JP6796934B2 - Manufacturing method of rod-shaped molded product - Google Patents

Description

The present invention relates to a method for producing a rod-shaped molded product.

Although resin bolts are advantageous in terms of weight reduction, they are not sufficient in terms of strength as compared with metal, so the strength is increased by blending a fibrous filler with resin.
When a fibrous filler is blended into a rod-shaped molded body such as a resin bolt to increase the strength, it is important that the fibers are contained in a state of being oriented in the length direction.
However, when a normal injection molding method is applied, the fibers of the surface layer portion of the rod-shaped molded product are oriented in the length direction, but the central portion is randomly present, so that the degree of orientation as a whole is low and sufficient. Cannot give strength.

Patent Documents 1 and 2 describe resin bolts in which fibers are oriented parallel to the axial direction by injection molding using a mold composed of a specific combination of a fixed mold and a movable mold, and a method for manufacturing the same. Has been done.

Japanese Unexamined Patent Publication No. 7-293534 Japanese Unexamined Patent Publication No. 7-293535

An object of the present invention is to provide a method for producing a rod-shaped molded product having a high degree of orientation of the fibrous filler in the long axis direction.

The present invention is a method for producing a rod-shaped molded product, which comprises a step of injection molding a thermoplastic resin composition containing a fibrous filler into a mold by an injection molding machine.
The injection nozzle of the injection molding machine and the gate of the mold are connected by a spool and a runner.
The rod-shaped molded product includes a portion having a uniform outer diameter, and has a circular or regular polygonal cross-sectional shape in the width direction.
The mold has a plurality of gates for injecting a thermoplastic resin into one cavity of the mold.
The runner has one trunk runner connected to the spool and a plurality of branch runners branched from the one trunk runner by the number corresponding to the number of gates of the mold. ,
Each of the plurality of branch runners is connected to each of the plurality of gates of the mold.
Provided is a method for producing a rod-shaped molded product in which the distances of the plurality of branch runners from the branch portion of the trunk runner to the plurality of gates of the mold are all the same.

According to the production method of the present invention, it is possible to obtain a rod-shaped molded product having a high axial orientation of the fibrous filler. Therefore, the mechanical strength of the obtained rod-shaped molded product is also increased.

(A) is a perspective view of a rod-shaped molded product obtained by the production method of the present invention, and (b) is a bottom view of (a). (A) is a perspective view of a rod-shaped molded product of another embodiment obtained by the production method of the present invention, and (b) is a bottom view of (a). (A) is a perspective view of a rod-shaped molded product of still another embodiment obtained by the manufacturing method of the present invention, and (b) is a bottom view of (a). (A) to (c) are plan views of the gate leading to the cavity in the mold used in the manufacturing method of the present invention. (A) is a side view of a runner used in the manufacturing method of the present invention, and (b) is a side view of a runner of another embodiment. (A) is a perspective view of a long screw bolt obtained by the manufacturing method of the present invention, and (b) is a perspective view of a full screw hexagon bolt obtained by the manufacturing method of the present invention. Side view of the runner used in the prior art manufacturing method. The plan view which shows the arrangement of the runner of another embodiment. (A) is an axial cross-sectional view of the rod-shaped molded product obtained in Example 1, and (b) is an axial cross-sectional view of the rod-shaped molded product obtained in Comparative Example 1.

