JP2010119818A - Cloth cutting apparatus of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the cloth cutting apparatus of a sewing machine which aims at a decrease in a running cost by improving the employment life of a sheet of lower knife and the durability of an upper knife mechanism and can maintain sharp cutting action with sufficient stability over a long period. <P>SOLUTION: In the cloth cutting apparatus of the sewing machine consisting of the lower knife 13 fixed to a needle plate 3 and an upper knife 15 attached to a movable knife rest 17 prepared in a way that it can reciprocate rockably up and down around a shaft center perpendicular in a cloth feed direction to a bracket 20 fixed to the lower part of the needle plate 3, blade parts 13A and 13B in a linear form along a back and forth both-side marginal part in a thickness direction are formed in the lower knife 13, and the linear blade parts 13A and 13B of the lower knife 13 in a location in contact with the linear blade part 15A of the upper knife 15 can be replaced back and forth by changing this lower knife 13 in a posture with the front and back reversed and fixed in a thickness direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention, for example, women's and women's underwear or the like, is used when a thin fabric is cut in accordance with the shape of the lace while the lace and the thin fabric are sewn in two layers. The present invention relates to a sewing machine cloth cutting device. Specifically, a lower knife having a blade portion fixed to the needle plate and parallel to the upper surface of the needle plate in parallel with the feed direction of the cloth by the feed dog, and a linear blade portion of the lower knife. As well as a straight blade section along the fabric feed direction, and can be reciprocated up and down around an axis perpendicular to the fabric feed direction on a fixed bracket disposed in the lower part of the needle plate An upper knife attached to the movable knife table provided, and a knife table driving means for reciprocating and swinging the movable knife table up and down around the axis, the movable knife through the knife table driving means. The sewing machine cloth cutting device is configured to cut the end portion of the cloth by bringing the linear knife part of the upper knife into contact with the linear knife part of the lower knife by reciprocatingly driving the table up and down. It is about.

  2. Description of the Related Art Conventionally, as this type of sewing machine cloth cutting device, one having a configuration as disclosed in, for example, Patent Document 1 is known. In the conventional cloth cutting device disclosed in Patent Document 1, as a lower knife, a straight blade portion is formed along only one edge portion of the front and rear side edges in the thickness direction. The lower knife having this one linear blade portion was attached to the needle plate so as to be attachable / detachable through a pressing fixing bolt or the like.

  In addition, the upper knife having the linear blade portion that contacts the linear blade portion of the lower knife is a step perpendicular to the cloth feeding direction by the feed dog that is inserted and fixed to the fixed bracket provided in the lower portion of the needle plate. The other end of the leaf spring is mounted on a movable knife base supported so as to be reciprocally swingable up and down around the center (axial center) of the attached shaft, and one end of the stepped shaft is fitted to the other end of the leaf spring. It is configured to elastically press and urge the blade portion of the upper knife toward the contact position with the blade portion of the lower knife by elastically contacting the side surface of the movable knife base, and further, the other end of the leaf spring The pressing biasing force to the side of the movable knife base by the leaf spring is adjustable by rotating the screw member screwed into the side of the movable knife base and adjusting it in and out (hereinafter referred to as the following). Such a configuration is referred to as an upper knife mechanism).

  Japanese Utility Model Publication No. 58-125580

  However, in the conventional cloth cutting apparatus disclosed in Patent Document 1, the blade portion of the lower knife generally made of tool steel or the like that is relatively softer than the upper knife is the blade portion of the upper knife. The dough is cut by contact, but at this time, the blade part of the upper knife in a state of receiving the pressing biasing force by the leaf spring elastically contacts the blade part of the lower knife. The blade of the knife is worn out in a short period of time, or the blade sharpens, and the sharpness is likely to deteriorate. The lower knife cannot be made large enough to be reused by sharpening a worn blade part or the like because it is attached to a very narrow portion of the needle plate where there is not enough space. Therefore, once the sharpness is reduced due to wear or the like, it must be replaced with a new lower knife prepared separately. Therefore, the service life (durability) of one lower knife is very short, and repeated replacement of the lower knife is one of the factors that increase the running cost.

