JPH0233500B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a heat insulating cover made of foamed resin, and in particular, when molding a cylindrical heat insulating cover used for pipes, etc. By using a mold consisting of a fixture and a two-part outer cylinder, using release paper or a mold release agent on the outside of the inner cylinder, and performing split processing and finishing of the inner diameter after molding, extremely good results are obtained. The present invention relates to a method of molding a heat insulating cover made of foamed resin, which provides a heat insulating cover with high quality at a low cost.

Liquefied natural gas and liquefied petroleum gas have been widely used as fuel for power generation and city gas due to the effects of the recent oil crises and for the purpose of controlling pollution. As is well known, since these liquefied gases are stored or transported at low temperatures, their storage tanks, piping, etc. must be insulated. These storage tanks, piping, etc. have recently become larger and larger. Taking piping as an example, the size ranges from 20 ^B to 40 ^B , and the insulation thickness needs to be 150 to 250 mm. FIG. 1 (A is a sectional view, B is a front view) is a diagram showing an example of such a piping insulation method. In the figure, a heat insulating cover 2 is attached to the outside of the pipe 1. The heat insulating cover 2 has the shape of a cylinder divided in half, and is molded to a predetermined length for ease of handling. Meji 3 is filled between the piping 1 and the heat insulating cover 2 and between the heat insulating covers 2 and fixed to each other. When the diameter of the pipe is large and the insulation thickness is large, a heat insulation cover with a cylinder divided into three or four parts may be used.

Foaming urethane resin is often used as the material for this heat insulating cover. This is because, in addition to its extremely excellent insulation performance, it can be easily foamed on-site, which has the advantage of significantly reducing transportation costs.

Conventionally, this heat insulating cover made of foamable urethane resin has been molded using a mold as shown in FIG. 2 (perspective view). That is, in the figure, the mold 11 has a female mold 12, a male mold 13, and two end plates 14.
It consists of A half-cylindrical space 12A having a diameter approximately equal to the outer diameter of the required heat insulating cover is provided in the center of the female mold 12.
A half-cylindrical convex portion 13A having an outer diameter approximately equal to the inner diameter of the required heat insulating cover is provided at the center of the heat insulating cover 3 . The lengths of the space portion 12A and the convex portion 13A are both made to substantially match the length of the required heat insulating cover. The end plate 14 is a plate having a height and width approximately equal to the height and width of the female mold 12.

The following procedure is used to mold a heat insulating cover using this mold 11.

Two end plates 14 are attached to the female mold 12.

Set the male mold 13 onto the female mold 12.

The female mold 12 and the male mold 13 are tightened using a tightening tool (not shown in FIG. 2).

Mix and stir the foaming urethane resin stock solution.

A foamable urethane resin stock solution is poured into the space 12A of the female mold 12.

After foaming and a predetermined curing period after foaming, the mold is disassembled in the reverse order to take out the heat insulating cover 2 (shown on the recess 12A of the female mold 12 in FIG. 2).

The conventional method of forming a heat insulating cover described above did not have any major drawbacks while the size of the heat insulating cover was small, but as the size of the heat insulating cover gradually increases, the following drawbacks appear. It became.

When foaming urethane resin, foaming pressure is applied to each part of the mold, which tends to cause mold deformation.
In order to prevent this, the mold needs to be thick and highly rigid, which makes the mold expensive.

Since each component of the mold is heavy, it takes a lot of time to disassemble and assemble, and a large crane is also required, which increases equipment costs and ultimately increases the cost of the heat insulating cover.

The heat insulating cover is formed in the shape of a cylindrical half, but the density tends to be high near the half face, which increases the thermal conductivity of that part and deteriorates the heat insulation performance.

As described above, since the density of each part of the molded product varies, it may deform after molding.

Deformation of the molded product can be prevented by leaving it in the mold for a long period of time, but this makes the rotation of the mold difficult, necessitating a large number of molds, and ultimately leading to an increase in the cost of the heat insulating cover.

It is desirable to preheat or heat the mold to 40° to 50°C to promote foaming, but as each component is thick as described above, it has a large heat capacity and takes time to heat. There is a lot of wasted heating energy.

