JP3112717B2 - Injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for injection molding. More specifically, the present invention relates to an injection molding die in which burrs are not easily generated when a thin and lightweight plastic housing of a portable electronic device or the like is formed.

[0002]

2. Description of the Related Art Conventionally, housings used for home electric appliances, toys, telephones, OA equipment, portable personal computers, portable word processors, and the like have been made of metal or plastic. Most are made of plastic to meet the demand for miniaturization.
The plastic material is inexpensive and easy to mold A
BS resin is generally used, and the thickness of the housing formed by the resin is usually 2.5 to 3 mm because it is necessary to secure strength.
That is all.

FIG. 6 shows a cross section of a cavity portion of an injection mold according to the prior art and a partial view of a molded article formed by the mold. (A) In the mold shown in the figure, 1 is a core mold, 2 is a mold mold, 3 is a parting part, 4 is a cavity, 5 is a gate, 6 is a sprue, 7 is a direction of mold clamping pressure, and 8 is injection. 9 is the direction of the pressure of the resin to be
Reference numeral 10 denotes an abutting portion for providing a hole 12 in the molded product 11.

[0004] A molded product injection-molded with this mold is as shown in FIG. 1 (b), and its thickness is the same as the thickness of the cavity 4 of the mold. When the thickness of such a molded product is 2.5 to 3 mm or more, the injection pressure during molding does not need to be particularly high, and burrs hardly occur on the parting line of the mold. However, there is a limit in realizing a thin and lightweight housing. In order to further reduce the weight, it is necessary to reduce the thickness of the housing.

[0005]

In order to reduce the thickness of the plastic housing to 1 mm or less, the following problems occur. If the conventional ABS resin is made thinner as it is, the strength is extremely reduced and the content cannot be protected. Therefore, it is necessary to use a resin material such as a high-strength engineering plastic. However, when the thickness is less than 1 mm, the flow of the material is poor, and a high injection pressure is required to fill the narrow mold cavity with the resin.

When the injection pressure is set to a high pressure, a mold clamping pressure that is not inferior to the injection pressure is required. However, since the mold may be deformed, the size of the mold is increased, and the cost is increased. Further, when the injection pressure becomes higher than the specified mold clamping pressure, the mold clamping pressure loses the injection pressure to open the mold, and burrs 12a are generated along the parting line of the molded article 11 as shown in FIG. The cost of the deburring operation raises the unit price of the molded product and lowers the yield of the molded product.

An object of the present invention is to realize an injection molding die in which burrs are less likely to be generated even when the injection pressure is high when a thin and lightweight plastic housing is formed.

[0008]

According to the injection molding die of the present invention, the thickness of the side rising portion 11a is 2 mm or less.
A mold for injection-molding a plastic housing 11 having a thickness of 1 mm or less in other portions, wherein the side-surface rising portion 1
It is characterized in that the mold part in contact with the outer surface of 1a has a slide structure, and the parting part 3 is set parallel to the mold clamping direction. Further, in addition to the above, the mold corresponding to the hole 12 formed in the housing 11 has a spigot structure. By adopting this configuration, an injection molding die in which burrs are unlikely to appear can be obtained.

[0009]

FIG. 1 is an explanatory view of the principle of the present invention, and shows a sectional view. In the figure, 1 is a core type, 2 is a mold type,
3 is a parting part, 4 is a cavity, 5 is a gate, 6
Is a spool, 7 is the direction of the mold clamping pressure, 8 is the direction of the pressure of the resin, 9 is a fitting portion with other parts, 13 is a slide type, 1
Reference numeral 4 denotes a slide-type operation direction, and reference numeral 15 denotes a spigot structure. Although there are four slide dies 13 in front, rear, left and right, only one on the left is shown.

When a thin wall is formed with such a mold structure,
The molten resin injected at a high pressure is pressed in the cavity 4 in a direction to open the mold as indicated by an arrow 8. However, since the parting line 3 of the slide die 13 is parallel to the arrow 8, there is almost no gap. For this reason, burrs hardly appear, and extra work such as deburring is not required.

[0011]

2 and 3 show an embodiment of the present invention. FIG. 2 shows a state in which the mold is opened, and FIG. 3 is a sectional view showing a state in which the mold is closed. FIG. 4 is a view showing an example of a thin plastic casing formed by the injection molding die of the present invention. The plastic housing 11 shown in FIG. 4 has a bottom surface thickness of 1 mm, a side rising portion 11a of 2 mm for fitting with another housing, and a hole 12 through which components are inserted is provided on the bottom surface. I have.

