JPH0738284B2 - Method for manufacturing inner / outer communication tube of vehicle lamp - Google Patents

Description

Detailed Description of the Invention

[Field of Industrial Application] The present invention relates to a method for manufacturing a novel inner / outer connecting tube of a vehicle lamp. Specifically, a U-shaped or U-shaped (hereinafter collectively referred to as U-shaped) connecting tube that is attached to a water drain hole or an air circulation hole of a vehicle lamp, for example, an automobile lamp, is inexpensive. It is intended to provide a manufacturing method. [Prior Art] In a vehicle lamp, for example, an automobile lamp, the inside and outside of the lamp are communicated with each other for the purpose of draining water or removing cloudiness. When the inside and outside of the lamp are communicated with each other, in order to prevent water, for example, rainwater or dust from entering the lamp through the communication hole, as shown in FIG. 12, it has a substantially U shape. The connecting tube a is attached to the connecting hole b. [Problems to be Solved by the Invention] By the way, conventionally, for example, EPT rubber was press-molded in order to form the connecting tube a bent into a substantially U-shape as described above. However, press molding of a rubber material has a problem that productivity is poor, the production cost of the connecting tube is increased accordingly, and the price of the connecting tube is increased. The present invention has been made in view of the above problems of the prior art,
Its purpose is

[Means and Actions for Solving the Problems]