  Further, in the upper knife mechanism in the conventional dough cutting apparatus adopting the above-described configuration, the sliding contact portion between the movable knife table and the stepped shaft is worn by the reciprocating swing of the movable knife table. When it is easy to occur and wear occurs, the contact angle with the lower knife of the upper knife varies, and a fabric cutting error or cutting failure occurs. In particular, as shown in Patent Document 1, in the case where the support width of the movable knife base by the stepped shaft is small, the contact angle with the lower knife of the upper knife greatly changes even by slight wear of the sliding contact portion. Therefore, it is more likely to cause mistakes in cutting and poor cutting of the fabric.

  Further, the axis of the stepped shaft whose urging force acting position of the leaf spring that elastically presses and urges the blade portion of the upper knife toward the contact position with the blade portion of the lower knife is the vertical reciprocating swing center of the movable knife base. Therefore, the sliding contact portion between the movable knife base and the stepped shaft is subject to twisting, and uneven wear tends to occur. This uneven wear causes contact between the blade portion of the upper knife and the blade portion of the lower knife. There is a problem that it is difficult to maintain the angle at a sharp and normal angle, and the durability of the entire upper knife mechanism becomes extremely poor without being limited to a cutting error or cutting failure.

  The present invention has been made in view of the above-mentioned circumstances. By improving the service life of one lower knife and the durability of the upper knife mechanism, it is possible to reduce the running cost and achieve a sharp cutting action over a long period of time. It is an object of the present invention to provide a cloth cutting device for a sewing machine that can be maintained stably and stably.

  The cloth cutting device for a sewing machine according to claim 1 of the present invention devised to achieve the above object is fixed to the needle plate and is linearly parallel to the cloth feed direction by the feed dog and is the upper surface of the needle plate. A lower knife having a blade part parallel to and substantially flush with the straight knife part, and a straight blade part along the cloth feeding direction, like the straight knife part of the lower knife, and arranged at the lower part of the needle plate An upper knife attached to a movable knife base provided on a fixed bracket so as to be able to reciprocate up and down around an axis perpendicular to the material feed direction, and the movable knife table reciprocating up and down around the axis. A knife base drive means for driving and swinging, and by moving the movable knife base up and down and swinging through the knife base drive means, the linear blade portion of the upper knife is moved to the linear blade of the lower knife. Of the sewing machine that is configured to cut the edge of the fabric In the ground cutting device, the lower knife is formed with straight blade portions along both front and rear edges in the thickness direction, and the front and rear in the thickness direction are inverted with the lower knife as a needle plate. It is characterized in that the straight blade portion of the lower knife at the position in contact with the straight blade portion of the upper knife is replaceable in the front-rear direction by changing and fixing to the changed posture.

  With this configuration, when one of the blades formed on the front and rear side edges in the thickness direction of the lower knife is worn or sharpened, the lower knife is attached to the needle plate. By replacing the front and rear in the thickness direction and fixing it, it is possible to replace the other blade part with the position of contact with the blade part of the upper knife and use it with one lower knife. In addition, it is possible to obtain a service life equivalent to the case where the two lower knives are replaced and used in the conventional cloth cutting device. Therefore, it is possible to lengthen the lower knife replacement cycle to maintain a sharp state, thereby reducing the running cost and reducing the troublesome labor of replacing the knife in a place where there is not enough space.

In the above-mentioned Claim 1, at least one linear blade part is formed at least twice as long as the linear blade part of the upper knife among the linear blade parts of the front and rear side edges of the lower knife, It is preferable that the long straight blade portion of the lower knife is configured to be interchangeable at least twice in the longitudinal direction by sliding the lower knife in the longitudinal direction thereof at a position in contact with the linear blade portion of the upper knife ( Claim 2).
In this case, it is possible to obtain a service life equivalent to the case where at least three lower knives are replaced and used in a conventional cloth cutting device with one lower knive, further reducing running costs and changing the number of knives. Further reduction can be achieved.