In FIGS. 2 and 3, reference numeral 16 denotes a sprue support plate, reference numeral 17 denotes a cabinet plate, and reference numeral 18 denotes a core plate. These three plates are not shown, but four plates penetrating four corners of each plate. The plate moves along the axis, and the mold can be opened and closed.

A sprue bush 19 is attached to the sprue support plate 16. The cavity 4 is formed on the lower surface of the cavity plate 17, the runner 20 is formed on the upper surface, and the sprue 6 and the gate 5 connecting the two are formed. A cavity 21 for accommodating the slide core is formed around the cavity 4.
An angular pin 22 for driving a slide core is implanted in 1 at an angle.

Further, a core mold 1 having a plurality of extrusion pins 23 is formed on a core plate 18, and a slide mold 13 forming a side rising portion of an injection-molded casing is formed around the core mold 1. The slide die 13 is provided with a hole 24 for engaging with an angular pin 22 provided on the cabinet plate 17.

Further, a projection 25 for forming a hole provided in the bottom of the casing to be injection-molded is provided in the cavity 4 of the cabinet plate 17 and the core plate 18 so as to fit into the projection 25. A recess 26 having a spigot structure is provided in the core plate 18. In this embodiment, the slide die 13 is provided on the core plate 18 side, but may be provided on the cabinet plate 17 side. Of course, in that case, the angular pins 22 need to be provided on the core plate 18 side.

In this embodiment constructed as described above, by closing the mold as shown in FIG. 3 from the state in which the mold shown in FIG. 2 is opened, the slide mold 13 is also guided by the angular pins 22 so as to be at a predetermined position. Moving. By injecting a resin from the sprue bush 19 in the state of FIG. 3, a plastic housing as shown in FIG. 4 is formed. In this case, the force for opening the mold due to the pressure of the injected resin is mainly in the direction of arrow 8, and the parting line 3 is parallel to this force. Does not occur. Therefore, no burrs are generated.

Since the structure of the mold with respect to the hole 12 is a spigot structure, as shown in FIG. 5A, a burr 12a is conventionally formed on the inner surface of the hole 12 as shown in FIG. b) Burrs do not occur as shown in the figure. Therefore, in the case where the component 27 enters the hole 12, a deburring operation has conventionally been required, but in the present embodiment, it is not necessary, and cost reduction and constant quality can be achieved.

[0018]

According to the present invention, the mold portion in contact with the outer surface of the rising portion of the side of the plastic housing has a sliding structure,
Further, by forming the mold at the part formed in the housing with the spigot structure, it is possible to suppress the generation of burrs, and it is possible to contribute to cost reduction and stabilization of quality by eliminating the need for deburring work.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a view showing an embodiment of the present invention, and is a view showing a state in which a mold is opened.

FIG. 3 is a view showing an embodiment of the present invention, and is a view showing a state in which a mold is closed.

FIG. 4 is a view showing an example of a plastic housing formed by the injection molding die of the present invention.

FIG. 5 is a diagram showing a hole portion of a plastic housing;
(A) is a conventional example, and (b) is the present invention.

FIG. 6 is a view for explaining a conventional technique of plastic housing injection molding.

FIG. 7 is a view showing burrs generated in a conventional plastic housing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Core type | mold 2 ... Cabinet type | mold 3 ... Parting part 4 ... Cavity 5 ... Gate 6 ... Sprue 7 ... Direction of clamping pressure 8 ... Pressure direction of resin 9 ... Fitting part with other parts 11 ... Molded article (plastic Housing 12) Hole 13 ... Sliding type 14 ... Sliding type operating direction 15 ... Inlay structure 16 ... Sprue support plate 17 ... Cabinet plate 18 ... Core plate 19 ... Sprue bush 20 ... Runner 21 ... Void 22 ... Angular pin 23 ... Extrusion pin 24 ... Hole 25 ... Protrusion 26 ... Recess 27 ... Parts

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-270114 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/26 45/44

Claims (2)

(57) [Claims] 1. A mold for injection-molding a plastic housing (11) in which a thickness of a side rising portion (11a) is 2 mm or less and a thickness of another portion is 1 mm or less, wherein the side rising portion is provided. The mold part in contact with the outer surface of (11a) has a sliding structure, and its parting part (3) is
A mold for injection molding characterized by being set parallel to a tightening direction. 2. The injection molding die according to claim 1, wherein the die corresponding to the hole (12) formed in the housing (11) has a spigot structure.