JPS649936B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a synthetic resin pipe having an inorganic coating layer using a form made of an elastic and flexible material such as urethane, other synthetic rubber, or natural rubber.

In order to manufacture a synthetic resin pipe having an inorganic coating layer on a desired part of the outer surface, which is made by appropriately blending an inorganic binder such as cement or gypsum, inorganic fibers such as glass fiber or asbestos, and other ingredients, it is necessary to use vinyl chloride, for example. A synthetic resin pipe made of synthetic resin is housed and fixed only in the desired portion inside a mold made of two or more split molds, and then, for example, cement slurry is press-fitted into the mold to form an inorganic coating layer. Conventionally, this manufacturing method has used molds made of metal, hard plastic, wood, etc. that are not elastic or flexible, so when removing the mold after the cement has hardened, the peelability from the hardened cement body is extremely poor. In addition to requiring time and effort to remove the mold, the surface layer of the molded product is often damaged, scratched, or peeled off, resulting in a rough surface, resulting in a loss of commercial value of the molded product. In this case, a mold release agent may be applied to the inner surface of the mold, but it is necessary to apply it every time the mold is formed, which not only complicates the work but also causes an economic loss.

The present invention has been proposed in view of the above, and uses a mold having elasticity and flexibility to provide an inorganic coating layer that has good releasability without using a mold release agent and is highly economical. Provided is a method for manufacturing a synthetic resin pipe having the following properties.

The present invention will be explained in detail below with reference to an embodiment shown in the drawings.A mold 1 used in this embodiment is a two-piece mold consisting of a lower mold 2 and an upper mold 3. Both are made of materials with elasticity and flexibility, such as synthetic rubber containing urethane as a main component, synthetic rubber containing other components, and natural rubber.

In the embodiment shown in the drawings, the inorganic coating layer b is provided on the entire surface of the L-shaped synthetic resin pipe a, so the lower mold 2 and the upper mold 3 are provided with an L-shaped depression 2' having a semicircular cross section. , 3'. Each recess 2', 3' opens to the upper surface of the lower mold 2 and the lower surface of the upper mold 3, and when the lower mold 2 and upper mold 3 are joined, both the recesses 2', 3' form an L-shaped cavity with a circular cross section. constitute the department. Each recess 2', 3' has a larger diameter than the synthetic resin pipe a, but the ends of the recess 2', 3' are closed in accordance with the cut end surface of the synthetic resin pipe to be stored, In addition, at least a portion of the closing portion is extended until it is flush with the inner surface of the synthetic resin pipe, and a fixing portion 4 is formed for fixing the position of the synthetic resin pipe from the outside with a fixing device such as a holder. . The lower mold 2 has an injection hole 5 for inorganic coating material slurry that communicates between the outer lower surface and the recess 2', and the upper mold 3 has an exhaust hole that communicates from the recess 3' to the outer upper surface. 6 will be established. The exhaust hole 6 in the upper mold 3 is preferably located at a position where the air inside can completely escape when the inorganic coating material slurry is injected. Although this position is difficult to determine simply due to misalignment of the synthetic resin pipe a, distortion of the formwork, etc., it should normally be provided at the highest position.
Moreover, providing a plurality of exhaust holes is effective in solving this problem.

In order to manufacture a synthetic resin pipe having an inorganic coating layer using the formwork 1 consisting of the lower mold 2 and upper mold 3 described above, each end of the synthetic resin pipe a is supported by a holder attached to the fixing part 4, and the recessed part 2 ', and the upper die 3 is placed on top and pressed. In this state, the synthetic resin pipe a
is positioned by the holder in a suspended manner within the space constituted by the recesses 2', 3', and a gap 7 having an equal width is formed between the outer circumferential surface of the synthetic resin pipe a and the inner surface of the recesses 2', 3'. is formed.

After holding the synthetic resin pipe a in the formwork 1 in this way, the inorganic coating material slurry is pumped into the gap 7 through the injection hole 5, and the inorganic coating layer is removed while the air in the gap 7 is released through the exhaust hole 6. Fill. When the inorganic coating material begins to flow out from the exhaust hole 6, the gap 7
Since the inside is now filled, the pressure feeding of the inorganic coating material is stopped, the injection hole 5 is plugged, and the inorganic coating material slurry is cured without removing the formwork.

Therefore, it is preferable to use components that can be cured at low temperatures as the inorganic coating material. For example, use a cement slurry made by mixing cement with one or more of calcined vermiculite, alkali-resistant glass fiber, and pearlite and kneading with water. can do.

Once the inorganic coating material slurry has hardened within the formwork, release the pressure between the lower mold and the upper mold, bend the upper mold 3 outward using the elasticity of the formwork, remove the upper mold 3, and do the same with the lower mold. Remove the lower mold 2 while bending the mold 2 outward. When using this mold removal method, the hardened inorganic coating layer surface hardly adheres to the mold, so it is not only extremely simple, but also the surface of the coating layer is smooth.

The above explanation was given regarding the manufacturing method of an L-shaped synthetic resin pipe with an inorganic coating layer, but even a straight pipe can be used.
Alternatively, T-shaped or Y-shaped tubes can also be manufactured by the same method. Furthermore, when it is desired to coat a desired part of the synthetic resin pipe, leaving only the ends, it is easier than in the case described above, since it is sufficient to use a formwork that clamps and fixes the ends. The formwork is not limited to an upper and lower half-split type, but may also be a three-split type or a four-split type. Furthermore, if the inside of the mold is evacuated while each split mold is crimped, the inorganic covering material is likely to be filled.

In summary, the present invention covers the inner surface of the space of the mold made of two or more split molds using a material having elasticity and flexibility in the step of coating the outer surface of the synthetic resin pipe with an inorganic coating layer. It is formed larger than the outer surface of the desired part of the synthetic resin pipe to be covered with the inorganic coating layer, and only the desired part of the synthetic resin pipe to be covered with the inorganic coating layer is accommodated in the space of the formwork by the fixing part provided in the formwork. The inorganic coating material is then pressure-fed through the injection hole provided in the formwork into the gap between the inner surface of the space in the formwork and the outer surface of the synthetic resin pipe, and then cured. After the inorganic coating material has hardened, each The feature is that the split mold is removed by bending it outward, and since there is no adhesion between the formwork and the inorganic coating material, it is extremely easy to remove without using a release agent on the inner surface of the formwork, but it is time-consuming. The molded product can be demolded without any damage, and the surface layer of the molded product becomes smooth and there is very little possibility of breakage or damage. In addition, even if the inorganic coating material is alkaline, it has better alkali resistance than metal formwork, so it has a long service life, and is lightweight and easy to handle, and has good workability, so it can be easily manufactured. is easy and has high practical value.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the mold used in the present invention, Fig. 2 is a plan cross-sectional view of the same synthetic resin tube housed therein, and Fig. 3 is a longitudinal cross-sectional view during molding. .

Claims (1)

[Claims] 1. In the step of coating the outer surface of the synthetic resin pipe with an inorganic coating layer, the inner surface of the space of the formwork consisting of two or more split molds is coated with the inorganic coating layer of the synthetic resin pipe using a material that has elasticity and flexibility. The inorganic coating layer of the synthetic resin pipe is formed larger than the outer surface of the desired part to be coated, and the fixing part provided in the formwork stores and holds only the desired part of the synthetic resin pipe to be coated with the inorganic coating layer in the space of the formwork, and the above-mentioned The inorganic coating material is pumped into the gap between the inner surface of the space of the mold and the outer surface of the synthetic resin tube through the injection hole provided in the molded formwork, filled and cured, and after the inorganic coating material has hardened, each split mold is turned outward. A method for manufacturing a synthetic resin pipe having an inorganic coating layer, characterized in that the pipe is removed while being bent.