  A cloth cutting device for a sewing machine according to a third aspect of the present invention devised to achieve the same object as described above is fixed to a needle plate and is linear in a direction parallel to the cloth feeding direction by the feed dog. And a lower knife having a blade portion parallel to and substantially flush with the upper surface of the needle plate, and a straight blade portion along the cloth feeding direction, similar to the straight blade portion of the lower knife, and below the needle plate An upper knife attached to a movable knife base provided on a fixed bracket disposed in a portion so as to be able to reciprocate up and down around an axis perpendicular to the material feed direction, and the movable knife table around the axis And a knife base driving means for reciprocating and swinging up and down, and by moving the movable knife table up and down and swinging through the knife base driving means, the linear blade portion of the upper knife is moved by the lower knife. It is configured to cut the edge of the fabric by intermittent contact with the straight blade. The upper knife shaft that forms the vertical reciprocating swing axis of the movable knife base is fixed to the movable knife table, and the upper knife shaft is provided with a pair of supports provided on the bracket. A coil spring that is rotatably supported by the portion and elastically presses and urges the upper knife toward the contact position with the lower knife via the movable knife base is provided between the movable knife base and one support part. The collar member that is fitted to the upper knife shaft and that is fitted to the upper knife shaft is configured to be movable and fixed in the axial direction of the upper knife shaft. The pressing biasing force by the coil spring is configured to be adjustable.

With this configuration, the upper knife shaft that forms the vertical reciprocating pivot axis of the movable knife base is rotatably supported by the pair of support portions provided on the bracket and is fixed to the movable knife table. There is no wear between the two due to the relative sliding contact between the base and the upper knife shaft, only wear between the bracket support and the upper knife shaft, and the distance between the pair of support portions is large. Even if the support portion of the knife shaft is worn, the change in the contact angle with the lower knife of the upper knife can be kept very small. In addition, since the coil spring that elastically presses and urges the blade part of the upper knife to the contact position with the blade part of the lower knife is fitted on the outer periphery of the upper knife shaft, the pressing urging force by the coil spring is movable It will act on the movable knife base on the vertical reciprocating swing axis of the knife table, so that no biased force is applied to the movable knife table and the change in the contact angle with the lower knife of the upper knife is reduced. Is possible. Through these synergies, the contact angle between the blade part of the upper knife and the blade part of the lower knife can be maintained at a sharp and normal angle even after a long period of use. Generation | occurrence | production can fully be suppressed.
Also, the pressing force applied by the coil spring is adjusted by releasing the fixation of the upper knife shaft to the movable knife base and moving the collar member fitted to the upper knife shaft in the axial direction of the upper knife shaft. Adjust both the upper and lower knives to a sharp state, and then oscillate the appropriate pressing biasing force against the upper knife adjusted to a sharp state by fixing the movable knife base and collar member to the upper knife shaft. It can be held almost constant without being increased or decreased even if it acts. Therefore, it is possible to reliably exert a sharp cutting action for a long time while minimizing the wear of the blade portion of the lower knife.

  Furthermore, the cloth cutting device for a sewing machine according to claim 4 of the present invention devised to achieve the same object as described above is fixed to the needle plate and is formed in a linear shape parallel to the cloth feeding direction by the feed dog. And a lower knife having a blade portion parallel to and substantially flush with the upper surface of the needle plate, and a straight blade portion along the cloth feeding direction, similar to the straight blade portion of the lower knife, and below the needle plate An upper knife attached to a movable knife base provided on a fixed bracket disposed in a portion so as to be able to reciprocate up and down around an axis perpendicular to the material feed direction, and the movable knife table around the axis And a knife base driving means for reciprocating and swinging up and down, and by moving the movable knife table up and down and swinging through the knife base driving means, the linear blade portion of the upper knife is moved by the lower knife. Configured to cut the edge of the fabric intermittently in contact with the straight blade In the sewing machine cloth cutting device, the lower knife is formed with straight blade portions along both front and rear edges in the thickness direction, and the lower knife is attached to the needle plate in the thickness direction. The front and back of the upper knife is replaced and fixed, so that the lower knife's linear blade at the position where it comes into contact with the upper knife's linear blade can be exchanged between the front and rear. An upper knife shaft that forms a reciprocating swing axis is fixed to a movable knife base, and the upper knife shaft is rotatably supported by a pair of support portions provided on the bracket. A coil spring that elastically presses and urges the upper knife to a contact position with the lower knife is fitted on the upper knife shaft located between the movable knife base and one of the support parts, and the upper knife The collar member fitted to the shaft Are positional movement and fixably configured in the axial direction of the knife shaft, the position movement fixing of the collar member, the urging pressure by the coil spring is characterized by being configured to be adjustable.

