JP2008173427A - Method for manufacturing round brush element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise the mechanical strength of a welded part formed in the center part of a round brush element. <P>SOLUTION: A small-diameter rod body 3a of a welding horn 3 is compulsorily pushed into the center part of a fiber bundle 1 pushing aside a fiber material. At the same time, the fiber bundle 1 is orthogonally pushed outward to the surroundings on the body tip face of the welding horn 3. The air discharged from the air hole 3a of the welding horn 3 is heated to 80-120°C. Because of this, the fiber bundle 1 is pushed outward and molded, and is preheated to about 100°C prior to welding. By this preheating, the moldability of the fiber bundle 1 becomes good in spite of the thick fiber bundle 1, and the fiber bundle 1 can be molded as it remains orthogonally opened to the surroundings without a large fiber press even on the horn tip face of a relatively small diameter. Also, since welding can be done by the small power welding horn, excess heating can be prevented, the quality of the welded part can be finished to the quality equivalent to a nylon yarn, and its mechanical strength can be drastically raised. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a round brush element used for a cylindrical brush.

  One type of toothbrush is a cylindrical toothbrush. As shown in Patent Document 1, a cylindrical brush head is attached to the tip of a handle that is operated in the axial direction, and since there is no direction around the center line of the handle, a conventional toothbrush is used. It has a number of features that are not available and is attracting attention among dentists.

  JP-A-2005-103225

  This cylindrical toothbrush includes a handle formed so as to be reciprocated in the axial direction in the same manner as a normal toothbrush, and a cylindrical brush head fitted into a small-diameter shaft portion formed at the tip of the handle. . The brush head is configured by laminating a plurality of round brush elements in the central axis direction. Each round brush element is composed of a thin disk-shaped welded portion having a through hole (center hole) in the central portion, and a brush portion made of a large number of yarn materials extending radially from the entire circumference of the welded portion. Composed.

  This round brush element is manufactured from a yarn bundle in which a predetermined number of yarn materials made of nylon resin are bundled. Specifically, a thread bundle is passed from below through a through hole provided in the processing table, and is projected on the processing table by a predetermined length. The ultrasonic welding horn descends from above the protruding portion of the yarn bundle. The welding horn has an air hole in the center, and the air bundle is blown downward from here to widen the protruding portion of the yarn bundle to the periphery. As the welding horn continues to descend as it is, the protruding portion of the yarn bundle is pushed down to the surroundings at a right angle to complete the expansion. In this state, the center part of the spread yarn bundle is melt-bonded by the flat tip surface of the welding horn to form a thin disk-like welded part.

  When the welding is finished, the welding horn is retracted, and instead, the cutter is positioned on the through hole of the processing table, descends, and a center hole is formed by cutting the center of the welded portion into a circle. Also, the yarn bundle is separated from the welded portion. Thus, the round brush element described above is manufactured. The tip welded portion of the yarn bundle from which the round brush element has been removed is cut off in preparation for the production of the next round brush element.

  There is also known a toothbrush in which a cylindrical brush head formed by laminating a plurality of such round brush elements in the central axis direction is rotatably attached to the tip of the handle.

  One of the problems of the cylindrical toothbrush described above is that the mechanical strength of the round brush element constituting the cylindrical brush head is low. Specifically, the disk-shaped welded portion of the round brush element is easily broken. The individual yarn materials constituting the round brush element are nylon yarns, and even one piece is very strong and cannot be easily torn by human power. Since the welded portion is formed by integrating a large number of yarn materials, it should be extremely high in nature. However, the actual welded portion has only a strength that can be easily broken by hand.

  Since the cylindrical toothbrush has no directionality, it is suitable as a toothbrush for elderly people and a toothbrush for infants. Infants, etc., often have unexpected behavior unlike adults, and often brush their brush heads while brushing their teeth. In that case, with conventional cylindrical toothbrushes, there is a risk that the round brush element is broken and detached from the brush head, and it cannot be said that the safety is necessarily high.

  The objective of this invention is providing the manufacturing method of a round brush element which can provide high mechanical strength efficiently to the welding part of a round brush element.

  In order to achieve the above object, a method of manufacturing a round brush element according to the present invention includes a step of projecting a yarn bundle in which a predetermined number of yarn materials are bundled through a guide hole onto a table, and the yarn bundle radially around the table. A method of manufacturing a round brush element, including a step of opening to a center, a step of welding a central portion of a yarn bundle radially opened on a table to form a round brush element, and a step of separating the round brush element from the yarn bundle. The yarn bundle is preheated before welding the central portion of the yarn bundle that is radially opened on the table.

  An ultrasonic welding horn is usually used for welding the central portion of the yarn bundle that is radially opened on the table, but a rod-shaped head (heat welding rod) heated by an electric heater or the like may be used. .

  FIG. 1 is a graph showing a change in temperature of a portion to be welded when manufacturing a round brush element. The resin used for the material of the round brush element is a thermoplastic resin, and is usually three types of nylon 610, nylon 612, and PBT. The melting point of nylon resins such as nylon 610 and nylon 612 is about 230 ° C. When the center portion of the yarn bundle that is radially opened on the table is welded by the front end surface of the welding horn, the temperature change of the portion to be welded is as indicated by line A. That is, a high-power welding horn is used to shorten the welding time per round brush element, and as a result, the planned welding portion suddenly reaches the melting point of the nylon resin from room temperature. Specifically, the melting point is reached in about 0.5 seconds from the start of welding.

  However, since temperature setting and time setting in welding are programmed by a sequencer or the like and performed electrically, a time lag is unavoidable, and the temperature rises excessively even with a slight time lag. For example, if the time lag is 0.1 second, the temperature is increased to about 270 ° C. because the temperature gradient is steep. As a result, the welded portion is overheated and loses the physical properties inherent to the nylon resin, becomes a crumpled state and becomes very brittle and easily crushed. This was found to be the cause of the low mechanical strength of the weld.

  In addition to this, the rapid heating causes the surface of the nylon yarn to become brittle and makes the center portion brittle, and conversely the central portion remains as an unmelted portion due to insufficient heat. The best welded portion has the same color as nylon yarn (in the case of transparent yarn, a transparent welded portion). In order to prevent overheating of the welded portion, the welding may be performed with a small output welding horn over time. However, in this case, the welding time becomes long and the productivity is lowered.

  In view of such circumstances, the present inventor paid attention to preheating before welding the yarn bundle. If the yarn bundle is preheated, for example, preheated to 100 ° C, the temperature difference up to the melting point decreases to 130 ° C, and it is only necessary to raise the temperature to 130 ° C in 0.5 seconds. Thus, even if there is a time lag of 0.1 seconds, the ultimate temperature decreases to 250 ° C. Actually, since a welding horn with a small output is used (the ultrasonic capacity is drastically reduced), it becomes like the line C. As a result, even if there is a slight time lag, the temperature of the welding part does not greatly exceed the melting temperature. Therefore, the physical property change of a welding part is suppressed and the outstanding physical property which the material has originally is provided also to a welding part.

  In addition, since the yarn bundle is softened by preheating, the formability of the yarn bundle is improved. That is, the moldability when the yarn bundle is radially opened on the table is improved.

  In order to increase the number of yarn materials in the round brush element, the present inventor provided a small-diameter shaft portion at the tip of the welding horn, and inserted the small-diameter shaft portion into the center portion of the yarn bundle radially opened on the table. A method has been developed in which the yarn bundle in the guide hole of the table is welded in a cylindrical shape from the center side by the outer peripheral surface of the rod body, and the center hole is simultaneously formed inside the welded portion. According to this method, since there is no need to cut the center hole in the center part of the disk-shaped welded portion, there is no restriction on the number due to the inner diameter of the through hole of the table, and a thick thread bundle made of a large number of thread materials And a small central hole can be formed. By using a thick yarn bundle made of a large number of yarn materials, the thickness of the round brush element can be increased.

  When a thick yarn bundle is used, the volume of the welded portion is increased, and extension of the welding time and excessive heating of the welded portion by large-capacity ultrasonic waves are serious problems. However, this problem can be solved by preheating. Moreover, although the operation | work which opens a yarn bundle radially becomes difficult, this shaping | molding operation | work becomes easy by preheating.

  Of course, it is also effective to use preheating when forming a conventional disk-shaped welded portion.

  As a method for preheating the yarn bundle, a method such as heating the welding horn, heating the table, heating the yarn bundle lifting device under the table, heating the gas blown toward the center of the yarn bundle, or the like alone, or Multiple combinations can be used. In the case of gas heating, it is reasonable to discharge the heated gas from the center of the welding horn.

