JP2001293752A - Method for insert molding for resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method for insert molding for a resin capable of improving adhesive properties of a resin with an insert component and reducing a cost. SOLUTION: The method for molding the resin by insert molding on a periphery of the insert component having a predetermined length comprises the steps of setting a cavity shape so that a part of the resin to be molded at the periphery of the component becomes a short-diameter part of a diameter shorter than the other part over a predetermined range of a lengthwise direction of the component, and distributing the resin in the lengthwise direction of the component in the cavity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin insert molding method, and more particularly to a resin insert molding method in which the adhesion between a resin and an insert part is improved.

[0002]

2. Description of the Related Art As an injection molding method for a thermoplastic resin, an insert molding method in which an insert part such as a metal is inserted into a mold and molded is well known. This insert component is installed in a cavity in a mold and is used for reinforcing a molded product, attaching another component, or forming an electric circuit.

FIG. 4 is a schematic cross-sectional view showing an example of a conventional insert molded product, wherein 1 is an insert part, 2 is a resin, and 4 is a gate from which a molten resin is injected. In this method, depending on the thickness of the resin portion and the type of resin used, the adhesiveness between the insert component and the resin may be insufficient due to the influence of the resin shrinkage during molding.
In consideration of this point, a method for improving the adhesion regardless of the use or non-use of an adhesive or the like is disclosed in Jpn.
Japanese Patent Application Laid-Open Publication No. H11-133, etc. proposes a method of providing an uneven part, a lateral groove, or the like in the shape of an insert part (metal). That is, FIG. 5 is a schematic cross-sectional view showing an example of the insert molded product improved in this way, 6 is a concave portion of an insert component provided for improving adhesion, and 7 is provided for improving adhesion. 2 shows a projected portion of the inserted insert part. In this method, the adhesion can be improved by forming the concave and convex portions, but the processing method of the insert component becomes complicated and the cost increases. Considering this point, it may be desirable to improve the shape of the resin material rather than the shape of the insert part. From this viewpoint, as shown in FIG. 6 (schematic sectional view), it has been proposed to provide a thin portion 8 of resin in the vicinity of the insert part in order to improve the adhesion (Japanese Patent Laid-Open No. 11-10648). .

In this method, as described above, the flow of the resin is made uniform and the adhesion is improved by thinning the vicinity of the insert part. However, in this method, general-purpose applicability in actual products is difficult because the shape of the molding resin is restricted.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resin insert molding method capable of improving the adhesion between an insert part and a resin and reducing the cost.

[0006]

Means for Solving the Problems The present inventor has made various studies to solve the above-mentioned problems and to obtain an efficient insert molding method for resin, and has reached the present invention. That is, the gist of the present invention is to provide an insert molding method for molding a resin around an insert part having a predetermined length, wherein the resin is molded around the insert part over a predetermined range in the length direction of the insert part. The cavity shape is set so that a portion of the resin to be formed has a shorter diameter portion having a shorter diameter than the other portion, and the resin is characterized by flowing the resin in the length direction of the insert component in the cavity. In the insert molding method.

Hereinafter, the present invention will be described in detail. First, as the resin used in the present invention, general thermoplastic resins such as an olefin resin, a vinyl chloride resin, a polyester resin, a polyamide resin, an ABS resin, a polycarbonate resin, an acetal resin, and a fluororesin can be used. These resins may contain additives such as a stabilizer, an antistatic agent, a flame retardant, a plasticizer, a reinforcing agent, and the like according to a conventional method. Also, insert parts are metal,
It can be made of ceramics or the like, and its size and shape are not particularly limited.

[0008] In the method of the present invention, a resin is molded around an insert part having a predetermined length. And
In the present invention, the cavity, which is a space portion for directly forming a molded product in the mold, extends over a predetermined range in the longitudinal direction of the insert component, and a part of the resin molded around the insert component is formed. It is set to be a short diameter portion having a shorter diameter than the other portions.

Then, the molten resin is caused to flow in the cavity in the length direction of the insert part.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the present invention will be described with reference to the drawings. 1 to 3 show schematic cross-sectional views of an insert molded body according to the insert molding method of the present invention. 1 is an insert member, 2 is a resin, 3 is a short-diameter portion (thin portion) provided on the whole or a part of the portion requiring adhesion to enhance adhesion, 4 is a gate, 5 is a resin flow. The short-diameter portion (thin portion) 9 provided over the entire circumference provided for uniformity of the surface is a portion requiring close contact.