In order to eliminate the drawbacks of the conventional method of molding a heat insulating cover made of foamed resin as described above, the applicant has conventionally invented and proposed the following molding method. In other words, this method adopts the method of forming into a cylindrical shape and then cutting it in half using a saw, etc., and uses a mold as shown in Figure 3 (A is a plan view, B is a cross-sectional view). . In the figure, the mold 21 is composed of an upper end plate 22, a lower end plate 23, an outer plate 24, an inner plate 25, etc., which are formed by bending a thin plate into a cylindrical shape.
The outer diameter and inner diameter of the upper end plate 22 and the lower end plate 23 are approximately equal to the outer diameter and inner diameter of the product insulation cover, respectively, and a resin injection hole 22A is bored in the upper end plate. Further, the inner diameter of the outer plate 24 and the outer diameter of the inner plate 25 are bent so as to be approximately equal to the outer diameter and inner diameter of the product heat insulation cover, respectively, but the edges 24A and 25A of both are cutter-shaped. The diameter of both side plates can be easily changed by applying a slight force. A tightening band 26 having a tightening flange 26A is hung on the outside of the outer plate 24.
A bolt or the like is inserted through A, thereby tightening the tightening band 26 to prevent the outer plate 24 from deforming.

Two flange plates 27 are fixed near the edge 25A of the inner plate 25. Bolts or the like are inserted through the flange plates 27, and by tightening or loosening them, the diameter of the inner plate 25 can be reduced. Or get bigger. A support jig 28 is provided inside the inner plate 25. The support jig 28 is the center pipe 2
8A, and a plurality of support rods 28B which are pivotally fixed to the center pipe via pins so as to be rotatable on a plane including the axis of the center pipe. Support rod 2
8B has a length slightly larger than the value obtained by subtracting twice the wall thickness of the inner plate 25 from the inner diameter of the product heat insulation cover.

This mold is assembled as shown in Figure 3,
A foamed resin such as urethane resin is injected through the resin injection hole 22A, taken out after a predetermined period of time, and divided into two or more parts to form a product insulation cover.

In the improved molding method described above, since there are no irregular parts such as half-split surfaces during foam molding, the density of each part is extremely uniform, and a product of extremely good quality can be obtained. It takes less time and can greatly increase the mold turnover rate. Furthermore, since there is no part where stress is concentrated due to foaming pressure, each part of the mold can be made lightweight, making it easy to handle, improving product quality, and reducing cost.

However, even with this improved molding method, the following drawbacks still cannot be avoided.

When the product insulation cover is large, a large number of tightening bands 26 are required, and a large number of man-hours are required to attach and detach them.

To adjust the diameter of the inner plate 25, the flange plate 27 is tightened or loosened using bolts or the like, but this requires a lot of man-hours.

When the heat insulating cover is large, a considerable number of support rods 28B of the support jig 28 are required, and a large number of man-hours are required for attachment and detachment.

In short, the cost of the heat insulating cover cannot be reduced sufficiently.

An object of the present invention is to eliminate the drawbacks of the conventional molding method for a foamed resin heat insulating cover as described above, and to provide a molding method capable of molding a foamed resin heat insulating cover at a sufficiently low cost.

The present invention provides an improved conventional molding method that includes:
Focusing on the fact that it takes a lot of man-hours to attach and remove the support jig, we used a cylindrical mold instead of the inner plate to eliminate the need for a support jig, and used mold release agent or release paper to separate the mold from the product. The above objective is achieved by using a 2-piece outer mold, followed by further finishing, and by using a two-part outer mold instead of an outer plate.

Embodiments of the present invention will be described below based on the drawings. FIG. 4 shows a mold used in the method for molding a foamed resin heat insulating cover according to the present invention, in which A is a plan view and B is a sectional view. In the figure, a mold 31 includes a ring-shaped upper flange 32, a lower flange 33 of the same shape, an outer cylinder 34, an inner cylinder 35, and the like. The outer diameters of the upper and lower flanges 32 and 33 are almost the same as the outer diameter of the product insulation cover,
Its inner diameter is smaller than the inner diameter of the product insulation cover by a predetermined dimension. Also, the upper flange 3
2 is provided with a resin injection hole 32A.

