BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an umbrella frame part, more particularly to an umbrella frame part that includes a support and decorative bars fitted into retaining grooves in the support. 2. Description of the Related Art As shown in FIG. 1, a conventional umbrella 2 includes a frame part having a shaft 20 and a plurality of ribs 21. The shaft 20 or each rib 21 is made from a hollow metal extrudate, which has an appearance that is dull and which has an inferior mechanical strength. SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide an umbrella frame part that can overcome the aforesaid drawbacks associated with the prior art. Accordingly, an umbrella frame part of the present invention comprises: a slender support of a metal extrudate, the support being formed with at least one retaining groove extending along the length of the support and defined by a grove-defining wall, the groove-defining wall having two opposite end portions extending toward each other to define a constricted opening therebetween, the constricted opening in a normal direction relative to the length of the support; and at least one slender decorative bar inserted fittingly into the retaining groove, having an outer surface exposed from the constricted opening, and restricted by the end portions of the groove-defining wall so as to prevent removal thereof through the constricted opening.
BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which: FIG. 1 is a perspective view of a conventional umbrella; FIG. 2 is a fragmentary perspective view of the first preferred embodiment of an umbrella frame part serving as a shaft of an umbrella according to the present invention; FIG. 3 is a fragmentary perspective view of the second preferred embodiment of an umbrella frame part serving as a rib of the umbrella according to the present invention; FIG. 4 is a perspective view of the umbrella having frame parts made from the first and second preferred embodiments; FIG. 5 is a partly cross-sectional view of the third preferred embodiment of an umbrella frame part serving as a shaft of the umbrella according to the present invention; FIG. 6 is a partly cross-sectional view of the fourth preferred embodiment of an umbrella frame part serving as a shaft of the umbrella according to the present invention; FIG. 7 is a partly cross-sectional view of the fifth preferred embodiment of an umbrella frame part according to the present invention; and FIG. 8 is a partly cross-sectional view of the sixth preferred embodiment of an umbrella frame part according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before the present invention is described in greater detail with reference to the accompanying preferred embodiments, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure. Referring to FIGS. 2 and 4, the first preferred embodiment of an umbrella frame part 1, which serves as a shaft 31 of an umbrella 3, according to the present invention is shown to include: a slender support 10 of a metal extrudate, the support 10 being formed with a plurality of retaining grooves 11, each of which extends along the length of the support 10 and each of which is defined by a groove-defining wall 111, the groove-defining wall 111 of each of the retaining grooves 11 having two opposite end portions 1111 extending toward each other to define a constricted opening 1112 therebetween, the constricted opening 1112 opening in a normal direction relative to the length of the support 10; and a plurality of slender decorative bars 12, each of which is inserted fittingly into a respective one of the retaining grooves 11, each of which has an outer surface 120 exposed from the constricted opening 1112 of the groove-defining wall 111 of the respective one of the retaining grooves 11, and each of which is restricted by the end portions 1111 of the groove-defining wall 111 of the respective one of the retaining grooves 11 so as to prevent undesired removal thereof through the constricted opening 1112 of the groove-defining wall 111 of the respective one of the retaining grooves 11. In this embodiment, the metal extrudate is made from aluminum, and each decorative bar 12 is made from a material selected from the group consisting of wood, plastic materials, and metal, and is used to enhance the strength and aesthetic appearance of the support 10. Referring back to FIG. 2, the support 10 of the first preferred embodiment includes a center portion 13 that has a crisscross cross-section and four radial ends 131, and two arcuate portions 14, each of which interconnects two adjacent ones of the radial ends 131 of the center portion 13, and each of which has two opposite circumferential end portions defining a pair of the end portions 1111 of the groove-defining walls 111 of an opposite pair of the retaining grooves 11. Each decorative bar 12 has a quarter-circular cross-section. Referring to FIG. 3, in combination with FIG. 4, the second preferred embodiment of the umbrella frame part 1 differs from the previous embodiment in that it serves as a rib 32 of the umbrella 3, and that the support 10 thereof includes a rectangular loop-shaped plate 15, and four L-shaped recessed portions 16 extending respectively from four corners of the loop-shaped plate 15 and defining the end portions 1111 of the groove-defining walls 111 and the constricted openings 1112 of the retaining grooves 11. Each of the decorative bars 12 is fitted into a corresponding one of the retaining grooves 11. In this embodiment, each of the decorative bars 12 has a rectangular cross-section. Referring to FIG. 5, the third preferred embodiment of this invention differs from the first preferred embodiment in that the support 10 includes a center portion 13 that has a crisscross cross-section and four radial ends 131, and four arcuate portions 14, each of which is connected to a respective one of the radial ends 131 of the center portion 13 and each of which has two opposite circumferential end portions defining an adjacent pair of the end portions 1111 of the groove-defining walls 111 of an adjacent pair of the retaining grooves 11. Referring to FIG. 6, the fourth preferred embodiment of this invention differs from the first preferred embodiment in that the support 10 includes a loop-shaped plate 15 that defines an inner chamber 150 therein and that has recessed portions 151 protruding inwardly of the inner chamber 150. Each of the recessed portions 151 defines a respective one of the groove-defining walls 111 of the retaining grooves 11. In this embodiment, the loop-shaped plate 15 has circumferentially extending portions 152 that are angularly displaced and that are alternately and angularly disposed with the retaining grooves 11. In this embodiment, each of the decorative bars 12 has a circular cross-section. Referring to FIG. 7, the fifth preferred embodiment of this invention differs from the fourth preferred embodiment in that the loop-shaped plate 15 is four-sided and is formed with four retaining grooves 11, each of which is disposed at a respective one of the four sides thereof. In this embodiment, each of the decorative bars 12 has a rectangular cross-section. Referring to FIG. 8, the sixth preferred embodiment of this invention differs from the fourth preferred embodiment in that the loop-shaped plate 15 is three-sided and is formed with three retaining grooves 11, each of which is disposed at a respective one of the three sides thereof. In this embodiment, each of the decorative bars 12 has a rectangular cross-section. With the inclusion of the decorative bars 12, which are fitted into the retaining grooves 11 in the support 10, in the umbrella frame part 1 of this invention, the aforesaid drawbacks associated with the prior art can be eliminated. While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. |