JP2928045B2 - Method of forming lining layer of lining pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump in which the inner wall of a pump casing is lined with a fluorine resin and a method for forming a lining layer thereof.

[0002]

2. Description of the Related Art Pumps used for treating waste liquids in factories and for pumping fluids in various chemical plants and the like are provided with a lining treatment so as to prevent corrosion of internal flow passages and to be applicable to fluids from low to high temperatures. What was given is used. This lining treatment is performed by injecting a fluororesin into the pump casing after casting and processing by, for example, a transfer molding method, and cooling it while pressurizing.

FIG. 3 is a longitudinal sectional view showing a general example in which a lining layer is formed on a spiral type pump casing.

[0004] Casing 1 manufactured by casting and processing
Has a spiral chamber 1a for accommodating an impeller (not shown), has an inlet 1b coaxially with the spiral chamber 1a, and has an outlet 1c open on the peripheral surface. The inlet 1a forms a flange 1d therearound and is connected to an upstream pipe (not shown).

[0005] Outlet 1 from the center of the flange 1d
A lining layer 2 made of a fluororesin is integrally joined to the entire surface facing the flow path up to c by the transfer molding method described above.

Here, when the fluid passes through the inside of the casing 1, the flow velocity in the inlet 1b sucked by the impeller is large, and the internal flow passage is likely to be negative pressure. For this reason, if the lining layer 2 is not firmly joined to the casing 1, the lining layer 2 peels off from the inner wall of the casing 1 or generates chattering vibration and the like every time a fluid passes.

In order to avoid such a phenomenon, dovetail grooves 1e, 1e are formed in the inner peripheral surface of the inlet 1b and the spiral chamber 1a, respectively.
1f is formed, and the injected fluororesin is
The lining layer 2 is formed so as to form the ants 2a and 2b that fit into e and 1f.

The dovetail grooves 1e, 1f and the dovetails 2a,
2b, the casing 1 of the lining layer 2
The restraint on the side is strengthened, and the separation or the like is prevented.

[0009]

However, the lining layer 2 formed by injecting a fluororesin heated to a melting point or higher and cooling it while pressurizing it and cooling it to room temperature has the resin. Attempts to shrink at the rate of expansion.

[0010] Such shrinkage deformation is in the range i.e. inlet 1b portion A in FIG tends to shrink toward the center contact and the axial direction. For this reason, stress tends to concentrate on the dovetail portion 2a restrained by the dovetail groove 1e. Further, in the portion hanging on the flange 1d, the flange 1d tries to contract in the axial direction of the inlet 1b,
The stress is concentrated on a portion corresponding to a corner portion where the and the inlet 1b intersect.

Since the fluororesin tends to shrink after molding as described above, the use temperature is reduced to the molding completion temperature (15 to 30).
When the lining pump is used in a temperature range lower than (° C.), the concentration of stress increases. In particular, when the fluid further flows at a high speed in the inlet 1b and a negative pressure is generated in the internal flow path, the lining layer 2 is pulled toward the center of the flow path, and a crack is formed in a portion where stress is concentrated. Occur. For this reason, the lining layer 2 is partially damaged, and the internal corrosion of the casing 1 proceeds from this portion.

As described above, in the case of the pump casing, there is a high possibility that the lining layer on the inlet side may be peeled or damaged due to the heat shrinkage of the fluororesin.

The problem to be solved in the present invention is to improve the durability of the pump casing of the lining pump, in particular, by preventing the coating from being damaged by the shrinkage deformation of the lining layer at the inlet.

[0014]

SUMMARY OF THE INVENTION The present invention relates to a lining pump for forming a synthetic resin lining layer through a dovetail groove on an inner peripheral wall of a casing which forms an internal flow path from an inlet to a outlet via a spiral chamber. Wherein the inner peripheral wall of the inlet is not restricted without forming a dovetail groove, and the inner peripheral wall of the casing is formed of the synthetic resin lining layer.