The rod-shaped molded product that can be produced by the method for producing a rod-shaped molded product of the present invention includes a portion having a uniform outer diameter and has a circular or regular polygonal cross-sectional shape in the width direction.
The rod-shaped molded product may have a uniform outer diameter over the entire length direction, or may include a portion having a large outer diameter or a portion having a small outer diameter. The portion having a large outer diameter or the portion having a small outer diameter may be located at one end or both ends of the rod-shaped molded product, or may be located at an intermediate portion of the rod-shaped molded product.
Examples of the rod-shaped molded product that can be produced by the method for producing the rod-shaped molded product of the present invention include, but are not limited to, those shown in FIGS. 1 to 3.
The rod-shaped molded body 1 shown in FIGS. 1 (a) and 1 (b) is a cylinder having a length L, and the bottom surfaces 2 and 3 are circular and have a diameter D.
The rod-shaped molded body 11 shown in FIGS. 2A and 2B is a triangular prism having a length L, the bottom surfaces 12 and 13 are equilateral triangles, and the diameter of the inscribed circle is D.
The rod-shaped molded body 21 shown in FIGS. 3A and 3B is a square pillar having a length L, the bottom surfaces 22 and 23 are regular quadrangles, and the diameter of the inscribed circle is D.

<Thermoplastic resin composition containing a fibrous filler>
The thermoplastic resin composition used in the production method of the present invention contains a thermoplastic resin, a fibrous filler, and if necessary, a known additive for resin.
The thermoplastic resin is not particularly limited and can be selected according to the application, and is a polyolefin such as polyamide, polyethylene or polyprene, a polyester such as thermoplastic polyurethane (TPU) or PBT, PPS or ABS resin. It can be selected from styrene-based resins such as, and various polymer alloys.

The fibrous filler is not particularly limited and can be selected according to the application, and is selected from glass fiber, carbon fiber, inorganic fiber (excluding glass fiber), organic fiber, metal fiber and the like. be able to.
The content of the fibrous filler is preferably 10 to 60 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

Known additives include mold release agents, antistatic agents, flame retardants, colorants, plasticizers, softeners, dispersants, stabilizers (hindard phenolic antioxidants, phosphorus-based antioxidants, sulfur-based additives). Examples include antioxidants such as antioxidants, ultraviolet absorbers, heat stabilizers, etc.), antiblocking agents, crystal nucleation growth agents, fillers (granular fillers such as silica and talc), lubricants, etc. ..

The resin composition containing the fibrous filler used in the present invention preferably contains a resin-impregnated fiber bundle obtained by impregnating a bundle of fibrous filler with a thermoplastic resin and cutting it in the range of 6 to 50 mm.
The resin-impregnated fiber bundle has a length of 6 to 30 mm after bundling the fibrous filler in a state of being aligned in the length direction, impregnating the bundle of the fibrous filler with the thermoplastic resin in a molten state, and integrating them. It is preferably cut into pieces.
The length of the fibrous filler contained in the resin-impregnated fiber bundle is the same as the length of the resin-impregnated fiber bundle.
The diameter of the resin-impregnated fiber bundle is preferably in the range of 0.8 to 3 mm.

As the fibrous filler contained in the resin-impregnated fiber bundle, one having a fiber diameter (single thread diameter) of 6 to 30 μm can be used.
Since the fiber diameter varies depending on the type of fiber, the number of fibers constituting the fiber bundle can be selected according to the type of fiber.
For example, when glass fiber (fiber diameter 17 μm) is used as the fibrous filler, 100 to 100 to
The number is preferably 30,000, more preferably 500 to 20,000, and even more preferably 1,000 to 10,000.
Further, for example, when carbon fibers (fiber diameter 7 μm) are used as the fibrous filler, the number is preferably 1000 to 40,000, more preferably 5,000 to 35,000, and even more preferably about 1,000 to 30,000.

The resin-impregnated fiber bundle can be produced by a well-known manufacturing method using a die. For example, in addition to paragraph number 7 of JP-A-6-313050 and paragraph number 23 of JP-A-2007-176227, JP-A-6-2344 (Manufacturing method and molding method of resin-coated long fiber bundle), JP-A-6-114832 (Fiber-reinforced thermoplastic resin structure and manufacturing method thereof), JP-A-6-293023 (Length) (Method for producing fiber-reinforced thermoplastic resin composition), JP-A-7-205317 (Method for taking out fiber bundles and method for producing long-fiber reinforced resin structure), JP-A-7-216104 (Method for producing long-fiber reinforced resin structure) (Method for manufacturing products), JP-A-7-251437 (Method for manufacturing long-fiber reinforced thermoplastic composite material and manufacturing equipment), JP-A-8-118490 (Method for manufacturing cross-head die and long-fiber reinforced resin structure) ) Etc. can be applied.
As the resin-impregnated fiber bundle, Plastron (registered trademark) containing various thermoplastic resins sold by Daicel Polymer Co., Ltd. and fibrous fillers such as glass fiber, carbon fiber, stainless fiber, and aramid fiber. You can also use the series.