In order to achieve the above-mentioned object, in the method for manufacturing the inner / outer communication tube of the vehicle lamp of the present invention, by blow molding,
A tube continuity consisting of a straight tube body along the axial direction of the parison and a U-shaped tube body communicating with the straight tube body and continuously formed on at least one side of the straight tube body at a predetermined pitch. A body is formed, and the tube continuum is cut and separated in the direction along the axial direction of the parison and between the adjacent U-shaped tube bodies including the branch portion of the straight portion and the U-shaped portion. . Therefore, according to the method for manufacturing the inner / outer connecting tube of the vehicular lamp of the present invention, a large number of connecting tubes can be formed by one molding, and the cost of the connecting tube is reduced. In addition, since the straight tube body acts to suppress kinking and bending as a tube continuum due to molding shrinkage of a plurality of U-shaped tube bodies, it is possible to form a straight tube continuum, and therefore cutting and burrs. Easy to take. [Embodiment] Next, an example of an embodiment of a method for manufacturing an inner / outer connecting tube of a vehicular lamp of the present invention will be described in detail with reference to the accompanying drawings (Figs. 1 to 3). First, as shown in FIGS. 1 (A) to 1 (E),
A tube continuum 9 including a straight tube body 10 and a U-shaped tube body 12 communicating with the straight tube body 10 and continuously formed on both sides of the straight tube body 10 at a constant pitch is formed. . In FIG. 1 (A), reference numeral 1 is a die, and a die core 2 is fitted in the center of the die. A molten resin passage 3 is formed between the die 1 and the die core 2, and the molten resin passage 3 is formed. The lower end opening edge 3a of 3 has a substantially circular shape when viewed from below. In addition, the air passage 4 penetrates through the center of the die score 2.
Is formed, and an air pin 5 is connected to the lower end of the air passage 4. Therefore, a molten resin, for example, a molten polyethylene resin, is injected downward through the molten resin passage 3 by an injection device (not shown), whereby a parison 6 extending downward in a tubular shape is formed. This state is shown in FIG. 1 (A). Next, as shown in FIGS. 1 (B), (C), (D), and FIG. 2, a mold clamping step of clamping the parison with a mold is performed. In these drawings, reference numerals 7 and 7'represent a molding die,
The parison 6 is arranged so as to be movable in and out of contact with the parison 6 in a direction orthogonal to the axial direction of the parison 6, and upper and lower continuous recesses 8 and 8'for molding are formed on the abutting surfaces of the parison 6 ( (See FIG. 2). Therefore, as described above, when the parison 6 is formed, the molding dies 7 and 7'are clamped, and at the same time, air is introduced into the parison 6 through the air passage 4 and the air pin 5 by an air pressure feeding device (not shown). Supply (first
(See FIG. (C)). As a result, the outer wall of the parison 6 is each molding die 7,
It is in a state of being pressed against the inner surfaces of the recesses 8 and 8'formed in 7 '. Therefore, after cooling the forming dies 7, 7 ',
The molded product, that is, the tube continuum 9 is taken out from the molding dies 7 and 7 '(see FIG. 1 (D)). Next, the tube continuous body cutting step shown in FIGS. 1 (D), (E), and (F) is performed. As described above, when the parison 6 is molded by the molding dies 7 and 7 ', the U-shaped tube body 12 is continuously formed on both sides of the straight tube body 10, and the tube continuum 9 is formed.
Are formed (see FIG. 1 (D)). Therefore, first, the upper and lower portions 11a and 11b of the parison 6 are cut off from the tube continuum 9, and then the tube continuum 9 is formed into a parison including a branch portion between the straight tube body 10 and the U-shaped tube body 12. Cut along the axial direction of 6 (first
See figure (E). In addition, each cutting position is shown by a dashed-dotted line. ). Then, a large number of substantially U-shaped connecting tubes 12a, 12a, ...
, Which are continuous with each other through the burr portions 13, 13, ..., That is, two U-shaped tube bodies 12 are continuously formed. Therefore, from each U-shaped tube body 12, 12, ...
Separate 3 ... (You can tear it off by hand.)
A large number of communication tubes 12a, 12a, ... Are completed (see FIG. 1 (F)). In the embodiment of the manufacturing method of the present invention described above, when the tube continuous body 9 which is a blow molded body is cooled and contracts, the orientation of the molten resin and the deviation of the thickness of the parison pinched by the mold are unbalanced. Due to the above, the difference in molding shrinkage at each part of the U-shaped tube body 12 acts as a force for twisting or bending the tube continuum 9, but the linear tube body 10 is molded and shrinks for the resin. It functions to absorb and relieve internal stress caused by the above, and to suppress kinking and bending of the tube continuum 9. Therefore, a substantially straight tube continuum 9 is obtained, and the cutting process and the deburring process can be performed quickly and easily. In addition, in the above-described embodiment, U is provided on both sides of the straight tube body 10.
The case where the continuous tube body 9 in which the character-shaped tube body 12 is continuously formed is blow-formed has been described, but as shown in FIG. 3, U is formed on one side of the straight tube body 10.
The continuous tube body 9A in which the U-shaped tube body 12 is continuously formed may be molded to cut and separate the straight tube body side and the U-shaped tube body side. According to this method, in addition to the effect that the kinking and bending of the tube continuum are reduced in the same manner as the above-mentioned method of the embodiment,
Since the straight part of the formed tube continuum can be arranged on the cutting machine as a reference plane, there is also an advantage that the cutting and deburring steps become easy. In each of the two examples of the above-described manufacturing method, after the blow-molded tube continuous body was cut and separated into the straight tube body side and the U-shaped tube body side, the U-shaped tube body became discontinuous. By removing the burrs, each connecting tube is obtained. However, as a procedure for cutting and deburring, in addition to the procedure described above, first, burrs are removed from a blow-molded tube continuum, and then cut and separated to obtain a U-shaped connecting tube, and a tube continuum is used. Deburring may be performed simultaneously with cutting, and cutting and deburring may be performed in any order. Next, an actual usage of the connecting tube manufactured by the method of the present invention will be described. The connecting tube manufactured by the method according to the present invention is made of synthetic resin, and there is a rotation preventing means at the attaching portion and a drop-off preventing means from the attaching portion, which has not been a problem in the conventional rubber connecting tube. is necessary. The connecting tube is attached by covering the one end opening part of the tube with the tube attaching part which is the tip part of the boss where the water drainage hole and the air circulation hole of the lamp are formed, as shown in FIG. As described above, it is most desirable that the tube is arranged so as to extend in the up-down direction with the opening at the other end facing downward, from the viewpoint of preventing the intrusion of water. It is also necessary to prevent the boss from falling off from the tube attachment part even if an external force acts on the other end side of the communication tube attached to the tube attachment part. From such a point of view, it is necessary to devise a rotation preventing means and a dropout preventing means in the attachment portion of the connecting tube. The rotation preventing means shown in FIG. 4 forms a rib 22 projecting inward on the curved side of the opening 12b of the communication tube 12a by utilizing burrs generated during blow molding, and at the tube attachment portion 32 at the tip of the boss 30. When the connecting tube 12a is attached, the rib 22
A pair of stopper ribs 34 are formed so as to project on the back surface of the lamp so as to sandwich it. And contact tube 12a
If the rib 22 tries to rotate, the movement of the rib 22 is restricted by the stopper rib 34, so that the connecting tube is prevented from rotating. 4 (a) and 4 (b) show a side view and a horizontal cross-sectional view of the connecting tube attached state. The stopper rib 34 may be formed so as to project from the side surface of the boss 30. The detent means shown in FIG. 5 has a pair of axially extending projections 33a formed on the outer circumference of the tube attachment portion 32 of the boss 30, and is engaged with the projection on the inner circumference of the tube opening 12b. A possible vertical slit 33b is formed, and the protrusion 33a and the vertical slit 33b are engaged with each other to prevent the communication tube 12a from rotating. 5 (a) and 5 (b) are a plan view and a side view of the tube attachment part, and FIGS. 5 (c) and 5 (d) are a side view and a bottom view of the connecting tube. The detent means shown in FIG. 6 has a vertical groove 35 having a triangular cross-section provided around the outer periphery of the tube attachment portion 32 of the boss 30.
The inside diameter of the tube opening 12b is formed smaller than the outside diameter of the tube attachment portion 32, and when attaching the connecting tube 12a, the tube attachment is performed by applying hot air to the tube and expanding the inside diameter of the tube opening 12b. It is adapted to cover the dressing portion 32. Then, when the temperature becomes room temperature, the tube opening is in close contact with the outer peripheral surface of the tube adhered portion 32, the apex region of the triangular cross section is hard to fit into the inner peripheral surface of the tube, and the connection tube 12a is prevented from rotating and is prevented from falling off. . Figure 6 (a), (b)
Shows a side view and a horizontal cross-sectional view with the connecting tube attached. The detent means shown in FIG. 7 uses a punching jig 40 as shown in FIG. 7 (c) in which a pair of recesses 36 are formed on the outer peripheral surface of the tube adhered portion 32 of the boss 30. The portion 37 of the tube opening 12b covered by the tube attachment portion 32 corresponding to the recess is thermally deformed and press-fitted into the recess 36, thereby preventing the communication tube 12a from rotating.
It is also prevented from falling off. The punching jig 40 has a pair of punching protrusions 41 that can be brought into and out of contact with each other and are heated to a high temperature. 7 (a) is a front view of the state in which the connecting tube is attached, and FIG. 7 (b) is a side view thereof. In all of the tube dropout prevention means shown in FIGS. 8 to 10, the U-shaped horizontal rod-shaped portion 12c connecting the tube openings 12b has a constricted shape so that an external force as indicated by an arrow in the drawing acts. In this case, the tube is bent and deformed at this constricted portion, whereby the axial component force (component force acting in the vertical direction in the figure) is suppressed as much as possible, and the connecting tube 12a is prevented from falling off. In FIG. 8, the constricted portion has a shape constricted in the vertical direction in the figure, in FIG. 9, the constricted portion has a concave shape in the width direction circular arc shape in the figure, and in FIG. The part has a shape in which the diameter is reduced in the entire radial direction. 8 to 8
In FIG. 10, (a) shows a side view of each connecting tube, and (b) shows a bottom view of each. The tube dropout prevention device shown in Fig. 11 is
The U-shaped horizontal bar-shaped portion 12c connecting 12b and 12b has a substantially semi-cylindrical shape with a large cross-section coefficient (see Fig. 11 (b)) to enhance the rigidity of this part and the bottom of the U-shaped horizontal bar-shaped portion of the tube. The structure is such that the surface 24 is extendedly contacted to the tube attached portion 32 side, and the tip of the tube attached portion 32 is projected above the inner surface 24. When the force P indicated by the arrow in the drawing acts, the region of the tube U-shaped horizontal rod portion 12c is unlikely to be deformed, so that the action direction of the force transmitted to the tube attached part 32 is equal to the action direction of the force P. , The component force acting in the direction to drop the communication tube is small. Furthermore, the fitting length of the tube opening 12b and the tube attached portion 32 is long,
The contact area between the two is large, so they do not easily fall off. 11 (a) is a side view of the connecting tube attached, and FIG. 11 (b) is a side view.
Is a central cross-sectional view thereof. [Effects of the Invention] As described above, according to the method for manufacturing an inner / outer communication tube for a vehicular lamp according to the present invention, a straight tube body along the axial direction of the parison and a straight tube connected to the straight tube body are provided. A tube continuum comprising a U-shaped tube body continuously formed at a predetermined pitch on at least one side of the body is formed, and the tube continuum includes a branch portion of a straight portion and a U-shaped portion of a parison. The U-shaped tube body is cut and separated in a direction along the axial direction and between adjacent U-shaped tube bodies. Therefore, according to the method for manufacturing the inner / outer connecting tube of the vehicular lamp of the present invention, a large number of connecting tubes can be formed by one molding, and the cost of the connecting tube is reduced. In addition, since the straight tube body acts to suppress kinking and bending as a tube continuum due to molding shrinkage of a plurality of U-shaped tube bodies, it is possible to form a straight tube continuum, and therefore a cutting process and a burr. The taking process is facilitated and the cost of the connecting tube is further reduced.

