JP2021102913A - Ball splitting method for splitting ball part fitted on cord part of string member and ball splitting tool - Google Patents

Abstract

To relatively easily split different-pitch ball parts without damaging a cord part.SOLUTION: A cord part 12 formed in a string shape is connected by a connecting member 20 to make up a string member 11. A ball splitting method for ball parts fitted on the cord part of the string member includes: a step where blades 42b, 42b of a pair of ball-splitting molds 42a, 42a abut on outer peripheral surfaces of different-pitch ball parts 13 among a plurality of ball parts 13 used for a mechanism preventing the string member from falling off the connecting member; and a step where a force-applying mechanism applies a force to the pair of ball-splitting molds 42a, 42a in a direction in which the pair of blades 42b, 42b get close to each other to split the different-pitch ball parts 13. A distance between tips of each of the pair of blades 42b, 42b is formed so as to become slightly larger than a diameter of the cord part 12 when the pair of blades 42b, 42b get closest to each other.SELECTED DRAWING: Figure 5

Description

In the present invention, a ball portion fitted to a cord portion of a string-shaped member composed of an operation chain or an operation cord or an elevating cord for raising and lowering a shield to be operated when opening and closing a roll screen, a horizontal blind, a vertical blind, etc. It relates to a method of breaking and a ball breaking tool thereof.

Conventionally, as a connection structure of this type of operation member, a method of manufacturing an operation cord connector for connecting an operation cord at an intermediate portion (see, for example, Patent Document 1) or an endless shape in which both ends are connected by a connecting portion. A ball chain (see, for example, Patent Document 2) and an endless cord in which both ends are connected by connecting portions (see, for example, Patent Document 3) are disclosed.

In the method for manufacturing an operation cord connector shown in Patent Document 1, the first connecting member to which the first operation cord is attached and the second connecting member to which the second operation cord is attached are elastically fitted. An endless operation code composed of a first operation code and a second operation code is configured to be connected at an intermediate portion. Further, the first connecting member or the second connecting member is outsert-molded at at least one of the first operation code and the second operation code at predetermined intervals. By cutting the first operation cord or the second operation cord at the tip edge of the outsert-molded first connection member or the second connection member, the first operation cord or the second connection member provided with the first connection member can be obtained. The provided second operation code is formed. Further, the first connecting member is a male type member, and the second connecting member is a female type member.

In the method of manufacturing the operation cord connector configured in this way, the male member is attached to the end of the operation cord by outsert molding the male member to the operation cord, and the insertion hole of the female member is inserted. By attaching the caulking member to the end of the operation cord inserted into, the female member is attached to the end of the operation cord. As a result, it is not necessary to store the knot or the like in the male-shaped member and the female-shaped member, and the caulking member has substantially the same diameter as the operation cord. Can be miniaturized. Further, by outsert-molding male members on the operation cord at predetermined intervals and cutting the operation cord at the tip of the male member, a large number of male members having the same length of operation cord can be easily formed. it can. As a result, if the operation cord provided with the male-shaped member is attached to the bottom rail, a large number of horizontal blinds having a constant distance between the bottom rail and the connector can be easily assembled.

In the ball chain shown in Patent Document 2, a ball chain is formed by forming synthetic resin balls on a cord at equal intervals and fixing them, and by connecting both ends of the ball chain with connecting portions, the balls are formed. The chain is formed endlessly. Further, the connecting portion includes a fitting portion having the same shape as the ball. This fitting portion is composed of a first fitting portion having a fitting protrusion of a solid body and a second fitting portion having a fitting hole into which the fitting protrusion can be fitted. Then, the fitting protrusion is formed so that it can be elastically fitted and removed from the fitting hole. Further, the connecting portion includes a connecting member having a fitting protrusion at one end of the first connecting cord and a connecting member having a fitting hole at one end of the second connecting cord. Then, a ball is formed by welding the hemisphere portion provided at the other end of each connecting cord and the hemisphere portion provided at the end portion of the cord. Further, the fitting protrusion is outsert-molded at one end of the first connecting cord. Specifically, a hemispherical portion having a shape slightly larger than half of the ball is outsert-molded at one end of the first connecting cord, and the first fitting portion is solidified to the tip of the other end of the first connecting cord. Outsert molded to.

In the ball chain configured in this way, balls of the same shape are formed at the same interval over the entire length of the cord of the ball chain and the connecting cord of the connecting portion. Can be raised and lowered. In addition, when a large tensile force exceeding the normal tensile force is applied to the ball chain, the fitting protrusion of the connecting portion and the fitting hole are disengaged, so that the endless edge of the ball chain moves in the room. When caught in other moving objects, the ball chain can be cut at the connecting portion to ensure the safety of the resident and prevent damage to the pulley or the like on which the ball chain is hung. Further, since the first fitting portion is outsert-molded with a solid body so that the connecting cord is embedded from the tip end to the base end, sufficient joint strength between the first fitting portion and the connecting cord is ensured. Can be done.

In the cord shown in Patent Document 3, a ball chain is formed by forming balls on the cord at equal intervals, both ends of the cord are connected by a connecting portion, and a pair of axial fittings of the connecting portion are fitted. A collision portion is provided at both ends of the cord, and a single tubular connecting member of the connecting portion is configured to be fitted with the pair of fitting protrusions facing each other. Further, the fitting protrusion and the connecting member are formed of synthetic resin, and a bulging portion having a diameter larger than that of the base end portion of the fitting protrusion is provided at the tip of the fitting protrusion. A locking portion that engages with the expanded diameter portion is provided by inserting the expanded diameter portion into the openings on both sides of the connecting member, and the engaging position between the locking portion and the expanded diameter portion at the openings on both sides of the connecting member. Is relatively displaced in the circumferential direction of the connecting member. Further, the fitting protrusion is outsert-molded to the connecting cord of the connecting portion.

In the cord configured in this way, balls of the same shape are formed at the same interval over the entire length of the cord of the ball chain and the connecting cord of the connecting portion. Therefore, the ball chain is rotated around the pulley without limitation to raise and lower the slats. Can be operated. Further, since the operating force for fitting the fitting protrusion to the cylindrical connecting member is small, the fitting protrusion can be refitted to the connecting member without using a tool, so that the connecting portion can be fitted. Even if it comes off, the resident can easily return it. Further, the fitting protrusion can be easily outsert-molded to the end of the connecting cord.

