JPH05220782A - Plastic molded product - Google Patents

Abstract

PURPOSE:To omit a process for applying a coating agent in order to improve the adhesion of a primary molding member and a secondary molding member after molding, to dispense with a washing process using liquid fluorocarbon becoming an environmental pollution source and to also dispense with the break-in operation of the primary and secondary molding members. CONSTITUTION:A rotary shaft 1 using a polyester liquid crystal polymer and a bearing 2 using a crystalline resin are combined and the bearing 2 generates the rotatable clamping force to the rotary shaft 1 by its molding shrinking force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molded product applied to hinges, gears, desk lamps and the like applied to opening and closing covers of portable personal computers and word processors, for example.

[0002]

2. Description of the Related Art Most portable so-called OA (office automation) devices, such as personal computers (personal computers), word processors, printers, etc., have a foldable lid because of their portability. For example, in a laptop computer, a keyboard etc. is arranged on the front side, and on the other side, a lid with a display screen is attached via a hinge, and the lid is rotated a half turn so that the display screen faces the operating side. Is becoming The display screen is
When viewed from the front of the operation side, it is desirable that the lid portion be stopped at an arbitrary position in view of the rotational movement of the display screen from the viewpoint of usability such that ambient light is reflected by the glass plate on the surface and becomes difficult to see. In view of such a situation, a hinge with a torque function has been proposed in which a rotating torque function is added to the hinge to stop the display screen at an arbitrary position.

As an injection molding method for molding a hinge with a torque function, a primary side member is inserted into a mold and a secondary side member is filled in the mold, and the primary side is formed by the molding shrinkage force of the secondary side material. There is one that generates a tightening force on a material to make a primary side member rotatable or slidable with respect to a secondary side member. In this example, when injection molding is performed, when a resin is used as the material of the insert side (primary side) member, the resin on the secondary side to be molded and injected must withstand heat and pressure and be incompatible. That's a good translation. This is because the primary side member, for example, the shaft can be rotated or slidable with respect to the secondary side member, for example, the bearing, if such conditions are satisfied.

[0004]

However, in injection molding, when various resins are actually combined and molded, the heat of molding is not affected even if the interface between the insert side and the injected resin is not melted. The resin injected into the member on the insert side is brought into a close contact state due to the pressure and the pressure, the starting force is high, and there is a drawback that the product cannot be directly commercialized.

As a solution to this problem, the surface of the insert-side member is coated with fluorine, silicone oil or the like to improve the adhesion, or after secondary molding, the coating agent adhering to other than the sliding portion is washed with CFC liquid. A process was required, and a process of releasing the starting force by a habituation operation after molding was required.

An object of the present invention is to eliminate the coating agent application step for improving the adhesion between the primary side molding member and the secondary side molding member after molding, and to eliminate the step of cleaning with a CFC liquid which is a source of air pollution. Therefore, the running-in operation between the primary molding member and the secondary molding member is not required.

[0007]

The fine structure of a polyester liquid crystal polymer such as Vectra (trade name: Celanese Co., Ltd.) is called an extended molecular chain structure, as shown in FIG. It is very different from the structure, and the molecular chain does not bend easily even in the molten state and maintains a rod shape, so there is little entanglement of molecules during melting, and it is oriented in the flow direction only by receiving a slight shearing stress during molding, The skin layer on the surface of the molded product is called fibril, and has a unique chemically finely fibrous surface structure. As a characteristic of this structure, the compatibility with ordinary polymer plastics is extremely poor. As a result, even in the same molded product, the mechanical strength of the part where the skin layers are joined together like the welded part is weak, and this is often pointed out as a disadvantage of this liquid crystal polymer.

In the present invention, the disadvantage of such a liquid crystal polymer is utilized as an advantage on the contrary. This invention combines a primary molding member and a secondary molding member, and the secondary molding member generates a movable tightening force on the primary molding member by its molding shrinkage force. It is a thing. A polyester liquid crystal polymer is used as the primary molding member. The polyester-based liquid crystal polymer exhibits a unique skin layer property with respect to other resins, has no compatibility, has a weak adhesive force, and has a very small difference in starting force from that during use torque. For this reason, it becomes possible to omit the steps of releasing the starting force by the acclimation operation as described above, coating the coating agent for preventing adhesion, and eliminating the need for the CFC liquid as the air pollution source.