<Manufacturing method of rod-shaped molded product>
The method for producing a rod-shaped molded product of the present invention is produced by using a thermoplastic resin composition containing the above-mentioned fibrous filler (preferably the above-mentioned resin-impregnated fiber bundle) and applying a known injection molding method. ..
The injection nozzle of the injection molding machine and the gate of the mold are connected by a spool and a runner.

The mold used in the manufacturing method of the present invention has a plurality of gates connected to one cavity in the mold, and for example, 2 to 4 shown in FIGS. 4 (a) to 4 (c). A mold with a gate can be used.
FIGS. 4A to 4C show a state in which two gates 31, 32, three gates 31 to 33, and four gates 31 to 34 are provided in a portion of the mold leading to one cavity. Has been done.
The shape of the gate is not particularly limited, but is preferably circular or oval, but more preferably circular.
The gates may be arranged at intervals (preferably evenly spaced) between the gates.

When there are two gates as shown in FIG. 4A, it is preferable that the two circular gates 31 and 32 are arranged so that the centers of the two circular gates 31 and 32 are located on the same straight line (diameter) passing through the center O.
Further, the two circular gates 31 and 32 are preferably formed in the range of 0.1r to 0.9r when the radius from the center O is r.

As shown in FIG. 4B, when there are three gates, the lengths of the three lines connecting the center and the center O of the three circular gates are the same with the center O as the base point, and the center O and the three lines are the same. It is preferable that the lines are arranged so that the angles of the lines are the same (120-).
Further, the three circular gates 31 to 33 are preferably formed in the range of 0.1r to 0.9r when the radius from the center O is r.

As shown in FIG. 4C, when there are four gates, the lengths of the four lines connecting the centers and the centers O of the four circular gates are the same with the center O as the base point, and the four lines are the same as the center O. It is preferable that the lines are arranged so that the angles of the lines are the same (90-).
Further, the four circular gates 31 to 34 are preferably formed in the range of 0.1r to 0.9r when the radius from the center O is r.

The runner connected to the plurality of gates of the mold has one trunk runner connected to the spool and a plurality of branch runners branched by the number corresponding to the number of gates and connected to the gates.
The runner 50 shown in FIG. 5A corresponds to two molds having the two gates 31 and 32 shown in FIG. 4A, and simultaneously manufactures two rod-shaped molded bodies. be able to.
The runner 50 shown in FIG. 5A is different from one trunk runner 51 connected to the spool 80 and a pair of substantially U-shaped branch runners 53 and 54 branched from the trunk runner 51. It has a pair of branch runners 56 and 57, for a total of four branch runners.
In FIG. 5A, the trunk runner 51 and the pair of branch runners 53 and 54 are connected via the branch portion 52, and the trunk runner 51 and the pair of branch runners 56 and 57 are connected via the branch portion 55. It is connected.
It is preferable to have the branch portions 52 and 55 because the function of simultaneously distributing an equal amount of molten resin to the pair of branch runners 53 and 54 and the pair of branch runners 56 and 57 is enhanced, but the branch portion 52 is preferable. , 55 may be absent, and a pair of branch runners 53, 54 and a pair of branch runners 56, 57 may be directly branched from the trunk runner 51.
The pair of branch runners 53 and 54 have the same shape and dimensions, and the distance from the branch 52 to the tip (tip opening) 53a of the branch runner 53 and the distance from the branch 52 to the tip (tip opening) of the branch runner 54. Part) The distance to 54a is the same.
The pair of branch runners 56 and 57 have the same shape and dimensions, and the distance from the branch portion 55 to the tip portion (tip opening) 56a of the branch runner 56 and the tip portion (tip opening) of the branch runner 57 from the branch portion 55. Part) The distance to 57a is the same.

