PLASTIC HINGE

Description

FIELD OF THE INVENTION

The invention relates to plastic hinges and more particularly to a plastic hinge having elastic deformation.

BACKGROUND OF THE INVENTION

A conventional cosmetic container comprises a container lid including two first holes, a base including two spaced second holes, and two metal pins inserted into the second and first holes respectively to pivotably fasten them together. The damaged cosmetic container can be recycled. But the metal pin, and the container lid and the base both made of plastic are required to recycle separately due to different materials. Otherwise, recycling machines may be damaged in the recycling process and this causes troubles to an operator of the recycling plant.

For solving the above problem, the present inventor invented a conventional cosmetic container comprises a container lid including two first holes, a base including two spaced second hole, and two plastic pins inserted into the second and first holes to pivotably fasten them together. The damaged cosmetic container can be recycled in one process because the pins, the container lid, and the base all are made of plastic.

However, the plastic pins are subject to thermal expansion, i.e., shape change in response to a change of temperature. The pin may expand when temperature rises. The first and second holes may expand accordingly by the expanding pins. To the contrary, the pins may shrink to its original shape when temperature drops. Unfortunately, the first and second holes are permanently deformed, i.e., being larger than their original shapes. There is a gap between each pin and each of the first and second holes when the pins are inserted into the second and first holes. A rotation of the pins of a predetermined degree will not cause the container lid to rotate the same degree due to insufficient friction between the pins and the container lid. It may cause inconvenience in use.

Thus, the need for improvement still exists.

SUMMARY OF THE INVENTION

It is therefore one object of the invention to provide a plastic hinge comprising a body formed of plastic and shaped as a solid cylinder, the body including a groove having a depth extending from an outer surface of the body to an axial center of the body, the groove including a bottom and an opening, a width of the groove being gradually increased from the bottom to the opening, and the bottom being shaped as an U.

The invention has the following advantages and benefits in comparison with the conventional art:

No change of a diameter of the body. The provision of the groove provides a space to accommodate a shape change of the body in response to a change of temperature. The adverse effect of the permanent shape change of the body in response to a change of temperature is avoided. Further, compressibility of the body is increased.

Elastic deformation and returning to original shape. Since the depth of the groove extends from the outer surface of the body to the axial center of the body and the width of the groove is gradually increased from the bottom to the opening, the body is shaped as a bow. And in turn this makes the body to be easy to elastically deform and return to its original shape after a force causing the deformation is removed. Also, a structural strength of the solid, cylindrical body remains the same.

Wide range of applications and easy recycling. Since the body has the same shape and size as that of the conventional metal pin, the body can be used to pivotably fasten the container lid and the base of the conventional cosmetic container together. That is, the conventional metal pin can be replaced by the body of the invention. In an assembly of the container lid and the base, the nailing machine for the assembly of the conventional cosmetic container can be used to drive the body into the first hole and the second hole rather than using a new nailing machine to do the same job. The plastic hinge of the invention has a wide range of applications. Moreover, the body, the container lid, and the base are all made of plastic and thus the damaged cosmetic container can be recycled as a whole. Therefore, the problem of recycling the conventional cosmetic container is solved.

The above and other objects, features and advantages of the invention will become apparent from the following detailed description taken with the accompanying drawings

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a plastic hinge according to the invention;

FIG. 2 is a front view of the plastic hinge;

FIG. 3 is a perspective view of a cosmetic container incorporating two plastic hinges of the invention, the cosmetic container being closed;

FIG. 4 is an exploded view of the cosmetic container; and

FIG. 5 is a sectional view in part section of the cosmetic container in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a plastic hinge in accordance with the invention comprises the following components as discussed in detail below.

A body 10 is formed of plastic and shaped as a solid cylinder. In the embodiment of the invention, a diameter of the body 10 is between 1.4 mm and 3.5 mm. The body 10 includes a groove 11 and is formed by injection molding. The groove 11 extends from an outer surface of the body 10 to an axial center of the body 10. The groove 11 includes a bottom 111 and an opening 112. Width of the groove 11 is gradually increased from the bottom 111 to the opening 112. The bottom 111 is shaped as an U when viewed from either end of the body 10. Specifically, the bottom 111, being proximate to the axial center of the body 10, has a first width W1 of 0.3 mm and the opening 112, being proximate to the outer surface of the body 10, has a second width W2 of 0.38 mm. The second width W2 is greater than the first width W1.

