JP3585513B2 - Method of manufacturing brush by insert molding and mold for manufacturing brush by insert molding - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a brush, such as a toothbrush, including a bristle part and a resin base by insert molding, and a mold used for the method for manufacturing the brush.
[0002]
[Prior art]
Conventionally, a brush consisting of a bristol portion and a resin base is manufactured by a method of implanting bristles into the base. That is, after a base having a hole for inserting a bristol is manufactured by injection molding, the bristles 41 bundled as shown in FIG. 4A are folded in two, and together with a locking plate 42 such as brass, a hole in the base 43 is formed. 44, and is manufactured by a method of fixing as shown in FIG.
[0003]
However, the conventional method requires two steps of injection molding of the base and locking of the bristles to the base, and has a problem that the working efficiency is poor.
[0004]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a method for manufacturing a brush in one step by insert molding.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for manufacturing a brush comprising a bristol portion and a resin base, wherein a plurality of through holes for inserting and passing a predetermined bristol corresponding to the brush and the plurality of through holes are provided. Forming a core mold having a cutter insertion opening for inserting a cutter for cutting the bristles inserted into each of the above, and a brush base portion for fixing the bristles at positions facing the plurality of through holes. comprising a cavity mold having a cavity for the cutter insertion slot using an injection mold which is provided across said through hole a in the core mold, Bristol to each of the plurality of through-holes insert the post lock the bristles in position the tip of the bristles reaches into the cavity, by the Bristol said cutter And cutting the length of the constant, in combination with the step of injection molding the base and filled with a resin while retaining the cutter to the cutter insertion opening into the cavity, to secure the bristles to the base upon completion of the injection molding And a method of manufacturing a brush characterized by being integrally molded .
[0006]
The bristles used in the present invention are conventionally used bristles, and have a material, shape, hardness, and thickness suitable for a brush application. For example, when a toothbrush is manufactured by the manufacturing method of the present invention, a resin such as polypropylene or polyamide and a natural material such as pig hair can be used.
[0007]
The base of the present invention is manufactured using a resin having mechanical properties such as a flexural modulus suitable for a brush application. If both the material of the bristol and the material of the base are made of the same material such as nylon, it is easy to recycle the brush, and if the type (composition) is the same, for example, nylon 612, it is more suitable for recycling.
[0008]
The injection molding die used in the brush manufacturing method of the present invention is inserted into each of a plurality of through holes for inserting and passing a predetermined bristol corresponding to the brush and the plurality of through holes. A core mold having a cutter insertion opening for inserting a cutter for cutting the bristle, and a cavity for molding a base portion of a brush for fixing the bristle at a position facing the plurality of through holes. A cavity mold , wherein the cutter insertion port is provided in the core mold and across the through-hole, and the cutter is inserted from the cutter insertion port to penetrate the core mold and form the cavity. The bristle protruding into the mold is cut to a length sufficient to fix it to the base portion of the brush by the resin injected into the cavity. Characterized in that way the.
[0009]
The cavity mold and the core mold are formed of a metal material having a predetermined thickness and good thermal conductivity.
[0010]
[Action]
In the present invention, first, the bristles are inserted into through holes provided in the core mold to penetrate the bristles from the core mold to the cavity for molding the base portion of the brush. More specifically, the bristol tip protrudes into a cavity provided in the cavity mold by a length sufficient to secure the bristol by the resin injected into the base of the brush. To do so, the bristles may be moved by a predetermined length, or the bristles may be retracted by a predetermined length after the bristol tip reaches the bottom of the cavity mold.
[0011]
The size of the through hole provided in the core mold is determined according to the thickness and the number of the inserted bristles, and the number of the through holes is determined according to the size of the brush and the like. In the case of a normal brush, dozens of bristles are bundled into bundles, and each bundle is inserted into the through hole. A tubular guide may be provided for each bundle so that bundles of Bristles can be easily inserted into the through holes.
[0012]
The bristles that penetrate the core mold and protrude into the cavity are cut into a predetermined length by inserting a cutter through a cutter insertion port provided in the core mold. The cutter insertion opening is a portion through which the core type bristles penetrate, and is provided at a position considering the length of the bristles according to the material and use of the brush.
[0013]
After the cutter is inserted through the cutter insertion slot to cut the bristles, the mold is closed, and the resin material is injected into the cavity through the sprue, the runner, and the gate. The cut bristles are held in the through hole during resin injection by friction with the through hole wall and the cutter surface. The resin filled in the cavity is cooled by the core mold and the cavity mold, and the resin material is solidified. When the resin material has solidified, remove the inserted cutter. Thereafter, the mold is opened from the parting line, and the sprue, runner, and molded product move about the core mold. After the mold is completely opened, the ejector pins protrude the sprue, the runner, and the molded product. At this time, the bristles for the next shot are inserted into the through holes provided in the core mold. The bristol for the next shot projects the molded product together with the ejector pin, and a brush is manufactured in which the tip of the bristol is fixed to the base.
[0014]
If the Bristol can be locked by other means regardless of the cutter surface, the Bristol may be cut after the resin is solidified, and the Bristol may be inserted into the through-hole provided in the core mold, and inserted into the cutter insertion port. May be automatically inserted and removed.
[0015]
Thus, according to the present invention, the bristles are locked to the base by insert molding, so that the brush can be manufactured in one step.
[0016]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to the following Examples.
[0017]
FIG. 1 is a perspective view of an embodiment of a mold for manufacturing a brush according to the present invention. The mold includes a core mold 1 and a cavity mold 2, and a bristle supply guide 12 having a plurality of through holes 11 is integrally incorporated in the core mold 1. A cutter insertion opening 13 for inserting the cutter 3 for cutting the bristles is provided between the bristle supply guide 12 and the main body of the core mold 1. A protruding plate 15 is provided on the core mold 1 side. A cavity 21 is formed in the cavity mold 2 for molding a base by injecting a resin, and the core mold 1 and the cavity mold 2 are closed or released by the guide pins 14 and the guide holes 22. The core mold 1 and the cavity mold 2 are mounted on an injection molding machine via a movable mounting plate 16 and a fixed mounting plate 23, respectively. The bristle 4 is gripped by a bristle gripping / supplying tool (not shown), and is transported / supplied so that the tip of the bristle 4 reaches a predetermined position in the cavity 21 through the through hole 11.
[0018]
FIG. 2A is a cross-sectional view of a main part in a closed state of a mold, and FIG. 2B is a top view of a cavity mold. The cavity 21 has a base 21A for fixing the bristles, a handle 21B, and a connection 21C between the base and the handle. The base portion 21A of the cavity is located opposite to the core type bristle supply guide device 12, more specifically, the region where the plurality of through holes 11 provided in the guide device 12 are present.
[0019]
Using such a mold, a toothbrush having a bristol portion of 10 mm was manufactured by the manufacturing method of the present invention.
[0020]
The mold was made of structural carbon steel, and the cavity of the mold was formed such that the base portion for fixing the bristles had a size of 22 mm × 12 mm and a thickness of 3.5 mm. In the core of the mold, 34 holes having a diameter of 1.7 mm are provided in order to insert the bristles, and a portion where the bristles of the core penetrates is provided at a position 12 mm away from the parting line of the mold. Was provided.
[0021]
The base material used was nylon 612 (Zuitel, DuPont). Bristol was used in bundles of 40 filaments each using nylon 612 filament (Dupont, Inc., Tynex) having a thickness of 0.2 mm.
[0022]
After inserting the bristles into the through holes of the core mold, the mold was closed, and the above-described base material was injected and injected into the cavity to produce a toothbrush in which the base and the bristles were integrally molded. FIG. 3 shows a partial sectional view of the manufactured toothbrush. Bristol was firmly held in the base.
[0023]
【The invention's effect】
As described above, according to the brush manufacturing method of the present invention, the bristles are locked to the base by insert molding, so that the brush can be manufactured in one step.
[Brief description of the drawings]
FIG. 1 is a perspective view of an embodiment of a mold according to the present invention.
FIGS. 2A and 2B show an embodiment of a mold according to the present invention, wherein FIG. 2A is a sectional view of a main part, and FIG.
FIG. 3 is a partial cross-sectional view of a toothbrush manufactured according to the present invention.
4A and 4B are cross-sectional views showing a conventional method for manufacturing a toothbrush, in which FIG. 4A shows a press-fitting step, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Core mold 2 Cavity mold 3 Cutter 4 Bristol 11 Through hole 12 Bristol supply guide 13 Cutter insertion port 14 Guide pin 21 Cavity 21A Base part 21B Handle part 21C Connection part 22 Guide hole 41 Bristol 42 Locking plate 43 Base 44 Hole