  The method of manufacturing a round brush element of the present invention prevents deterioration due to overheating of the welded portion by preheating the yarn bundle before welding the central portion of the yarn bundle that is radially opened on the table. Excellent physical properties equivalent to the constituent material of the thread material constituting the bundle (a characteristic of having a unique viscosity in the case of nylon resin and excellent in both tensile strength and bending strength) can be imparted to the welded portion. As a result, when used in a brush head of a cylindrical toothbrush, the round brush element is not inadvertently damaged, and a highly safe product that can be used safely for infants, elderly people, and nursing care can be provided. In addition, since it is not necessary to extend the time required for welding and there is no possibility of reducing productivity, the economy is high.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram of a manufacturing apparatus suitable for carrying out the method for manufacturing a round brush element of the present invention.

  The manufacturing apparatus manufactures a round brush element from a yarn bundle 1 configured by bundling a predetermined number of yarn materials made of nylon resin, and includes a horizontal processing table 2 for the manufacture. The processing table 2 has a through hole for the yarn bundle 1 through which the yarn bundle 1 passes from the bottom to the top. Here, for example, when the yarn diameter is 1.2 mm, the yarn bundle 1 is composed of 800 to 1200 yarn materials, which is two to three times as many as the conventional one. Along with this, the through holes of the processing table 2 are also enlarged.

  The thread bundle 1 is supplied to the through hole of the processing table 2 from below by a thread bundle lifting device installed below the processing hole.

  On the processing table 2, an ultrasonic welding horn 3 is provided concentrically with respect to the through hole. The welding horn 3 has an air hole 3a at the center of a vertical cylindrical main body, and has a small-diameter rod projecting downward at the center of the downward leading end surface of the main body. The main welding surfaces of the welding horn 3 are the front end surface of the main body and the outer peripheral surface of the small-diameter rod. The outer diameter of the front end surface is substantially the same as the inner diameter of the through hole, for example, 5 to 7 mm, and the diameter of the small-diameter bar is smaller, for example 2.3 mm.

  The welding horn 3 is also equipped with a heating device 4 for heating the air discharged from the central air hole 3a. The heating device 4 heats the air above the softening point of the nylon resin and below the melting point, for example, about 80 to 120 ° C.

  In order to manufacture a round brush element using the above manufacturing apparatus, first, the yarn bundle 1 is projected on the processing table 2 by about 10 mm. At this time, the welding horn 3 is retracted upward. When the yarn bundle 1 protrudes on the processing table 2, the welding horn 3 descends while discharging air from the air holes 3a and oscillating ultrasonically. By discharging air from the air holes 3a, the yarn bundle 1 protruding above the processing table 2 starts to open to the periphery. The tip of the welding horn 3 is pushed there, and the yarn bundle 1 opens further to the periphery.

  When the welding horn 3 continues to descend further, the small-diameter bar 3a of the welding horn 3 is forced into the center portion of the yarn bundle 1 by scraping the thread material. At the same time, the yarn bundle 1 is pushed to the periphery at a right angle by the front end surface of the main body of the welding horn 3. The surrounding thread material is heated and melted in a cylindrical shape by the small-diameter rod body 3a while being pressed and fixed between the outer peripheral surface of the small-diameter rod body 3a and the inner peripheral surface of the through hole. In addition, the yarn bundle 1 that has been spread around is formed into the spread state.

  Here, the air discharged from the air holes 3a of the welding horn 3 is heated to 80 to 120 ° C. For this reason, the yarn bundle 1 is preheated to about 100 ° C. prior to the spreading and welding. This preheating improves the formability of the yarn bundle 1 despite the thick yarn bundle 1, and makes the yarn bundle 1 perpendicular to the surroundings without a large yarn presser or even with a relatively small diameter horn tip. Can be molded open. Further, since welding can be performed with a welding horn having a small output, excessive heating can be prevented, the quality of the welded portion can be finished to the same quality as nylon yarn, and the mechanical strength can be dramatically increased.

  The cylindrical melted portion is solidified to form a cylindrical welded portion. Then, the welding horn 3 is retracted upward. Since the welding horn 3 can be instantly peeled at the same time as molding a thermoplastic resin such as a nylon resin, there is no risk of deformation when the welding horn 3 is retracted. In order to improve the releasability, it is recommended that at least the processed part surface of the welding horn 3 be subjected to hard chrome plating hub (HCR-B) processing or fluororesin processing.

  When the welding horn 3 is retracted, the yarn bundle 1 is raised so that the welding portion protrudes above the processing table 2. The cylindrical weld has a concave shape with a closed bottom. Therefore, the welded part is cut at a right angle on the bottom by a cutter (not shown). Thus, a round brush element having a cylindrical welded portion and a thick brush portion formed at one end thereof is manufactured. A welded portion remains at the tip of the yarn bundle 1 after the round brush element is cut off. It is a part corresponding to the bottom. For this reason, the yarn bundle 1 is slightly raised and the welded portion is cut off to prepare for the production of the next round brush element.

