JPS6224252B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a sleeve or the like used in a pipe joint such as a dresser type joint by processing a thermoplastic resin pipe.

(Prior Art) As shown in Fig. 5, a dresser type joint consists of a sleeve a whose diameter is reduced at both ends to form a packing receiving part, a flange b located at both ends of the sleeve a, and a flange b. It consists of a bolt and nut (c) to be fastened, and is often made of cast iron, but recently some sleeves (a) are made of synthetic resin such as hard vinyl chloride. still,
d and d are packing, and c and c are pipes. A dressage joint is used as a method of connecting two pipes, as shown in Figure 5, but during its use, unexpected external stress may be applied to the pipe due to uneven ground subsidence, etc. Even if the sleeve a
Since there is a space between the pipe e and the seal, external stress applied to the pipe can be absorbed by deformation and bending of the pipe in the space inside the joint, preventing damage to the pipe. It has a function.

(Problem to be Solved by the Invention) This synthetic resin sleeve is manufactured by using a thermoplastic resin short tube that matches the diameter of the sleeve, heating and softening both ends of the tube, and inserting it into a female mold to reduce the diameter. was. However, as the variety of products has increased, none of the thermoplastic resin pipes that have been manufactured in the past are suitable for the diameter of the sleeve, and a separate thermoplastic resin pipe must be manufactured just for this purpose. However, manufacturing thermoplastic resin pipes is not economical because it requires a great deal of labor and expense due to mold manufacturing and other reasons.

In view of the above points, this invention does not require the separate molding of a thermoplastic resin tube that matches the diameter of the sleeve.
This was completed as a result of various studies with the aim of processing and manufacturing a sleeve from a thermoplastic resin tube with a larger diameter than the sleeve.

(Means for Solving the Problems) The gist of the present invention is to heat and soften one half of a thermoplastic resin pipe, and to transform the heat-softened portion into at least two stages of diameter-reducing slopes having a diameter-reducing holding portion 12 in the middle. Part 11,
13 and a receiving part 14 for receiving the end of the tube in the inner part of the diameter-reducing inclined part 13. By press-fitting the heated softened part of the tube into a female mold, the diameter of the heated softened part is reduced along the diameter part of the female mold. After that, the tube is cooled and solidified and removed from the female mold, and then the other half of the tube that has not been reduced in diameter is heated and softened, and the heated and softened portion is molded into a structure that is the same as or similar to the female mold. A method for processing a thermoplastic resin tube, characterized in that the tube is press-fitted into a female mold and the diameter is reduced in the same manner as in the above step.

(Example) Next, the method of this invention will be explained with reference to the example of the drawings.

Reference numeral 1 designates a female mold, the inner diameter of which is comprised of a diameter-reducing inclined part 11 that reduces in diameter toward the back, a diameter-reducing holding part 12 following this, and a second diameter-reducing inclined part 13 at the back of this diameter-reducing holding part 12.
Further, a receiving portion 14 is formed at the back of this second diameter-reducing inclined portion 13. This receiving part 14
The tip of the thermoplastic resin tube A that is press-fitted into the female mold 1 comes into contact with the female mold 1, compressing the tube A in its axial direction and increasing the thickness of the tube wall. Diameter reduction holding part 1
2. The dimensions, shape, etc. of the second diameter-reducing inclined portion 13 are appropriately determined depending on the purpose, etc., and another diameter-reducing inclined portion may be provided at the tip of the second diameter-reducing inclined portion 13.

2 is an adapter used auxiliary to the female mold 1, and is a short tube of a predetermined length whose inner diameter is the same as that of the female mold 1.
The inner diameter of the open end is equal to or slightly larger than the inner diameter of the open end. Reference numeral 3 denotes a press-fitting plate for press-fitting the resin pipe A into the female mold 1. This press-fitting plate 3 is connected to a press machine (not shown), and its operation causes the press-fitting plate 3 to reciprocate and press the resin pipe A into its shape. It is designed to be pressed in the axial direction. The resin pipe A is a short pipe having an outer diameter slightly smaller than the inner diameter of the open end of the female mold 1, and its length is slightly longer than the sum of the length of the insertion part of the female mold 1 and the length of the adapter 2. Heat and soften one half.
The length that is heated and softened is the length that the resin pipe A of the diameter-reducing inclined portion 11 in the female mold 1 is guided by contacting with it,
The length corresponds to the sum of the length of the diameter-reducing holding part and the length of the second diameter-reducing inclined part, or the length is slightly longer than this length.