Claims (2)

In a method of manufacturing a brush composed of a bristol portion and a resin base, a plurality of through holes for inserting and passing through a predetermined bristol corresponding to the brush and cutting the bristles inserted into each of the plurality of through holes are cut. and the core mold having a cutter insertion opening for inserting a cutter for, and a cavity mold having a cavity for molding a base portion of the brush for securing the bristles in a position opposed to said plurality of through-holes Equipped, the cutter insertion port is in the core mold , using an injection molding die provided across the through hole, inserting a bristol into each of the plurality of through holes, the tip of the bristles is after locking the bristle at the position reached in the cavity, and cutting to length the bristles by the cutter, prior to The combination of the step of injection molding the base cutter filled with resin while holding the cutter insert opening into the cavity, upon completion of the injection molding to secure the bristles to the base, of the brush, characterized in that integrally molded Production method. A injection mold for manufacturing a brush comprising a bristle section and resin base, a plurality of through-holes and the plurality of through holes for passing by inserting a predetermined bristles in accordance with the brush To mold a core type having a cutter insertion port for inserting a cutter for cutting the bristles inserted therein, and a brush base portion for fixing the bristles at positions facing the plurality of through holes. A cavity mold having a cavity , wherein the cutter insertion port is provided in the core mold and traversing the through-hole, and the core mold is inserted by inserting the cutter from the cutter insertion port. A bristle penetrating and protruding into the cavity mold is fixed to a base portion of the brush by a resin injected into the cavity. Injection molding die for the brush manufacturing which is characterized in that so as to cut long enough.

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