Molding process for manufacturing a molded article

A molding process for manufacturing a molded article includes the steps of placing a flexible hollow member in a mold cavity, inserting a supporting member in the hollow member, introducing a molding raw material into the mold cavity around the hollow member to form a molded part that encloses a portion of the hollow member, removing the molded part together with the hollow member and the supporting member from the mold cavity, and withdrawing the hollow member and the supporting member from the molded part to form a channel in the molded part.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT For the sake of brevity, same reference numerals are used to denote similar elements throughout the specification. FIGS. 8, 12 , 15 , and 17 illustrate different configurations of molded articles 6 prepared according to a molding process embodying this invention. Each of the molded articles 6 is formed with a channel 61 therein. Referring to FIG. 7 , the molding process includes the steps of: (a) preparing a mold 2 having a mold cavity 23 that has a shape conforming to that of the molded article 6 ; (b) preparing a flexible hollow member 3 and a supporting member 4 , the hollow member 3 having an open end 32 and defining an inner passage 33 that extends from the open end 32 ; (c) inserting the supporting member 4 into the flexible hollow member 3 in a manner that the supporting member 4 extends through the open end 32 and into the inner passage 33 in a direction along the inner passage 33 so as to prevent the hollow member 3 from collapsing during a subsequent molding step; (d) placing assembly of the hollow member 3 and the supporting member 4 in the mold cavity 23 ; (e) closing the mold 2 and introducing a molding raw material into the mold cavity 23 around the hollow member 3 to form a molded part around the hollow member 3 in a manner that the open end 32 of the hollow member 3 is exposed from the molded part; (f) removing the molded part together with the hollow member 3 and the supporting member 4 from the mold cavity 23 ; and (g) withdrawing the supporting member 4 and the hollow member 3 from the molded part to form the channel 61 in the molded part. Referring to FIGS. 7 and 8 , the mold 2 includes upper and lower mold halves 21 , 22 that confine the mold cavity 23 . A pair of upper positioning grooves 210 , 211 are formed in a bottom face of the upper mold half 21 . A pair of lower positioning grooves 220 , 221 are formed in a top face of the lower mold half 22 , and respectively complement with the upper positioning grooves 210 , 211 . A runner has complementary runner halves 223 that are formed respectively in the upper and lower mold halves 21 , 22 . The upper and lower positioning grooves 210 , 211 , 220 , 221 are disposed externally of and in communication with the mold cavity 23 . The hollow member 3 is in the form of a flexible tube 3 that has a bent portion 31 which confines a curved section 330 of the inner passage 33 . The supporting member 4 is in the form of a flexible supporting wire that is inserted into the tube 3 , that extends through and along the entire length of the tube 3 for supporting the tube 3 , and that has a pulling end 41 exposed from the tube 3 for facilitating withdrawal of the wire 4 from the tube 3 . The tube 3 has two opposite ends (one of which defines the open end 32 ) that are positioned in the upper and lower positioning grooves 210 , 211 , 220 , 221 for facilitating withdrawal of the tube 3 from the molded part. The molding raw material is introduced through the runner and into the mold cavity 23 . The molded part encloses the assembly of the tube 3 and the supporting member 4 in a manner such that the two opposite ends of the tube 3 are exposed from the molded part. Since the supporting member 4 is flexible, it is relatively easy to withdraw the same from the tube 3 . In addition, since the tube 3 is also flexible, it becomes even easier to withdraw the tube 3 from the molded part once the supporting member 4 has been removed, thereby eliminating the aforesaid drawbacks as encountered in the prior art. The molding process of this invention is preferably adopted for manufacturing a molded article made of metal, such as a Pb—Sn alloy (Pewter). As such, the flexible tube 3 employed in the molding process is preferably made of silicone rubber having a melting point higher than that of the material of the molded article, and the supporting member 4 is made of a metal having a melting point higher than that of the material of the molded article. Since the structure and the property of the tube 3 remain unchanged after the molding process, it can be reused for subsequent molding of another article. As illustrated in FIG. 9 , one of the two opposite ends of the flexible tube 3 can have a threaded outer face 30 so as to form the channel 61 with an inner threaded end. As illustrated in FIG. 10 , since both the tube 3 and the supporting member 4 are flexible, it is relatively easy to remove a molded article 6 , which has channels 61 , 61 ′ extending in different planes in the molded article 6 , from a two-piece mold 2 . In the example of FIG. 10 , one channel 61 ′ is formed in the lower mold half 22 and is inclined relative to a horizontal plane defined by the mating faces of the upper and lower mold halves 21 , 22 where the other channel 61 is formed. Referring to FIGS. 11 to 13 , the hollow member 3 employed in the molding process is configured for forming a human-like pattern on an inner face 611 of the molded article 6 that defines the channel 61 . The mold 2 employed in the molding process can be an open mold (see FIG. 11 ) or a closed mold (see FIG. 13 ). A flexible cap member 42 is used for isolating the pulling end 41 of the supporting member 4 and the open end 32 of the hollow member 3 from the molding raw material when introducing the molding raw material into the mold cavity 23 . The cap member 42 has a peripheral wall defining a recess which has an enlarged portion 421 and a reduced portion 422 reduced from the enlarged portion 421 . The cap member 42 is placed in the mold cavity 23 in a manner that the peripheral wall fits snugly in an end portion 230 of the mold cavity 23 , that the open end 32 of the hollow member 3 is fittingly received in the enlarged portion 421 of the recess, and that the pulling end 41 of the supporting member 4 is fittingly received in the reduced portion 422 of the recess so as to permit exposure of the open end 32 of the hollow member 3 and the pulling end 41 of the supporting member 4 from the molded part, thereby facilitating withdrawal of the hollow member 3 and the supporting member 4 from the molded part. It is noted that the cap member 42 has a cross-section larger than that of the hollow member 3 so as to separate the hollow member 3 from an inner wall of the mold cavity 23 . Referring to FIGS. 14 and 15 , the hollow member 3 employed in the molding process can be in the form of a cylindrical tube with a patterned outer face 30 ′ so as to form the same pattern on the inner face 611 of the molded article 6 . Two cap members 42 are used for preparing the molded article 6 . Referring to FIGS. 16 and 17 , the hollow member 3 employed in the molding process is the same as the hollow member of FIG. 14 , while the mold cavity 23 of the mold employed in the molding process is cylindrical in shape so as to form the molded article 6 with a cylindrical shape. It is noted that each of the supporting members 4 , illustrated in FIGS. 11, 14 , and 16 , is in the form of a rigid rod in contrast to the flexible wire shown in FIG. 7 . With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims.