Bulb socket and the manufacturing method of the same

Abstract: In molding a bulb socket (1) having L-letter form arrangements of a bulb inserting part (11) and a connector inserting part (16), firstly a bottomed tubular memher (4) is molded as a part corresponding to the bulb inserting part (11). And, through a terminal inserting hole (8) provided on the bottom face of the tubular member (4), a terminal metal fitting (6) is thrusted, and then the part projecting outward is bent in an L-letter form. The thus obtained core member (2) is applied to the metal mold for insert molding to obtain a bulb socket having the predetermined shape.

Description: The present invention relates to a bulb socket wherein a bulb inserting part and a connector inserting part are disposed in L-letter shape relative to each other, and a method for producing the same. For the bulb sockets to be used for the lighting means for automobiles there is a requirement for making the amount of projection rearward as small as possible, in view of the restriction on the installation space. To meet this purpose there has been known a bulb socket in which the whole system is formed in an L-letter shape, hereinafter to be referred to as L-type socketand for example known from Japanese Utility Model Examined Publication No. 3-17429. Such a bulb socket is constituted by a synthetic resin socket body and a bulb to be set inside. In an L-type socket, the socket body also has an L-letter shape, so that it is difficult physically to take a method of inserting a terminal metal fitting after formation of the socket body. Accordingly, there is considered a method of assembling a terminal metal fitting by insert molding. However, the method by insert molding cannot be easily adopted for the reasons given below. In case of carrying out an insert molding, a terminal metal fitting is applied to the metal mold for molding, under which the molten resin is to be injected in the metal mold. In such a case, as it is necessary to mold the socket body while evading the terminal metal fitting, the metal mold is required to be formed with a part to cover the terminal metal fitting part. However, the terminal metal fitting to be used for the type called a wedge base bulb has in many cases complicated configuration. Accordingly, it is inevitable for the metal mold to be applied to such a terminal metal fitting to have complicated structure in the cover part. This leads to a rise in the metal mold cost due to the complication of the mold structure. Additionally, when the shape of the terminal metal fitting becomes complicated, an increase in the errors of the size of manufacture is also conceivable. In such a case, it will be impossible to cover the insert molding to a satisfactory degree, and in such a case, there is an apprehension for intrusion of the molten resin into the terminal metal fitting side. There has also been known a method of inserting an L-type terminal metal fitting into the socket body without resorting to the insert molding. For example, there is a method of providing the terminal metal fitting in two members, namely a bulb holding part and an electric supply part to be connected to the power source, and joining them together after insertion (ref. Japanese Utility Model Laid-open Publication HEI 1-86085), or there is a method of forming a notched slit for bypassing on the socket body so as to permit the L-type terminal metal fitting to be inserted as such in the socket body. However, the former system requires complicated constitution of the terminal metal fitting such that the terminal metal fitting requires to be of two members, and further there is necessitated a constitution to make mutual connection. The latter method is inadequate when waterproofing is considered, because a slit for insertion is formed. According to US-A 5 080 615 there is provided a bulb socket for holding a bulb having wedge-shaped contact portions, which comprises a socket housing composed of a bulb holding portion and a connector holding portion formed integral with each other. Thereby, an auxiliary core is used together with a core in order to prevent the molding resin material from entering into the space through a gap during molding process. Since the core is used, after the core has been removed from the molding dye, it is possible to form a core space in the socket housing. As reviewed above, it is the present status that there has not yet been established the optimum method for producing an L-type socket. It is accordingly an object of the present invention to provide an L-type bulb socket which is easy to manufacture and a method for production thereof. Solution of this object is achieved by what is claimed in claims 1 and 4, respectively. According to the method of the present invention as defined in claim 1, firstly a tubular member is formed with an open end as the bulb inserting port and a terminal inserting hole on the opposite bottom side. Then a terminal metal fitting is inserted into said terminal inserting hole. The part of the terminal metal fitting projecting from the tubular member is bent in L-letter form, thereby obtaining a core fitted with the terminal metal fitting. Thereafter, the core is set to the metal mold for secondary molding and insert molding is carried out using the core as a core material to obtain a bulb socket of a predetermined configuration. A bulb socket according to the invention is defined in claim 4. According to the an advantageous modification of the present invention the bent bent part of the terminal metal fitting is that formed by bending a single plate, thereby bending work of the terminal metal fitting is facilitated. According to a further advantageous modification of the present invention (claim 6) a cylindrical part with a predetermined diameter is integrally connected to the outer tube. The