  Since the manufactured round brush element uses a thick material in which the yarn material is increased 2 to 3 times as much as the conventional yarn bundle 1, the thickness becomes thicker than the conventional one and can be 1 to 1.5 mm. The cylindrical welded portion does not supply material from the disk-shaped welded portion, but uses the yarn bundle 1 in the through hole of the processing table 2 separately, so that the length can be increased. Since the outer diameter corresponds to the inner diameter of the through hole, the outer diameter can be increased. Since the inner diameter is governed by the outer diameter of the small-diameter rod body of the welding horn 3, it can maintain the same level as the conventional level of 2.3 mm. As a result, the thickness of the cylindrical welded portion can be increased. There is no disc-like welded portion, and even if it exists, it can be reduced. If the outer diameter of the disk-shaped welded portion is reduced, the hair length in the surrounding radial brush portion can be increased. Instead of increasing the hair length, the outer diameter of the round brush element can be reduced.

  If such a thick round brush element is used for the brush head of a cylindrical toothbrush, it has rigidity and an excellent usability can be obtained. A boss height of 1 mm can be secured, and the yarn material density in the brush head can be lowered to an appropriate value. In addition, the number of round brush elements used can be reduced to several, and no washers and spacers are required. That is, a cylindrical toothbrush with an ideal brush design can be manufactured very economically with a small number of round brush elements.

  FIG. 3 is a block diagram of another manufacturing apparatus suitable for carrying out the method for manufacturing a round brush element of the present invention. In this manufacturing apparatus, the main body of the welding horn 3 is heated by the horn heating device 5. As a result, the yarn bundle 1 spread by the welding horn 3 can be preheated. The air passing through the central air hole can also be heated, and the yarn bundle 1 can be preheated from both sides.

  FIG. 4 is a block diagram of still another manufacturing apparatus suitable for carrying out the method for manufacturing a round brush element of the present invention. In this manufacturing apparatus, the yarn bundle 1 is preheated by heating the periphery of the through hole of the yarn bundle 1 provided in the processing table 2 with a heater 2a. According to this preheating method, the yarn bundle 1 can be preheated before welding and before forming.

  FIG. 5 is a block diagram of still another manufacturing apparatus suitable for carrying out the method for manufacturing a round brush element of the present invention. In this manufacturing apparatus, the yarn bundle 1 is preheated by incorporating a heater 6 a in a yarn bundle lifting and lowering device 6 that raises the yarn bundle 1 under the processing table 2. This preheating method can also preheat the yarn bundle 1 before welding and before forming.

  FIG. 6 is a configuration diagram of still another manufacturing apparatus suitable for carrying out the manufacturing method of the round brush element of the present invention, FIGS. 7 and 8 are structural explanatory views of the main part of the manufacturing apparatus, and FIGS. It is process explanatory drawing which shows the manufacturing method by an apparatus in steps.

  In this manufacturing apparatus, as shown in FIG. 6, an air tube 7, a thread presser 9, and a heat welding rod 10 are provided on the processing table 2. As shown in FIGS. 7 and 8, the thread retainer 9 is an annular body surrounding the air tube 7 and is an ultrasonic vibrator. The air pipe 7 is configured to discharge heated air for preheating.

  As a first stage of the manufacturing method, the yarn bundle 1 is pushed out from the through hole onto the processing table 2 by a predetermined amount. As a second stage, as shown in FIG. 9, the air tube 7 is positioned on the yarn bundle 1. The air tube 7 includes an air heating device 8 for heating the discharge air, and discharges the air heated to 80 to 120 ° C. directly below. Thereby, the protrusion part of the yarn bundle 1 opens to the periphery. Next, as a third stage, as shown in FIG. 10, the thread bundle 1 opened to the periphery is pressed against the processing table 2 by the thread presser 9. The thread retainer 9 is composed of an annular ultrasonic vibrator provided concentrically around the air tube 7, and smoothly lowers the thread bundle 1 by its lowering. Since the yarn bundle 1 is preheated with heated air, the formability by the yarn presser 9 is good. Then, as a fourth step, as shown in FIG. 10, the thermal welding rod 10 is positioned right above the through hole of the processing table 2 and descends.

  The heat welding rod 10 has a cylindrical main body and a small-diameter shaft portion protruding from the front end surface of the main body. The outer diameter of the main body is the same as or slightly larger than the inner diameter of the through hole, and the outer diameter of the small diameter shaft portion is smaller than the inner diameter of the through hole. This heat welding rod 10 is heated by a heater 10a to a temperature slightly higher than the melting temperature of the yarn bundle 1, specifically, about 230 ° C. which is the melting point.

  When the heat welding rod 10 is lowered, the small diameter shaft portion is inserted into the center portion of the yarn bundle 1 opened to the periphery. Further, the periphery of the insertion portion is pressed from above by the main body end surface around the small diameter shaft portion. Thereby, the center part of the yarn bundle 1 opened to the periphery is welded in a cylindrical shape. Here, ultrasonic waves are used for opening the yarn bundle 1, and a heat welding rod 10 is used for welding. The advantages of thermal welding are as follows.

  Since the heating temperature of the heat welding rod 10 is constant, the welding temperature can be kept constant. For this reason, there is no change in physical properties of the nylon resin during welding. Therefore, the worry on the strength of the welded portion is completely wiped out. Low cost. Even in the case of high-speed welding, troubles on the welding surface can be solved by performing surface treatment (Teflon processing, fluorine processing). Although it is inferior to the function of aligning the yarn bundle as a disadvantage, it can be solved by using the ultrasonic yarn presser 9 together.

It is a graph which shows the heating temperature change when manufacturing a round brush element. It is a block diagram of the manufacturing apparatus suitable for implementation of the manufacturing method of the round brush element of this invention. It is a block diagram of another manufacturing apparatus suitable for implementation of the manufacturing method of the round brush element of this invention. It is a block diagram of another manufacturing apparatus suitable for implementation of the manufacturing method of the round brush element of this invention. It is a block diagram of another manufacturing apparatus suitable for implementation of the manufacturing method of the round brush element of this invention. It is a block diagram of another manufacturing apparatus suitable for implementation of the manufacturing method of the round brush element of this invention. It is structure explanatory drawing of the principal part of the manufacturing apparatus. It is structure explanatory drawing of the principal part of the manufacturing apparatus. It is process explanatory drawing which shows the manufacturing method by the same apparatus in steps. It is process explanatory drawing which shows the manufacturing method by the same apparatus in steps. It is process explanatory drawing which shows the manufacturing method by the same apparatus in steps.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Yarn bundle 2 Table 2a Heater 3 Ultrasonic welding horn 4 Air heating device 5 Horn heating device 6 Yarn bundle raising / lowering device 6a Heater 7 Air tube 8 Air heating device 9 Ultrasonic pressure holding plate 10 Thermal welding rod 10a Heater

Claims (7)

  A process of projecting a thread bundle of a predetermined number of thread materials onto the table through the guide hole, a process of radially opening the thread bundle to the periphery on the table, and welding the center of the thread bundle that is radially opened on the table In the round brush element manufacturing method including the step of forming a round brush element and the step of separating the round brush element from the yarn bundle, before welding the central portion of the yarn bundle radially opened on the table, A method of manufacturing a round brush element, wherein the yarn bundle is preheated.   2. The method for manufacturing a round brush element according to claim 1, wherein a preheating temperature of the yarn bundle is equal to or higher than a softening point of a constituent material of the yarn material constituting the yarn bundle and lower than a melting point.   2. The method of manufacturing a round brush element according to claim 1, wherein an ultrasonic welding horn or a thermal welding rod is used for welding the central portion of the yarn bundle radially opened on the table.   In the manufacturing method of the round brush element of Claim 3, the center part of the yarn bundle radially opened on the table is welded in a disk shape by the front end surface of the welding horn or the front end surface of the heat welding rod. A manufacturing method of a round brush element.   4. The method of manufacturing a round brush element according to claim 3, wherein the welding horn or the heat welding rod has a small-diameter rod body whose outer diameter is smaller than the inner diameter of the guide hole of the table and whose outer peripheral surface is a heating surface. The small-diameter rod is inserted into the central portion of the yarn bundle that is radially opened on the table, and the yarn bundle in the guide hole is welded in a cylindrical shape from the center side by the rod outer peripheral surface. A method for manufacturing a brush element.   2. The method of manufacturing a round brush element according to claim 1, wherein in order to preheat the yarn bundle, heating of a welding tool, heating of the table, heating of a yarn bundle lifting device under the table, and opening of the yarn bundle radially. Therefore, a method of manufacturing a round brush element using any one or a combination of heating of gas sprayed toward the center of the yarn bundle.   The manufacturing method of the round brush element of Claim 6 which discharges the said heating gas from the center part of the welding horn in the manufacturing method of Claim 6.

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