JP3481490B2 - Resin bent hose and method of forming the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bent hose made of resin, for example, an air duct for feeding air from an air cleaner to an engine as an intake duct of an automobile engine, and its length. The present invention relates to a resin bent hose having a bent portion that is bent two-dimensionally or three-dimensionally in a vertical direction. 2. Description of the Related Art Conventionally, a rubber duct, which is an injection molded product made of a vulcanized rubber material, has been required as the above-mentioned intake duct because of its demand for flexibility and mechanical strength capable of maintaining a hollow shape. Is used. [0003] However, rubber ducts are heavier than resin ducts, cannot satisfy the demand for lighter vehicles, are inconvenient to handle at the time of assembling work, etc., and have recently made effective use of resources. However, there is a problem that the rubber material cannot be recycled under the circumstances where the importance is placed on the rubber material. That is, the burrs, runner portions and sprue portions generated with the product during the rubber injection molding cannot be reused at all, and the product after use is only treated as industrial waste and not reused. Is the actual situation. [0005] On the other hand, there is an example in which a resin duct is used as the air duct. However, this is a duct formed by a blow molding method, and its inner surface dimensional accuracy is inferior. It is difficult to secure airtightness with
After blow molding, it is necessary to improve the dimensional accuracy of the inner surface by secondary processing such as polishing the inner surface of the end of the duct. SUMMARY OF THE INVENTION In view of the above problems, the present invention has been developed to replace conventional vulcanized rubber with a lightweight, recyclable and flexible and strong material similar to vulcanized rubber. It is a resin hose that has such characteristics as that it can achieve high inner surface dimensional accuracy at the same time as molding, and even if it has a bent part that undercuts in the length direction, it is less elastic than rubber An object of the present invention is to provide a bent hose made of resin that can be easily pulled out of a core mold without causing deformation or damage to a product. [0007] The present invention is configured as follows as means for solving the above-mentioned problems. (1) As a method for forming a hose having a bent portion by injection molding a TPE to cavity formed by the core mold to form the cavity mold and the hose inner surface defining a hose outer surface, said bent as said core mold 2 in the axial direction
Using a split core mold consisting of a split first core mold and a second core mold, pulling out the first core mold while injecting air into the contact surface of the split core mold when the mold is opened after injection molding. 1
The mold release part is removed, then the end of the first mold release part is closed, air is injected into the inside of the first mold release part, the second mold release part is released from the second core mold, and the undercut is released. This is done by using a means. In the present invention, the resin hose is made of TPE.
For example, a polyolefin-based thermoplastic elastomer (TP
Injection molding is performed using O) as a material. TPO means that the hard segment is composed of one or more crystalline polymers selected from polypropylene (PP), ethylene copolymerized PP, and polyethylene (PE), and the soft segment is a binary copolymer ethylene propylene. Rubber (EP
M), consisting of one or more amorphous polymers selected from non-conjugated diene copolymer-based ethylene propylene rubber (EPDM) and butyl rubber (IIR). Simple blend type TPO, implantable TPO
And dynamic vulcanization type TP0. The hardness of the above TPE is H _S (JIS
A) 50 to 95, preferably 60 to 90 materials are used. In the case of TPO, the ratio of the hard segment to the soft segment which is a component thereof is changed, for example, in the range of hard segment 70 to 30 / soft segment 30 to 70. Is selected. If the ratio of hard segments is too high,
The hardness becomes too high, the flexibility loses flexibility, and it becomes very difficult to remove the bent part that becomes an undercut.On the other hand, if the ratio of the soft segments is excessive, the hardness becomes too low, and the physical properties such as the mechanical strength of the hose Decrease. In the present invention, TP
It is preferable to use a dynamically vulcanized type in which O has PP as a hard segment and EPDM as a soft segment, and EPDM is partially or completely crosslinked with an organic peroxide during kneading. When the soft segment is partially or completely cross-linked, the oil resistance, heat resistance, tensile strength, tear strength and the like of the hose are increased as compared with the case where the soft segment is not cross-linked. [0010] In the present invention, when releasing the bent portion that becomes an undercut, high-pressure air is blown between the core mold and the injection-molded product to expand the diameter of the product over its entire length, and the entire product is expanded. Is not carried out at once from the core mold, but the mold is removed stepwise by the split core mold divided into two in the axial direction at the bent part. That is, in a state where the mold is opened after the injection step, first, the first core mold of the split core mold is pulled out from the product, so that the part extending to one end from substantially the center of the bent portion of the product is removed. Then, the second mold extends from the second core mold of the split core mold to the other end with substantially the center of the bent portion as a boundary.
Part is removed from the mold to form a second mold removal part, whereby the bent part of the TPE hose, which does not have sufficient elasticity as rubber, is formed at a substantially right angle or more sharply at an undercut. Even if it is done, the release from the core mold can be performed with a very small degree of forcible removal, or it can be performed without forcibly removing it at all, and the whole product can be removed at once There is no possibility that the product will be deformed or damaged due to forcible removal. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a resin-made bent hose 1 formed by injection molding and having a bent portion 2 bent at a substantially right angle near a central portion in a longitudinal direction. Are connected and fixed to the engine main body or the air cleaner with fasteners, and constitute a part of an intake passage for supplying outside air taken in through the air cleaner to the engine main body. FIG. 2 shows a state in which the hose 1 is injection-molded. A pair of half-cavity molds 11, 11 forming the outer shape of the hose and split core molds 12, 13 forming the inner shape of the hose. The TPO is injection-molded into the cavity of an injection mold 10 made of The split core type is formed as a part of the center core 16, and the first core type 12 and the second core type 13 are formed along the axial direction with the substantially center of the bent portion 2 of the hose 1 as a boundary.