The outer cylinder 34 has a shape in which a cylinder having an inner diameter approximately equal to the outer diameter of the product heat insulation cover is divided into two on a plane including its axis, and consists of a pair (two pieces), and the two halves are divided into two parts. Each has a tightening flange 34A on the outside thereof. The inner cylinder 35 has a cylindrical shape and has an outer diameter that is approximately the same as the inner diameter of the upper and lower flanges. The heights of the outer tube 34 and the inner tube 35 are both larger than the length of the product heat insulation cover by a predetermined dimension.

A ring-shaped fixture 36 is attached near the inner diameter of one surface of each of the upper and lower flanges 32 and 33, and the fixture 36 has a plurality of attachment holes 3 in the radial direction.
6A (shown as a center line in the figure for simplicity) is drilled. In addition, a plurality of holes 35A are bored near the upper and lower ends of the inner cylinder 35 (indicated by the center line in Figure B).
The inner cylinder 35 and the upper and lower flanges 32 and 33 are removably rotated by passing bolts or the like (not shown) through A and 36A.

A plurality of tightening holes 34B are bored in the tightening flange 34A of the outer cylinder (indicated by the center line in Fig. 1), and by inserting bolts or the like into these holes 34B and tightening them, the pair of outer cylinders can be tightened. 34 is attached to the outer periphery of the upper and lower flanges.

Next, the procedure for molding a foamed resin heat insulating cover using this mold 31 is shown in Figures 5, 6, and 7 for a product with dimensions of 1400 mm in outer diameter, 1000 mm in inner diameter, and 1000 mm in length. This will be explained using examples. FIG. 5 is a perspective view showing the finished dimensions of the product heat insulation cover 2. The molding procedure is as follows.

(a) Apply a release agent 37 to the outer periphery of the inner cylinder 35 or wrap a release paper 37 (see FIG. 6).

(b) Attach the upper flange 32 and lower flange 33 to the inner cylinder 35. As described above, the attachment is carried out using the fixture 36 and the holes 36A, 35A, and by passing bolts or the like therethrough.

(c) An outer cylinder 34 is attached to the outer periphery of the upper and lower flanges 32 and 33.
Install. As described above, the attachment is performed by inserting bolts or the like into the holes 34B of the tightening flange 34A and tightening both outer cylinders 34. This completes the assembly of the mold 31, but
The situation during assembly is as shown in FIG. Here, the inner diameter of the outer cylinder 34 is 1400 mm, which is the same as the outer diameter dimension of the product heat insulation cover 2, but the outer diameter of the inner cylinder 35 is 980 mm, which is 20 mm smaller than the inner diameter of the product heat insulation cover 2, which is 1000 mm.

(d) Inject a foamed resin such as urethane resin through the resin injection hole 32A of the mold 31.

(e) After the specified foaming and curing period, mold 3
Disassemble 1 and take out the molded product. At that time, the molded product 2 has the shape and dimensions as shown in FIG. 7A. That is, the outer diameter is 1400 mm and the inner diameter is 980 mm.

(f) Cut into two or three or more parts using a saw, etc. (in the case shown, it is cut into two). Figure 7b,
(g) As shown in Figure 7 C, the molded product 2 at this stage has a part 37 containing release paper or a release agent attached to its inner diameter. Process it to the required size (in this case, 1000 mmφ) using a rotating knife or the like (see Figure 7 D and E).

Through the above steps, the foamed resin insulation cover 2 is completed. In this description, the case where urethane resin is mainly used as the foamed resin is explained, but it goes without saying that the present invention can be effectively implemented even when other foamed resins are used. Further, although the mold 31 is used in an upright configuration with the axes of the inner and outer cylinders being vertical, the present invention can also be effectively implemented when used in a horizontal configuration with the axes of the inner and outer cylinders set vertically. In this case, the resin injection hole must be provided in part of both flanges 32 and 33 or in the outer cylinder 34.

Furthermore, in the above explanation, the upper and lower flanges 32, 3
3 and the outer cylinder 34 are separate, but the upper and lower flanges 32 and 33 are each divided into two parts, which are fixed to one set of the outer cylinder 34 and the tightening flange 34
The present invention can also be effectively implemented when used with tightening at A. This increases the rigidity of the outer cylinder 34, which is particularly effective when molding a large heat insulating cover.