The secondary molding member is preferably made of a material having a large molding shrinkage in order to generate a torque in the primary molding member. Further, after molding, it is preferable to select a material in which the tightening force (force for holding the insert member) is less likely to cause stress relaxation due to creep due to softening due to water absorption or the like. Therefore, from the viewpoint of having a high molding shrinkage, a resin having a low water absorption rate may be selected from the crystalline resins. The shrinkage rate may be adjusted according to the torque required for the secondary molding member.
That is, when a large torque is required, a material having a relatively large shrinkage ratio such as polyacetal may be selected. When a medium torque is required, for example, polybutylene terephthalate having a relatively small shrinkage ratio may be selected. To meet the demand for smaller torque, a relatively small shrinkage ratio such as 12 nylon may be selected.

If necessary, for example, silicon oil, molybdenum sulfide, the number of fluorine, etc. may be mixed as a lubricant in each of the molding members on the primary side and the secondary side. Further, as a reinforcing method, carbon fiber, glass fiber, potassium titanate whisker, graphite whisker, or the like may be mixed.

The scope of application of the present invention is that, in addition to the hinge of the office automation equipment, for example, the arm stand can be tilted with respect to the gear, which is composed of a gear body and a shaft slidable in the body in the axial direction, and the base. It includes a desk lamp.

The method for producing a plastic molded article of the present invention is as follows:
After fixing the primary-side molding member in the molding die, the secondary-side molding member is molded, and a clamping force is generated in the primary-side molding member by the molding contraction force, so that the primary-side or secondary-side A torque function is added to an operation such as rotation of the molding member.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, a case where the invention is applied to a hinge of a folding lid having a display screen of a personal computer will be described with reference to FIGS. 1 to 3, the hinge is a combination of a rotary shaft 1 that is a primary molding member and a bearing 2 that is a secondary molding member that pivotally supports the rotary shaft. The rotating shaft 1 is made of a polyester liquid crystal polymer, and the rotating protrusions 1b and 1c are integrally formed on both sides of the positioning 1a of the intermediate portion. The rotating protrusions 1b, 1c are formed in an abacus ball shape in cross section,
They are adjacent to each other at a predetermined interval.

The bearing 2 is made of crystalline resin and has bearing portions 2a, 2a, respectively. The bearing portion 2a is
It covers the rotating protrusions 1b and 1c. The bearing portion 2a is rotated by the molding contraction force generated when the bearing portion is injection-molded.
A tightening force is generated in c, and a torque function is added to the rotation of the rotary protrusion. The mechanism of torque generation is as described later.

As shown in FIG. 4, the bearing 2 is fixed to the main body 3. The rotating shaft 1 is connected to a lid portion 4 which also serves as a display. A keyboard 5 is provided on the front side of the main body 3.

Next, a method of manufacturing the hinge will be described. As shown in FIG. 5, the pre-molded rotary shaft 1 is inserted and fixed in the cavity of the injection molding die 6, and the liquid synthetic resin 7 is filled in the cavity for molding.
Reference numeral 8 is a gap generated by shrinkage of the synthetic resin.

The contracting force of the synthetic resin 7 tightens the slopes 1b1 and 1c1 of the rotary protrusions 1b and 1c from the direction of the arrow in FIG. As a result, the tightening force causes friction on the slopes 11b1 and 11c1 with respect to the rotation of the rotary shaft 1, and a torque function is added. This is the mechanism of torque generation.

In the above example, the shaft may be fixed and the bearing may be rotatable.

[0019]

According to the present invention, since the polyester type liquid crystal polymer is used for the primary molding member and the crystalline resin is used for the secondary molding member, respectively, the primary molding member and the secondary molding member after molding are molded. Adhesion with members can be improved, and the coating agent application process for improving the adhesion described above can be omitted, and the cleaning process with CFC liquid, which is a source of air pollution, becomes unnecessary, and the primary molding member and secondary The running-in operation with the side molding member can be eliminated.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view of a rotating shaft.

FIG. 3 is a sectional view of a main part.

FIG. 4 is a perspective view adapted to a notebook computer.

FIG. 5 is an enlarged cross-sectional view showing one step of molding.

FIG. 6 is a diagram showing a microstructure of a liquid crystal polymer and a conventional polymer plastic.

[Explanation of symbols]

 1 Primary Side Forming Member (Rotating Shaft) 1b Rotating Protrusion 1c Rotating Protrusion 2 Secondary Side Forming Member (Bearing) 2a Bearing

Claims (1)

[Claims] 1. A combination of a primary molding member made of a polyester liquid crystal polymer and a secondary molding member made of a crystalline resin, wherein the secondary molding member is molded by the molding shrinkage force of the primary molding member. A plastic molded product characterized in that a movable clamping force is generated in the side molding member.