And the projection 14 is formed on the contact surface of the first core mold 12.
A concave portion 15 is formed on the contact surface of the second core mold 13 so that they engage when butted against each other. The second core mold 13 is integrally and downwardly extended from the upper portion 17 of the main body of the core 16, and the tip portion has a curved shape adapted to substantially half of the bent portion 2 of the hose 1, and has the upper portion of the main body inside. 17
An air circulation hole 19 is formed to communicate with the front end. The first core mold 12 is rotatably mounted by an arm 20 pivotally supported by a lower portion 18 of the body 16 of the core 16, and the tip of the second core mold 13 that abuts on the tip of the hose 1 is bent. It has a curved shape adapted to approximately the other half of the part 2. FIG. 3 shows a state in which the mold is opened after the injection molding, and the whole core 16 is mounted and supported by the cavity 11 on one side in a state of being suspended between the cavities 11, 11. The injection-molded hose 1 is held outside the mold 12 and the second core mold 13 with its bent portion being undercut. FIG. 4 shows a part of the demolding process. In the first stage of the demolding process, the second core die 13 is moved from the air flow hole 19 at the tip end surface to the contact surface with the first core die 12. While discharging air, preferably compressed air, the first core mold 12 is turned in the direction of the arrow and pulled out of the hose 1. At this time, since the hose portion corresponding to the first core mold 12 is only about half the length of the entire length of the hose 1, it is easily removed without deformation using the elasticity of the TP0, and the first removed portion is removed. Constituting No. 3. The first core mold 12 may have its turning radius coincident with the bending radius of the hose bending portion so that almost no forcible removal occurs. In this case, the former may be made larger than the latter so as to draw out a gentle curve, or the hose may be pulled out in a substantially straight line without turning when the bending of the hose bending portion is gentle. Next, as the second stage of the demolding process, the first
Air, preferably compressed air, is blown out from the air circulation hole 19 into the inside of the product while the end of the detachable portion 3 is closed by a drawing jig (not shown) to greatly expand the diameter of the first detachable portion 3 and to enter the inside of the product. The diameter of the hose portion 4 held by the second core mold 13 is expanded by allowing the ejected air to also enter between the second core mold 13 and the product, and the second jig is removed by the extraction jig. 13, the second mold release part 4 is formed easily, and the undercut of the entire hose can be released from the core mold. In the above embodiment, the present invention is applied to a resin hose having a bellows portion formed on the first detachable portion 3 and the second detachable portion 4 to easily detach from the core mold. The present invention is also applied to a hose having a shape in which the bent portion 2 is bent two-dimensionally or three-dimensionally, in addition to being shaped. Similarly, the hose 5 with the bent portion shown in FIG. 5 bent in a V-shape or the hose 6 bent into the offset type shown in FIG. 6 can be easily formed by using the split core types 21, 22, 23, and 24 in the same manner. By releasing the undercut, a resin bent hose by injection molding can be obtained. According to the present invention, the mastication step, compounding step, kneading step and vulcanization kneading required for the conventional rubber injection molding can be omitted, and the efficiency of the injection molding of TPE can be reduced. Can be molded well. The molded resin hose has excellent inner surface dimensional accuracy and is light in weight and recyclable, while having the same greeting and strength as vulcanized rubber. Although the resin hose of the present invention has a bent portion as an undercut portion, instead of forcibly removing the core type from the product at once and removing it from the product, a split core type is used to remove the core type in steps. Since it is molded, even if it is a TPE hose having less elasticity than rubber, it can be smoothly removed from the hose, and there is an advantage that a defective product is not generated without damaging or deforming the product in the removing process.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a hose of the present invention. FIG. 2 is a cross-sectional view showing a state where the hose of the present invention is injection-molded. FIG. 3 is a side view showing a state in which an injection molding die is opened. FIG. 4 is an explanatory view showing a part of a hose demolding step. FIG. 5 is a sectional view showing a hose according to another embodiment of the present invention. FIG. 6 is a sectional view showing a hose according to another embodiment of the present invention. [Description of Signs] 1 Hose 2 Bending part 3 First demolding part 4 Second demolding part 5 Hose 6 Hose 10 Injection molding dies 11, 11 Cavity mold 12 First core mold 13 Second core mold 14 Convex part 15 recess 16 core 17 upper body 18 lower body 19 air flow hole 20 arms 21, 22, 23, 24 split core type

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B29K 19:00 B29K 19:00 B29L 23:00 B29L 23:00 (56) References JP-A-3-221423 (JP, A) JP-A-7-164467 (JP, A) JP-A-10-156959 (JP, A) JT Table 10-502881 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 33/44 B29C 45/43 B29C 45/44

Claims (1)

(57) [Claim 1] A cavity formed by a cavity mold forming an outer surface of a hose and a core mold forming an inner surface of a hose.
A method for molding a hose having a bent portion by injection molding a thermoplastic elastomer (hereinafter referred to as " TPE ") , wherein the core mold is formed in the axial direction with the bent portion as a boundary.
Using a split core mold consisting of a split first core mold and a second core mold, pulling out the first core mold while injecting air into the contact surface of the split core mold when the mold is opened after injection molding. 1
The demolded part is demolded, and then the end of the first demolded part is closed and air is injected into the interior to release the second demolded part from the second core mold and release the undercut. A method of forming a bent hose made of resin, characterized in that it is molded.