Referring to FIGS. 3 to 5 in conjunction with FIG. 1, a use of the plastic hinge of the invention is discussed in detail below. Two plastic hinges are incorporated in a cosmetic container 20 which may have a shape other than the one as shown. That is, the shape of the cosmetic container 20 is not limited by the embodiment of the invention as shown. In the embodiment of the invention, the disc shaped cosmetic container 20 comprises a container lid 21 including a knuckle 211 extending downward from a bottom of an outer surface, and two spaced, aligned first holes 212 through two ends of the knuckle 211 respectively; and a base 22 configured to close or open the container lid 21 and including a cavity 221 corresponding to the knuckle 211 and being complementary thereto, and two spaced, aligned second holes 222 through two ends of the cavity 221 respectively. The first holes 212 are aligned with the second holes 222 when the container lid 21 and the base 22 are put together. Then either of the bodies 10 is inserted into the second hole 222 and the first hole 212. As a result, the container lid 21 and the base 22 are joined by the bodies 10, i.e., the container lid 21 and the base 22 being pivotably fastened together by the bodies 10.

The body 10 is formed of plastic and has a diameter slightly greater than that of each of the first hole 212 and the second hole 222. After the bodies 10 have been disposed in the second holes 222 and the first holes 212, a sufficient friction is generated on the bodies 10 when the container lid 21 is opened. Advantageously, an angle of the open container lid 21 with respect to the base 22 can be kept due to the sufficient friction. Otherwise, the container lid 21 may fall onto the case 22 and close same. It increases convenience in use.

Further, the provision of the groove 11 not only increases compressibility of the body 10 but also makes the body 10 to be easier to insert into the second hole 222 and the first hole 212. More importantly, the provision of the groove 11 provides a space to accommodate a shape change of the body 10 in response to a change of temperature. The adverse effect of the permanent shape change of the body 10 in response to a change of temperature is avoided. Since the diameter of the body 10 is not changed, the body 10 will not expand each of the first hole 212 and the second hole 222. There is no gap between the body 10 and each of the first hole 212 and the second hole 222 when the body 10 is inserted into the second hole 222 and the first hole 212. A sufficient friction is generated on the bodies 10 when the container lid 21 is opened. Advantageously, an angle of the open container lid 21 with respect to the base 22 can be kept due to the sufficient friction. Otherwise, the container lid 21 may fall onto the case 22 and close same.

Furthermore, a depth of the groove 11 extends from the outer surface of the body 10 to the axial center thereof and the width of the groove 11 is gradually increased from the bottom 111 to the opening 112. Thus, the body 10 is shaped as a bow. And in turn this makes the body 10 to be easy to elastically deform and return to its original shape after a force causing the deformation is removed. Also, a structural strength of the solid, cylindrical body 10 remains the same.

It is noted that an assembly of the conventional cosmetic container involves activating a nailing machine (not shown) to drive the metal pin into the second and first holes to pivotably fasten the container lid and the base together. The diameter of the body 10 of the invention is between 1.4 mm and 3.5 mm. The conventional metal pin can be replaced by the body 10 of the invention. In an assembly of the container lid 21 and the base 22, the nailing machine can be used to drive the body 10 into the second hole 222 and the first hole 212 rather than using a new nailing machine to do the same job. This can save cost. The body 10 is sufficiently small so that the bodies 10 can be inserted into the second holes of the base of the conventional cosmetic container and the first holes of the container lid thereof sequentially without adversely affecting aesthetic appearance of the conventional cosmetic container. The plastic hinge of the invention has a wide range of applications. Moreover, the body 10, the container lid 21, and the base 22 are all made of plastic and thus the damaged cosmetic container can be recycled as a whole. Therefore, the problem of recycling the conventional cosmetic container is solved.

While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the appended claims.