Each part of the mold used in the present invention has no stress concentration area due to foaming pressure, so it can be made relatively lightweight and therefore extremely easy to handle.
Furthermore, since no supporting jig or the like is required for the inner mold, the time required for disassembly and assembly is extremely short, and the mold can be manufactured at extremely low cost. Furthermore, since the mold parts are lightweight, there is no need for a large crane, etc., and equipment costs are low, making it possible to reduce product costs.

Separation of the inner cylinder and the product is extremely easy because release paper or a release agent is used.
Separation will be easier if the inner cylinder is tapered if necessary. Since the inner diameter of the product insulation cover after separation from the mold is finished using a rotating knife, there is no concern that the insulation performance will deteriorate due to the influence of the release agent or release paper.

Further, in the molding method according to the present invention, since there are no irregularly shaped parts as described above, each part of the heat insulating cover can be molded with extremely uniform density, and the quality of the molded product is extremely good. Furthermore, since there is less deformation after molding, the curing time after molding can be shortened, and the rotation rate of the mold can be greatly increased, which also makes it possible to reduce the product cost.

Further, depending on the properties of the foamed resin, preheating or heating may be required during molding, but since each part of the mold is thin, the heat capacity is small, the heating time is short, and there is no wastage of energy.

In summary, it can be said that the present invention improves the quality of foamed resin heat insulating covers and makes it possible to significantly reduce the cost, making an extremely large contribution to the stable supply of energy in Japan during the oil crisis. .

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a piping insulation method, where A is a sectional view, B is a front view, and Figure 2 is a perspective view showing a mold used to mold a heat insulating cover made of foamable urethane resin. Figures 3 and 3 show improved molds used in the past, where A is a plan view, B is a sectional view, and Figure 4 is a molding used in the method of molding a foamed resin heat insulating cover according to the present invention. In the drawings showing the mold, A is a plan view, B is a sectional view, FIG. 5 is a perspective view illustrating the product dimensions of the heat insulating cover, FIG. -E are explanatory diagrams showing the process order of the method for molding a foamed resin heat insulating cover according to the present invention. 1...Piping, 2...Insulation cover, 3...Meji,
11... Molding die, 12... Female die, 13... Male die, 14... End plate, 21... Molding die, 22... Upper end plate, 23... Lower end plate, 24... Outer plate, 25...
... Inner plate, 26 ... Tightening band, 27 ... Flange plate, 28 ... Supporting jig, 31 ... Molding mold, 32 ... Upper flange, 32A ... Resin injection hole, 33 ... Lower flange, 34 ... ...Outer cylinder, 34
A...Tightening flange, 35...Inner cylinder, 36...
...Mounting tool, 37...Release paper or mold release agent.

Claims (1)

[Scope of Claims] 1. A ring-shaped lower flange having an outer diameter that is approximately the same as the outer diameter of a cylindrical heat-insulating cover product and an inner diameter that is smaller than the inner diameter of the heat-insulating cover product by a predetermined dimension, and the lower flange an upper flange having the same shape as that and having a hole for resin injection, and a cylinder having an inner diameter that is approximately the same as the outer diameter of the upper and lower flanges, and which is divided into two by a plane containing the axis thereof. The two halves include a pair of outer cylinders each having a tightening flange, a cylindrical inner cylinder having an outer diameter that is approximately the same as the inner diameter of the upper and lower flanges, and a pair of outer cylinders that are provided with a tightening flange. Using a mold consisting of a fitting that is attached to one side of the inner cylinder and removably attached to the other side,
A method for molding a cylindrical foamed resin heat insulating cover according to the process steps shown in the following (a) to (g). (a) Apply a mold release agent or wrap release paper around the outer circumference of the inner cylinder. (b) Attach the lower flange and upper flange to the inner cylinder using fittings. (c) Attach the outer cylinder to the outer periphery of the upper and lower flanges. Install, insert bolts, etc. into the tightening flange and tighten. (d) Inject foamed resin through the resin injection hole in the upper flange. (e) After the specified foaming and curing period, disassemble the mold and start molding. Take out the product (f) Cut it into two or three or more parts using a saw, etc. (g) Process the inner diameter using a rotary knife, etc. so that it matches the inner diameter of the product.