The runner 60 shown in FIG. 5 (b) corresponds to two molds, and can manufacture two rod-shaped molded bodies at the same time.
The runner 60 shown in FIG. 5B is different from one trunk runner 61 connected to the spool 80 and a pair of substantially C-shaped branch runners 63 and 64 branched from the trunk runner 61. It has a pair of branch runners 66 and 67, for a total of four branch runners.
In FIG. 5B , the trunk runner 61 and the pair of branch runners 63 and 64 are connected via the branch portion 62, and the trunk runner 61 and the pair of branch runners 66 and 67 are connected via the branch portion 65. It is connected.
It is preferable to have the branch portions 62 and 65 because the function of simultaneously distributing an equal amount of molten resin to the pair of branch runners 63 and 64 and the pair of branch runners 66 and 67 is enhanced. , 65 may be absent, and a pair of branch runners 63, 64 and a pair of branch runners 66, 67 may be directly branched from the trunk runner 61.
The pair of branch runners 63 and 64 have the same shape and dimensions, and the distance from the branch portion 62 to the tip portion (tip opening) 63a of the branch runner 63 and the tip portion (tip opening) of the branch runner 64 from the branch portion 62. Part) The distance to 64a is the same.
The pair of branch runners 66 and 67 have the same shape and dimensions, and the distance from the branch portion 65 to the tip portion (tip opening) 66a of the branch runner 66 and the tip portion (tip opening) of the branch runner 67 from the branch portion 65. Part) The distance to 67a is the same.

One runner may be, for example, a combination of a pair of branch runners 53 and 54 shown in FIG. 5A and a pair of branch runners 63 and 64 shown in FIG. 5B.
Further, the shape of the pair of branch runners is not limited to those shown in FIGS. 5A and 5B, and may be V-shaped or the like.

When three pairs of branch runners are used as runners, it can be used for a mold having three gates 31 to 33 as shown in FIG. 4B, and four pairs of branch runners are used as runners. When used, it can be used for a mold having four gates 31 to 34 as shown in FIG. 4 (c).

The action and effect when the runner 50 shown in FIG. 5A and the mold shown in FIG. 4A are used will be described. In addition, the case where the runner 70 of the prior art shown in FIG.
The runner 70 of FIG. 7 is a total of 4 of one trunk runner 71 connected to the spool 80, a pair of branch runners 72 and 73 connected to the trunk runner 71, and another pair of branch runners 74 and 75. It has book branch runners 72-75.
The four branch runners 72 to 75 have the same shape, but the distance from the connection point between the spool 80 and the trunk runner 61 is different between the branch runner 72 and the branch runner 73, and the branch runner 74 and the branch runner 75 have different distances. It's different.

(Use of runner 50 in FIG. 5A)
When the molten resin is injected from the nozzle of the injection molding machine, the molten resin enters the trunk runner 51 through the spool 80 and passes through the branch liner 52 and the pair of branch liners 52 and 53 to the gate 31. It is injected from 32 into one mold cavity (a cavity having a shape corresponding to a target rod-shaped molded product).
At this time, since the distances (tip openings 53a, 54a) from the branch portion 52 to the two branch liners 52, 53 are all the same, the resin in the molten state is simultaneously sent from the two branch liners 52, 53, respectively. It is injected into the cavity of the mold.
Therefore, in the obtained rod-shaped molded product, the degree of orientation of the fibrous filler in the long axis direction is high, and the bending strength is also high.
The same effect can be obtained when a pair of branch liners 56, 57 are injected into the cavity of the mold.

