Body ply cord cutting device and cutting method for improving tire dents

Abstract

The present invention relates to a body ply cord cutting device and cutting method for preventing a phenomenon in which a dent occurs when an overlapping portion of a body ply does not expand uniformly together with other portions during tire inflation due to increased rigidity of the overlapping portion of the body ply during a tire molding process. The device comprises a conveyor for transporting a body ply material and two or more serviors arranged side by side, a base arranged between the serviors, a knife arranged below the base, and a knife lifting mechanism for raising and lowering the knife so that the knife passes through the base. The knife is composed of at least one first knife forming a cut line on the leading edge of the body ply transported toward the base and at least one second knife forming a cut line on the trailing edge of the body ply that has passed through the base. A knife movement groove is formed in the base through which the first knife and the second knife can pass. By preventing the dent phenomenon occurring at the joint portion of the body ply in an air-filled tire, the tire finish becomes clean, and the possibility of mistaking it for a performance defect is eliminated, thereby providing satisfaction to the user. We intend to provide a cutting method.

Description

Technology Field

[0001] The present invention relates to a body ply cord cutting device and cutting method for preventing the phenomenon in which a dent occurs when the overlapping part of the body ply is not uniformly expanded together with other parts during tire inflation due to increased rigidity of the overlapping part of the body ply during the tire molding process. Background Technology

[0002] Referring to FIG. 1a, when the body ply (1) is wound in the circumferential direction during the green tire molding process, a part where the beginning and end of the body ply (1) overlap is created, and a joint part (4) is formed to prevent the phenomenon of the overlapping part spreading apart.

[0003] There is a difference in rigidity between this cylindrical body ply joint (4) and the rest of the parts, and as shown in FIG. 1b, when air is injected into the tire after manufacturing, an external defect called a dent occurs in which the joint (4) is indented due to the rigidity of the joint (4).

[0004] Although cosmetic defects caused by dents do not cause problems with the tire's performance itself, cosmetic defects can be mistaken for performance defects and result in an uneven finish on the tire, so technology is required to suppress the occurrence of dents during the tire manufacturing process. Prior art literature

[0005] Patent Registration Publication No. 10-0168600 (Date of publication: January 15, 1999) The problem to be solved

[0006] Accordingly, the present invention aims to provide a body ply cord cutting device and cutting method that can prevent dents occurring at the joint portion of the body ply in an air-filled tire, thereby making the tire finish neat and eliminating the possibility of mistaking it for poor performance, and thus providing satisfaction to the user. means of solving the problem

[0007] A body fly cord cutting device according to the present invention for achieving such an objective comprises a conveyor for transporting a body fly fabric, two or more servos arranged side by side, a support placed between the servos, a knife placed below the support, and a knife lifting mechanism for raising and lowering the knife so that the knife passes through the support.

[0008] The above knife comprises at least one first knife forming a cut line on the front end of a body fly being transported toward the base, and at least one second knife forming a cut line on the rear end of a body fly passing through the base, and the base has a knife movement groove formed therein through which the first knife and the second knife can pass.

[0009] Here, the knife lifting mechanism preferably includes a lifting plate that supports the knife in an upright position and a driving cylinder that moves the lifting plate in an up and down direction, and the first knife is installed such that a cutter part sharpened from the first knife is directed toward the front end of the body fly from the upper part of the lifting plate, and the second knife can be installed such that a cutter part sharpened from the first knife is directed toward the rear end of the body fly that has passed through the support from the upper part of the lifting plate.

[0010] Additionally, the base may preferably be equipped with a length measuring sensor that measures the transport distance of the body fly so that the leading or trailing end of the body fly being transported to the servicer is accurately positioned at the site to be cut by the knife.

[0011] Alternatively, a plurality of knife cases are installed on the upper part of the above-mentioned base, corresponding to the shape of the knife and having a thickness greater than that of the knife, and a knife protrusion slit is formed on the front side facing the front end of the body fly and on the back side facing the rear end of the body fly, respectively, through which the knife can protrude or be retracted, and the knife embedded so as to protrude into the knife case has a sharply machined cutter part formed in both the direction facing the front end of the body fly and the direction facing the rear end, the first knife corresponds to the cutter part facing the front end, and the second knife corresponds to the cutter part facing the rear end, and the first knife and the second knife may be integrally formed with a support part in the form of a thin rigid plate having the same thickness as the first and second knives.

[0012] Here, the knife case is preferably provided with a knife horizontal movement mechanism that varies the first knife or the second knife so that it protrudes into either of the knife protrusion slits, and the knife horizontal movement mechanism moves the support member in the direction of travel or the opposite direction of travel of the body fly to protrude the first or second knife, and the knife horizontal movement mechanism may include a guide arm that is fixedly formed at a predetermined part of the support member and protrudes outside the knife case.

[0013] At this time, the knife case preferably has a horizontal guide slit formed therein, which is a passage through which the guide arm can move in a horizontal direction, and the knife horizontal movement mechanism can move the guide arm horizontally.

[0014] Here, the knife horizontal movement mechanism preferably comprises a rack gear connected to the guide arm and formed along the horizontal movement direction of the first or second knife, a pinion gear meshing with the rack gear, a servo motor that rotates the pinion gear, and a pinion gear horizontal rotation axis that passes through all the knife cases and rotates the pinion gear provided in each knife case, and the knife cases can pass through the knife movement groove.

[0015] Additionally, the knife case may be able to pass through the knife moving groove, and the rotating shaft may be provided with a step motor that moves the entire horizontal moving mechanism horizontally in the horizontal direction by moving the rotating shaft horizontally in a horizontal direction perpendicular to the direction of travel of the body fly, such that the positions of the first cutting line and the second cutting line formed by the first knife and the second knife are formed to be staggered from each other, the distance the step motor moves the rotating shaft horizontally corresponds to the spacing of the moving groove, and the moving groove may be formed at twice the number of the knife case.

[0016] Meanwhile, a body fly cord cutting method according to one embodiment of the present invention is a cutting method using a body fly cutting device according to the first embodiment described above, comprising the steps of: lowering a first knife and a second knife to the lower part of a support and waiting; raising the first and second knives to the upper part of the support when the leading edge of one body fly approaches the support; measuring the length of the leading edge of the body fly passing the support using a length measuring sensor; stopping the body fly by a servist when the body fly approaches the first knife by a length required for cutting at the lower part of the cutter portion forming the blade portion of the first knife; lowering the first knife to the lower part of the knife moving groove to form a first cut line on one body fly; lowering the first knife and the second knife to the lower part of the support, then moving the body fly with the first cut line formed thereon to pass through the upper part of the support, and bringing the next body fly to the support using a servist; raising the first knife and the second knife to the upper part of the moving groove, then the body fly with the first cut line formed The method includes the step of moving the body fly backward to move the rear end side to the lower part of the cutter section of the second knife using a length measuring sensor and moving the front end side of the next body fly to the lower part of the cutter section of the first knife, and the step of lowering the first and second knives to the lower part of the moving groove to form a second cut line on the rear end side of the body fly where the first cut line is formed and forming a first cut line on the front end side of the next body fly.

[0017] In particular, before executing the step of moving the leading edge of the next body fly to the lower part of the cutter of the first knife, the method further includes the step of moving the first and second knives in the lateral direction perpendicular to the direction of travel of the body fly using the step motor, and the distance of movement in the lateral direction corresponds to the spacing of the moving groove. Effects of the invention

[0018] The body ply cord cutting device and cutting method according to the present invention can prevent dents occurring at the joint portion of the body ply in an air-filled tire, thereby making the tire finish neat and eliminating the possibility of mistaking it for poor performance, which can provide satisfaction to the user. Brief explanation of the drawing

[0019] Figure 1a is a conceptual diagram showing the position of the overlap portion of the body ply in the molding drum. Figure 1b is a conceptual diagram illustrating the principle of dent formation in the joint area. FIG. 2 is a front view according to one embodiment of a cord cutting device according to one embodiment of the present invention. FIG. 3 is a conceptual diagram of a joint portion in which a cut line is formed by a cord cutting device according to an embodiment of the present invention. Figure 4 is a side view of the first and second knives in Figure 2. FIG. 5 is a conceptual diagram showing the gap between the knife and the moving groove in a cord cutting device according to an embodiment of the present invention. FIG. 6 is a side view showing the operation sequence of a code cutting device according to an embodiment of the present invention. FIGS. 7a to 7f are perspective views showing the operation sequence of a code cutting device according to an embodiment of the present invention. FIG. 8a is a partial perspective view of a cord cutting device according to another embodiment of the present invention. FIG. 8b is a partial perspective view showing the state in which the knife has moved horizontally in FIG. 8a. FIG. 9 is a front view of FIG. 2 with another embodiment according to FIG. 8a and FIG. 8b applied. FIG. 10 is a table showing the degree of dent formation before and after the application of the bi-fly cord cutting device according to the present invention. Specific details for implementing the invention

[0020] Hereinafter, various embodiments of the present invention are described by way of specific embodiments illustrated in the attached drawings. Differences between embodiments should be understood in the context of the drawings as they are not mutually exclusive, and specific shapes, structures, and characteristics described in relation to the embodiments may be implemented in other embodiments without departing from the spirit and scope of the present invention.

[0021] The location or arrangement of individual components according to embodiments of the present invention should be understood as changeable through the combination of drawings, and similar reference numerals in the drawings may indicate the same or similar functions across various aspects, and the specific shapes of lengths, areas, thicknesses, etc., may be exaggerated for convenience of explanation.

[0022] Each unit, module, part, component, or arbitrary structure for which sub-elements are not described is assumed to include or may include conventional sub-elements to have the respective assigned function, and is not limited to the sub-elements or detailed structures depicted in the drawings. Components that are depicted but omitted from description in the ordinary sense should be understood as being inherent in the detailed description of the embodiments.

[0023] The present invention will be described in detail below with reference to the attached drawings.

[0024] A body fly cord cutting device according to one embodiment of the present invention includes, with reference to FIGS. 2 and FIGS. 5, a servo (110), a base (120), a knife (130), and a knife lifting mechanism (140).

[0025] Referring to FIG. 6, the servicer (110) is a conveying means equipped with a conveyor so that a body ply (1), cut to correspond to the circumference of each tire, is spread out and transported to a molding drum (hatched area in FIG. 1a). Two or more servicers (110) may be provided as in FIG. 6 or FIG. 7a, and a support (120), which will be described later, is provided between the servicers (110).

[0026] The base (120) is a mechanism provided between the servicers (110) such that a knife (130), which will be described later, can protrude upward so that a cut line (3) can be formed at the end of the body fly (1) being transported to the servicers (110) as shown in FIG. 3.

[0027] The device shown in the lower part of FIG. 2 is a front view of a body fly cord cutting device according to an embodiment of the present invention, and the device shown in the upper part is a plan view, in which only the upper surface of the base (120) is shown.

[0028] At this time, the base (120) has a knife moving groove (121) formed therein through which the first knife (130a) and the second knife (130b), which will be described later, can pass, as shown in the upper part of FIG. 2.

[0029] Referring to FIG. 4, the knife (130) has a support portion (132) formed straight in a vertical direction, and a sharply machined cutter portion (131) formed in a shape facing downward on one side of the support portion (132). Therefore, when the end of the body fly (1) is positioned at the bottom of the cutter portion (132), the knife (130) descends immediately from that spot, and the cutter portion (132) passes through the end of the body fly (1) to make a cut. Thus, the length of the cut line (3) can be determined by how close the body fly (1) approaches the bottom of the cutter portion (131).

[0030] When a cut line (3) is formed at the end of the body ply (1), referring to FIG. 1a and FIG. 1b, when the overlapping portion of the body ply (1) is joined to form a joint portion (4), the upper cord (2) and the lower cord (2) of the overlapping portion are joined while being dispersed by a certain width from each other, thereby preventing the phenomenon where each cord (2) is forcibly joined with a strong force and the rigidity increases.

[0031] In particular, as illustrated in FIG. 1b, when the first cut line (3a) and the second cut line (3b) are formed on both sides, not just on one side of the front or rear end of the body ply (1) that forms the overlapping portion of the body ply (1), the dispersion effect during the process of forming the joint portion (4) occurs more naturally, thereby preventing the phenomenon where the rigidity of the joint portion (4) differs too drastically from the adjacent portion, and thus the formation of dents can be suppressed more effectively.

[0032] To this end, in the embodiment according to FIGS. 3 to 7f of the present invention, particularly when viewed with reference to FIGS. 7a to 7f, if the direction of travel of the body fly (1) is considered to be from left to right in the drawing, the knife (130) in which the cutter part (131) is directed toward the body fly (1) (the body fly (1) on the upper side of FIG. 7a) approaching the base (120) is the first knife (130a), and the cut line (3) formed by the first knife (130a) corresponds to the first cut line (3a).

[0033] In this case, since the second knife (130b) is alternately positioned at a position opposite to the first knife (130a), the second cutting line (3b) and the first cutting line (3a) do not meet parallel to each other but are formed opposite to each other, so it can be seen that the dispersion effect of the cord (2) can occur smoothly in the formation of the joint part (4).

[0034] As shown in FIG. 2, the knife lifting mechanism (140) may include a lifting plate (141) that supports the knife (130) in an upright position and a driving cylinder (142) that moves the lifting plate (141) in an up and down direction.

[0035] At this time, the first knife (130a) is installed such that the cutter part (131), sharpened from the first knife (130a), faces the front end of the body fly (1) from the upper part of the lifting plate (141), and the second knife (130b) can be installed such that the cutter part (131), sharpened from the first knife (130a), faces the rear end of the body fly (1) that has passed through the support (120) from the upper part of the lifting plate (141).

[0036] Additionally, a length measuring sensor (122) for measuring the transport distance of the body fly (1) can be installed on the base (120) so that the front or rear end of the body fly (1) being transported to the servo (110) is accurately positioned at the area to be cut by the knife (130).

[0037] The length measuring sensor (122) measures the length of the body ply (1) moving in the forward or reverse direction, thereby enabling the cutting line (3) to be formed at an accurate length under the cutter portion (131) of the first or second knife (130a, 130b), respectively, at the front or rear end of the body ply (1). To this end, the length measuring sensor (122) may be linked with a servist (110), and a control unit (not shown) that links the length measuring sensor (122) with the servist (110) may be separately provided.

[0038] In FIG. 4, the first knife (130a) and the second knife (130b) appear to overlap each other when viewed from the side, appearing as if they share a single support (132); however, in the embodiment according to FIG. 3 to 7f, the first and second knives (130a, 130b) are installed separately and spaced apart from each other.

[0039] FIG. 5 is an enlarged view of one of the knife moving grooves (121) formed parallel to each other on the base (120) at the top of FIG. 3, where the darkly colored area is an enlarged cross-section of the knife (130) and the edge represents the knife moving groove (121).

[0040] FIG. 6 illustrates operation in the order from the scene shown at the top to the scene shown at the bottom, wherein the front end of the body fly (1) is located on one side of the front and rear directions of the base (120) and the rear end of the body fly (1) is located on the other side.

[0041] Looking at Fig. 6, the right side shows the front end of the newly entering body fly (1), and the left side shows the rear end of the body fly (1) where the first cut line (3a) has already been formed on the front end, which is just being cut.

[0042] FIGS. 7a to 7f illustrate the operation sequence of a body fly cord cutting device according to an embodiment of the present invention in sequence.

[0043] First, in FIG. 7a, a first body fly (1a) with a first cut line (3a) already formed on the tip side and a second body fly (1b) with no cut line (3) formed yet are each transferred to a servicer (110).

[0044] In FIG. 7b, the gap between the first and second body flies (1a, 1b) is widened by the servo (110) to secure space for the protrusion of the first and second knives (130a, 130b).

[0045] FIG. 7c shows the first and second knives (130a, 130b) rising through the knife moving groove (121) formed in the base (120).

[0046] FIG. 7d is a scene in which the rear end of the first body fly (1a) and the front end of the second body fly (1b) are approached to the lower part of the cutter section (131) of the second knife (130b) and the lower part of the cutter section (131) of the first knife (130a) so that the accurate length of the incision line (3) is secured, respectively.

[0047] FIG. 7e is a scene in which the first and second knives (130a, 130b) descend, and the second cut line (3b) and the first cut line (3a) are formed on the rear end side of the first body fly (1a) and the front end side of the second body fly (1b), respectively.

[0048] FIG. 7f is a scene in which the first body ply (1a), having incision lines (3) formed on both the front and rear sides, moves toward the molding drum (see hatched area in FIG. 1a), and the second body ply (1b) waits to move toward where the first body ply (1a) was.

[0049] Hereinafter, a second embodiment, which is a modified embodiment of the first embodiment described above, will be described with reference to FIGS. 8a to 9.

[0050] As shown in FIGS. 8a to 9, the cord cutting device according to the second embodiment has a first knife (230a) and a second knife (230b) formed in one body, and the first knife (230a) and the second knife (230b) formed in one body are housed in a knife case (234) that is thinly formed along the line direction of the body fly (1) so as to protrude.

[0051] At this time, a knife protrusion slit (2341) is formed in the knife case (234) such that a knife (230) can protrude or be inserted, on the front side facing the front end of the body fly (1) and on the back side facing the rear end of the body fly (1).

[0052] For reference, the front of the knife case (234) is defined to face the newly entering body fly (1), and the back of the knife case (234) is defined to face the rear end of the body fly (1) on which the first cut line (3a) has already been formed on the front end.

[0053] Accordingly, in FIG. 8a and FIG. 8b, the back of the knife case (234) is shown. Additionally, in FIG. 8a, the first knife (230a) can be defined as protruding toward the front of the knife case (234), and in FIG. 8b, the second knife (230b) can be defined as protruding toward the back of the knife case (234).

[0054] Here, as shown in FIG. 8a, the knife (230) may have a cutter portion (231a, 231b) formed with a sharp edge in both the direction toward the front end of the body fly (1) and the direction toward the rear end.

[0055] Referring to FIG. 8a, the specific shape of the knife (230) is formed such that, similar to that shown in FIG. 4, the first knife (230a) and the second knife (230b) are integrally formed with a support member (232) in the form of a thin rigid plate having the same thickness as the first and second knives (230a, 230b).

[0056] That is, the first knife (230a) and the second knife (230b) formed on both sides of a single support member (232) both form a single body. Therefore, even if the knife case (234) is formed with a thin thickness, it is possible to store the knife (230).

[0057] However, referring to FIG. 10, as described below, the knife moving groove (121) formed in the base (120) in this case can be formed in a size that allows the knife case (234) to pass through.

[0058] And, referring to FIGS. 8A and 8B, the knife case (234) may be provided with a knife horizontal movement mechanism (235) that moves the knife (230) so that the first knife (230a) or the second knife (230b) protrudes into either the front or rear knife protrusion slit (2341).

[0059] The knife horizontal movement mechanism (235) moves the support member (232) in the direction of travel or opposite to travel of the body fly (1) to protrude the first or second knife (230a, 230b), and the knife horizontal movement mechanism (235) may include a guide arm (2351) that is fixedly formed on a predetermined part of the support member (232) and protrudes outside the knife case (234).

[0060] At this time, a horizontal guide slit (2342) is formed in the knife case (234) as a passage through which the guide arm (2351) can move horizontally as shown in FIG. 8a and FIG. 8b, and a knife horizontal movement mechanism (235) is formed to move the guide arm (2351) horizontally.

[0061] More specifically, the knife horizontal movement mechanism (235) may be composed of a rack gear (2352) that is connected to a guide arm (2351) and extends along the horizontal movement direction of the first or second knife (230a, 230b), a pinion gear (2353) that meshes with the rack gear (2352), a servo motor (2355) that rotates the pinion gear (2353), and a pinion gear horizontal rotation axis (2354) that passes through all the knife cases (234) and rotates the pinion gear (2353) provided in each knife case (234).