Further, when the internal flow path is covered with a lining layer of a synthetic resin for a casing having an internal flow path from the inlet to the outlet via the spiral chamber, the end face of the flange at the open end of the inlet. in, covered with a spacer having a thickness corresponding to the residual shrinkage due to a difference in expansion coefficient between the casing and the synthetic resin have a shape along the open end, outside the spacer
A molten synthetic resin is injected along the surface and the inner peripheral wall of the casing, and cooled and solidified to a temperature below the melting point of the synthetic resin, and then the spacer is removed.

[0016]

[Action] In the inlet where the flow velocity is large,
The lining layer is only joined to the inner wall of the casing, and if this joining degree is appropriate, there is no stress concentration due to the generation of negative pressure, and the lining layer will not be constrained by the dovetail and the dovetail groove. The occurrence of peeling and damage is prevented.

Further, if the residual shrinkage ratio of the molten synthetic resin is previously absorbed by the spacer, the residual shrinkage force in the axial direction of the inlet after cooling and solidification can be eliminated, and the corner portion at the boundary between the flange and the inlet can be eliminated. Cracks and damage can be prevented from occurring.

[0018]

FIG. 1 is a longitudinal sectional view of a main part showing a casing of a pump manufactured by a method for forming a lining layer according to the present invention. The illustrated example is the same as the casing described in the related art, and the same members are designated by the same reference numerals, and detailed description thereof will be omitted.

The lining layer 2 is integrally joined from the inlet 1b including the flange 1d of the casing 1 to the spiral chamber 1a and the outlet 1c. The lining layer 2 is made of a fluororesin, for example, a PFA resin heated to a melting point or higher, as in the case of the prior art.
Into the creation space between the inner mold and
It is formed by cooling under normal temperature (about 20 ° C.) while pressurizing.

The dovetail groove 1f is formed in the casing 1 so as to run annularly only in a region facing the spiral chamber 1a, and the inner peripheral wall of the inlet 1b has a uniform opening cross section. Therefore, it differs from the conventional example in that a dovetail groove is not formed in the inlet 1b portion.
Has an outer shape without ants in the portion corresponding to.

FIG. 2 is a longitudinal sectional view of a main part showing a step of forming the lining layer 2.

The mold 3 is inserted into the inlet 1b, and a space for injecting PFA resin is formed between the outer peripheral surface of the mold 3 and the inner peripheral surface of the inlet 1b. It goes without saying that this injection space communicates from the spiral chamber 1a toward the outlet 1c.

The mold 3 communicates with a pot (not shown) in which the PFA resin is heated and melted, and the PFA resin is supplied to the mold 3 and the casing from the lower gate portion by a piston provided in the pot. Inject between 1.

When joining the casing 1 to the mold 3, an annular spacer 4 is set on the outer surface of the flange 1d as shown in FIG. The spacer 4 is made of metal, for example, and is placed on the outer surface of the flange 1d and on the side near the opening of the inlet 1b.

On the other hand, the PFA resin in the pot is in a molten state heated to about 350 ° C., and is cooled at room temperature (about 20 ° C.) after being poured into the casing 1. Before the injection of the PFA resin, the casing 1 has been heated and expanded in advance, but contracts by cooling and returns to its original state. After the injection of the PFA resin, the P
The FA resin shrinks with cooling. During expansion and contraction in the above temperature range, the contraction of the PFA resin has a residual contraction rate of about 3% due to a difference from the linear expansion coefficient of the material of the casing 1.

Therefore, the spacer 4 to be set at the time of molding is used.
Is equivalent to the magnitude of the residual shrinkage. After cooling to at least a temperature below the melting point at which the molten PFA resin solidifies after the injection, the spacer 4 is removed. The procedure for removing the spacer 4 is such that the spacer 4 can be partially divided in the radial direction, so that the spacer 4 may be separated and separated in the left and right directions in FIG. Also, from the viewpoint of the workability of removing the spacer 4,
It is preferable to remove the PFA resin when it is cooled to room temperature (about 20 ° C.).

As described above, after removing the spacer 4 having a thickness corresponding to the residual shrinkage based on the difference in linear expansion coefficient from the casing 1, the lining layer 2 shrinks and the gap remaining after the spacer 4 disappears. Shrink and deform in the direction of As a result, as shown in FIG. 1, a molded product in which the lining layer 2 is in close contact with the end surface of the flange 1d is obtained, and the lining layer 2 itself has no internal residual stress and can be reduced to zero.