(Use of runner 70 in FIG. 7)
When the molten resin is injected from the nozzle of the injection molding machine, the molten resin enters the trunk runner 71 through the spool 80, and from there through the pair of branch liners 72 and 73 from the gates 31 and 32. It is ejected into the cavity of one mold, through a pair of branch liners 74, 75, and ejected from gates 31, 32 into the cavity of another mold.
At this time, the branch liner 72 and the branch liner 73 have different distances from the connection point between the spool 80 and the trunk runner 71, and the branch liner 74 and the branch liner 75 are the distances from the connection point between the spool 80 and the trunk runner 71. Is different, so that the molten resin is injected with a slight time lag.
Therefore, in the obtained rod-shaped molded product, the degree of orientation of the fibrous filler in the long axis direction is low, and the bending strength is also low.

FIG. 8 describes a preferred embodiment for producing many rod-shaped molded products at one time by applying the method for producing a rod-shaped molded product of the present invention.
The trunk runner can use the first trunk runner to the nth trunk runner, and the branch runner can use the first branch runner to the nth branch runner.
Here, the number of n is not particularly limited, but can be, for example, in the range of 2 to 10.
The embodiment of FIG. 8 is an example of n = 3.

Two first branch runners 101 and 102 (first branch runner group) are branched from one first trunk runner 100. The first branch runner group consists of two branch runners.
The first branch runner 101 is connected to the second a trunk runner 103, and the first branch runner 102 is connected to the second b trunk runner 104. The second trunk runner group consists of two trunk runners.

Two second branch runners 105 and 106 (second branch runner group) are branched from the second a trunk runner 103, and two branch runners 107 and 108 (second branch runner group) are branched from the second b trunk runner 104. Has been done. The second branch runner group consists of four branch runners.
The second branch runner 105 is connected to the third trunk a runner 109, the second branch runner 106 is connected to the third b trunk runner 110, the second branch runner 107 is connected to the third c trunk runner 111, and the second branch runner is connected. 108 is connected to the 3rd trunk runner 112. The third trunk runner group consists of four trunk runners.

From the third trunk a runner 109, two branch runners 121 and 122 are branched via a branch portion 120, and are connected to two gates facing the cavity of one mold.
Further, from the third trunk a runner 109, two branch runners 131 and 132 are branched via the branch portion 130, and are connected to two gates facing the cavity of one mold.

From the third trunk b-runner 110, two branch runners 141 and 142 are branched via a branch portion 140, and are connected to two gates facing the cavity of one mold.
Further, from the third trunk b-runner 110, two branch runners 151 and 152 are branched via a branch portion 150, and are connected to two gates facing the cavity of one mold.

From the third trunk c runner 111, two branch runners 161, 162 are branched via a branch portion 160, and are connected to two gates facing the cavity of one mold.
Further, from the third trunk c runner 111, two branch runners 171, 172 are branched via a branch portion 170, and are connected to two gates facing the cavity of one mold.

From the third trunk d-runner 112, two branch runners 181, 182 are branched via a branch portion 180, and are connected to two gates facing the cavity of one mold.
Further, from the third trunk d-runner 112, two branch runners 191, 192 are branched via a branch portion 190, and are connected to two gates facing the cavity of one mold.
In the embodiment shown in FIG. 8, eight rod-shaped compacts can be manufactured by using eight molds at a time.
By repeatedly connecting the trunk runner and the branch runner a required number of times (n times) by the tournament branching method in this way, it is possible to manufacture a large number of rod-shaped molded bodies at one time using more molds.

<Bolt manufacturing method>
By applying the method for manufacturing a rod-shaped molded product of the present invention described above, in addition to bolts such as long screw bolts as shown in FIG. 6 (a) and full screw hexagon bolts as shown in FIG. 6 (b), wood screws Etc. can be manufactured.
The long screw bolt 40 shown in FIG. 6A has a thread 41 on the entire peripheral surface, and contains a fibrous filler in a state of being oriented in the long axis direction. Note that D is the diameter of the bottom surface 42.
The full-threaded hexagon bolt 45 shown in FIG. 6B has threads 46 from under the head 47 to the entire peripheral surface, and at least the inside where the threads 46 are formed is filled with fibrous material. The material is contained in a state of being oriented in the axial direction. Note that D is the diameter of the bottom surface 48.