However, in the method for manufacturing the operation cord connector shown in the conventional patent document 1, the ball chain shown in the conventional patent document 2, or the cord shown in the conventional patent document 3, the first connection is made. Since the device for outsert molding the member, the first fitting part or the fitting protrusion is large and extremely heavy, it is not suitable for carrying or moving. 1 There was a problem that the connecting member and the like could not be outsert molded. Further, in the ball chain shown in the conventional Patent Document 2, a male-shaped first connecting member having a fitting protrusion and a female having a fitting hole to be fitted to the fitting protrusion are formed. Two types of connecting members with a second connecting member having a shape are required, and in the cord shown in the conventional Patent Document 3, a pair of first connecting members having the same shape in which fitting protrusions are formed and a pair of first connecting members having the same shape are used. Since two types of connecting members with a single tubular second connecting member having a fitting hole into which these fitting protrusions are fitted are required, a molding mold for these connecting members is required. Since they must be manufactured separately, there is a problem that the number of processing steps increases and the number of parts increases, which makes parts management complicated. Further, in the ball chain shown in the conventional patent document 2, the hemisphere portion of the first connecting member and the hemisphere portion of the second connecting member are welded and fixed to a pair of hemisphere portions formed at both ends of the cord. Therefore, if it becomes necessary to shorten the length of the ball chain after these welding and fixing, it is necessary to break one of the above two welding and fixing portions to make a hemispherical portion again, and then the ball chain is determined. A hemisphere must be formed at the end of the ball chain by cutting to the length of the ball chain, and the hemispheres must be welded and fixed again. There was also the problem that the difficulty of the work was high. Further, the code shown in the conventional Patent Document 3 has a problem that a large number of man-hours are required to shorten the length of the code as in the case of the above-mentioned Patent Document 2.

In order to solve these problems, the operation chain has a single cord portion formed in a string shape and a plurality of ball portions fixed at intervals in the longitudinal direction of the cord portion, and this operation is performed. A connecting structure of an operating chain is disclosed in which an operating chain is formed in an endless ring shape by connecting both ends of the chain with connecting members (see, for example, Patent Document 4). In this operation chain connecting structure, the connecting member has a first connecting piece having a substantially U-shaped first connecting body and a base attached to one end of the operating chain, and a substantially U-shaped second connecting body. The holding base is attached to the other end of the operation chain and is composed of a second connecting piece formed in the same shape as the first connecting piece. Further, the tips of the first and second connecting pieces are opposed to each other, and the first and second connecting pieces are engaged with each other in a state where the first or second connecting piece is rotated 90 degrees around the axis of the cord portion. When combined, the outer shapes of the first and second connecting pieces are configured to have substantially the same shape as the outer shape of the ball portion. Further, the cord portion of the operation chain is formed of a thermoplastic resin, and the first retaining portion is a first flange portion formed by thermally deforming one end of the cord portion to have a diameter larger than that of the cord portion, and the second retaining portion is formed. The portion is a second flange portion formed by thermally deforming the other end of the cord portion to have a diameter larger than that of the cord portion.

In the connecting structure of the operation chain configured in this way, the first and second connecting pieces are formed in the same shape, respectively, and these connecting pieces are united so as to have substantially the same outer shape as the ball portion. , The first and second connecting pieces can be manufactured with a single molding die, the man-hours for processing by the die can be reduced, and the number of parts can be reduced. Further, one end of the cord portion protruding from the first through hole is thermally deformed to form a first flange portion having a diameter larger than the diameter of the cord portion, and the other end of the cord portion protruding from the second through hole is thermally deformed. Since the second flange portion having a diameter larger than the diameter of the cord portion is formed, the first connecting piece cannot be pulled out from one end of the cord portion, and the second connecting piece cannot be pulled out from the other end of the cord portion.

Japanese Patent No. 5376733 (claims 1 and 2, paragraphs [0025], FIGS. 1 to 3) Japanese Patent No. 5442331 (claims 1 and 2, paragraphs [0024], [0034], FIGS. 2 to 4) Japanese Patent No. 5439055 (claims 1 and 6, paragraphs [0020], [0033], FIGS. 2 to 5) JP-A-2015-30992 (Claims 1 and 4, paragraphs [0017], FIGS. 1 to 3)

However, in the conventional operation chain connection structure shown in Patent Document 4, since the first flange portion and the second flange portion having a diameter larger than that of the cord portion are formed by thermal deformation of the cord portion, the first flange When the strength of the first neck part of the part and the second neck part of the second flange part varies greatly and tension is applied to the cord part, before the engagement between the first connecting piece and the second connecting piece is released, The first flange portion or the second flange portion may be damaged at the first neck portion or the second neck portion.

The purpose of the present invention, without damaging the code portion of the string member, relatively easily different pitches, it is possible to divide the ball portion is fitted into the code portion, the ball portion of the string member It is an object of the present invention to provide a ball splitting method for a fitted ball portion and a ball splitting tool thereof.

The first aspect of the present invention, as shown in FIG. 5, a plurality of balls 13 for use in retaining structure from the connecting member of the string-shaped members connecting the connecting member code portion formed in string-like Of these, the step of bringing the blades 42b and 42b of the pair of ball splitting molds 42a and 42a into contact with the outer peripheral surfaces of the ball portions 13 having different pitches, and the pair of force applying mechanisms in the direction of bringing the pair of blades 42b and 42b closer to each other. A method of splitting balls fitted to the ball portions of a string-shaped member, which includes a step of applying force to the ball splitting molds 42a and 42a to split the ball portions 13 having different pitches, wherein the pair of blades 42b , 42b, when the distance between the tips of the pair of blades 42b, 42b is formed to be slightly larger than the diameter of the cord portion 12, the ball fitted to the ball portion of the string-shaped member. It is a method of splitting the ball of the part .

A second aspect of the present invention is, as shown in FIG. 5, a plurality of ball portions 13 used for a structure for retaining a cord-shaped member from a connecting member, which connects the cord-shaped cord portions with a connecting member. Among them, a pair of ball splitting molds 42a and 42a in which blades 42b and 42b abutting on the outer peripheral surfaces of ball portions 13 having different pitches are formed, and the blades 42b and 42b of these ball splitting molds 42a and 42a are brought closer to each other. A ball splitting tool for a ball portion fitted to a ball portion of a string-shaped member provided with a force applying mechanism for applying a force to the pair of ball splitting molds 42a, 42a, and the pair of blades 42b, 42b are closest to each other. When the ball splitting tool is fitted to the ball portion of the string-shaped member, the distance between the tips of the pair of blades 42b, 42b is formed to be slightly larger than the diameter of the cord portion 12. There is .