  When configured in this way, as described above, with a single lower knife, it is possible to obtain a service life equivalent to the case where two lower knife are replaced and used in a conventional cloth cutting device, and the lower knife replacement cycle In addition to reducing the running cost and troublesome labor of replacing the knife, the upper knife mechanism and the lower knife blade and The contact angle with the knife edge of the knife can be maintained at a sharp and normal angle, and the pressing force after adjusting to a sharp condition can be maintained almost constant to reduce the wear of the knife edge of the lower knife. The dough cutting action can be surely exerted while keeping to a minimum.

In claim 3 or 4, an oil supply hole is formed in the axial center portion of the upper knife shaft along the axial direction, and an oil supply member that absorbs and holds lubricating oil is loaded in the oil supply hole. (Claim 5).
In this case, it is possible to supply enough oil to the sliding contact part between the movable upper knife base and the bracket support part located under the condition that the oil stain on the fabric must be avoided because it is close to the upper surface of the needle plate. Thus, the wear of the sliding contact portion can be further reduced, and the improvement in the durability of the upper knife mechanism can be promoted.

In the above third to fifth aspects, it is preferable that a wear-resistant surface treatment film such as diamond-like carbon (DLC) is formed on the outer peripheral surface of the upper knife shaft (claim 6).
In this case, the wearability of the upper knife shaft can be further improved, and the contact angle between the upper and lower knife can be kept longer and sharper.

  In short, according to the present invention, the service life of one lower knife and the durability of the upper knife mechanism can be improved, and the cutting action with a sharpness can be achieved over a long period while reducing the running cost. A cloth cutting device for a sewing machine that can be stably maintained can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a main part of a straight stitch or staggered sewing machine to which a cloth cutting device for a sewing machine according to the present invention is applied, FIG. 2 is an enlarged exploded perspective view of the main part showing components of the cloth cutting apparatus, and FIG. It is an expanded sectional view of the principal part which shows the sewing and cutting | disconnection state of two-ply cloth. 1 to 3, reference numeral 1 denotes a sewing machine bed, and a sewing machine table (not shown) that is flush with the upper surface of the sewing machine bed 1 is provided so as to surround the sewing machine bed 1.

  A needle plate 3 and a sliding plate 4 are attached to the sewing bed 1 with their upper surfaces substantially flush with the upper surface of the sewing bed 1. The needle plate 3 has two rows of slot-like long holes 5a and 5b parallel to each other. One of the long holes 5b is divided into two stages, front and rear, with a needle drop portion 10 for performing predetermined sewing by dropping the needle 9 moving up and down. In these long holes 5a, 5b, a double-layered fabric of a body fabric (lower fabric) 7 and an upper fabric 8 such as a lace fabric is sequentially transferred in the feed direction X by a combined horizontal and vertical movement. Teeth 6 are provided. Since the feed driving mechanism for synthesizing the feed dog 6 in the horizontal direction and the vertical direction is well known, its details are omitted.

  A slit groove 11 for attaching a lower knife is formed in the lateral side portion of the front and rear slot-like long holes 5b in the needle plate 3 along the cloth feeding direction X, and the longitudinal direction of the slit groove 11 A substantially rectangular opening 12 for vertically swinging movement of the upper knife, which will be described later, is formed in the needle plate 3 portion at a portion corresponding to the needle drop portion 10 at a substantially central portion of the upper knife 12.

  The slit groove 11 has a lower knife 13 having a linear blade portion (details will be described later) at the upper edge of the slit groove 11 parallel to the material feed direction X. The pieces 13a and 13b are attached to the needle plate 3 so as to be attachable and detachable by pressing and fixing with the heads of screws 14 and 14 screwed into the bottom of the needle plate 3 from the upper surface side of the needle plate 3.

