JPS5920646A - Manufacture of molding - Google Patents

Abstract

PURPOSE:To easily product a high-quality molding of a desired shape by a method in which a straight shape of a core metal made of a shape-memory alloy is covered on a molding uniformly, and the core metal is deformed into a memory shape at the same time as molding is made by heating and then pulled out. CONSTITUTION:A shape-memory alloy (e.g., Ni-Ti, etc.) is deformed into a given shape, put in a high-temperature furnace, and heated at about 500 deg.C for about 20min to memorize a given shape in it. The bent core metal 20 is tensed into a straight form by using a corrector 8 to obtain a straight core metal 21. The core metal 21 is inserted into an extruder and a primary molding 22 covered with an unvulcanized rubber is obtained. The primary molding 22 is cut into a given size by a cutter 2 and then held at 150 deg.C for 15-20min in a vulcanizing machine 5. When the temperature of the core metal 21 reaches 100 deg.C, for example, the shape is restored to obtain a shape similar to that of a final molding covered with an unvulcanized rubber having a desirably bent portion. At a time when 150 deg.C is reached thereafter, the molding is vulcanized to obtain a core- inserted molding 24, and the core metal 20 is then taken out of the molding 24 to obtain a tubular hose 25 with a bend portion as a final product.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a molded article.

More specifically, the present invention relates to a method of manufacturing a tubular member having a bent portion, such as a rubber hose. For example, a conventional method for manufacturing a molded article of a tubular rubber hose having a bent portion consists of the steps shown in FIG.

This process will be explained next.

A linear mandrel 10 is inserted into an extruder 1, and unvulcanized rubber compound is coated around the mandrel to form a linear primary molded material 1.
2 is extruded using extruder 1. Next, this primary molded material 1
2 is cut to a predetermined length by M cutting 1112 to obtain a fixed-sized primary molded material 13. Thereafter, the linear mandrel 10 is extracted from the sized fire-formed material 13, and a tubular next molded product 14 made of unvulcanized compounded rubber is made. A mandrel 11 bent into a predetermined shape is inserted into this next molded product 14, and the unvulcanized compounded rubber is plastically deformed along the bent mandrel to obtain a secondary molded material 15 bent into a desired shape. . This is placed in a vulcanizing device 5 and heated to a predetermined temperature to perform a vulcanization process. Then, a cored molded product 16 made of vulcanized rubber bent into a desired shape and a mandrel is obtained. And next, this heart molded product 1
The bent mandrel 11 was pulled out from 6 to obtain a bent rubber boce 17 which is a cotton product.

As can be seen from the above explanation, in the conventional process, the bending part is formed in step 3 to form the primary molded product 14 into a straight tube shape, and in order to obtain the desired bent shape, The method was divided into two steps: 1) culm 4, in which a bent mandrel is inserted into the molded product 14 to obtain the secondary molded material 15; For this reason, two types of scales are required: one with a straight shape and one with a bent shape. The process of inserting the bent mandrel was difficult. Because the process of inserting this bent mandrel is in an unvulcanized state, it is forced into place, creating external stress on the unvulcanized rubber and reducing product quality. It was a problem.

Therefore, the present invention has been made to improve such drawbacks, and by using a shape memory alloy as a core metal, it is possible to eliminate the process of drawing out a conventional straight core metal and the bending process. The purpose of this invention is to eliminate the process of inserting a cored metal core, and to obtain a desired bent shape at the same time in the heating process of a molded product.

That is, the present invention involves bending a forming mandrel made of a shape memory alloy into a shape required for forming, and heating the bent forming mandrel to the shape memory temperature of the shape memory alloy to memorize the shape.
Step: stretching the formed mandrel having the shape memorized in a straight line after cooling;
A second step of coating the periphery of the linear molded mandrel with a molding material, and heating the coated molded mandrel to reproduce the memorized shape of the molded mandrel, in conjunction with which the coating material is applied. A third step of plastically deforming and molding the molded mandrel along the reproduced shape, and a fourth step of cooling the molded product obtained in the third step and taking out the molded mandrel from the molded product. Consists of methods for manufacturing molded products.

Here, the shape memory alloy is an alloy having a martenitic transformation, such as a Nijinol alloy made of Niracle titanium, or a brass-based alloy made of copper, zinc, and aluminum. After bending this shape memory alloy into a predetermined shape, it is heated to memorize the shape. The shape memory temperature varies depending on the types of components of the shape memory alloy and the ratio of the components. Generally it is 200-500 degreeC. In short, the alloy is heated to a shape-memory temperature range specified depending on the type of alloy.