In the ball splitting method according to the first aspect of the present invention or the ball splitting tool according to the second aspect of the present invention, when the pair of blades are closest to each other, the distance between the tips of the pair of blades is calculated from the diameter of the cord portion. Since it is formed to be slightly larger, by using this ball splitting method or tool, it is possible to split the ball portions having different pitches relatively easily without damaging the cord portion. As a result, it is possible to contribute to the reduction of work man-hours when shortening the length of the cord portion.

FIG. 3 is a cross-sectional view taken along the line AA of FIG. 3 showing a connecting structure of an operation chain according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view taken along the line BB of FIG. It is a main part perspective view which shows the state just before the 1st connection piece and the 2nd connection piece of the connection member of an operation chain are engaged. FIG. 5 is a cross-sectional view of a main part showing a procedure for forming first and second flange portions at one end and the other end of the cord portion by thermally deforming one end and the other end of the cord portion of the operation chain with a thermoforming tool. It is a main part perspective view which shows the procedure of dividing a ball part with a different pitch by a ball splitting type. It is a front view of the roll screen to which the operation chain is attached. It is sectional drawing corresponding to FIG. 1 which shows the connection structure of the operation code of 2nd Embodiment of this invention. It is sectional drawing corresponding to FIG. It is a perspective view of the horizontal blind to which the operation code is attached. FIG. 5 is a cross-sectional view of a main part showing a procedure for forming first and second flange portions at one end and the other end of the cord portion by thermally deforming one end and the other end of the cord portion according to the third embodiment of the present invention with a thermoforming tool. .. A perspective view showing a procedure for forming first and second flange portions at one end and the other end of the cord portion by thermally deforming one end and the other end of the cord portion of the operation chain according to the fourth embodiment of the present invention with a thermoforming tool. It is a figure. FIG. 5 is a cross-sectional view corresponding to FIG. 7, showing a structure for retaining a cord portion from a connecting member according to a fifth embodiment of the present invention. FIG. 6 is a cross-sectional view taken along the line CC of FIG. 14 showing a structure for retaining a cord portion from a connecting member according to a sixth embodiment of the present invention. It is a cross-sectional view taken along the line DD of FIG. (A) is an enlarged perspective view of part E of FIG. 16 showing a state immediately before the first and second connecting pieces are combined, and (b) is a state of combining the first and second connecting pieces of FIG. It is an enlarged perspective view of part E. It is a perspective view of the Roman shade including the 1st and 2nd cord portions and a string-like member.

Next, a mode for carrying out the present invention will be described with reference to the drawings.

<First Embodiment>
As shown in FIGS. 1 to 3, in this embodiment, the string-shaped member 11 is fixed to a single cord portion 12 formed in a string shape at intervals in the longitudinal direction of the cord portion 12. It is an operation chain having a plurality of ball portions 13. The connection structure of the operation chain 11 includes the operation chain 11 and a connecting member 20 in which the operation chain 11 is formed into an endless ring-shaped chain by connecting both ends of the operation chain 11. The cord portion 12 is formed of a braided cord or a twisted cord of a thermoplastic resin such as polyester, and the ball portion 13 is formed of a thermoplastic resin such as polyacetal or acrylic. By forming the cord portion 12 with a braided cord or a twisted cord of a thermoplastic resin such as polyester, both ends of the cord portion 12 can be easily thermally deformed. Further, the ball portion 13 is formed in a substantially spheroidal shape extending in the longitudinal direction of the cord portion 12. That is, the ball portion 13 has a shape of a rotating body obtained with the long axis of the ellipse as the rotation axis, and is formed in a shape in which the long axis coincides with the axis of the cord portion 12. Further, the operation chain 11 is formed by first forming the cord portion 12 and then forming the ball portion 13 on the cord portion 12 and heat-sealing them (FIGS. 1 and 2). Therefore, only the ball portion 13 of the operation chain 11 can be broken and removed, and only the cord portion 12 can be left.

On the other hand, the connecting member 20 includes a first connecting piece 21 whose base is attached to one end of the operation chain 11 and a second connecting piece 22 whose base is attached to the other end of the operation chain 11 (FIGS. 1 to 1). 3). The first connecting piece 21 is a first connecting main body 21a having a substantially U-shaped outer peripheral surface formed in an arc shape, and a first connecting main body 21a formed at the base of the first connecting main body 21a and capable of being loosely fitted to one end of the cord portion 12. It has a through hole 21b and a pair of elastically deformable first locking portions 21c and 21c formed at both the tips of the first connecting main body 21a (FIGS. 1 and 2). The second connecting piece 22 is loosely fitted to the other end of the cord portion 12 formed at the base of the second connecting main body 22a and the second connecting main body 22a having a substantially U-shaped outer peripheral surface formed in an arc shape. It has a possible second through hole 22b and a pair of elastically deformable second locking portions 22c and 22c formed at both the tips of the second connecting main body 22a, respectively. The first connecting piece 21 and the second connecting piece 22 are formed in exactly the same shape, that is, the first connecting piece 21 and the second connecting piece 22 are formed in the same shape and the same size. Therefore, since the first connecting piece 21 and the second connecting piece 22 are molded by a single molding die, the man-hours for molding the first connecting piece 21 and the second connecting piece 22 can be reduced, and the number of parts can be reduced. it can. Here, the fact that the outer peripheral surfaces of the first and second connecting bodies 21a and 22a are formed in an arc shape is a cross section cut by a surface orthogonal to the hole centers of the first and second through holes 21b and 22b. It means that the outer peripheral surfaces of the first and second connecting bodies 21a and 22a are formed in an arc shape (FIG. 3). In addition, in this specification, the same shape means the same shape and the same size.

Further, the first connecting piece 21 is formed with a pair of first locked portions 21d and 21d that can be locked by elastically deforming the pair of second locking portions 22c and 22c, respectively, and the second connecting piece 22 is formed. Is formed by elastically deforming the pair of first locking portions 21c and 21c to form a pair of second locked portions 22d and 22d that can be locked (FIGS. 1 to 3). The second locking portion 22c is formed in a hook shape having a predetermined width, and the first locked portion 21d is formed in a concave shape having a predetermined width and in which the hook-shaped second locking portion 22c is locked. (Fig. 1 and Fig. 2). Further, the first locking portion 21c is formed in a hook shape having a predetermined width, and the second locked portion 22d is formed in a concave shape having a predetermined width and in which the hook-shaped first locking portion 21c is locked. Will be done. The second locking portion 22c and the first locking portion 21c are formed in the same shape, and the first locked portion 21d and the second locked portion 22d are formed in the same shape.