When manufacturing the full-thread hexagon bolt 45 shown in FIG. 6 (b), the gate is located at the portion of the mold cavity facing the head 47 or at the portion facing the bottom surface 48. It can be injection molded using a mold.
When using a runner composed of a combination of the trunk runner and a plurality of branch runners of the present invention, the head 47 is used so that the gate is located in the portion of the mold cavity facing the head 47. It is preferable to inject the resin from the surface to the bottom surface 48 side because the orientation of the fibrous filler in the long axis direction is enhanced.

(1) Residual fiber length (weight average fiber length)
About 3 g of a sample was cut out from the molded product, and the fibers were taken out by the following method. The weight average fiber length was calculated from a part of the extracted fibers (500 fibers). As the calculation formula, [0044] and [0045] of JP-A-2006-274061 were used.
Carbon fiber: The PPS resin was dissolved and removed with sulfuric acid, and the fiber was taken out.
Glass fiber: The PPS resin was heated and incinerated at 650 ° C. to take out the fiber.

(2) Tensile strength The tensile strength of the rod-shaped compacts obtained in Examples and Comparative Examples was measured under the following conditions.
Measuring equipment: Autograph AG2000 (manufactured by Shimadzu Corporation)
Test speed: 5 mm / min
Distance between chucks: 40 mm

Examples 1-3, Comparative Examples 1-3
In Example 1 and Comparative Example 1, a resin-impregnated fiber bundle (Plastron PAX-GF50-02; 1.0 mm in diameter) composed of 50% by mass of polyamide MXD6 and 50% by mass of long glass fibers (LGF) as a thermoplastic resin composition. , 9 mm long cylindrical shape; Daicel Polymer Co., Ltd. was used.
In Example 2 and Comparative Example 2, a resin-impregnated fiber bundle (1.0 mm in diameter and 9 mm in length, Plastron PAX) composed of 50% by mass of polyamide MXD6 and 50% by mass of long carbon fibers (LCF) as a thermoplastic resin composition. -CF40-02; Cylindrical shape; Daicel Polymer Co., Ltd. was used.
In Example 3 and Comparative Example 3, a resin-impregnated fiber bundle (1.0 mm in diameter and 9 mm in length, Plastron PPS-GF50-01) composed of 50% by mass of PPS and 50% by mass of long glass fibers as a thermoplastic resin composition was used. Cylindrical shape; Daicel Polymer Co., Ltd. was used.
In each example, the length of the cylindrical resin-impregnated fiber bundle and the contained fiber length are the same.

Using each composition (resin-impregnated fiber bundle) of Example 1 and Comparative Example, injection molding was performed under the following conditions to obtain a round bar having a diameter (D) of 12 mm and a length (L) of 80 mm. The residual fiber length and tensile strength of the obtained round bar were measured. The results are shown in Table 1 (injection molding conditions).
Injection molding machine: J150EII of Japan Steel Works
Cylinder temperature: 280 ° C
Back pressure: 2 MPa
Mold temperature: 160 ° C

FIG. 9A shows an axial cross-sectional view of the rod-shaped molded product obtained in Example 1, and FIG. 9B shows an axial cross-sectional view of the rod-shaped molded product obtained in Comparative Example 1.
In the first embodiment, since the resin material containing the fibrous filler is uniformly (simultaneously) ejected from the two gates, a weld line exists along the central axis of the rod-shaped molded product.
In Comparative Example 1, since the resin material containing the fibrous filler was injected non-uniformly (with a time lag) from the two gates, the weld line was present at a position deviated from the central axis of the rod-shaped molded product. ..
This difference in orientation is due to the difference in the branch runners used in the examples and the comparative examples. Similar results were obtained even when the runner shown in FIG. 5 (b) was used instead of the runner shown in FIG. 5 (a).
Due to such a difference in the orientation of the fibrous filler, Example 1 and Comparative Example 1 had the same residual fiber length, but there was a clear difference in tensile strength, and other Examples 2 and 3 And Comparative Examples 2 and 3 had similar results.