The heat-softened portion of the resin pipe A is inserted into the female mold 1 and pressed with the press-fitting plate 3. At this time, it is desirable that the female mold 1 be preheated. This preheating temperature is, for example, about the temperature at which the resin pipe A is heated and softened. In this way, the tip of the heat-softened portion of the resin tube A is guided to the diameter-reducing inclined portion 11 of the female mold 1, and its diameter is reduced along the diameter-reducing holding portion 12 and the diameter-reducing inclined portion 13, and its wall thickness is The leading edge of the resin tube A 1 hits the receiving portion 14 and is pressed in the axial direction of the resin tube A by the press-fitting plate 3, so that a thickened resin tube A ₁ is formed. In this state, the resin pipe _A1 is cooled. The degree of thickness increase is determined by the relationship between the length of the resin tube A before processing, the length of the tube insertion part of the female mold 1, and the length of the adapter 2, so each relationship depends on the product to be processed. may be determined.

After cooling the resin pipe A ₁ , the press-fitting plate 3 is moved back and the resin pipe A ₁ is removed from the female mold 1 . At this stage, the resin pipe _A1 is in a semi-finished state as shown in FIG.

Next, the other half portion A _{1 ′} of this resin pipe A ₁ that was not heated and softened in the processing step and the portion A ₁ ″ in contact with the diameter-reducing inclined portion 11 of the female mold 1 are heated and softened, and this portion is Insert into female mold 1 (see Figure 3).
This process is almost the same as the diameter reduction process described above, but
It is preferable to use an adapter 4 different from the adapter 2 used in that case. This adapter 4 is for regulating the length of the final processed product.
It also has a cylindrical part 41 that is inserted into the open end of the female mold 1, and this part has an inner diameter that is equal to that of the female mold 1.
The portion _A1 , which has been made approximately equal to the inner diameter of the diameter-reduced holding portion 12, and which has been reduced in diameter in the above step, is held to prevent deformation or the like. After insertion, press with press-fit plate 3 and cool, then female mold 1
Remove from. Products obtained in this way
A ₂ is as shown in Fig. 4. Both ends thereof have sloped parts A ₂ ′ that are inclined toward the inside of the tube, and the central part
A ₂ ″ is smaller in diameter than the original resin pipe A and has the desired diameter, and is suitable for applications such as sleeve A used in dresser joint type pipe fittings as shown in Figure 5. It is suitably used for.

Modifications of the female mold 1 include those shown in FIGS. 6A and 6B, and the shapes processed by these female molds are shown in FIGS. 7A and 7B.

However, it is more convenient to have a dogleg-shaped cross section than a square-shaped sleeve end shape because it presses into contact with the sealing packing tube and further enhances the sealing effect.

Of course, it is also possible to use different female dies in the first diameter reduction step and the second diameter reduction step, and in this way, sleeves with different diameters as shown in FIG. 8, for example, are processed.

(Effects of the Invention) As described above, the method of this invention involves press-fitting one half of a thermoplastic resin pipe into a female mold to reduce its diameter to two or more stages, and then similarly reducing the diameter of the other half to two or more stages. Therefore, even if the diameter of the thermoplastic resin pipe used as the raw material pipe is large and the desired product cannot be obtained by just pipe end processing, it is possible to obtain a processed product with the desired dimensions from the pipe. This eliminates the need to separately extrude and mold a thermoplastic resin tube with a diameter that matches the main part of the final product as in the past.

In addition, during the diameter reduction process, the thermoplastic resin tube is press-fitted into the female mold and the end of the thermoplastic resin tube comes into contact with the receiving part, so the tube wall is thickened and reinforced, and the length of the thermoplastic resin tube is determined in advance. If this is done, a product with a desired wall thickness and sufficient strength can be obtained.

[Brief explanation of the drawing]

1 to 3 are partial cross-sectional front views showing embodiments of the method of the present invention in the order of their steps, and FIG. 4 is a partial sectional front view of a product obtained by the embodiment shown in FIGS. 1 to 3. Figures 5 and 5 are usage patterns of the product shown in Figure 4, Figures 6A and 6B are cross-sectional front views of other embodiments of the female mold used in this invention, and Figures 7A and 7B are respectively FIG. 6 is a partially sectional front view of a product processed by the female molds shown in A and B, and FIG. 8 is a partially sectional front view of another product obtained by the method of the present invention. DESCRIPTION OF SYMBOLS 1... Female mold, 11... Diameter reducing inclined part, 12... Diameter reducing holding part, 13... Second diameter reducing inclined part, 14...
Receiving part, 2, 4...adapter, A...thermoplastic resin pipe.

Claims (1)

[Claims] 1 One half of the thermoplastic resin pipe is heated and softened, and the heated and softened part is attached to at least two stages of diameter-reducing inclined parts 11 and 13 having a diameter-reducing holding part 12 in the middle, and to the inner part of the diameter-reducing inclined part 13. By press-fitting the pipe into a female mold having a receiving part 14 for receiving the end of the pipe, the heated softened part of the pipe is reduced in diameter along the reduced diameter part of the female mold, and then the pipe is cooled and solidified to form the female mold. Cut out from the mold, then heat soften the other half of the tube that has not been subjected to the shrinkage process, and press fit the heated softened part into a female mold having the same or similar structure as the female mold, similar to the above process. A method for processing a thermoplastic resin pipe, which is characterized by reducing the diameter to .