JPH1024448A - Molding of insert resin molded product and mold therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the formation of a weld part bringing about the lowering of the strength of a molded product in molding an insert resin molded product integrally fitted with an insert metal fitting. SOLUTION: The respective pin gates 113 provided to a fixed mold 11 are opened so as to face to the outer periphery of the set position of a metal bush 32 in a cavity 13. Since fine clearance of a degree not easily generating the leak of burr is present between the both axial end surfaces of the metal bush 32 set in the cavity 13 and cavity inner wall surfaces 13a, 13b, torque is transmitted from a rotary shaft 14 through an engaging part 14a and the metal bush 32 can be rotated. Therefore, at a time of the filling of the cavity 13 with a plasticized resin material P from the pin gates 113, the metal bush 32 is rotated to stirr the plasticized resin material (P) and the formation of a weld part can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of molding an insert resin molded article integrally provided with an annular or cylindrical insert fitting, such as a synthetic resin pulley or a synthetic resin wheel. is there.

[0002]

2. Description of the Related Art Like a synthetic resin pulley (hereinafter, referred to as a resin pulley), an annular or cylindrical insert fitting such as a metal bush is provided on the inner periphery of a main body made of a synthetic resin mixed with reinforcing fibers. Conventionally, an integrally embedded insert resin molded product is typically molded using a mold 100 as shown in FIG. That is, this mold 100
Are brought into close contact with each other so that the cavity 101
And a plurality of pin gates 104 opened around a metal bush 201 concentrically arranged in the cavity 101 in the fixed mold 102. Then, a plasticized resin material 202 containing reinforcing fibers is injected and filled, followed by curing to form a resin pulley 200 in which a metal bush 201 is integrally inserted into the inner periphery as shown in FIG.

[0003]

According to the above-mentioned conventional molding technique, it is inevitable that a weld Wd is formed between the pin gate positions 104 'on the molded resin pulley 200. The weld portion Wd is a portion where the tip of the flow of the plasticized resin material 202 flowing from each pin gate 104 of the mold 100 into the cavity 101 in the molding process collides with each other and fuses with each other. However, at this collision surface, the plasticized resin material 202 is hardly sufficiently fused, and the blended fibers in the plasticized resin material 202 are aligned along the merging surface. There is a problem that the mechanical strength is significantly lower than that of the other parts.

The present invention has been made in view of the above circumstances, and a technical problem thereof is to reduce the strength of a molded product in molding an insert resin molded product integrally including an insert fitting. The purpose is to improve the quality by effectively preventing the formation of a welded portion that causes the problem.

[0005]

As a means for effectively solving the above-mentioned technical problems, a method for molding an insert resin molded product according to the present invention comprises the steps of: An insert fitting opposed to the inner wall surface of the insert with a minute clearance is arranged, and the plasticizing resin material is filled into the cavity from a plurality of pin gates opened facing the outer peripheral position of the insert fitting in the cavity. Before the material is cured, the insert is rotated about its axis. That is, according to this molding method, the flow of the plasticized resin material flowing into the cavity from each of the pin gates is agitated by the friction with the outer peripheral surface of the rotating insert fitting and the viscosity of the plasticized resin material, so that they are entangled. In addition, it is possible to effectively prevent the formation of a weld portion on a molded product.

Further, in order to realize the above-mentioned molding method, a molding die for an insert resin molded product according to the present invention is provided with a fixed die and a movable die which are in close contact with each other to form a cavity between the close contact portions. A mold, and a rotating shaft that is inserted into one of the fixed mold and the movable mold so as to be rotatable around an axis, and both end faces in the axial direction are provided at an end of the rotating shaft on the cavity side. An engagement portion is formed which is engaged with the inner peripheral surface of the insert fitting which is arranged in a state facing the inner wall surface of the cavity with a small clearance,
A plurality of pin gates opened in the fixed mold are opened facing the outer peripheral position of the insert fitting in the cavity. According to this mold, a rotational force is applied to the insert fitting set in the cavity through the engaging portion by the rotating shaft inserted through the fixed mold or the movable mold, and is rotated around its axis. Both ends in the axial direction of the insert fitting are allowed to rotate by opposing the inner wall surface of the cavity with a small clearance. Further, since the rotating shaft for rotating the insert metal fitting is located on the inner peripheral side of the clearance, burr leakage to the rotating shaft portion is effectively prevented.

[0007]

FIG. 1 is a sectional view of a mold 1 showing a preferred embodiment of the present invention. This mold 1 forms a resin pulley 3 as an insert resin molded product in which a metal bush 32 as an insert fitting is integrally embedded in the inner periphery of a disk-shaped main body 31 made of a synthetic resin as shown in FIG. Fixed die 1 which forms a cavity 13 between the closely abutting portions by closely abutting each other.
1 and a movable mold 12. The fixed mold 11 is composed of an outer mold plate 11A and an inner mold plate 11B closely contacted with each other, and the outer mold plate 11A extends from the sprue 111 to which the nozzle tip of the injection cylinder 2 comes into contact with and separates from the sprue 111. A runner 112 is formed, and a plurality of pin gates 113 branching from the runner 112 and opening toward the cavity 13 are formed on the inner mold plate 11B.

The movable die 12 is formed with a shaft hole 12a penetrating toward the center of the cavity 13, in which the rotating shaft 14 is rotatable around the axis. It has been inserted. At the tip of the rotating shaft 14 protruding toward the cavity 13, an engaging portion 14 a that is engaged with the inner peripheral surface of the metal bush 32 is formed, and the metal bush 32 provided on the inner peripheral portion of the resin pulley 3 is formed. As shown in FIG. 3, a spline groove 32a for fixing to the pulley shaft is formed on the inner peripheral surface, and the outer peripheral surface of the engaging portion 14a at the tip of the rotary shaft 14 is formed as shown in FIG. It has a shape that can be engaged with the spline groove 32a in the circumferential direction.

A bevel gear 15 is attached to the outer end of the rotary shaft 14 facing away from the cavity 13.
5 is a bevel gear 17 attached to the output shaft of the motor 16
And are engaged. The motor 16 is started in synchronization with the start of the injection of the plasticized resin material P by the extrusion screw (not shown) of the injection cylinder 2, and is stopped immediately before the filling of the cavity 13 with the plasticized resin material P is completed. , Its driving is controlled.

Each pin gate 113 opened on the inner die plate 11B of the fixed die 11 is open to the outer peripheral space at the set position of the metal bush 32 in the cavity 13. When the fixed mold 11 and the movable mold 12 are closed, the metal bush 32 set in the cavity 13 is closed.
Between the axial end surfaces of the inner mold plate 11B and the cavity inner wall surface 13b of the movable mold 12 is small enough to prevent burr leakage easily. From the rotating shaft 14 to the engaging portion 14a
The metal bush 32 to which the torque is transmitted through can rotate smoothly around its axis.

In order to insert-mold the resin pulley 3 using the mold 1 having the above configuration, first, the fixed mold 11 and the movable mold 12 are formed.
And the cavity inner wall surface 13b on the movable mold 12 side.
The metal bush 32 is set by fitting the spline groove 32a of the inner circumference of the metal bush 32 into and engaging with the outer circumference of the engagement portion 14a of the rotary shaft 14 protruding from the center of the metal bush 32. Thereafter, the movable mold 12 is advanced, and the movable mold 12 is brought into close contact with the fixed mold 11 to close the mold. The tip of the nozzle is inserted into the cavity 13 formed by the sprue 11 of the fixed mold 11.
The plasticized resin material P is injected from the injection cylinder 2 against the sprue 111, the runner 112, and the pin gate 113.
Injection filling through.

Since a required mechanical strength is required for the resin pulley 3 formed by the mold 1, a reinforcing fiber such as carbon fiber or glass fiber is blended as the plasticized resin material P. Things are used.

At the same time that the injection of the plasticized resin material P from the injection cylinder 2 into the cavity 13 is started, the motor 1
6, the driving force is transmitted to the rotating shaft 14 via bevel gears 17 and 15, and the metal bush 32 set in the cavity 13 is integrated with the rotating shaft 14 via the engaging portion 14a. Is rotated. Therefore, the metal bush 3
The plasticized resin material P flowing into the cavity 13 from each of the pin gates 113 facing the outer peripheral position 2 circulates and flows in the cavity 13 in the circumferential direction in the cavity 13 by contact with the outer peripheral surface of the rotating metal bush 32. . Moreover, since the flow velocity of the plasticized resin material P in the cavity 13 is different between the vicinity of the metal bush 32 and a position away from the metal bush 32, the plasticized resin materials P from the respective pin gates 113 are mixed with each other and stirred.

Further, the metal bush 3 is removed from the cavity 13.
2, a centrifugal force acts to remove the plasticized resin material P that is to enter into the small clearance between the both end surfaces in the axial direction and the fixed mold 11 and the movable mold 12. Burr leakage does not easily occur, and the engaging portion 14a for rotating the metal bush 32 is located on the inner peripheral side of the clearance. Therefore, for example, even when the plasticizing resin material P is a thermosetting resin, , Movable mold 12
A situation in which the rotation of the engaging portion 14a is prevented by the resin entering between the and the engaging portion 14a and hardening does not occur.