[Brief description of drawings]

1 (A) to 1 (F) are partially cutaway side views showing a method for manufacturing an inner / outer communication tube of a vehicle lamp of the present invention sequentially from (A) to (F), and FIG. The figure which shows the molding surface of a metal mold | die, FIG. 3 is a partially notched side view which shows the other tube continuous body at the time of forming a connection tube, and FIGS. 4-11 is the connection tube manufactured by the method of this invention. And FIG. 12 is a side view showing an example of a conventional connecting tube. 6 ... Parison, 7,7 '... Mold, 9 ... Continuous tube, 10 ... Linear tube, 12 ... U-shaped tube, 12a ... Communication tube, 13 ... Burr section.

Claims (1)

[Claims] 1. A cylindrical parison is formed by injecting a molten synthetic resin into a cylindrical shape, and the parison is sandwiched by a mold from a direction orthogonal to the axial direction thereof, and at the same time air is supplied into the parison for molding. By a so-called blow molding, a linear tube body along the axial direction of the parison and a U-shaped member which communicates with the linear tube body and is formed continuously on at least one side of the linear tube body at a predetermined pitch. A tube continuum consisting of a tube body is formed, and the tube continuum is separated by cutting the tube continuum including a branch portion of a straight portion and a U-shaped portion along the axial direction of the parison and between adjacent U-shaped tube bodies. A method of manufacturing an inner / outer connecting tube of a vehicle lamp, comprising: