JPH06299990A - Method for forming lining pump - Google Patents

Abstract

PURPOSE:To prevent the damage of a lining layer for covering the bent part of a casing, and improve the durability of a pump casing by designing the sectional shape of the lining layer at the part along the arc-shaped surface so that the thickness of the lining layer may be uniform or gradually increased between the layers on the upstream side and on the downstream side when viewed from the direction of the flow of the molten synthetic resin. CONSTITUTION:A lining layer 2 is formed by pouring the molten fluororesin into the space between a casing 1 and an inner mold to execute the pressurization and cooling. The molten fluororesin flows in a gradually bending manner along the arc-shaped surface 1c when being bent to the side of a generating surface 1b, and no disturbance of the flow caused by the generated eddy or the like is executed. Thus, no rough surface of the lining layer 2 forming the flow wall is obtained after cooling and solidification, and similarly excellent surface to be connected to the casing 1 side is obtained. The stress concentration at the part where the lining layer 2 is bent is prevented, and at the same time, the damage of the lining layer 2 or the separation from the casing 1 is prevented even when the negative pressure is generated in the flow passage.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Pumps used for waste liquid treatment in factories and for pressure-feeding of fluids in various chemical plants, etc. are lined so as to prevent corrosion of internal flow passages and to be applicable to fluids in a low temperature range to a high temperature range. The given one is used. This lining process 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 applying pressure.

FIG. 4 is a vertical sectional view showing a general example in which a lining layer is formed on a spiral pump casing.

Casing 1 produced by casting and processing
Is a member that forms a spiral chamber inside when the shaft of an impeller (not shown) penetrates and is connected to a mating casing (not shown).

A cylindrical shaft hole 1a through which the shaft of the impeller penetrates is provided in the center of the casing 1, and a lining layer 2 made of fluororesin is formed from the shaft hole 1a to the lower surface side. In the drawing, the lower surface side of the casing 1 becomes the surface facing the spiral chamber, and the lining layer 2 creates the inner wall of the flow path.

The method for forming the lining layer 2 is as follows. The inner mold 3 housed in the casing 1 is fixed by a jig to form an injection space between the casing 1 and the inner mold 3. The fluororesin heated to the above is injected under pressure, and is cooled and solidified under pressure. And
The open end of the injection space at the upper end of the shaft hole 1a is used as a gate, and the outlet of the pot in which the molten fluororesin is heated and sealed is connected to this gate to inject the molten fluororesin in the direction of the arrow in the figure.

[0007]

However, the boundary portion between the lower end of the shaft hole 1a and the creation surface 1b of the spiral chamber extending in the radial direction is bent at a substantially right angle, and as shown in FIG. Has been formed. On the other hand, the inner mold 3 is also the lining layer 2
In order to make the wall thickness uniform, the outer shape is in line with the shape of the generating surface 1b from the shaft hole 1a.

With such an injection space between the inner wall of the casing 1 and the inner mold 3, the flow channel cross-sectional area of the molten fluororesin of A in the figure increases to the flow channel cross-sectional area of B. That is, when the molten fluororesin flows from the shaft hole 1a to the generating surface 1b side, the cross-sectional area of the flow path becomes large at a stretch, causing turbulence such as vortex in the flow.

Further, when the molten fluororesin flows to the generation surface 1b side, the portion C in the figure is filled with the molten fluororesin in advance, and the inner wall side of the casing 1 becomes a flow later than this, and vortices are generated. Promote.

As described above, when the injection flow path is linearly bent, the flow of the molten fluororesin is modulated, and the joint surface with the casing 1 also has a rough surface on the surface of the lining layer 2 after release. Will result. Therefore, the stress is likely to be concentrated on the curved portion itself of the lining layer 2, and the stress is also concentrated due to the rough skin. Therefore,
Repeated fluctuations in the temperature and pressure of the passing fluid increase the risk of cracks, and internal corrosion of the casing 1 progresses from this portion.

Further, the surface roughness of the lining layer 2 on the surface facing the casing 1 weakens the degree of joining with the casing 1. For example, if the internal flow path is liable to be a negative pressure, the lining layer 2 may be used. There is also the problem of peeling of 2.

The problem to be solved in the present invention is to prevent the lining layer covering the bent portion of the casing from being damaged and improving the durability of the pump casing in the lining pump.

[0013]

SUMMARY OF THE INVENTION The present invention is a method for forming a lining pump in which a synthetic resin lining layer is integrally joined to a pump casing by means of die making, wherein the direction of injection flow of molten synthetic resin at the time of making the die. In view of the outer shape of the portion that bends inward or outward of the pump casing as an arc surface, the lining layer of the portion along the arc surface,
It is characterized in that it has a cross-sectional shape in which the thickness increases uniformly or gently between the upstream and downstream layers as seen in the flow direction of the molten synthetic resin.

[0014]

[Function] By making the profile of the curved portion of the casing into an arc surface, the molten synthetic resin injected along this portion can be made into a laminar flow, and a flow without separation of flow from the casing surface or generation of vortices can be obtained. To be Further, since the lining layer formed on the arc surface is formed so as to have a cross-sectional shape that increases uniformly or gently with the upstream and downstream layers in the flow direction of the molten synthetic resin, the molten synthetic resin is injected. At this time, it is possible to suppress the turbulence of the flow when passing through the arc surface.

In this way, even if the lining layer to be molded has a bend in the direction of injection flow of the molten synthetic resin, a lining layer is obtained by die production that does not disturb the flow of the molten synthetic resin, and the surface is not roughened. Is possible.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a vertical cross-sectional view of a main part showing a casing structure of a lining pump of the present invention. Note that the illustrated example is the same type as the casing described in the related art, and the same members are designated by common reference numerals, and detailed description thereof will be omitted.

The bent portion of the casing 1 from the shaft hole 1a to the generating surface 1b forms a gentle arcuate surface 1c, and the lining layer 2 is also formed with a substantially uniform thickness along the arcuate surface 1c. There is. It is needless to say that in order to form the lining layer 2 having such a cross-sectional shape, the corresponding portion of the inner mold 3 described in the section of the prior art may be formed into an arc surface shape.

The molding of the lining layer 2 is performed by supplying molten fluororesin to the injection space between the casing 1 and the inner mold and pressurizing and cooling it, as in the conventional example. At this time, the molten fluororesin is injected from a gate communicating with a pot (not shown) on the upper end side of the shaft hole 1a.
Flow toward the generating surface 1b via the arc surface 1c.

When the molten fluororesin bends toward the generating surface 1b, it flows while gently bending along the arcuate surface 1c. Therefore, compared with the curved flow path shape as in the conventional example, the flow due to the generation of vortices or the like occurs. There is no disturbance. Therefore, after cooling and solidification, the surface of the lining layer 2 forming the flow path wall is not roughened, and the surface joined to the casing 1 side also has a good surface. Therefore, the concentration of stress in the bent portion of the lining layer 2 is prevented, and at the same time, the degree of bonding to the casing 1 is maintained high, and even if a negative pressure in the flow channel occurs, the lining layer 2 may be damaged or the casing 1 may be damaged. Peeling is prevented.

FIG. 2 is a graph showing an example of an optimum arc-shaped profile from the shaft hole 1a of the casing 1 to the generating surface 1b, which is shown in comparison with the conventional structure.

In this diagram, the horizontal axis shows the distance in the axial direction of the axial hole 1a, and the vertical axis shows the flow channel cross-sectional area (unit: mm ² ) of the molten fluororesin.

The profile Q of the arc surface shown by the broken line is an example of the conventional structure, and the profile P shown by the solid line is the case of the present invention. As can be seen from the figure, the profile P is obtained by cutting the meat from the point R to the point S with respect to the conventional profile Q. Then, when the coordinate of the point R is set to 0 with reference to the position of the axial hole 1a in the axial direction of the point R, the distance to the point S is as shown on the horizontal axis ( unit of numerical value on the horizontal axis: mm). FIG. 3 is a diagram illustrating the positional relationship between the casing 1 having the profile P and the inner mold 3.

The outer shape of the inner mold 3 corresponding to the profile P from the point R to the point immediately before the point S is a straight line profile 3a parallel to the axis of the shaft hole 1a. The inclination profile 3b is directed toward the creation surface 1b. Such a profile P and a linear profile 3a
In the case of the above relationship, the flow passage cross section simply expands in accordance with the amount of the profile P moving away from the inner mold 3 in the flow direction of the fluororesin (indicated by an arrow in the drawing). The expansion is based on the rate of change of the flow passage cross-sectional area in the axial direction of the shaft hole 1a shown in FIG. 2, and the flow passage cross-sectional area may not be enlarged at a certain boundary point. Instead, it changes slowly and continuously.

Since the flow passage cross-sectional area at the bent portion gradually increases in this way, the flow of the molten fluororesin is not disturbed and the lining layer 2 is free from peeling and surface roughening, as in the example of FIG. Can be obtained.

[0025]

In the lining pump of the present invention, the cross-sectional area of the flow channel cut in the plane orthogonal to the flow is made from the injection side to the downstream side with respect to the portion where the flow channel in the injection flow direction of the molten resin is bent at a substantially right angle. It changes gradually and continuously. For this reason,
The molten resin can be caused to flow as a laminar flow, and the occurrence of roughening of the surface skin after solidification can be suppressed, as compared with the conventional one in which the flow path cross-sectional area expands at a stretch. Therefore, it is possible to prevent the lining layer from being damaged or peeled by preventing the concentration of stress and ensuring the degree of bonding to the casing side.
The durability is improved.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a profile of an arc surface of a casing (change in flow passage cross-sectional area) together with a conventional example.

FIG. 3 is a diagram for explaining the positional relationship between the profile of FIG. 2 and an inner mold and changes in the flow passage cross-sectional area.

FIG. 4 is a vertical sectional view showing a main part of a conventional lining pump.

5 is an enlarged cross-sectional view showing a change in flow path area at a bent portion in the example of FIG.

[Explanation of symbols]

 1 Casing 1a Shaft hole 1b Creation surface 1c Arc surface 2 Lining layer 3 Inner mold 3a Straight line profile 3b Inclination profile

Front Page Continuation (72) Inventor Katsuaki Nakagawa 59 Nippon Steel Plant Design Co., Ltd., 46 Nakahara, Tobata-ku, Kitakyushu, Fukuoka Prefecture (72) Inventor Hideki Tanaka 1 232, Tanasawa, Atsugi-shi, Kanagawa Japan Barker Industrial Co., Ltd. In-house (72) Inventor Yoshiyuki Imanishi 2-24, Yamaguchi-cho, Nishinomiya-shi, Hyogo Matsuda Pump Mfg. Co., Ltd. (72) Inventor Masataka Harada 1-1 No. 1 Tobata-ku, Kitakyushu, Fukuoka Prefecture New Japan Steelworks Yawata Works

Claims (1)

[Claims] 1. A method for forming a lining pump in which a synthetic resin lining layer is integrally joined to a pump casing by die manufacturing, wherein the inside of the pump casing or the inside of the pump casing is seen when viewed in the injection flow direction of the molten synthetic resin at the time of die manufacturing. The outer shape of the portion that bends to the outside is an arc surface, and the lining layer of the portion along the arc surface has a uniform thickness between the upstream and downstream layers as viewed in the flow direction of the molten synthetic resin, or A method of forming a lining pump having a gently increasing cross-sectional shape.