  Further, on the lower surface of the needle plate 3 below the opening 12, an upper knife 15 having a linear blade portion 15A along the material feeding direction X is reciprocated up and down in the same manner as the linear blade portion of the lower knife 13. An upper knife mechanism is provided. The upper knife 15 has a substantially inverted triangular shape in a plan view from the tip of the blade portion 15A in the direction opposite to the material feeding direction X, and extends obliquely upward from the blade portion 15A toward the tip side in a side view. A fabric guide piece 15B for guiding the upper fabric 8 out of the blade portion 15A is guided continuously.

  The lower knife 13 is made of tool steel or the like that is relatively more flexible than the upper knife 15, and as shown in FIGS. 4 to 7, the length of the knife at both front and rear upper edges in the thickness direction. Straight blade portions 13A and 13B each having a clearance angle θ of about 5 ° are formed at rotationally symmetric positions around the central portion O of the direction, and the lower knife 13 is shown in FIGS. 4 and 7. As described above, the needle plate 3 is brought into contact with the linear blade portion 15A of the upper knife 15 by being fixed to the needle plate 3 through the mounting pieces 13a and 13b and the screws 14 and 14 so that the front and rear in the thickness direction are reversed. The linear blade portions 13A and 13B at the position to be moved can be interchanged twice in the front and rear directions.

  The upper knife mechanism is configured as follows. That is, the movable knife base 17 with the upper knife 15 fixed in the fixed state via the screws 16 has a dough feeding portion 17b integrally protruding rearward in the dough feeding direction X from the upper knife fixing seat 17a. An upper female shaft 18 having an axis perpendicular to the direction X is inserted and fixed via a screw 19, and a bifurcated driven portion 17c that protrudes integrally in the opposite direction to the protruding portion 17b. Is a corner that is rotatably supported at the tip of the upper knife swinging arm 23 that swings back and forth twice in the direction of the arrow Y in FIG. 2 while the needle 9 reciprocates up and down once as the sewing machine rotates. The piece 24 is engaged.

  On the other hand, a pair of support portions 20a and 20a protrude from the lower portion of the upper knife base bracket 20 fixed to the lower surface of the needle plate 3 via screws 21 and 22 with a gap in the direction orthogonal to the fabric feed direction X. The upper knife shaft 18 is rotatably supported between the pair of support portions 20a and 20a, and is supported by the collar member 30 and the screw 31 so as not to move in the axial direction. As a result, the movable knife base 17 swings back and forth up and down around the axis of the upper knife shaft 18 via a knife table driving means comprising the upper knife swing arm 23, the square piece 24 and the bifurcated driven portion 17c. The upper and lower reciprocating rockers are configured to be driven, and the straight blade portion 15A of the upper knife 15 is intermittently brought into contact with the straight blade portion 13A or 13B of the lower knife 13, so that the lower fabric of the two-layered fabric immediately before sewing. (Body body) It is comprised so that the edge part of 7 may be cut | disconnected.

  Further, the upper knife shaft 18 positioned between the protruding portion 17b of the movable knife base 17 and one support part 20a of the bracket 20 has the movable knife base 17 on the other support part 20a side, that is, the upper knife. A coil spring 25 that elastically presses and biases 15 toward the contact position side with the lower knife 13 and a collar member 26 that is slidable in the axial direction are fitted and held. The collar member 26 can be arbitrarily moved in the axial direction. By being slid and fixed through a screw 27, the pressing biasing force by the coil spring 25 can be adjusted. Further, the pressing biasing force of the coil spring 25 is adjusted, the collar member 26 is fixed with the screw 27, and the movable knife base 17 is fixed to the upper knife shaft 18 with the screw 19, whereby the upper knife 15 is fixed to the lower knife 13. The pressure biasing force is configured to be kept substantially constant without increasing.

  Further, an oil supply hole 28 is formed in the axial center portion of the upper knife shaft 18 along the axial direction, and the upper knife shaft 18 portion corresponding to the pair of support portions 20a, 20a of the bracket 20 is formed. Are formed with oil supply holes 29 and 29 that communicate with the oil supply hole 28 and open radially outward, and an oil supply core member 30 that absorbs and holds lubricating oil is loaded in the oil supply hole 28. Has been. As a result, the sliding contact portion between the upper knife shaft 18 that reciprocally rotates together with the up and down reciprocating swing of the movable knife base 17 and the support portions 20a and 20a on the bracket 20 side can be lubricated.

  Furthermore, the outer peripheral surface of the upper knife shaft 18 and the outer peripheral surface of the square piece 24 are coated with, for example, DLC (diamond-like carbon), chrome or hard chrome plating, nickel plating, nickel / phosphorous plating, anodizing, or the like. Wear-resistant and low-friction surface treatment is applied.

  In the sewing machine cutting apparatus configured as described above, a double-layered fabric of a body fabric (lower fabric) 7 and an upper fabric 8 such as a lace fabric is set on the upper surfaces of the sewing machine bed 1, the needle plate 3 and the sliding plate 4. By rotating the sewing machine in this state, the two-ply dough is sequentially transferred in the dough feed direction X via the feed dog 6. At this time, as shown in FIG. 3, the upper fabric 8 of the two-layered fabric is guided by the fabric guide piece 15 </ b> B connected to the upper knife 15 to bypass the cutting action position, and the body 7 is Along the upper surface of the needle plate 3, the needle plate 3 is divided into upper and lower parts and transferred to the cutting action position.

  Then, the movable knife base 17 is connected to the movable knife base 17 via a knife base driving means comprising an upper knife swinging arm 23, a square piece 24, and a fork-like driven portion 17c that reciprocally swings in the direction of arrow Y in conjunction with the rotation of the sewing machine. The fixed knife 20 is reciprocated up and down around the axis of the fixed upper knife shaft 18, and the linear knife 15 A of the upper knife 15 is turned into the straight knife 13 A of the lower knife 13 by the vertical knife swinging of the movable knife base 17. Alternatively, the end portion of the lower fabric (body body) 7 is cut intermittently in contact with 13B and immediately before the sewing, and the needle 9 falls into the needle drop portion 10 immediately after the cutting, and the ends of the double-layer fabric are Is sewn, and the sewing location is transferred in the fabric feed direction X, and the sewing proceeds one after another.

  As such sewing is performed, as shown in FIG. 4, of the blade portions 13 </ b> A and 13 </ b> B formed on both front and rear edges in the thickness direction of the lower knife 13, If the blade portion 13A is worn or sharpened, and the sharpness is reduced, the lower knife 13 is fixed to the needle plate 3 in a posture in which the front and rear in the thickness direction are reversed and fixed to FIG. As shown, it is possible to use the other blade portion 13B by replacing it with the contact position of the upper knife 15 with the blade portion 15A. As a result, it is possible to obtain a service life equivalent to a case where two lower knives are exchanged and used in a conventional cloth cutting device with one lower knives 13.

  Further, since the upper knife shaft 18 that forms the vertical reciprocating swing axis of the movable knife table 17 is fixed to the movable knife table 17, there is no wear due to the relative sliding contact between the movable knife table 17 and the upper knife shaft 18. The pair of support portions 20a, 20a of the bracket 20 only wears between the upper female shaft 18 and the distance between the pair of support portions 20a, 20a is large, so that the upper female shaft 18 is temporarily supported. Even if the portion is worn, the change in the contact angle with the blade portion 13A or 13B of the lower knife 13 of the blade portion 15A of the upper knife 15 is very small. In addition, a coil spring 25 that elastically presses and urges the blade portion 15A of the upper knife 15 to a contact position with the blade portion 13A or 13B of the lower knife 13 is fitted on the outer periphery of the upper knife shaft 18, Since the pressing urging force by the spring 25 acts on the movable knife table 17 on the vertical reciprocating swing axis of the movable knife table 17, no biased force is applied to the movable knife table 17, thereby The change in the contact angle of the lower knife 13 with the blade part 13A or 13B of the lower knife 13 of the upper knife 15 becomes smaller, and thus the blade part 15A of the upper knife 15 and the blade of the lower knife 13 even after long-term use. The contact angle with the portion 13A or 13B can be maintained at a normal angle with good sharpness, and occurrence of mistakes in cutting and defective cutting of the fabric can be sufficiently suppressed.

  Further, the collar member 26 fitted to the upper knife shaft 18 is moved in the axial direction of the upper knife shaft 18 so that the pressing biasing force by the coil spring 25 is adjusted and both the upper and lower knife 15, 13 are sharp. After that, by fixing the collar member 26 to the upper knife shaft 18 via the screw 27, an appropriate pressing biasing force against the upper knife 15 adjusted to a sharp state can be obtained by vibration at the time of sewing. Even if it acts, it can be kept almost constant without increasing or decreasing.