The driving of the motor 16 is stopped immediately before the filling of the plasticized resin material P into the cavity 13 is completed, that is, the rotation of the metal bush 32 is stopped at this time. The plasticized resin material P in the filled cavity 13 hardens with the passage of time, and is thereby integrally joined to the outer peripheral surface of the metal bush 32. After a predetermined time required for the resin material to sufficiently cure, the movable mold 1 is moved from the fixed mold 11 to the movable mold 1.
The mold is opened by separating and moving 2, and the resin pulley 3 as a molded product shown in FIG. 2 is taken out. In the main body 31 of the resin pulley 3, there is no weld portion Wd extending between the pin gate positions as shown in FIG. This is because the plasticized resin material P is stirred by the rotation of the metal bush 32 during the filling process into the cavity 13 as described above, so that the fiber orientation and the molecular orientation due to the collision / merging at a specific position between the pin gates 113 are reduced. This is because the plasticized resin materials P flowing from the respective pin gates 113 are not fused and are sufficiently fused with each other.

In the above method, as shown in FIG. 4, it is more effective if the outer peripheral surface 32b of the metal bush 32 is formed in a bevel gear shape. That is, in this case, since the outer peripheral surface 32b of the rotating metal bush 32 has a gear shape, the frictional force with the plasticized resin material P is increased, and therefore, a remarkable circulating flow in the circumferential direction occurs. In addition, the centrifugal force given by the circulating flow is relatively large on the large diameter side of the outer peripheral surface 32b, so that the plasticized resin material P is combined with the primary circulating flow in the circumferential direction in combination with the flow from the pin gate 113. A composite flow is generated by the secondary circulation flow in the radial direction as shown by the thick arrow in the figure, and the stirring action becomes remarkable.

Further, if the rotation of the motor 16 is set to be reversed every predetermined time from the start to the stop, a more complicated flow is caused in the plasticized resin material P.

The present invention is not construed as being limited to the illustrated embodiment. For example, the engaging portion 14
Various shapes are conceivable for a, such as a shape in which a slit is formed in a collet shape to chuck the inner peripheral surface of the insert fitting. In the above embodiment, the rotating shaft 14 is provided on the movable mold 12 side.
2 and the position of the pin gate 113, etc.
It is also possible to provide it on one side.

[0019]

According to the present invention, the following effects are realized. (1) Since the plasticized resin material that has flowed into the cavity from each pin gate is stirred by the rotation of the insert, the formation of welds in the insert resin molded product is effectively prevented, and insert resin molding with high mechanical strength is performed. Goods are obtained. (2) No burrs leak to the outer periphery of the core that rotates the insert bracket.

[Brief description of the drawings]

FIG. 1 is a sectional view of a molding die showing a preferred embodiment of the present invention.

FIG. 2 is a view of a resin pulley formed according to the embodiment as viewed from an axial direction.

FIG. 3 is a view of a metal bush used in the embodiment as viewed from an axial direction.

FIG. 4 is an explanatory diagram showing an operation when the outer peripheral surface of the metal bush is formed in a bevel gear shape in the embodiment.

FIG. 5 is a cross-sectional view of a molding die according to the related art.

FIG. 6 is a view of a resin pulley molded according to the above-described conventional technique as viewed from an axial direction.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mold 11 fixed mold 11A outer mold plate 11B inner mold plate 111 sprue 112 runner 113 pin gate 12 movable mold 13 cavity 13a, 13b inner wall surface 14 rotation shaft 14a engaging portion 15, 17 bevel gear 16 motor 2 injection cylinder 21 nozzle tip 3 Resin pulley (insert resin molded product) 31 Main body 32 Metal bush (insert fitting) 32a Spline groove 32b Outer peripheral surface

Claims (2)

[Claims] 1. Both ends of an axial direction inside a cavity (13) of a mold (1) are formed on inner wall surfaces (13) of the cavity (13).
a, 13b) and an insert fitting (32) facing with a minute clearance, and a plurality of pin gates (113) opened facing the outer peripheral position of the insert fitting (32) in the cavity (13). (13) Filling the plasticized resin material (P), and rotating the insert fitting (32) around its axis before curing the plasticized resin material (P). Product molding method. 2. A fixed mold (1) in which the cavities (13) are formed by closely abutting each other to form a cavity (13) between the closely abutting portions.
1) and a movable mold (12), and a rotary shaft (14) inserted into one of the fixed mold (11) and the movable mold (12) so as to be rotatable around an axis. An insert fitting (32) is set at an end of the rotating shaft (14) on the side of the cavity (13) so that both axial end surfaces thereof face the inner wall surfaces (13a, 13b) of the cavity (13) with a small clearance. An engaging portion (14a) to be engaged with the inner peripheral surface of the fixed die (11) is formed.
A molding die for an insert resin molded product, wherein 13) is opened facing an outer peripheral position of an insert fitting (32) in the cavity (13).