In the second step, the molded mandrel bent into a predetermined shape is stretched in a straight line in order to uniformly and easily coat the molding material around the molded mandrel. The molding material may be coated around the linear shaped mandrel by extrusion molding together with the mandrel, or the mandrel may be attached to a primary molded product formed into a tubular shape by extrusion molding or the like. The third step is a heating and shaping step. The heating humidity is set at a temperature range at which the shape memory alloy of the mandrel can reproduce the memorized shape, and near the end temperature of the martenriedite reverse transformation, and at which the molding material coated on the mandrel can be plastically deformed along the reproduced shape. It's humidity.

The shape reproduction temperature varies depending on the composition of the shape memory alloy.

As the molding material for the molded article, a polymeric material having a plasticity of 11 at the shape reproducing temperature of the shape memory alloy can be considered.

For example, plastics or synthetic rubber. In addition, it is also possible to use molded material such as ceramics. When a ceramic molding material is used, a binder and a plasticizer may be used to impart plasticity during shape reproduction. Then, the molded product from which the mandrel has been pulled out in the fourth kneading step is further heated and fired to obtain the final ceramic molded product. Further, when a rubber material is used, the heat molding step and the vulcanization step can be made common. In this case, the shape reproduction temperature of the mandrel needs to be lower than the vulcanization temperature. The cross-sectional shape of the mandrel used above is arbitrary.

Hereinafter, the present invention will be described in more detail based on examples.

FIG. 2 shows an embodiment of a method for manufacturing a tubular rubber bowse having a bent portion that specifically realizes the present invention. A shape memory alloy made of nickel and titanium is bent into the shape required for the core metal of the product, placed in a high temperature furnace 7, and heated at about 500° C. for about 20 minutes. This predetermined shape is then stored. The mandrel 20 bent into a predetermined shape is pulled straight using the straightening device 8 to obtain a straight mandrel 21. This is inserted into an extruder 111 and extrusion molded together with the linear mandrel 21 by an extrusion mi in order to cover the periphery of the linear mandrel 21 with unvulcanized compounded rubber, thereby obtaining the next molded moon 22. After cutting this into a predetermined size through a cutting machine 2, it is placed in a vulcanizer 5 and heated to a temperature of about 150°C for 15 minutes to 20 minutes.
Hold for minutes. In this process, the shape reproduction temperature of the core metal is approximately 1
Since it is set at 00℃, the core metal is heated to 100℃.
When the shape is reached, the shape is reproduced, and the surrounding unvulcanized compound rubber undergoes plastic deformation, resulting in a shape similar to the final molded product with the desired bends. After that, vulcanization treatment is performed when the temperature reaches 150°C. As a result, molded product 2 with mandrel
Get 4. From this, the mandrel 20 is removed and a final product, a tubular hose 25 having a bent portion, is obtained.

In addition to the above embodiments, the step of covering the molded material can also be carried out by preparing an unvulcanized rubber compound previously formed into a tubular shape and inserting a linear mandrel into it.

In summary, the present invention uses a shape memory alloy in the mandrel of a molded product, so that the mandrel can be made into a straight shape, uniformly and easily coated with the molding material, and the shape memory alloy can be memorized at the same time as the molded product is heated and formed. The shape is changed to a desired bent mandrel edge molded product at step 19, and the mandrel is pulled out from this to obtain a molded product.

Therefore, according to the method of the present invention, there is no need for a specially bent mandrel, and there is no need to insert a bent mandrel into the material before forming. Shape memory alloys have superelasticity, so in the final process, the mandrel can be easily pulled out and broken into one piece. Effects such as not causing As a result, production efficiency is improved and product quality can be improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram illustrating a conventional method for manufacturing a bent tubular rubber hose, and FIG. 2 is an explanatory diagram illustrating a manufacturing method according to an embodiment of the present invention. 1... Extruder 2... Cutting machine 5.
... Vulcanization equipment 7 ... High temperature furnace 8 ...
... Orthodontic device patent applicant Toyoda Gosei Co., Ltd. agent Patent attorney Hirodo Okawa Patent attorney Shudo Hizuki Patent attorney Akio Maruyama

Claims (1)

[Claims] (1) A process in which a shaped mandrel made of a shape memory alloy is bent into the shape required for forming, and the bent shaped mandrel is heated to the shape memory temperature of the shape memory alloy to memorize the shape. In one step, the molded mandrel with the shape memorized is stretched linearly after cooling,
A second step of coating the periphery of the linear molded mandrel with a molding material, and molding the covering material in conjunction with heating the coated molded mandrel and reproducing the molded mandrel into the memorized shape. A third step of plastically deforming and forming the mandrel along the reproduced shape, and a fourth step of cooling the molded product which has been deformed by 1η in the third step and removing the molded mandrel from the molded product. Method of manufacturing molded products. (2) The method for manufacturing a molded article according to claim 1, wherein the molding material is made of a thermoplastic polymer material. (3) The method for manufacturing a molded article according to claim 1, wherein the molding material is made of a rubber material, and the third step of heat molding includes a vulcanization step.