15 after cutting is sufficiently ensured.
[0033]
As can be seen by comparing FIGS. 3 and 10, when the thread guide groove 24 is not formed (in the case of FIG. 10), the upper thread U1 is folded back from the lower end surface of the projection by the thread pulling member 112. Because the distance in the height direction from the lower end surface of the protrusion to the thread pulling member 112 is short, the angle θ2 formed by both sides of the upper thread U1 that is folded back through the thread pulling member 112 is Therefore, sliding friction easily occurs in the thread pulling member 112.
On the other hand, when the thread guide groove 24 is provided (in the case of FIG. 3), the upper thread U1 is folded back from the bottom surface of the thread guide groove 24 above the lower end of the needle hole 23 of the projection 22 by the thread pulling member 112. In this case, the distance to the fixed knife 113 is increased, so that an extra distance in the height direction to the thread pick-up member 112 can be secured by the depth of the groove. Accordingly, the angle θ1 formed between the both sides of the upper thread U1 that is folded back via the threading member 112 becomes large, and the sliding friction in the threading member 112 can be reduced.
Therefore, due to the presence of the thread guide groove 24, when the moving knife 111 is moved backward, the upper thread U1 slides smoothly, thereby achieving a good payout from the supply source. The remaining length is more sufficiently secured.
[0034]
(Effects of the embodiment)
As described above, in the cylinder bed sewing machine 10, the thread guide groove 24 is provided in the needle hole 23 of the needle plate 20, so that the upper thread U1 can move without falling off when performing the thread cutting operation. Since the scalpel 111 is satisfactorily transported to the thread pulling member 112, the remaining length of the upper thread after cutting with the sewing needle 15 can be sufficiently secured with high reliability. Thereby, it is possible to effectively suppress the occurrence of sewing errors due to the needle thread coming off at the time of next sewing, and the reliability of the cylinder bed sewing machine 10 is also improved.
[0035]
Further, it is not necessary to form the concave portion 111a of the moving knife 111 deep in order to prevent the upper thread U1 from dropping from the moving knife 111, and it is possible to avoid an increase in the width of the thread cutting device 110 in the X-axis direction. It becomes. For this reason, even if the thread cutting device 110 is arranged at a place where the width in the X-axis direction is narrow like the cylinder-shaped portion 14 of the cylinder bed sewing machine 10, the upper thread U1 from the moving knife 111 is effectively prevented from falling off, In particular, it is possible to improve the reliability.
[0036]
Further, if the effect of preventing the upper thread U1 from falling off due to the thread guide groove 24 is more remarkable, the recess 111a of the moving knife 111 can be made shallower, and thus the X-axis width of the thread cutting device 110 can be reduced. Further, the cylinder-shaped portion 14 can be further narrowed.
[0037]
(Other)
The needle plate 20 is provided with the protrusion 22 and the yarn guide groove 24 is formed on the lower end surface thereof, but it goes without saying that the protrusion 24 may not be provided. FIG. 6 is a diagram showing an example in which a needle hole 23A and a thread guide groove 24A are provided for a needle plate 20A consisting of only a plate-like portion 21A, and FIG. 6 (A) shows the needle plate 20A in the same manner as FIG. 1 (A). FIG. 6B shows a state where the main part of the needle plate 20A is viewed from the Y-axis direction (left side in FIG. 6A), and FIG. 6C shows a state where it is viewed from the X-axis direction. 7 shows a state viewed from the direction (upper side in FIG. 6A).
[0038]
The needle plate 20A is disposed on the cylinder-shaped portion of the cylinder bed sewing machine 10 like the needle plate 20, and the shape, direction, and width of the needle hole 23A are the same as those of the above-described needle hole 23. The orientation, arrangement, width and function of the thread guide groove 24A and the curvature of the boundary curved surface between the bottom surface and the inner surface of the needle hole 23A are the same as those of the thread guide groove 24.
The difference is that the exit of the thread guide groove 24 is provided on the side surface of the protruding portion 22, whereas the thread guide groove 24A is provided on the lower surface of the plate-like portion 21A. It does not affect its function.
The needle plate 20A also performs exactly the same operation as the above-described needle plate 20, and can obtain the same effect.
[0039]
【The invention's effect】
According to the first aspect of the invention, since the thread guide groove is provided in the needle hole, it is possible to prevent the yarn from swaying when the upper thread is carried to the thread pulling member by the moving knife of the thread cutting device. This prevents accidental detachment of the upper thread from the moving knife, and makes it possible to steadily lock the upper thread to the thread pulling member. Therefore, it is possible to secure a sufficient remaining length of the upper thread after the sewing needle is cut and to reliably perform the thread cutting with high reliability. Furthermore, this makes it possible to effectively suppress the occurrence of sewing errors due to the needle thread coming off during the next sewing.
[0040]
Also, there is no need to provide a deep recess on the forward movement direction side of the moving knife, and it is not necessary to extend the reciprocating stroke length of the moving knife, and it is possible to shorten the reciprocating stroke length. This can be prevented and further downsizing can be achieved.
[0041]
Furthermore, since it is possible to prevent the thread trimming device from being enlarged and to further reduce the size thereof, it is possible to prevent the width of the sewing machine bed from being increased and to further reduce the size when installing the device on the sewing machine bed. It becomes. For this reason, in the cylinder bed sewing machine in which it is necessary to reduce the width of the sewing machine bed, it is difficult to prevent the needle thread from detaching from the sewing needle. However, the present invention can effectively suppress this. This makes it possible to further reduce the width of the sewing machine bed.
[0042]
Further, by providing the thread guide groove, when the upper thread enters, the inclination angle of the upper thread passing from the needle hole to the thread pulling member and the degree of bending of the angle formed by the upper thread before and after the thread pulling member are reduced. As a result, the sliding frictional force at the bent portion can be reduced, and the operation of feeding the upper thread by moving the moving knife can be performed smoothly. Therefore, the upper thread is smoothly fed by the movement of the moving knife, and the remaining length of the upper thread after cutting at the sewing needle can be appropriately secured.
[0043]
According to the second aspect of the present invention, since a curved surface having a larger radius of curvature than other portions is formed at the boundary between the inner surface of the needle hole and the bottom surface of the yarn guide groove, the radius of curvature is increased when the upper thread enters the yarn guide groove. In contact with a large curved surface. Therefore, it becomes possible to smoothly perform the upper thread feeding operation by moving the moving knife, the upper thread is smoothly fed by moving the moving knife, and the remaining length of the upper thread after cutting at the sewing needle is properly adjusted. It is possible to secure.
[Brief description of the drawings]
FIG. 1A shows a state where a main part of a needle plate mounted on a cylinder bed sewing machine according to an embodiment of the present invention is viewed from an X-axis direction, and FIG. 1B is a view seen from a Y-axis direction. FIG. 1C shows a state viewed from the Z-axis direction.
FIG. 2 is a perspective view of the cylinder bed sewing machine according to the embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of a configuration located below a needle plate as viewed from a Y-axis direction.
FIG. 4 is an explanatory view of a main part of the thread cutting device and a thread guide groove as viewed from above in order to show a relationship between the thread guide groove and the thread guide groove.
FIG. 5 is an explanatory view showing the relationship between the main part of the thread cutting device and the thread guide groove as viewed obliquely from the perspective view.
6A shows a state of another example of the needle plate viewed from the X-axis direction, FIG. 6B shows a state viewed from the Y-axis direction, and FIG. This shows a state viewed from the axial direction.
FIG. 7 is an explanatory diagram of the operation of the conventional example, and shows each step which proceeds in the order of FIGS. 7 (A) to 7 (C).
8 is an explanatory view of the operation of the conventional example following the step of FIG. 7, and shows each step which proceeds in the order of FIGS. 8 (A) and 8 (B).
FIG. 9 is a plan view showing a conventional thread cutting device.
FIG. 10 is a schematic configuration diagram of a configuration located below a needle plate in a conventional example, viewed from a hook shaft direction.
[Explanation of symbols]
10 Cylinder bed sewing machine
11 sewing machine bed
14 Cylinder shape
20 Needle plate
23 Needle hole
24 thread guide groove
103 Hook mechanism
110 Thread trimmer
111 moving knife
112 Thread picking member

Claims (2)

A thread cutting device for cutting the upper thread, and a shuttle mechanism provided below the thread cutting device for passing the lower thread through a loop formed by the upper thread, and the thread cutting device is provided in a substantially horizontal direction. A moving knife that selects an upper thread upstream with respect to the shuttle mechanism by forward movement of a reciprocating rotation operation along with and moves the upper thread downstream with respect to the shuttle mechanism to a cutting position by backward movement; A needle plate provided on a sewing machine bed upper surface of a sewing machine including a thread take-up member that locks the upper thread selected as the moving knife on the upstream side,
A needle hole into which a sewing needle is inserted is provided, and the width of the needle hole is smaller than the width of the needle hole so that the lower surface of the needle hole extends substantially in the same direction from the forward end of the moving knife in the forward direction. A needle plate for a sewing machine, wherein a narrow thread guide groove is provided. A curved surface connects the inner surface of the needle hole and a boundary between the lower surface of the needle plate, and a curved surface connects the inner surface of the needle hole and the bottom surface of the thread guide groove.
A radius of curvature of a curved surface between the inner surface of the needle hole and the bottom surface of the thread guide groove is larger than a curved surface between an inner surface of the needle hole and a surface below the needle plate. Item 7. A needle plate of the sewing machine according to Item 1.

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