The rod-shaped molded product obtained by the method for producing a rod-shaped molded product of the present invention can be used as bolts such as various pins, various wood screws (counterhead or round head), long screw bolts, hexagon bolts, and full screw hexagon bolts. it can.

1, 11, 21 Rod-shaped molded body 31, 32, 33, 34 Gate 40, 45 Bolt 50, 60 Runner 51, 61 Trunk runner 52, 55 Branch part 53, 54, 56, 57 Branch runner 62, 65 Branch part 63, 64, 66, 67 branch runner 80 spool

Claims (5)

A method for producing a rod-shaped molded product, which comprises a step of injection molding a thermoplastic resin composition containing a fibrous filler into a mold by an injection molding machine.
The thermoplastic resin composition containing the fibrous filler contains a resin-impregnated fiber bundle in which a bundle of fibrous filler impregnated with resin is cut in the range of 6 to 30 mm.
The injection nozzle of the injection molding machine and the gate of the mold are connected by a spool and a runner.
The rod-shaped molded product includes a portion having a uniform outer diameter, and has a circular or regular polygonal cross-sectional shape in the width direction.
The mold has a plurality of gates for injecting a thermoplastic resin into one cavity of the mold.
The runner has one trunk runner connected to the spool, a plurality of branch runners branched from the one trunk runner by the number corresponding to the number of gates of the mold, and a plurality of branching portions. Is what you are doing
One trunk runner and a plurality of branch runners have a flow direction of a molten resin passing through one trunk runner and a flow of a plurality of branch portions through a plurality of branch portions branched from one trunk runner. The directions are different, and the molten resin is connected so that the flow direction of the molten resin passing through the plurality of branch portions and the flow direction of the molten resin passing through the tip openings of the plurality of branch runners are the same .
For each of the plurality of branch runners, the flow direction of the molten resin passing through the tip openings of the plurality of branch runners and the length direction of the gate leading to one cavity in the mold are made the same. , Which is connected to each of a plurality of gates connected to one cavity in the mold.
A method for producing a rod-shaped molded product, wherein the distances of the plurality of branch runners from the plurality of branch portions of the trunk runner to the plurality of gates of the mold are all the same. The trunk runner and the branch runner
A plurality of first branch runners are branched from one first trunk runner via a branch portion, and the first branch runners are branched .
Each of the plurality of first branch runners is connected to one second trunk runner.
The tournament branching method in which a plurality of second branch runners are branched from each of the plurality of second trunk runners via a branching portion has a connection state in which the tournament branching method is repeated n times.
It has a plurality of n-th trunk runners and a plurality of n-th branch runners connected to each of the n-th trunk runners via a branch portion .
Each of the plurality of n-th branch runners is connected to each of the plurality of gates of the mold.
The method for producing a rod-shaped molded product according to claim 1, wherein the distances of the plurality of n-th branch runners from the branch portion of the trunk runner to the plurality of gates of the mold are all the same. The method for producing a rod-shaped molded product according to claim 1 or 2, wherein the number of gates of the mold is 2 to 4, and the number of branch runners corresponds to the number of gates. The thermoplastic resin is selected from polyamide, polyolefin, thermoplastic polyurethane (TPU), polyester, PPS, and styrene resin, and the fibrous filler is glass fiber, carbon fiber, organic fiber, metal fiber, or inorganic. The method for producing a rod-shaped molded product according to any one of claims 1 to 3, which is selected from fibers (excluding glass fibers). The method for producing a rod-shaped molded product according to any one of claims 1 to 4 , wherein the rod-shaped molded product has a circular cross section in the width direction and has a thread on the peripheral surface.