Therefore, the lining layer 2 is
Even in the portion where the stress is likely to concentrate on the corner portion at the boundary between d and the inlet 1b, since there is no shrinkage in the axial direction after molding, the occurrence of cracks and the like can be prevented.

Further, the outer peripheral surface of the lining layer 2 at the portion located inside the inlet 1b of the casing 1 is merely joined following the inner wall of the inlet 1b, and the engagement between the ants and the dovetails as in the conventional example is performed. No relationship. For this reason, even when the internal flow path has a negative pressure due to the high-speed flow of the fluid, there is no local concentration of stress, and peeling and cracking are prevented.

Since there is no joining relationship between the ants and the dovetail groove, it is effective to increase the thickness of the lining layer 2 to some extent in order to prevent the internal flow path from being deformed in the peeling direction due to the generation of negative pressure. It is. In this case, the amount of the PFA resin increases, but from the viewpoint of the structure of the mold for forming the dovetail groove in the casing 1, it is advantageous in terms of cost.

[0031]

According to the lining pump of the present invention, the stress is not concentrated even if the shrinkage in the radial direction occurs on the lining layer at the inlet portion of the casing where the flow velocity is large and negative pressure is likely to occur, so that the lining layer is not damaged. Can be prevented, and internal corrosion of the casing can be prevented.

When the lining layer is formed, a spacer is arranged around the flange of the inlet, and after the molten synthetic resin is cooled and solidified, the spacer is removed, thereby eliminating the residual shrinkage force of the lining layer in the axial direction of the inlet. it can. For this reason, the concentration of stress is also eliminated in the direction of the inlet axis, and the lining layer can be prevented from being damaged.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a lining pump of the present invention.

FIG. 2 is an enlarged vertical sectional view of a main part showing the incorporation of a spacer to be set when a molten fluororesin is injected.

FIG. 3 is a longitudinal sectional view showing a main part of a conventional lining pump.

[Explanation of symbols]

 Reference Signs List 1 casing 1a spiral chamber 1b inlet 1c outlet 1d flange 1f dovetail groove 2 lining layer 2b dovetail 3 mold 4 spacer

Continued on the front page (72) Inventor Katsuaki Nakagawa 59-46 Nakahara, Toba-ku, Kitakyushu-city, Fukuoka Prefecture Inside Nippon Steel Plant Design Co., Ltd. Nippon Steel Plant Design Co., Ltd. (72) Inventor Hideki Tanaka 232-1, Tanasawa, Atsugi-shi, Kanagawa Japan Nippon Balcar Industries Co., Ltd. (56) References JP-A-60-184482 (JP, U) JP 5-45798 (JP, B2) JP-A 61-11609 (JP, Y2) Patent 2518367 (JP, B2) (58) Field surveyed (Int.Cl. ⁶ , DB name) F04D 29/40-29/56 F04D 29/58-29/70 B29L 31:00 B29D 31/00

Claims (2)

(57) [Claims] 1. A method of forming a lining layer of a lining pump for forming a lining layer of a synthetic resin through an dovetail groove on an inner peripheral wall of a casing forming an internal flow path from an inlet to a outlet via a spiral chamber. A method of forming a lining layer of a lining pump, wherein an inner peripheral wall of the inlet is not formed without forming a dovetail groove and an inner peripheral wall of the casing is formed of a lining layer of the synthetic resin. 2. An end face of a flange at an opening end of the inlet when the internal flow path is covered with a lining layer of a synthetic resin for a casing having an internal flow path from an inlet to an outlet via a spiral chamber. in, covered with a spacer having a thickness corresponding to the residual shrinkage due to a difference in expansion coefficient between the casing and the synthetic resin have a shape along the open end, an outer surface of the spacer
And a method of forming a lining layer of a lining pump for injecting a molten synthetic resin along an inner peripheral wall of the casing , cooling and solidifying the synthetic resin below a melting point of the synthetic resin, and then removing the spacer.