[0062] At this time, the knife case (234) can pass through the knife moving groove (121), and a step motor (250) may be provided on the horizontal rotation axis (2354) to move the entire knife horizontal moving mechanism (235) horizontally in the horizontal axis direction by moving the horizontal rotation axis (2354) horizontally in a lateral direction perpendicular to the direction of travel of the body fly (1). (See FIG. 9)

[0063] Accordingly, the positions of the first cutting line (3a) and the second cutting line (3b) formed by the first knife (230a) and the second knife (230b) are formed to be staggered from each other, and the distance the step motor (250) moves horizontally along the horizontal rotation axis (2354) corresponds to the spacing of the knife moving groove (121), and the total number of knife moving grooves (121) can be formed as twice the number of knife cases (234).

[0064] Therefore, in the embodiment according to FIGS. 8a to 9, the cutting line (3) is not formed simultaneously on the rear end of the body fly (1) on which the first cutting line (3a) has already been formed on the front end and on the front end of the newly entering subsequent body fly (1). Instead, the knife horizontal movement mechanism (235) is first moved by the step motor (250) by the distance of the knife movement groove (121), and then the second cutting line (3b) is formed on the rear end of the body fly (1) on which the first cutting line (3a) has already been formed on the front end. Then, before the knife (230) rises again, the step motor (250) moves the knives (230a, 230b) back to their original positions, and then the knife (230) rises to form the first cutting line (3a) on the front end of the newly entering body fly (1). (Not shown)

[0065] Meanwhile, a body fly cord cutting method according to one embodiment of the present invention is a cutting method using a body fly cutting device according to the first embodiment described above, comprising the steps of: lowering a first knife (130a) and a second knife (130b) to the lower part of a base (120) and waiting; raising the first and second knives (130a, 130b) to the upper part of the base (120) when the leading end of one body fly (1) approaches the base (120); measuring the length of the leading end of the body fly (1) passing the base (120) using a length measuring sensor (122); stopping the body fly (1) with a servo (110) when the body fly (1) approaches the first knife (130a) by a length required for cutting at the lower part of the cutter part (131) forming the blade part of the first knife (130a); and moving the first knife (130a) to the knife moving groove (121). A step of lowering to form a first cut line (3a) on one of the body flies (1) (not illustrated up to this point), and as shown in FIGS. 7A and 7B, lowering the first knife (130a) and the second knife (130b) to the bottom of the base (120), then moving the body flies (1) with the first cut line (3a) formed thereon to pass over the top of the base (120), and then bringing the body flies (1) to approach the base (120) with a servo (110), and as shown in FIGS. 7C and 7D, raising the first knife (130a) and the second knife (130b) to the top of the knife moving groove (121), then moving the body flies (1) with the first cut line (3a) formed thereon backward to move the rear end side to the bottom of the cutter part (131) of the second knife (130b) using a length measuring sensor (122), and then A step of moving the front end of the body fly (1) to the lower part of the cutter portion (131) of the first knife (130a), and as shown in FIG. 7e, the first and second knives (130a,The method includes the step of lowering 130b) to the lower part of the knife moving groove (121) to form a second cut line (3b) on the rear side of the body ply (1) where the first cut line (3a) is formed, and forming the first cut line (3a) on the front side of the next body ply (1).

[0066] A more detailed explanation of the cutting method will be omitted as it overlaps with the aforementioned body fly cutting device.

[0067] For reference, FIG. 10 shows a table of the degree of dent formation when the first and second cutting lines are not applied and when they are applied. As can be seen from the table, when the cutting method and cutting device according to the present invention are applied, dent formation is suppressed to about 15% to 20%, although there are differences depending on the type of tire, so that a tire with a higher quality finish can be produced.

[0068] The present invention described above is not limited by the aforementioned embodiments and attached drawings, and it will be obvious to those skilled in the art that various substitutions, modifications, and changes are possible within the scope of the technical concept of the present invention. Explanation of the symbols

[0069] 1 : Bodyfly 1a : First bodyfly 1b : 2nd Bodyfly 2 : Chord 3 : Incision line 3a : First incision line 3b : Second incision line 4 : Joint section 110 : Service 120 : Stand 121: Knife movement groove 122: Length measuring sensor 130,230: Knife 130a,230a: First knife 130b, 230b: Second knife 131: Cutter part 132,232 : Support section 140 : Knife lifting mechanism 141,241 : Lifting plate 142,242 : Driving cylinder 234: Knife case 235: Knife horizontal movement mechanism 250: Stepper motor 2341: Knife protrusion slit 2342: Horizontal guide slit 2351: Guide arm 2352: Rack gear 2353: Pinion gear 2354 : Horizontal rotation axis 2355 : Servo motor

Claims

Claim 1 A conveyor for transporting bodyfly fabric is provided, and two or more servicers are arranged side by side; a support stand is placed between the servicers; and a knife is placed at the bottom of the support stand. and, a knife lifting mechanism for raising and lowering the knife so that the knife passes through the base; wherein the knife comprises at least one first knife forming a cut line on the front end of the body fly being transported toward the base, and at least one second knife forming a cut line on the rear end of the body fly passing through the base; wherein the base has a knife moving groove formed therein through which the first knife and the second knife can pass; wherein a plurality of knife cases are installed on the upper part of the base, corresponding to the shape of the knife and having a thickness greater than the thickness of the knife; wherein a knife protrusion slit is formed on the front side facing the front end of the body fly and on the rear side facing the rear end of the body fly, respectively, through which the knife can protrude or be retracted; wherein the knife embedded so as to protrude into the knife case has a sharply machined cutter part formed in both the direction facing the front end of the body fly and the direction facing the rear end, wherein the first knife corresponds to the cutter part facing the front end, and the second knife corresponds to the cutter part facing the rear end A body fly cord cutting device corresponding to a cutter part, characterized in that the first knife and the second knife are integrally formed with a support part in the form of a thin rigid plate having the same thickness as the first and second knives. Claim 2 A body fly cord cutting device according to claim 1, wherein the knife lifting mechanism comprises a lifting plate that supports the knife in an upright position and a driving cylinder that moves the lifting plate in an up and down direction, wherein the first knife is installed such that a cutter portion sharpened from the first knife is directed toward the front end of the body fly on the upper part of the lifting plate, and the second knife is installed such that a cutter portion sharpened from the first knife is directed toward the rear end of the body fly that has passed through the support base on the upper part of the lifting plate, and wherein a length measuring sensor is installed on the support base to measure the transport distance of the body fly so that the front or rear end of the body fly being transported to the servo is accurately positioned at the part to be cut by the knife. Claim 3 delete Claim 4 A body fly cord cutting device according to claim 1, wherein the knife case is provided with a knife horizontal movement mechanism that varies the first knife or the second knife so that it protrudes into either of the knife protrusion slits, the knife horizontal movement mechanism moves the support member in the direction of travel or opposite to travel of the body fly to protrude the first or second knife, the knife horizontal movement mechanism includes a guide arm fixedly formed at a predetermined part of the support member and protruding outside the knife case, the knife case has a horizontal guide slit formed as a passage through which the guide arm can move in a horizontal direction, and the knife horizontal movement mechanism moves the guide arm horizontally. Claim 5 In claim 4, the knife horizontal movement mechanism comprises a rack gear connected to the guide arm and formed lengthwise along the horizontal movement direction of the first or second knife, a pinion gear meshing with the rack gear, a servo motor that rotates the pinion gear, and a pinion gear horizontal rotation axis that passes through all the knife cases and rotates the pinion gear provided in each knife case, wherein the knife case is capable of passing through the knife movement groove, and the rotation axis is provided with a step motor that moves the entire horizontal movement mechanism horizontally in the lateral direction by moving the rotation axis horizontally in a lateral direction perpendicular to the direction of travel of the body fly, such that the positions of the first cutting line and the second cutting line formed by the first knife and the second knife are formed to be staggered from each other, the distance the step motor moves the rotation axis horizontally corresponds to the spacing of the movement groove, and the movement groove is formed to be twice the number of knife cases. Claim 6 delete

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