diameter of this cylindrical part can be adjusted to the specific mounting arrangements of applications having an L-type bulb socket. According to the present invention, the following effects are obtainable. Since the system is such that, after forming the tube member, the terminal metal fitting is inserted to form a core member, and then insert molding is carried out, it is unnecessary to form on a metal mold any part to cover the terminal metal part, and accordingly the structure of the metal mold can be simplified. For the same reason, it is also possible to obviate intrusion of resin in the terminal metal fitting. Further advantages, details and aspects of the present invention will become more readily apparent from the following description of preferred embodiments to be taken in conjunction with the accompanying drawings, in which: Fig. 1 is a sectional view of the bulb socket; Fig. 2 is a sectional view taken along the line II-II in Fig. 3 which shows a core member; Fig. 3 is a front elevation of the core member; Fig. 4 is a front elevation of the terminal metal fitting; Fig. 5 is a plan view of the terminal metal fitting; Fig. 6 is a plan view of the bulb socket, and Fig. 7 is a sectional view to show the insert molding condition. Hereinafter, the present invention will be described on the preferred embodiments in more detail with reference to the drawings. In this illustrative embodiment, explanation is made on a bulb socket 1 to be applied to a wedge base bulb. The bulb socket 1 is constituted by a core member 2 fitted with a terminal metal fitting which is a primary molding and an outer shell 3 of a secondary molding in which the core member 2 is inserted. Firstly, to explain about the core member 2 (Figs. 2 and 3), the core member 2 is constituted by a tubular member 4 made of synthetic resin (e.g. nylon resin) and a terminal metal fitting 6 to be inserted under pressure therein. The tubular member 4 is formed in a straight square tube shape open to one side (left side in Fig. 1), and this opening becomes a valve inserting port 5. The tubular member 4 is made to accommodate a couple of terminal metal fittings therein. A projection 7 is formed on the outer surface of the bottom part of the tubular member 4, and a couple of terminal inserting holes 8 are provided on the bottom surface of the tubular member 4 in a manner to thrust through to the projection 7 to make it possible to insert the electric supply side terminal of the terminal metal fitting 6 in the terminal metal fitting 6 without a gap. Further, the tubular member 4 has, along the whole circumference of the outer periphery of the bottom part, a flange 9 as a mechanical stopper for the outer shell 3. Next, to explain about the terminal metal fitting 6 to be set in the tubular member 4 (Figs. 4 and 5), the two terminal metal fittings 6 are both formed by subjecting the conductor metal plate to bending work. They have each a wall plate member 6A running along the inner wall surface of the tubular member 4. The wall plate member 6A has each a pressor piece 6B formed by cutting inward so as to provide warp deformation. Being in direct contact with the lateral side of the opposed wedge base bulb, it can restrict idling of the bulb in the right-left direction in Fig. 6. Also, being bent at right angles from a lateral side end of the wall plate member 6A, there are a couple of long and short elastic pieces 6C and 6D arranged in parallel. The illustrated long side elastic piece is the elastic stopper piece 6C, which is engaged with the non-illustrated wedge base bulb to perform a role of providing stopgap to the whole member. Also, the short side elastic piece becomes a terminal piece 6D which can come into elastic contact with the two electrodes of the wedge base bulb (not illustrated). Furthermore, from the end periphery on which the above elastic stopper piece 6C and terminal piece 6D are formed, the material is bent inward at right angles, and further bent outward at right angles to form an electric supply terminal 6E. This electric supply terminal 6E is at the outset straightly extended and formed as to be insertable into the terminal inserting hole 8 of the tubular member 4, but after the setting onto the tubular member 4 is bent at right angles to a state as shown by the imaginary line in Fig. 2. Further, with respect to the electric supply terminal 6E, the part to be thrusted into the bulb socket 1 and buried and the part to be concerned with the connection with the connector for electric supply (not illustrated) are bent together in tight contact from both sides to form double layers for improving strength. However, the part positioned between them to be subjected to bending is left in a state of a single plate so as to facilitate the work of bending. Next, to explain about the outer shell 3, the outer shell 3 is formed by the resin of the same quality material as the tubular member 4, and has a square tubular outer tube 10 covering the outer side surface and the bottom surface of the tubular member 4, so that the bulb inserting part 11 is constituted by the tubular member 4 and the outer tube 10. Between the open end of the outer tube 10 and the open end, a thin wall groove 12 is formed along the whole periphery. This is in order to prevent the molten resin from going into the tubular member 4 during the molding of the outer shell 3. Around the outer tube 10, there is provided a cylindrical part 13 in a manner to surround the outer tube 10, and the cylindrical part 13 is formed in linkage with the end part of the short piece side of the outer tube 10 and in a height lower than that of the outer tube 10. On the outer peripheral surface of the cylindrical part 13 and in the area near the opening of the core 2, there are formed four slip-proof projections 14 at each equal angular distance, and further in an area nearer than it to the bottom surface a flange part 15 is formed in projection along the whole periphery. At the bottom surface of the outer tube 10, there is provided a continued part 16 for insertion of the connector. The connector inserting part 16 is disposed such that the mutual axial lines are in approximately orthogonal crossing relations with respect to the above-mentioned bulb inserting part 11. This bulb inserting part 11 is formed in cylindrical shape, and at its foremost end there is opened a connector inserting port 17 which can accommodate a connector for power supply (not illustrated), and in the inside a foremost end side of the power supply terminal 6E of the terminal metal fitting 6 is projected. Next, to explain the procedure of molding the above bulb socket 1, at first a tubular member 4 is formed by a - not shown - molding metal mold (primary molding). With respect to the thus obtained tubular member 4, the power supply terminal part 6E sides of the two terminal metal fittings 6 are inserted respectively in the terminal inserting hole 8 and exposed outside. The terminal inserting hole 8 has a hole diameter to such an extent as to permit insertion of the power supply terminal part 6E tightly without space, and accordingly the inserted part is water-tightly sealed. Thereafter, the part ranging from the middle position to the foremost end of the power supply terminal 6E is orthogonally bent. In this case, as the bent part of the power supply terminal 6E is the part which is not subjected to bending in tight contact, the bending work can be easily performed. Thus, the core member 2 with terminal metal fitting 6 is obtained. Next, the core member 2 is applied to the metal molds K1 to K3 for insert molding to carry out injection of molten resin (secondary molding). When, through this procedure, the mold is opened after curing, there are formed a bulb inserting part 11 with the outer tube 10 and the cylindrical part 13 surrounding the tube member 4 having the core member 2 as a core material, and also a connector inserting part 16 in a manner to surround the power supply terminal 6E of the terminal metal fitting 6 which is set in continuation with the bulb inserting part 11 and projecting from the tube member 4. Thus, an L-type bulb socket 1 having the predetermined shape is obtainable. In the course of the secondary molding, the opening periphery of the bulb inserting port is closed by the molding face 18 of the metal molds K1 - K3 to cover the bulb inserting side of the terminal metal fitting 6 and to prevent the molten resin from entering into the tube member 4. In other words, as the necessary step may be only to close the opening of the tube member 4, entry of the molten resin can be obviated without being related with the shape of the terminal metal fitting 6. Accordingly, there is no necessity to form a complicated cover part to cover the terminal metal fitting 6 on the metal mold, and simplification of the mold structure is possible. As this means that the shape of the terminal metal fitting 6 itself sustains no restriction in relation to the cover, there can be obtained an effect to enlarge the freedom of designing. Especially, in the present embodiment, the molding face of the metal mold is provided with a projecting edge 19 for forming the thin groove 12, which is in tight engagement with the outer peripheral surface of the tubular member 4, by which the intrusion of the molten resin is obviated to restrict entry of the resin into the tubular member 4 more definitely. As the terminal inserting hole 8 of the tubular member 4 receives the terminal metal fitting 6 tightly nearly without space, there does not occur entry of the molten resin therefrom. Moreover, because of the mechanical slip-proofing provided with the outer shell 3 by forming an extended flange 9 on the tubular member 4, bonding strength between the tubular member 4 and the outer shell 3 is increased to realize definite preservation of the integral relations between these two members. As described above, according to the manufacturing method of this embodiment of the present invention, a core member 2 for accommodating the terminal metal fitting 6 is formed and then the same is inserted to carry out molding. Accordingly, entry of the molten resin into the inside of the tubular member can be definitely prevented by a simple mold structure of only closing the bulb inserting port. Also, as the terminal metal fitting 6 is to be bent orthogonally after insertion in the tubular member 4, distinct from the conventional system, there is no case for the terminal metal fitting 6 to be formed in two members, and accordingly there is no need to connect them together. Therefore, no complication of the structure of the terminal metal fitting 6 itself is induced. Moreover, it is possible to maintain the strength of the terminal metal fitting 6 itself because the same can be used in an integrated state. While the invention has been explained with the embodiments as above, it is to be noted that various modifications are applicable to the present invention, such that for example the following modifications may be included in the technical teaching of the present invention: (1) Although, in the present embodiment, illustration and explanation hase been made on the metal mold to be applied to the wedge base bulb, the method of the present invention is applicable also to the bulbs of socket type. (2) The bent part of the power supply terminal 6E in the terminal metal fitting 6 may be thinned by pressing or the like, so as to facilitate bending work. It is to be noted that the foregoing explanation of the invention must be considered to be illustrative only and by no means limiting; various modifications going beyond the ones mentioned are applicable to the present invention without leaving its technical teaching.

Claims: A method for producing a bulb socket (1) comprising a socket body (11, 13, 16) with a bulb inserting part (11) having a bulb inserting port (5) and a connector inserting part (16) having a connector inserting port (17), the bulb inserting part (11) and the connector inserting part (16) being disposed in L-letter relations to each other, and terminal metal fittings (6) having end parts (6C, 6D, 6E) which are assembled into the socket body (11, 13, 16) and their end parts are disposed within the bulb inserting port (5) and the connector inserting port (17); respectively, said method comprising the steps: a) forming a tubular member (4) having an open end side forming the bulb inserting port (5) and an opposite bottom side having at least one terminal inserting hole (8) extending through the bottom side; b) forming at least one terminal metal fitting (6) with its end parts (6C, 6D, 6E); c) inserting the at least one terminal metal fitting (6) into the tubular member (4) via the bulb inserting port (5) so that at least one end part (6E) extends through said terminal inserting hole (8), and bending the at least one end part (6E) extending through the terminal inserting hole (8) to form a core member (2); and d) applying the core member (2) to a metal mold (K1, K2, K3) for secondary molding to mold the bulb inserting part (11) and the connector inserting part (16), with the bulb inserting part (11) surrounding the tubular member (4). The method of claim 1, wherein the metal mold (K1, K2, K3) comprises a molding face (18), covering the bulb inserting port (5), and projections (19) around the molding face (18), said projections (19) partially extending along the outer peripheral surface of the tubular member (4). The method of claim 1 or 2, wherein the secondary molding is carried out with a mold having three molding members (K1, K2, K3), one (K1) of them comprising the molding face (18) and the projections (19). A bulb socket (1) comprising a socket body (11, 13, 16) with a bulb inserting part (11) having a bulb inserting port (5) and a connector inserting part (16) having a connector inserting port (17), the bulb inserting part (11) and the connector inserting part (16) being disposed in L-letter relations to each other, and terminal metal fittings (6) which are assembled into the socket body (11, 13, 16) and their end parts are disposed within the bulb inserting port (5) and the connector inserting port (17), respectively, said socket body (11, 13, 16) having a core member (2) and an outer shell (3) separately formed around the outer peripheral surface of the core member (2) and having the connector inserting part (16), wherein said core member (2) includes a tubular member (4) having an open end side forming the bulb inserting port (5) and an opposite bottom side through which at least one L-letter shaped terminal metal fitting (6) extends. A bulb socket (1) according to claim 4, wherein said core member (2) comprises a tubular member (4) having an open side forming the bulb inserting port (5) and an opposite bottom side with at least one terminal hole (8) therethrough, said tubular member (4) containing the terminal metal fitting (6) having at least one end part (6E) extending through said terminal hole (8) and being L-letter shaped outside said tubular member (4), and said outer shell (3) comprises an outer tube (10), attached to the outer surface of the tubular member (4), and the connector inserting part (16) surrounding the end (6E) of the terminal metal fitting (6) extending through the terminal hole (8) of the tubular member (4) and being integrally connected to the outer tube (10). A bulb socket (1) according to claim 4 or 5, comprising a cylindrical part (13) integrally connected to the outer tube (10) and spaced apart thereof, said cylindrical part (13) having slip-proof projections (14) and a flange part (15) radially extending away from the cylindrical part (13). A bulb socket (1) according to anyone of claims 4 to 6, comprising an annular groove (12) around the bulb inserting port (5) between the outer shell (3) and the core member (2). A bulb socket (1) according to anyone of the claims 4 to 7, wherein the end part (6E) of the terminal metal fitting (6) to be bent in L-letter shape is formed in a single plate. A bulb socket (1) according to anyone of the claims 4 to 8, wherein the terminal inserting hole (8) is tight fitting around the end part (6E) of the terminal fitting (6) extending through the terminal inserting hole (8).

Inventors: OGAWA SHINJI, OGAWA, SHINJI, OGAWA, SHINJI, C/O SUMITOMO WIRING SYSTEMS, LTD.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1996
Main classification: H01R43
IPC codes: H01R43, H01R33