JP2021021416A - Piping and its manufacturing method - Google Patents

Abstract

To provide piping which can suppress the generation of a swirl flow of fluid such as oil, and its manufacturing method.SOLUTION: In piping 1 in which a fluid-passage space 2 is formed, at least one salient part 4 salient toward the space 2 from the piping 1, and suppressing a flow of fluid which swirls in the space 2 is formed at an inner wall face 1a of the piping 1 in a cross section view of the piping 1, and the salient part 4 is formed at least at a part of the piping 1 with respect to a passing direction of the fluid.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to piping and a method for manufacturing the same.

A technique has been proposed in which oil is circulated in a power unit to lubricate or cool each part of the power unit (see, for example, Patent Document 1).

JP-A-2010-255516

By the way, even in an engine (internal combustion engine) which is an example of a power unit, oil (fluid) is circulated in each part thereof, but a swirling flow of oil may occur in a pipe constituting an oil flow path. When a swirling flow of oil is generated, the discharge amount of the oil pump arranged in the oil flow path is reduced due to the pressure loss of the oil accompanying the generation. Therefore, it is important to suppress the generation of swirling oil flow.

An object of the present disclosure is to provide a pipe capable of suppressing the generation of a swirling flow of a fluid such as oil and a method for manufacturing the same.

The pipe of the aspect of the present invention for achieving the above object is a pipe in which a space for passing a fluid is formed inside, and the space is projected from the pipe toward the space in a cross-sectional view of the pipe. At least one protrusion for suppressing the flow of the fluid swirling around the pipe is formed on the inner wall surface of the pipe, and the protrusion is formed on at least a part of the pipe with respect to the passage direction of the fluid.

According to the present disclosure, it is possible to suppress the generation of a swirling flow of a fluid such as oil.

It is a figure which illustrates the structure of the inner wall surface of the pipe of embodiment of this invention in a plan view. It is a figure which illustrates the shape of the inner wall surface of the pipe of FIG. 1 in A cross-sectional view. It is a figure which illustrates the process flow of the manufacturing method of the pipe of this embodiment. It is a figure which illustrates the positional relationship of the mold for a core at the time of manufacturing a core in a cross-sectional view. It is a figure which illustrates the positional relationship of a mold for piping and a core at the time of manufacturing a pipe in a cross-sectional view.

Hereinafter, the piping and the manufacturing method thereof according to the embodiment of the present disclosure will be described with reference to the drawings. In this embodiment, oil O is exemplified as the fluid, but this is an example. The fluid may be a liquid such as water or a gas such as air.

As illustrated in FIG. 1, the pipe 1 of the present embodiment is a member in which a space 2 for passing oil O is formed inside the inner wall surface 1a thereof. A bent portion 3 is formed in a part of the pipe 1 with respect to the passing direction of the oil O. The bent portion 3 is a portion where the passage direction of the oil O changes before and after the passage direction of the oil O in the plan view of the pipe 1. In other words, the bent portion 3 is a portion where the radius of curvature of the inner wall surface 3a on the inner peripheral side or the inner wall surface 3b on the outer peripheral side thereof in a plan view of the pipe 1 is equal to or greater than a predetermined threshold value preset by an experiment or the like. In the present embodiment, the bent portion 3 is a portion where the radius of curvature R of the inner wall surface 3a on the inner peripheral side thereof is equal to or greater than a predetermined threshold value.

In the pipe 1 of the present embodiment, in the plan view of the pipe 1, a protruding portion 4 is formed on at least a part of the inner wall surface 1a of the pipe 1 with respect to the passage direction of the oil O. As illustrated in FIG. 2, the protruding portion 4 is a convex portion protruding from the inner wall surface 1a of the pipe 1 toward the space 2 in the A cross-sectional view of the pipe 1. The protruding portion 4 suppresses the swirling flow of the oil O (the flow of the oil O swirling in the space 2) when the oil O swirling on the outer peripheral side of the space 2 collides with the A cross-sectional view of the pipe 1. In other words, when the swirling flow of oil O collides with the protrusion 4, the swirling flow of oil O is canceled and the flow of oil O is rectified in the passing direction (extending direction of the pipe 1). At least one (two in this embodiment) projecting portion 4 is integrally formed with the inner wall surface 1a of the pipe 1. Here, "integration" means that the member constituting the protrusion 4 is not installed on the inner wall surface 1a of the pipe 1 afterwards by welding or the like, but the protrusion 4 is formed at the time of manufacturing the pipe 1. Means that is formed. Further, in the present embodiment, the number of the protruding portions 4 is two, but it may be one or three or more. The number of the protruding portions 4 is set by an experiment or the like according to, for example, the length of the stepped portion 7 described later.

As illustrated in FIG. 2, the shape of the inner wall surface 1a of the pipe 1 is such that the upper semicircular shape 5 and the lower semicircular shape 6 are connected by the shape of the step portion 7 in the A cross-sectional view of the pipe 1. It is a shape composed of. In other words, the shape of the inner wall surface 1a is such that the upper half (upper semicircle) 5 of the circular shape is horizontally displaced (offset) by a minute length with respect to the lower half (lower semicircle) 6. The shape is such that adjacent ends of a circle are connected by a step portion 7. The diameter of the upper semicircular shape 5 and the diameter of the lower semicircular shape 6 are substantially the same value. The protruding portion 4 is formed by the step portion 7 and the end portion of either the upper semicircular shape 5 or the lower semicircular shape 6.

The shape of the step portion 7 is a shape extending in the horizontal direction, and is the remaining shape of the inner wall surface 1a excluding the upper semicircular shape 5 and the lower semicircular shape 6. The length of the step portion 7 in the extending direction (horizontal direction, circular radial direction) is such that the step portion 7 has the effect of suppressing the swirling flow of the oil O, and the step portion 7 causes the oil O to pass through. The length is set so that the flow does not become turbulent. This setting is performed by an experiment or the like based on the diameter of the upper semicircular shape 5 (the diameter of the lower semicircular shape 6), the flow velocity and the flow rate of the oil O, and the like. An example of the length of the step portion 7 is 5% to 10% of the diameter of the upper semicircular shape 5.

The diameter of the upper semicircular shape 5 and the diameter of the lower semicircular shape 6 may be different values. The shape of the step portion 7 may be any shape as long as it can suppress the swirling flow of the oil O, and may be an inclined shape without being limited to the horizontal shape in the A cross-sectional view of the pipe 1. The length of the step portion 7 in the A cross-sectional view of the pipe 1 may be the same or different with respect to the passing direction of the oil O. The shape of the inner wall surface 1a may be a shape in which the upper portion of the elliptical shape or the polygonal shape is horizontally displaced with respect to the remaining lower portion by a minute length, and both shapes are connected by the step portion 7.

As the radius of curvature R of the inner wall surface 3a on the inner peripheral side of the bent portion 3 increases, the change in the flow of the oil O increases, and the swirling flow of the oil O tends to occur inside the pipe 1. Therefore, as illustrated in FIG. 1, the inner wall surface 3a on the inner peripheral side of the pipe 1 protrudes to a part downstream from the portion 8 (a part of the bent portion 3) in which the radius of curvature R is equal to or greater than the set threshold value R1. Part 4 is formed. In other words, the protruding portion 4 is formed in a part of the pipe 1 on the downstream side of the oil O passing region 9 corresponding to the portion 8. The oil O passage region 9 is a quadrangular region formed with both ends of the inner wall surface 3b on the outer peripheral side facing the portion 8 and both ends of the portion 8 as vertices. The set threshold value R1 is preset by an experiment or the like as a value at which a swirling flow of oil O may occur in the pipe 1 on the downstream side of the portion 8 when the threshold value is equal to or higher than this threshold value. The protrusion 4 may be formed continuously or intermittently with respect to the passage direction of the oil O. Further, the portion 8 can be said to be a portion in which the bending angle θ of the inner wall surface 3a, which is a parameter corresponding to the radius of curvature R, is equal to or greater than the set angle threshold value θ1.

More specifically, whether or not a swirling flow of oil O is generated inside the pipe 1 depends not only on the radius of curvature R, but also on the viscosity of oil O, the flow velocity of oil O, and upstream or downstream of the bent portion 3. It also depends on the presence or absence of another bent portion (the portion where the pipe 1 is bent) at the position of the pipe 1 on the side. Therefore, when the position where the swirling flow of the oil O is generated is selected based on not only the radius of curvature R but also the viscosity of the oil O, and the protrusion 4 is formed at the position of the inner wall surface 1a of the selected pipe 1. preferable.

The method of manufacturing the pipe of the present embodiment will be described in the form of a process flow with reference to FIG. The process flow of FIG. 3 is performed at the time of manufacturing the pipe 1.

The mold 11 for the core to be used when the core 10 to be described later is manufactured is manufactured in advance. As illustrated in FIG. 4, the mold 11 for the core is two molds having a semicircular shape 12 having the same diameter in cross-sectional view on the wall surface thereof. Regarding the mold 11 for the core, the wall surface on which the semicircular shape 12 is formed has an L-shape having a recess due to the semicircular shape 12 in a plan view.

In addition, a mold 13 for piping used at the time of manufacturing the piping 1 is also manufactured in advance. As illustrated in FIG. 5, the pipe mold 13 is two molds having a semicircular shape 14 having the same diameter in cross-sectional view on the wall surface thereof. The diameter of the semicircular shape 14 is larger than the diameter of the semicircular shape 12 of the mold 11 for the core. Regarding the mold 13 for piping, the wall surface on which the semicircular shape 14 is formed has an L-shape having a recess due to the semicircular shape 14 in a plan view.

When the process flow of FIG. 3 starts, the core 10 is manufactured in step S10 (first process). More specifically, as illustrated in FIG. 4, first, two molds 11 for cores are placed in a horizontal direction with each semicircular shape 12 facing each other, and only a minute length preset by an experiment or the like. Shift and bring them into close contact. Due to this close contact, the space (the space that becomes the core 10 later) whose outer edge is the shape (thick line portion) that becomes the inner wall surface 1a of the pipe 1 in which the protrusion 4 is formed in the cross-sectional view is used for the two cores. It is formed inside the mold 11.

Next, sand is packed in a space having the shape of the inner wall surface 1a as the outer edge thereof, and then the molds 11 for the two cores are heated to solidify the packed sand. The sand that has been solidified becomes the core (sand-shaped core) 10. The core 10 has a shape on the inner wall surface 1a of the pipe 1 on which the protruding portion 4 is formed in a cross-sectional view. The production of the core 10 is completed by cooling the solidified sand by natural cooling or the like (step S10 is completed).

After the completion of step S10, the process proceeds to step S20 (second step). In step S20, as illustrated in FIG. 5, molds 13 for two pipes are arranged and brought into close contact with each other so that one circular shape 15 is formed based on the two semicircular shapes 14. The circular shape 15 is a shape that later becomes the outer wall surface of the pipe 1. In other words, the mold 13 for piping can form a shape to be the outer wall surface of the piping 1 by the wall surface. Then, inside the molds 13 for the two pipes arranged in this way, the core 10 manufactured in step S10 becomes the shape of the core 10 that becomes the inner wall surface 1a of the pipe 1 and the outer wall surface of the pipe 1. It is set so that the circular shape 15 is separated from the circular shape 15 and faces each other. After completing step S20, the process proceeds to step S30.

In step S30 (third step), the molten metal (for example, aluminum) 16 constituting the pipe 1 is poured between the core 10 set in step S20 and the pipe mold 13. After completing step S30, the process proceeds to step S40.

In step S40 (fourth step), the molten metal 16 poured in step S30 is cooled to room temperature by natural cooling or the like. The molten metal 16 is solidified by this cooling, and the molten metal 16 that has been solidified constitutes the pipe 1. After the solidification of the molten metal 16 is completed, the core 10 is collapsed by applying an impact force from the outside to the mold 13 for piping. Step S40 is completed by the solidification of the molten metal 16 is completed and the core 10 is disintegrated. As described above, the production of the pipe 1 is completed, and the main process flow is completed.

Here, in the conventional method for manufacturing the pipe 1, the two molds 11 for the core illustrated in FIG. 4 are formed into one circular shape by these two semicircular shapes 12 in a cross-sectional view. By arranging and bringing them into close contact with each other and heating and cooling the sand packed in the internal space formed by this one circular shape, a circular sand-shaped core was produced in a cross-sectional view. Then, the manufactured core is arranged inside the circular shape 15 of the two pipe molds 13 illustrated in FIG. 5, and the molten metal 16 constituting the pipe 1 is formed between the core and the pipe mold 13. By pouring and cooling the pipe 1, a pipe 1 having a circular inner wall surface 1a in cross-sectional view was manufactured.

That is, the manufacturing method of the pipe 1 of the present embodiment is different from the manufacturing method of the pipe 1 of the prior art, in which the molds 11 for the two cores are mutually viewed in cross section in the manufacturing process of the core 10 (first step). Only a small length was shifted in the horizontal direction to bring them into close contact.

From the above, according to the pipe 1 of the present embodiment, it is possible to suppress the generation of a swirling flow of the fluid by colliding the swirling fluid such as oil with the step portion 7 of the protruding portion 4. Since the pressure loss of the fluid caused by the swirling flow is reduced by suppressing the generation of the swirling flow of the fluid, it is possible to suppress the decrease in the discharge amount of the oil pump arranged in the flow path of the fluid.

By forming a protruding portion 4 on a part of the pipe 1 on the downstream side of the portion 8 whose radius of curvature R is equal to or greater than the set threshold value R1, the swirling flow is suppressed in a place where a swirling flow of fluid is relatively likely to occur. Since the portion is formed, the generation of swirling flow can be suppressed more efficiently.

According to the method for manufacturing the pipe 1 of the present embodiment, the inner wall surface 1a of the pipe 1 having the protruding portion 4 can be formed only by changing the manufacturing process of the core 10, so that the efficiency of the manufacturing work of the pipe 1 can be achieved. Can be suppressed.

Since the core 10 of the present embodiment can be manufactured only by adding the work of shifting the molds 11 for the two cores by a small length in the horizontal direction in a cross-sectional view and bringing them into close contact with each other, it is possible to manufacture the core 10 of the present embodiment. It is easy to maintain efficiency.

Further, when the protruding portion 4 is integrally formed on the inner wall surface 1a of the pipe 1 by using this manufacturing method or the like, the pipe diameter of the pipe 1 cannot be set by welding or the like on the inner wall surface 1a. Even when is small, the swirling flow of the fluid can be suppressed.

In addition, in FIG. 5, the wall thickness (thickness in the radial direction) of the cross-sectional shape of the pipe 1 (the portion of the molten metal 16) is in a non-uniform state in the circumferential direction, but in reality, the step portion 7 is in the horizontal direction. Since the length of the wall is very small, the wall thickness becomes substantially uniform in the circumferential direction.

1 Piping 1a Inner wall surface 2 Space 3 Bending part 4 Protruding part 5 Upper semicircular shape 6 Lower semicircular shape 7 Step part 8 Part of bending part whose radius of curvature is equal to or greater than the set threshold 9 Part of bending part Corresponding oil passage area 10 Core 11 Mold for core 12 Semicircular shape of mold for core 13 Mold for piping 14 Semicircular shape of mold for piping 15 Circular shape 16 Molten metal of material constituting piping

Claims (4)

In piping where a space for fluid passage is formed inside
In a cross-sectional view of the pipe, at least one protrusion is formed on the inner wall surface of the pipe so as to project from the pipe toward the space and suppress the flow of the fluid swirling in the space, and with respect to the flow direction of the fluid. A pipe in which the protruding portion is formed in at least a part of the pipe. The pipe according to claim 1, wherein the protruding portion is formed in a part downstream of the portion where the radius of curvature of the pipe is equal to or more than a preset set threshold value. In the method for manufacturing a pipe according to claim 1 or 2.
The first step of manufacturing a core having a shape on the inner wall surface of the pipe on which the protruding portion is formed, and
The core manufactured in the first step is set in a mold capable of forming the shape of the outer wall surface of the pipe by the wall surface so that the shape of the inner wall surface and the shape of the outer wall surface face each other. The second step to do
The third step of pouring the molten metal constituting the pipe between the core and the mold set in the second step, and the third step.
The fourth step of cooling the molten metal poured in the third step and
A method for manufacturing a pipe, characterized in that it has. In the first step, two molds for cores having semicircular shapes having the same diameter in cross-sectional view on the wall surface were preset in the horizontal direction with each of the semicircular shapes facing each other in cross-sectional view. It is characterized by including the work of forming a space having the shape of the inner wall surface of the pipe as the outer edge in a cross-sectional view inside the molds for the two cores by shifting the molds by a small length and bringing them into close contact with each other. The method for manufacturing a pipe according to claim 3.

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