On the other hand, a first flange portion 12a is formed at one end of the cord portion 12 into which the first through hole 21b of the first connecting piece 21 is loosely fitted, and the first connecting piece 21 is the cord portion 12 of the first flange portion 12a. It has a function of preventing the detachment from one end of the flange (FIGS. 1 and 2). A second flange portion 12b is formed at the other end of the cord portion 12 into which the second through hole 22b of the second connecting piece 22 is loosely fitted, and the second connecting piece 22 is the cord portion 12 of the second flange portion 12b. It has a function of preventing the detachment from the other end of the. In this embodiment, since the cord portion 12 is formed of the thermoplastic resin as described above, the first flange portion 12a is formed to have a diameter larger than that of the cord portion 12 by thermally deforming one end of the cord portion 12. The second flange portion 12b is formed to have a diameter larger than that of the cord portion 12 by thermally deforming the other end of the cord portion 12.

Further, the first neck portion 12c of the first flange portion 12a is formed with a first diameter gradually increasing portion 12e that gradually increases from the cord portion 12 toward the first flange portion 12a, and the second neck portion 12d of the second flange portion 12b. A second diameter gradual increase portion 12f that gradually increases from the cord portion 12 toward the second flange portion 12b is formed in (FIGS. 1 and 2). In this embodiment, the first diameter gradual increase portion 12e and the second diameter gradual increase portion 12f are formed in a substantially truncated cone shape having a taper angle of less than 90 degrees. That is, in the first diameter gradual increase portion 12e and the second diameter gradual increase portion 12f, the length of the cord portion 12 in the longitudinal direction is formed in a tapered shape longer than the length of the cord portion 12 in the radial direction. Further, in this embodiment, since the cord portion 12 is formed of a braided cord or a twisted cord of a thermoplastic resin, each fiber in the first diameter gradual increasing portion 12e and the second diameter gradual increasing portion 12f melts at the time of thermal deformation. The first diameter gradual increase portion 12e and the second diameter gradual increase portion 12f are formed so as to remain without being formed. In this embodiment, the operation chain 11 is wound around a sprocket 33 provided at the end of a take-up pipe 32 for winding the screen body 31 of the roll screen 30 so as to be unwound (FIG. 6). Further, the take-up pipe 32 is rotatably held by a pair of brackets 34, 34, and these brackets 34, 34 are attached to the ceiling 38 via a single set bar 36 and a pair of mounting brackets 37, 37. ..

On the other hand, in order to thermally deform one end and the other end of the cord portion 12 to form the first flange portion 12a and the second flange portion 12b, respectively, the thermoforming tool 41 of the cord portion 12 is used (FIG. 4). The thermoforming tool 41 of the cord portion 12 has a pair of metal clamp molds 41a and 41a for gripping the vicinity of the end portion of the cord portion 12 and the end portions of the cord portion 12 protruding from these clamp molds 41a and 41a. A metal molding die 41b for thermally deforming the first flange portion 12a and the second flange portion 12b, respectively, is provided. Then, a pair of clamps having tapered surfaces 41c for forming the first diameter gradual increase portion 12e and the second diameter gradual increase portion 12f on the first neck portion 12c of the first flange portion 12a and the second neck portion 12d of the second flange portion 12b, respectively. It is formed in molds 41a and 41a. Further, in order to attach the first connecting piece 21 or the second connecting piece 22 to one end or the other end of the linear cord portion 12, a ball that breaks the ball portion 13 located at one end or the other end of the linear cord portion 12. A split tool 42 is used (FIG. 5). The ball splitting tool 42 includes a pair of metal ball splitting molds 42a and 42a on which blades 42b and 42b abutting on the outer peripheral surface of the ball portion 13 are formed, and blades 42b of these ball splitting molds 42a and 42a. A force applying mechanism (not shown) for applying a force to the pair of ball splitting molds 42a and 42a in a direction in which the 42b is brought closer to each other is provided. Then, when the pair of blades 42b, 42b are closest to each other, the distance between the tips of the pair of blades 42b, 42b is formed to be slightly larger than the diameter of the cord portion 12. It is preferable that the pair of clamp types 41a and 41a are provided at the tip of pliers (grip scissors type tool). Further, it is preferable that the pair of blades 42b, 42b are provided at the tip of the pliers, and the force applying mechanism is used as the grip portion of the pliers. Therefore, it is more preferable that the pair of clamp molds 41a and 41a and the pair of blades 42b and 42b are provided at the tip portions of the single pliers, respectively, and the force applying mechanism is used as the grip portion of the single pliers.

A method of connecting the operation chains 11 configured in this way in the manufacturing process will be described with reference to FIGS. 1 to 5. First, a linear operation chain 11 cut to a predetermined length is prepared. Next, the ball portion 13 at one end of the cord portion 12 of the operation chain 11 is divided by the ball splitting tool 42 and removed (FIG. 5). Specifically, the direction in which the blades 42b, 42b of the pair of ball splitting molds 42a, 42a of the ball splitting tool 42 are brought into contact with the outer peripheral surface of the ball portion 13, and the pair of blades 42b, 42b are brought closer to each other by the force applying mechanism. When a force is applied to the pair of ball splitting molds 42a and 42a, the ball portion 13 is cracked and the ball portion 13 can be removed from the cord portion 12. When the pair of blades 42b, 42b are closest to each other, the distance between the tips of the pair of blades 42b, 42b is formed to be slightly larger than the diameter of the cord portion 12, so that the cord portion 12 is not damaged. Then, the cord portion 12 is cut at a position substantially centered on the removed ball portion 13.

Next, after the first through hole 21b of the first connecting piece 21 is loosely fitted to one end of the cord portion 12 (FIG. 4A), the cord portion 12 protruding from the first through hole 21b of the first connecting piece 21. Is gripped by a pair of clamp molds 41a and 41a of the thermoforming tool 41 (FIG. 4B). In this state, after heating and melting one end of the cord portion 12 protruding from the pair of clamp molds 41a and 41a, when the molding mold 41b is pressed against the upper surface of the pair of clamp molds 41a and 41a, one end of the cord portion 12 is pressed. Is thermally deformed, and a first flange portion 12a having a diameter larger than the diameter of the cord portion 12 is formed at one end of the cord portion 12. At this time, a substantially truncated cone-shaped first diameter gradually increasing portion 12e is also formed on the first neck portion 12c of the first flange portion 12a. Then, when the pair of clamp molds 41a and 41a are removed after removing the molding die 41b from one end of the cord portion 12 (FIG. 4 (c)), the first connecting piece 21 cannot be removed from the cord portion 12 (FIG. 4). (D)), The distance between the first connecting piece 21 and the ball portion 13 adjacent to the first connecting piece 21 is substantially the same as the distance between the other adjacent ball portions 13. In this embodiment, since the cord portion 12 is a braided cord or a twisted cord made of a thermoplastic resin, the first diameter is such that each fiber in the first diameter gradually increasing portion 12e remains without being melted during thermal deformation. The gradual increase portion 12e is formed.

In the same manner as described above, the ball portion 13 at the other end of the cord portion 12 was split and removed by the ball splitting tool 42 (FIG. 5), and the cord portion 12 was cut at a position substantially center of the removed ball portion 13. Later, the second through hole 22b of the second connecting piece 22 is loosely fitted to the other end of the cord portion 12 (FIG. 4A), and the cord portion 12 projecting from the second through hole 22b of the second connecting piece 22. The other end of the cord portion 12 is thermally deformed by the thermoforming tool 41 to form a second flange portion 12b having a diameter larger than the diameter of the cord portion 12 at the other end of the cord portion 12 (FIGS. 4 (b) and (c)). .. At this time, a substantially truncated cone-shaped second diameter gradually increasing portion 12f is also formed on the second neck portion 12d of the second flange portion 12b. As a result, the second connecting piece 22 cannot be pulled out from the cord portion 12 (FIG. 4D), and the distance between the second connecting piece 22 and the ball portion 13 adjacent to the second connecting piece 22 is adjacent to the other. The distance between the ball portions 13 is substantially the same. In this embodiment, since the cord portion 12 is a braided cord or a twisted cord made of a thermoplastic resin, the second diameter is such that each fiber in the second diameter gradually increasing portion 12f remains without being melted during thermal deformation. The gradual increase portion 12f is formed.

Then, the tips of the first and second connecting pieces 21 and 22 are opposed to each other, and either one of the first or second connecting pieces 21 and 22 is rotated 90 degrees around the axis of the cord portion 12 ( FIG. 3), the second locking portion 22c is elastically deformed and locked to the first locked portion 21d, and the first locking portion 21c is elastically deformed and locked to the second locked portion 22d. The first and second connecting pieces 21 and 22 are engaged and united (FIGS. 1 and 2). As described above, the operation chain 11 can be formed into an endless ring shape by an extremely simple operation, and the outer shapes of the first and second connecting pieces 21 and 22 are substantially the same as the outer shape of the ball portion 13. When the endless operation chain 11 is hung on the sprocket 33 of the roll screen 30, the connecting member 20 functions as one of the plurality of ball portions 13, and the operation chain 11 can be operated smoothly.

Further, a substantially truncated cone shape that gradually increases from the cord portion 12 toward the first flange portion 12a and the second flange portion 12b on the first neck portion 12c of the first flange portion 12a and the second neck portion 12d of the second flange portion 12b. Since the first diameter gradual increase portion 12e and the second diameter gradual increase portion 12f of the above are formed respectively, even if tension acts on the operation chain 11 connected by the connecting member 20, the first cervical portion 12c and the second cervical portion 12d are generated. The stress is dispersed. As a result, no concentrated stress is generated in the first neck portion 12c and the second neck portion 12d, and the connecting strength of the connecting member 20 when the operation chain 11 is connected by the connecting member 20 can be increased. Further, the cord portion 12 is a braided cord or a twisted cord made of a thermoplastic resin, and the first diameter is such that the fibers in the first diameter gradual increase portion 12e and the second diameter gradual increase portion 12f remain without being melted during thermal deformation. Since the gradual increase portion 12e and the second diameter gradual increase portion 12f are formed, respectively, even if tension acts on the operation chain 11 connected by the connecting member 20, each of the first diameter gradual increase portion 12e and the second diameter gradual increase portion 12f is formed. The fibers have a strength that can sufficiently withstand the above tension, and the connecting strength of the connecting member 20 when the operating chain 11 is connected by the connecting member 20 can be further increased.

Next, a procedure for shortening the total length of the endless ring-shaped operation chain 11 will be described. First, the first and second connecting pieces 21 and 22 are disengaged, and either one of the first or second flange portions 12a and 12b is cut from the cord portion 12 to cut the first or second connecting piece 21. , 22 is removed. In this embodiment, an example of removing the first connecting piece 21 from one end of the cord portion 12 is shown. The ball portion 13 on one end side of the cord portion 12 is split and removed so that the total length of the operation chain 11 becomes a desired length, and then one end side of the cord portion 13 is cut. Specifically, the ball portion 13 existing at a position where the total length of the operation chain 11 has a desired length is divided by the ball splitting tool 42 and removed (FIG. 5), and the removed ball portion 13 is substantially at the center. The cord portion 12 is cut at the position. Then, the first through hole 21b of the removed first connecting piece 21 is loosely fitted to one end of the cord portion 12 (FIG. 4A). Next, one end of the cord portion 12 protruding from the first through hole 21b is thermally deformed by the thermoforming tool 41 to form a first flange portion 12a having a diameter larger than the diameter of the cord portion 12 at one end of the cord portion 12. (FIGS. 4 (b) to 4 (e)). At this time, a substantially truncated cone-shaped first diameter gradually increasing portion 12e is also formed on the first neck portion 12c of the first flange portion 12a. As a result, the first connecting piece 21 cannot be pulled out from the cord portion 12 (FIG. 4 (f)), and the distance between the first connecting piece 21 and the ball portion 13 adjacent to the first connecting piece 21 is adjacent to the other. The distance between the ball portions 13 is substantially the same. In this embodiment, since the cord portion 12 is a braided cord or a twisted cord made of a thermoplastic resin, the first diameter is such that each fiber in the first diameter gradually increasing portion 12e remains without being melted during thermal deformation. The gradual increase portion 12e is formed.