  As described above, the wear of the blade portions 13A and 13B of the lower knife 13 can be minimized, the service life of the lower knife 13 can be extended, and the above-described upper knife mechanism. As a synergistic effect of being able to maintain a sharp state for a long period of time, it is possible to ensure a sharp cutting action for a long period of time while improving the durability of the entire apparatus and sufficiently reducing the running cost. .

  In addition, it is possible to sufficiently supply oil to the sliding contact portion between the upper female shaft 18 and the pair of support portions 20a, 20a of the bracket 20 through the oil supply holes 29, 29 from the oil supply core member 30 loaded in the oil supply hole 28. And the durability of the upper knife mechanism can be promoted by the fact that the outer peripheral surface of the upper knife shaft 18 is surface-treated with wear resistance and low friction by DLC coating, etc., and The contact angle between the upper and lower knives 15 and 13 can be kept longer and sharper.

  In the embodiment described above, the straight blades having the clearance angle θ of about 5 ° at the rotationally symmetrical positions around the central portion O in the longitudinal direction of the knife at the front and rear side edges in the thickness direction of the lower knife 13. The parts 13A and 13B are formed, and the two blade parts 13A and 13B are described so as to be interchangeable with the blade part 15A of the upper knife 15 by reversing the front and rear. However, at least one blade of the lower knife 13 is described. The portion 13A or 13B is formed at least twice as long as the blade portion 15A of the upper knife 15, and the blade portion 13A or 13B formed longer by sliding the lower knife 13 in the longitudinal direction is at least 2 in the longitudinal direction. You may comprise so that rotation is interchangeable (illustration is abbreviate | omitted). In this case, the service life equivalent to the case where at least three lower knives are exchanged and used in the conventional cloth cutting apparatus can be obtained with one lower knives 13, and the running cost can be further reduced and the number of knife replacement operations is reduced. Can be further reduced.

  In the above embodiment, the bracket 20 for mounting the movable knife base 17 so as to be swingable up and down around the axis of the upper knife shaft 18 is fixed to the lower surface of the needle plate 3 via screws 21. However, the bracket 20 may be fixed to the lower surface of the sewing machine bed 1.

It is a perspective view of the principal part of the straight stitch or zigzag stitch sewing machine to which the cloth cutting device of a sewing machine concerning the present invention is applied. It is an expansion disassembled perspective view of the principal part which shows the component of the cloth cutting device of a sewing machine same as the above. It is an expanded sectional view of the principal part which shows the sewing and cutting | disconnection state of the two-ply fabric by a sewing machine same as the above. It is a top view of the principal part which shows the state which takes out only the up-and-down knife in the cloth cutting device same as the above, and uses one blade part of a lower knife. It is an expanded sectional view along the AA line of FIG. It is an expanded sectional view along the BB line of FIG. It is a top view of the principal part which shows the state which takes out only the up-and-down knife in the cloth cutting device same as the above, and replaces and uses the other blade part of a lower knife.

Explanation of symbols

1 Sewing machine bed 3 Needle plate 6 Feed dog 7 Lower fabric (body body)
8 Upper fabric 9 Needle 13 Lower knife 13A, 13B Blade 15 Upper knife 15A Blade 17 Movable knife base 18 Upper knife shaft 20 Bracket 20a Pair of support portions 25 Coil spring 26 Collar member 28 Oil supply hole 30 Oil core X Material Feed direction

Claims (6)

A lower knife that is fixed to the needle plate and has a straight blade parallel to the feed direction of the dough by the feed dog and parallel to the upper surface of the needle plate and substantially flush with the lower knife, as well as the linear knife of this lower knife It has a linear blade portion along the fabric feed direction, and is provided on a fixed bracket disposed at the lower portion of the needle plate so as to be able to swing back and forth around an axis perpendicular to the fabric feed direction. An upper knife attached to the movable knife table, and a knife table driving means for reciprocatingly swinging the movable knife table up and down around the axis, the movable knife table is moved up and down via the knife table driving means. In the cloth cutting device for a sewing machine configured to cut the end portion of the cloth by bringing the linear blade part of the upper knife into contact with the linear blade part of the lower knife by reciprocally swinging to
The lower knife is formed with straight blades along both front and rear edges in the thickness direction, and the lower knife is fixed to the needle plate in a posture that is reversed in the thickness direction. Thus, the cloth cutting device for a sewing machine is configured such that the straight blade portion of the lower knife at a position in contact with the straight blade portion of the upper knife is replaceable between front and rear.   At least one of the straight blade portions at the front and rear side edges of the lower knife is formed at least twice as long as the straight blade portion of the upper knife. The long linear blade portion of the lower knife at a position in contact with the linear blade portion of the upper knife is configured to be exchangeable at least twice in the longitudinal direction by sliding in the longitudinal direction. Sewing machine cutting device. A lower knife that is fixed to the needle plate and has a straight blade parallel to the feed direction of the dough by the feed dog and parallel to the upper surface of the needle plate and substantially flush with the lower knife, as well as the linear knife of this lower knife A movable knife having a linear blade portion along the cloth feeding direction and provided on a fixed bracket disposed at a lower portion of the needle plate so as to be reciprocally swingable up and down around an axis perpendicular to the cloth feeding direction. An upper knife attached to the table and a knife table driving means for swinging the movable knife table up and down around the axis, and the movable knife table is reciprocated up and down via the knife table driving means. In a sewing machine cloth cutting device configured to intermittently contact the linear blade part of the upper knife with the linear blade part of the lower knife to cut the end portion of the cloth by swinging and driving,
An upper knife shaft that forms a vertical reciprocating swing axis of the movable knife table is fixed to the movable knife table, and the upper knife shaft is rotatably supported by a pair of support portions provided on the bracket, and A coil spring that elastically presses and urges the upper knife toward the contact position with the lower knife via the movable knife base is fitted to the upper knife shaft positioned between the movable knife base and one support portion. In addition, the collar member fitted to the upper knife shaft can be moved and fixed in the axial direction of the upper knife shaft. By this position movement and fixation of the collar member, the pressing biasing force by the coil spring is reduced. A sewing machine cloth cutting device characterized by being configured to be adjustable. A lower knife that is fixed to the needle plate and has a straight blade parallel to the feed direction of the dough by the feed dog and parallel to the upper surface of the needle plate and substantially flush with the lower knife, as well as the linear knife of this lower knife A movable knife having a linear blade portion along the cloth feeding direction and provided on a fixed bracket disposed at a lower portion of the needle plate so as to be reciprocally swingable up and down around an axis perpendicular to the cloth feeding direction. An upper knife attached to the table and a knife table driving means for swinging the movable knife table up and down around the axis, and the movable knife table is reciprocated up and down via the knife table driving means. In a sewing machine cloth cutting device configured to intermittently contact the linear blade part of the upper knife with the linear blade part of the lower knife to cut the end portion of the cloth by swinging and driving,
The lower knife is formed with straight blades along both front and rear edges in the thickness direction, and the lower knife is fixed to the needle plate in a posture that is reversed in the thickness direction. By doing so, the linear blade portion of the lower knife at the position in contact with the linear blade portion of the upper knife is configured to be interchangeable in the front and rear,
The upper knife shaft that forms the vertical reciprocating swing axis of the movable knife base is fixed to the movable knife base, and the upper knife shaft is rotatably supported by a pair of support portions provided on the bracket. And a coil spring that elastically presses and urges the upper knife toward the contact position with the lower knife via the movable knife table is fitted to the upper knife shaft located between the movable knife table and one support portion. The collar member fitted to the upper knife shaft can be moved and fixed in the axial direction of the upper knife shaft, and the collar member can be pressed by the coil spring. A sewing machine cloth cutting device characterized in that the power is adjustable.   The sewing machine according to claim 3 or 4, wherein an oil supply hole along an axial direction is formed in an axial center portion of the upper knife shaft, and an oil supply member that absorbs and holds lubricating oil is loaded in the oil supply hole. Fabric cutting equipment.   6. The sewing machine cloth cutting apparatus according to claim 3, wherein a wear-resistant surface treatment film is formed on an outer peripheral surface of the upper knife shaft.

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