Plastic Hinge

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

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.

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

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

A bodyis formed of plastic and shaped as a solid cylinder. In the embodiment of the invention, a diameter of the bodyis between 1.4 mm and 3.5 mm. The bodyincludes a grooveand is formed by injection molding. The grooveextends from an outer surface of the bodyto an axial center of the body. The grooveincludes a bottomand an opening. Width of the grooveis gradually increased from the bottomto the opening. The bottomis shaped as an U when viewed from either end of the body. Specifically, the bottom, being proximate to the axial center of the body, has a first width Wof 0.3 mm and the opening, being proximate to the outer surface of the body, has a second width Wof 0.38 mm. The second width Wis greater than the first width W.

Referring toin conjunction with, a use of the plastic hinge of the invention is discussed in detail below. Two plastic hinges are incorporated in a cosmetic containerwhich may have a shape other than the one as shown. That is, the shape of the cosmetic containeris not limited by the embodiment of the invention as shown. In the embodiment of the invention, the disc shaped cosmetic containercomprises a container lidincluding a knuckleextending downward from a bottom of an outer surface, and two spaced, aligned first holesthrough two ends of the knucklerespectively; and a baseconfigured to close or open the container lidand including a cavitycorresponding to the knuckleand being complementary thereto, and two spaced, aligned second holesthrough two ends of the cavityrespectively. The first holesare aligned with the second holeswhen the container lidand the baseare put together. Then either of the bodiesis inserted into the second holeand the first hole. As a result, the container lidand the baseare joined by the bodies, i.e., the container lidand the basebeing pivotably fastened together by the bodies.

The bodyis formed of plastic and has a diameter slightly greater than that of each of the first holeand the second hole. After the bodieshave been disposed in the second holesand the first holes, a sufficient friction is generated on the bodieswhen the container lidis opened. Advantageously, an angle of the open container lidwith respect to the basecan be kept due to the sufficient friction. Otherwise, the container lidmay fall onto the caseand close same. It increases convenience in use.

Further, the provision of the groovenot only increases compressibility of the bodybut also makes the bodyto be easier to insert into the second holeand the first hole. More importantly, the provision of the grooveprovides a space to accommodate a shape change of the bodyin response to a change of temperature. The adverse effect of the permanent shape change of the bodyin response to a change of temperature is avoided. Since the diameter of the bodyis not changed, the bodywill not expand each of the first holeand the second hole. There is no gap between the bodyand each of the first holeand the second holewhen the bodyis inserted into the second holeand the first hole. A sufficient friction is generated on the bodieswhen the container lidis opened. Advantageously, an angle of the open container lidwith respect to the basecan be kept due to the sufficient friction. Otherwise, the container lidmay fall onto the caseand close same.

Furthermore, a depth of the grooveextends from the outer surface of the bodyto the axial center thereof and the width of the grooveis gradually increased from the bottomto the opening. Thus, the bodyis shaped as a bow. And in turn this makes the bodyto 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 bodyremains 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 bodyof the invention is between 1.4 mm and 3.5 mm. The conventional metal pin can be replaced by the bodyof the invention. In an assembly of the container lidand the base, the nailing machine can be used to drive the bodyinto the second holeand the first holerather than using a new nailing machine to do the same job. This can save cost. The bodyis sufficiently small so that the bodiescan 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, the container lid, and the baseare 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.