Then, the tips of the first and second connecting pieces 21 and 22 are opposed to each other, and either one of the first or second connecting pieces 21 and 22 is rotated 90 degrees around the axis of the cord portion 12 ( FIG. 5), the second locking portion 22c is elastically deformed and locked to the first locked portion 21d, and the first locking portion 21c is elastically deformed and locked to the second locked portion 22d. The first and second connecting pieces 21 and 22 are engaged and united (FIGS. 1 and 2). As a result, the first and second connecting pieces 21 and 22 can be engaged with each other to form the operation chain 11 into an endless ring shape again. In this way, even after the first and second connecting pieces 21 and 22 are engaged to form an endless ring, the length of the operation chain 11 can be shortened relatively easily with a simple operation. it can.

<Second embodiment>
7 to 9 show a second embodiment of the present invention. In FIGS. 7 and 8, the same reference numerals as those in FIGS. 1 and 2 indicate the same parts. In this embodiment, the string-shaped member 61 is an operation code having two cord-shaped cord portions 62 and 63 (FIGS. 7 and 8), and the string-shaped member 61 is attached to the horizontal blind 60. (Fig. 9). The horizontal blind 60 includes a head rail 64 attached to a ceiling, a wall, or a window frame, and a plurality of ladder tapes 66 hanging from the head rail 64 at intervals in the longitudinal direction and the front-rear direction of the head rail 64. A plurality of slat 67s arranged vertically at predetermined intervals between these ladder tapes 66 and extending in the horizontal direction, and a bottom provided below the lowermost slat 67 among the plurality of slat 67s. A rail 68 and a plurality of elevating cords 69 having one end attached to the bottom rail 68 and loosely inserted into each slat 67 and the head rail 64 and the other end protruding from the head rail 64 are provided.

One end of one of the two cord portions 62 and 63 is connected to the other end of the plurality of elevating cords 69, and one end of the other cord portion 63 is attached to the bottom rail 68 (FIG. 9). .. Further, the other end of one cord portion 62 and the other end of the other cord portion 63 are connected by a connecting member 20. The connecting member 20 is formed in the same manner as the connecting member of the first embodiment. That is, the connecting member 20 has the same shape as the first connecting piece 21 whose base is attached to the other end of one cord portion 62 and whose base is attached to the other end of the other cord portion 63. (FIGS. 7 and 8), the outer shape of the first connecting piece 21 and the second connecting piece 22 when the first connecting piece 21 and the second connecting piece 22 are united. Is configured to be a substantially spheroid (Fig. 9). The first connecting piece 21 is prevented from coming off from the one cord portion 62 by thermally deforming the other end of the one cord portion 62 to form the first flange portion 62a having a diameter larger than the diameter of the one cord portion 62. The second connecting piece 22 cannot be removed from the other cord portion 63 by thermally deforming the other end of the other cord portion 63 to form the second flange portion 63a having a diameter larger than the diameter of the other cord portion 63 ( 7 and 8). Further, the two cord portions 62 and 63 are, in this embodiment, a braided cord or a twisted cord of a thermoplastic resin, and the first diameter gradually increasing portion 62c formed on the first neck portion 62b of the first flange portion 62a. Is formed in a substantially truncated cone shape like the first diameter gradual increase portion of the first embodiment, and the second diameter gradual increase portion 63c formed on the second neck portion 63b of the second flange portion 63a is the first embodiment. It is formed in a substantially truncated cone shape like the second diameter gradually increasing portion of the form. Then, the first diameter gradual increase portion 62c and the second diameter gradual increase portion 63c are formed so that the fibers in the first diameter gradual increase portion 62c and the second diameter gradual increase portion 63c remain without being melted at the time of thermal deformation, respectively. .. Other than the above, the configuration is the same as that of the first embodiment.

A method of connecting the operation codes 61 configured in this way in the manufacturing process will be described. First, two linear cord portions 62 and 63 cut to a predetermined length are prepared. Next, after loosely fitting the first through hole 21b of the first connecting piece 21 into the other end of one of the two cord portions 62, 63, the first through hole 21b of the first connecting piece 21 One of the cord portions 62 protruding from the surface is gripped by a pair of clamp molds of a thermoforming tool. In this state, when the other end of one cord portion 62 protruding from the pair of clamp molds is heated and melted, and then the molding die is pressed against the upper surface of the pair of clamp molds, the other end of the one cord portion 62 heats up. By deformation, a first flange portion 62a having a diameter larger than the diameter of the cord portion 62 is formed at the other end of one cord portion 62. At this time, a substantially truncated cone-shaped first diameter gradually increasing portion 62c is also formed on the first neck portion 62b of the first flange portion 62a. Then, if the molding die is removed from the other end of one cord portion 62 and then the pair of clamp molds is removed, the first connecting piece 21 cannot be removed from the one cord portion 62. In this embodiment, since the cord portion 62 is a braided cord or a twisted cord made of a thermoplastic resin, the first diameter is such that each fiber in the first diameter gradually increasing portion 62c remains without being melted at the time of thermal deformation. A gradual increase portion 62c is formed.

In the same manner as described above, the second through hole 22b of the second connecting piece 22 is loosely fitted into the other end of the other cord portion 63 of the two cord portions 62 and 63, and further, the second through hole of the second connecting piece 22 is provided. The other end of the other cord portion 63 protruding from 22b is thermally deformed by a thermoforming tool to form a second flange portion 63a having a diameter larger than the diameter of the cord portion 63 at the other end of the other cord portion 63. At this time, a substantially truncated cone-shaped second diameter gradually increasing portion 63c is also formed on the second neck portion 63b of the second flange portion 63a. As a result, the second connecting piece 22 cannot be removed from the other cord portion 63. In this embodiment, since the cord portion 63 is a braided cord or a twisted cord made of a thermoplastic resin, the second diameter is such that each fiber in the second diameter gradually increasing portion 63c remains without being melted during thermal deformation. The gradual increase portion 63c is formed.

