Composite material bush

1. A composite material bush comprising a core having a center portion and end portions, wherein the core comprises:

a center plate; and

an outer foam arranged outside the center plate to surround the center plate and is made of different kinds of materials,

wherein a central area of the center plate includes a specific portion to prevent the outer foam from being separated from the center plate,

wherein the center plate contains a steel material that provides uniform strength throughout the center portion of the core up to the end portions of the core,

wherein the outer foam is arranged outside the center plate and contains a plastic material,

wherein the specific portion includes a separation preventing jaw formed on the central area of the center plate, and a protruding jaw which is in contact with the separation preventing jaw is formed on an inner side of the outer foam, such that the outer foam is prevented from being separated from the center plate,

wherein fastening holes are arranged at respective ends of the center plate in a longitudinal direction,

wherein a center of each fastening hole deviates from a central axis of the center plate in the longitudinal direction to increase a width of the center plate around a bonding area between the center plate and the outer foam, and

wherein the center plate is obliquely provided on the outer foam in which an imaginary first line segment passing through the central axis of the center plate is inclined at an angle with an imaginary second line segment passing through a central axis of the outer foam to facilitate fastening of the bush.

2. The composite material bush of claim 1 , wherein a hole is arranged at a center of the center plate to prevent the outer foam from being separated from the center plate.

3. The composite material bush of claim 2 , wherein a pin having a length larger than the thickness of the center plate and smaller than the thickness of the outer foam is mounted in the hole.

4. The composite material bush of claim 1 , wherein the separation preventing jaw is placed at a corner of the center plate.

5. The composite material bush of claim 4 , wherein the center plate has a rectangular shape, and

wherein the separation preventing jaws are arranged at any one of long corners of the center plate to face each other.

6. The composite material bush of claim 4 , wherein the center plate has a rectangular shape, and

wherein the separation preventing jaw is arranged by being cut inwardly from an outer side of a long corner of the center plate.

7. The composite material bush of claim 1 , wherein the center plate and the outer foam selectively include a material having target strength or ductility among metals or nonmetals.

8. The composite material bush of claim 1 , wherein a guide pin is arranged at each fastening hole.

9. The composite material bush of claim 1 , wherein radii of curvature of each corner of the center plate are different from each other.

10. The composite material bush of claim 1 , wherein the imaginary first line segment passes through two sides of the center plate in a width direction and the imaginary second line segment passes through two sides of the outer foam in a width direction, wherein the imaginary first and second line segments do not coincide with each other.

11. The composite material bush of claim 1 , wherein a boding material is disposed on a central area of the center plate which is in contact with the outer foam.

12. The composite material bush of claim 10 , wherein the angle between the imaginary first line segment and the imaginary second line segment is formed at 10° or more.

13. The composite material bush of claim 11 , wherein the bonding material is disposed on both sides of the center plate.

14. A method of manufacturing a composite material bush comprising a core containing a center plate and an outer foam arranged outside the center plate, the method comprising:

performing a press molding or an extrusion molding of a steel material to form the center plate;

providing a bonding material at a center portion of the center plate where at least some portion of the center plate contacts with the outer foam; and

performing injection molding of a material to form the outer foam, thereby melting the bonding material and bonding the center plate to the outer foam,

wherein a central area of the center plate includes a specific portion to prevent the outer foam from being separated from the center plate,

wherein the outer foam contains a plastic material,

wherein the specific portion includes a separation preventing jaw formed on the central area of the center plate, and a protruding jaw which is in contact with the separation preventing jaw is formed on an inner side of the outer foam, such that the outer foam is prevented from being separated from the center plate,

wherein fastening holes are arranged at respective ends of the center plate in a longitudinal direction,

wherein a center of each fastening hole deviates from a central axis of the center plate in the longitudinal direction to increase a width of the center plate around a bonding area between the center plate and the outer foam, and

wherein the center plate is obliquely provided on the outer foam in which an imaginary first line segment passing through the central axis of the center plate is inclined at an angle with an imaginary second line segment passing through a central axis of the outer foam to facilitate fastening of the bush.

15. The method according to claim 14 , wherein a melting point of the steel material forming the center plate is higher than that of the material forming the outer foam, and the melting point of the material forming the outer foam is higher than that of the bonding material.