In FIG. 1, the molten resin injected from the gate 4 flows in the length direction of the insert part,
In front of the short diameter portion 3 extending over the entire circumference or part of the portion requiring the adhesion in order to enhance the adhesion, before the resin flows into the short diameter portion 3, the resin is thickened in the entire circumferential direction. After filling, the short diameter portion 3 is filled with resin. Therefore, since the portion 9 requiring adhesiveness is thin (short diameter), the pressure and shear heat increase, and the shrinkage decreases.
From these facts, in the rear portion (downstream portion) of the short diameter portion 3, the transferability is improved, uniform adhesion is provided,
The adhesion is improved by reducing the amount of shrinkage. In addition, since the shear heat is increased, the reactivity with a sealant, an adhesive or the like is increased, and the adhesion is improved.

In FIG. 2, a short diameter portion 5 is formed over the entire circumference before the portion 9 requiring close contact in order to make the resin flow uniform.
An example in which is provided. In this example, before the molten resin injected from the gate 4 flows into the short diameter portion 5, the resin is filled in the entire circumferential direction where the thickness is large, and then the short diameter portion 5 is filled with the resin. Therefore, in the portion 9 where the adhesiveness is required, the flow of the resin is made uniform, so that there is no variation in the temperature, and the shrinkage does not increase partly, so that the adhesiveness is improved.

FIG. 3 shows an example in which short-diameter portions 3 and 5 are provided at a portion requiring close contact and at two locations upstream of the portion. In this example, the molten resin injected from the gate 4 first has a short-diameter portion before the short-diameter portion 5 extending over the entire circumference and provided in front of the portion 9 requiring adhesiveness for uniform resin flow. Before the resin flows into the small diameter portion 5, the resin is filled in the entire circumferential direction with a large thickness, and then the short diameter portion 5 is filled with the resin. Therefore, the flow of the resin is made uniform. Next, it flows into the short-diameter portion 3 provided in the portion 9 where the adhesion is required to enhance the adhesion. Therefore, since the portion 9 requiring the adhesion is thin, the pressure and the shear heat increase, and the shrinkage decreases. From these, the rear part (downstream part) of the short diameter part
Thus, the transferability is improved, uniform adhesion is provided, and the amount of shrinkage is reduced, whereby the adhesion is improved. In addition, since the shear heat is increased, the reactivity with a sealant, an adhesive, or the like is increased, and the adhesion is improved.

According to the method of the present invention, an insert molded article having improved adhesion between the resin and the insert part can be obtained, so that intrusion or leakage of water, air, oil or the like from the interface between them can be prevented. Further, since the short diameter portion can relatively flexibly correspond to the shape of the molded product, efficient insert molding can be performed at a relatively low cost. In order to ensure the airtightness and adhesion between the insert component and the resin, it is preferable to apply a sealant, an adhesive or the like to the insert component as described above. However, even when a sealant or the like is not used, the effect of increasing the adhesion between the insert component and the resin and reducing the gap therebetween can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an insert molded body according to the method of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of an insert molded body according to the method of the present invention.

FIG. 3 is a schematic cross-sectional view showing an example of an insert molded body according to the method of the present invention.

FIG. 4 is a schematic sectional view showing an example of a conventional insert molded body.

FIG. 5 is a schematic sectional view showing an example of a conventional insert molded body.

FIG. 6 is a schematic sectional view showing an example of a conventional insert molded body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insert member 2 ... Resin 3 ... Short diameter part 4 ... Gate 5 ... Short diameter part 6 ... Insert member concave part 7 ... Insert member convex part 8 ... Thin part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F202 AA03 AA15 AD03 AG21 CA11 CB01 CB12 CK11 CK15 4F206 AD03 AG21 JA07 JB12 JL02 JM05 JN25 5E063 JB01 XA01

Claims (4)

[Claims] 1. An insert molding method for molding a resin around an insert part having a predetermined length, wherein the resin is formed over a predetermined range in the length direction of the insert part.
The cavity shape is set so that a part of the resin molded around the insert part has a shorter diameter than the other part, and the resin flows in the cavity in the longitudinal direction of the insert part. A method for insert molding a resin. 2. The method according to claim 1, wherein the minor diameter portion is provided corresponding to a portion requiring adhesion. 3. The method according to claim 1, wherein the short diameter portion is provided on the upstream side in the resin flow direction from the portion having the adhesion. 4. The method according to claim 1, wherein the minor diameter portion is provided at at least two places separately in the flow direction of the resin.