Then, one end of one cord portion 62 is connected to a plurality of elevating cords 69 by a cord joint 71, and one end of the other cord portion 63 is attached to the bottom rail 68 (FIG. 9). Further, the tip of the first connecting piece 21 attached to the other end of one cord portion 62 and the tip of the second connecting piece 22 attached to the other end of the other cord portion 63 are opposed to each other, and the first or With one of the second connecting pieces 21 and 22 rotated 90 degrees around the axis of the cord portions 62 and 63, the second locking portion 22c is elastically deformed and engaged with the first locked portion 21d. By stopping and elastically deforming the first locking portion 21c to the second locked portion 22d to lock the first and second connecting pieces 21 and 22, the first and second connecting pieces 21 and 22 are engaged and united (FIGS. 7 and 7). 8). As described above, the two cord portions 62 and 63 can be connected by the connecting member 20 with an extremely simple operation, and the operation cord 61 can be prevented from extending in a state of being unnecessarily hung down.

Next, a procedure for shortening the total length of the operation cord 61 in which the two cord portions 62 and 63 are connected will be described. First, the engagement between the first connecting piece 21 and the second connecting piece 22 of the operation cord 61 is released, and the cord portion 62 on the first connecting piece 21 side or the cord portion 63 on the second connecting piece 22 side is designated. Cut by the length, and remove the first connecting piece 21 or the second connecting piece 22 from the other end of one cord portion 62 or the other cord portion 63. In this embodiment, an example of removing the first connecting piece 21 from the other end of one cord portion 62 is shown. After removing the first connecting piece 21 from the other end of one cord portion 62, the first connecting piece 21 is loosely fitted to the other end of one cord portion 62. Further, after the other end of one cord portion 62 is thermally deformed to form the first flange portion 62a, the first connecting piece 21 and the second connecting piece 22 are engaged with each other. The length of the operation cord 61 can be shortened relatively easily by such a simple operation. Since the operations other than the above are substantially the same as the operations of the first embodiment, the repeated description will be omitted.

In the first embodiment, a single operation chain in which both ends of the cord portion are connected by a connecting member is attached to the roll screen, and in the second embodiment, the ends of the two cord portions are attached. Attached the operation cord connected by the connecting member to the horizontal blind, but attached a single operation chain in which both ends of the cord part were connected by the connecting member to the horizontal blind, vertical blind, pleated screen, roman shade, etc. Alternatively, an operation cord in which the ends of the two cord portions are connected by a connecting member may be attached to a pleated screen, a roman shade, or the like. Further, in the first to fourth embodiments, the ball portion is formed in a substantially spheroidal shape, and the connecting member in which the first and second connecting pieces are united also has substantially the same outer shape as the ball portion (substantially spheroidal body). However, even if the ball portion is formed to have a substantially spherical shape and the connecting member in which the first and second connecting pieces are united is also configured to have substantially the same outer shape (approximately spherical shape) as the ball portion. Good.

Further, in the first and second embodiments, the first diameter gradual increase portion and the second diameter gradual increase portion are formed in a substantially truncated cone shape having a taper angle of less than 90 degrees, respectively, as shown in FIG. The first diameter gradual increase portion 82e and the second diameter gradual increase portion 82f may be formed in a substantially truncated cone shape having a taper angle of 90 degrees, respectively. That is, in the first diameter gradual increase portion 82e and the second diameter gradual increase portion 82f of the cord portion 82 of the operation chain 81, the length in the longitudinal direction of the cord portion 82 and the length in the radial direction of the cord portion 82 are formed in a tapered shape. You may. In this case, the pair of clamp molds 91a, 91a of the thermoforming tool 91 of the cord portion 82, the first neck portion 82c of the first flange portion 82a, the second neck portion 82d of the second flange portion 82b, the first diameter gradually increasing portion 82e and A C chamfer 91c for forming each of the second diameter gradually increasing portions 82f is formed. Reference numeral 91b is a molding die.

Further, in the first and second embodiments, the first diameter gradual increase portion and the second diameter gradual increase portion are formed in a substantially truncated cone shape having a taper angle of less than 90 degrees, respectively, as shown in FIG. , The first diameter gradual increase portion 112e and the second diameter gradual increase portion 112f may be formed in a substantially half-drum shape. That is, the first diameter gradual increase portion 112e and the second diameter gradual increase portion 112f of the cord portion 112 of the operation chain 111 are half obtained by cutting a drum whose center in the longitudinal direction is curved and narrowed at the center in the longitudinal direction. It may be formed in the shape of a drum. In this case, the pair of clamp molds 121a and 121a of the thermoforming tool 121 of the cord portion 111, the first neck portion 112c of the first flange portion 112a, the second neck portion 112d of the second flange portion 112b, the first diameter gradually increasing portion 112e and R chamfers 121c for forming the second diameter gradual increase portions 112f are formed. Reference numeral 121b is a molding die.

Further, in the second embodiment, the first connecting piece and the second connecting piece of the connecting member are formed in the same shape, but as shown in FIG. 12, the first connecting piece 151 and the second connecting piece 150 of the connecting member 150 are formed. The connecting piece 152 may be formed in a different shape. Specifically, a locking portion 151a made of ring-shaped protrusions is formed at the lower end portion (tip portion) of the first connecting piece 151, and a ring-shaped concave portion is formed at the upper end portion (tip portion) of the second connecting piece 152. By forming the locked portion 152a made of strips and engaging the locking portion 151a with the locked portion 152a, the first and second connecting pieces 151 and 152 are combined. In FIG. 12, the same reference numerals as those in FIG. 7 indicate the same parts.

Further, as shown in FIGS. 13 to 16, the string-shaped member 171 has a single first cord portion 172 for operating and two second cord portions 173, 174 for raising and lowering the shield 181. The connecting member 190 is configured to connect the single first cord portion 172 and the two second cord portions 173, 174, and the connecting member 190 has a first cord having a single end. A first connecting piece 191 attached to a second cord portion 173 attached to a portion 172 and the other end attached to one second cord portion 173 selected from two second cord portions 173 and 174, and two second cord portions 173. It has a second connecting piece 192 attached to one second cord portion 174 further selected from the remaining second cord portion 174 excluding one second cord portion 173 selected from 174. The two second cord portions 173 and 174 may be configured to be divided into two. In this case, the string-shaped member 171 is attached to the Roman shade 180 (FIG. 16). The head rail 182 of the roman shade 180 is attached to a window frame or the like of a room, and the shield 181 has a width substantially the same as the length of the head rail 182 and hangs from the head rail 182. Further, one end of the single first cord portion 172 is attached to the lower end of the shield body 181 and the first through hole 191b of the first connecting piece 191 is loosely fitted to the other end. Further, two cord insertion members 183 and 184 are housed in the head rail 182 at predetermined intervals in the longitudinal direction of the head rail 182, and one ends of the two second cord portions 173 and 173 are two cords. It hangs down from the insertion members 183 and 184 along the back surface of the shield 181 and is attached to the lower end of the shield 181 respectively, and the second through hole 191c of the first connecting piece 191 and the second of the second connecting piece 192 are attached to the other ends. Each of the through holes 192b is loosely fitted.

Here, the first connecting piece 191 is formed in a substantially barrel shape with the upper and lower surfaces closed and the opening 191a formed on the side surface, and the second connecting piece 192 has an eaves portion 192a formed on the upper surface and the opening 191a. It is formed in the shape of a substantially curved plate that closes the barrel (FIGS. 13 to 15). The first through hole 191b that can be loosely fitted to the other end of the single first cord portion 172 is formed on the lower surface of the first connecting piece 191 and is the second of the two second cord portions 173 and 174. The second through hole 191c that can be loosely fitted to the other end of the cord portion 173 is formed on the upper surface of the first connecting piece 191 and the second through hole 192b that can be loosely fitted to the other end of the other second cord portion 174. Is formed on the eaves portion 192a of the second connecting piece 192. Further, the first cord portion 172 and the second cord portion 173, 174 are formed of a thermoplastic resin to prevent the first connecting piece 191 from being separated from the other end of the first cord portion 172, and the first through hole 191b. The first flange portion 172a having a larger diameter is formed by thermally deforming the other end of the first cord portion 172, and the first connecting piece 191 is separated from the other end of one second cord portion 173. A second flange portion 173a having a diameter larger than that of the second through hole 191c is formed by thermally deforming the other end of one second cord portion 173, and the second connecting piece 192 is formed by thermally deforming the other second cord portion 192. A second flange portion 174a having a diameter larger than that of the second through hole 192b is formed by thermally deforming the other end of the other second cord portion 174 to prevent the 174 from being separated from the other end. Further, a first diameter gradually increasing portion 172c gradually increasing from the first cord portion 172 toward the first flange portion 172a is formed on the first neck portion 172b of the first flange portion 172a, and the second flange portions 173a and 174a are formed. Second diameter gradually increasing portions 173c and 174c are formed on the two neck portions 173b and 174b, respectively, which gradually increase from the second cord portions 173 and 174 toward the second flange portions 173a and 174a. Then, when a load in the direction of separating the two second cord portions 173 and 174 acts on the two second cord portions 173 and 174, the two second cord portions 173 and 174 are divided so as to be separated from each other. Therefore, a person or an object caught on the two second cord portions 173, 174 can be quickly released from the two second cord portions 173, 174.

On the other hand, when there are three or more second cord portions for raising and lowering the shield, one second cord portion (first cord portion) selected from the second cord portions having three or more first connecting pieces. ), And the second connecting piece is one second cord portion further selected from the remaining second cord portions excluding one second cord portion selected from three or more second cord portions. Attached to (2nd), the remaining 2nd cords (3rd and subsequent) are inserted into the slits formed in the 1st connecting piece, and the open ends of these slits are closed by the 2nd connecting piece. To. Then, three or more second cord portions are configured to be divided into two groups, and when a load in the direction of separating the second cord portions of these two groups from each other acts on the cord portions of the two groups, three or more cord portions are formed. It is configured to be separable so that the cord parts are separated from each other. In this case, when a load in the direction of separating the second cord portions of the second group acts on the second cord portion of the second group, the three or more second cord portions are divided so as to be separated from each other. A person or object caught in the 2nd code part can be quickly released from the 2nd code part. Here, when the plurality of second cord portions for raising and lowering the shield are two or three or more, the first connecting piece and the second connecting piece are separated from each other from the relative movement in the horizontal direction. It is preferable that the curved convex portion and the curved concave portion that guide the relative movement in the vertical direction are formed in the first connecting piece and the second connecting piece, respectively.

11,81,111,141 Operation chain (string-shaped member)
12, 82, 112 Cord part 12a, 62a, 82a, 112a, 172a First flange part (first retaining part)
12b, 63a, 82b, 112b, 173a, 174a 2nd flange part (2nd retaining part)
12c, 62b, 82c, 112c, 172b 1st cervical part 12d, 63b, 82d, 112d, 173b, 174b 2nd cervical part 12e, 62c, 82e, 112e, 172c 1st diameter gradual increase part 12f, 63c, 82f, 112f, 173c, 174c 2nd diameter gradual increase part 13 Ball part 20,150 Connecting member 21,151,191 1st connecting piece 21b, 151b, 191b 1st through hole 22,152,192 2nd connecting piece 22b, 152b, 191c, 192b 2nd Through holes 41, 91, 121 Thermoforming tools for cords 41a, 91a, 121a Clamp type 41b, 91b, 121b Molding type 41c Tapered surface 42 Ball splitting tool 42a Ball splitting type 42b Blade 61 Operation cord (string-shaped member)
62 One cord part 63 The other cord part 91c C chamfer 121c R chamfer 171 String-shaped member 172 First cord part (single cord part)
173,174 2nd code part (multiple code parts)
181 Shield

Claims (2)

Connected by connecting member is formed in string-like code portion of the pair of ball mold part to the outer peripheral surface of a different ball portion pitches among the plurality of ball portion for use in retaining structure from the connecting member of the string-shaped member A string-shaped member including a step of bringing the blades into contact with each other and a step of applying a force to the pair of ball splitting molds in a direction in which the force applying mechanism brings the pair of blades closer to each other to split the ball portions having different pitches. It is a method of splitting the ball part fitted to the ball part.
A ball fitted to a ball portion of a string-shaped member, characterized in that the distance between the tips of the pair of blades is formed to be slightly larger than the diameter of the cord portion when the pair of blades are closest to each other. How to split the ball in the club. Abutting blade formed respectively on the outer peripheral surface of a different ball portion pitches among the plurality of ball portion for use in retaining structure from the connecting member of the string-shaped members connecting the connecting member is formed in string-like code portion It was fitted to the ball portion of a string-shaped member provided with a pair of ball-splitting molds and a force applying mechanism for applying a force to the pair of ball-splitting molds in a direction in which the blades of the ball-splitting molds were brought closer to each other. It is a ball splitting tool for the ball part.
A ball fitted to a ball portion of a string-shaped member, characterized in that the distance between the tips of the pair of blades is formed to be slightly larger than the diameter of the cord portion when the pair of blades are closest to each other. Part ball splitting tool.

Images