JP3893581B2 - Manufacturing method of pipe flange - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing a pipe flange used in a fluid introduction part such as an intake pipe of an engine.
[0002]
[Prior art and problems]
Conventionally, in a fluid introduction part such as an intake pipe of a gasoline engine or a diesel engine for automobiles or industrial machines, a joint insertion part 51a is formed in a plate-like flange 51 as shown in FIG. The insertion straight pipe portion 52b is inserted into the joint insertion portion 51a and joined by brazing or welding, and the pipe 52 is provided with a bent portion 52a to avoid interference with the interference object 53. If the bending radius R of the bending portion 52a is not 1.2 times the diameter D of the pipe 52 or more, the pipe resistance increases rapidly. Therefore, the bending radius R is increased as much as possible. Therefore, there is a case where the bending radius R has to be made small, and there is a problem that the degree of freedom of design becomes small.
[0003]
In order to solve such problems, as shown in FIG. 14, a flange 55 is formed by casting, a bent portion 55b is formed inside, and a joint insertion portion 55a is formed at the end, and this joint insertion is performed. There is a configuration in which a straight pipe 52 is joined to the portion 55a. With such a structure, the bending radius R of the bent portion 55b can be increased, and an increase in pipe resistance due to bending can be suppressed. However, in order to form such a flange 55 by casting, a core is required, and the inner surface roughness of the bent portion 55b is increased due to the particle size of the core sand, thereby increasing the pipe resistance. In addition, there is another problem that the casting flange 55 requires a core and thus becomes expensive.
[0004]
Further, as shown in FIG. 15, the pipe 52 is changed from a perfect circle having a diameter D1 to an ellipse or an ellipse having a height dimension of D2 in the shape change section P, and the length of the plate-like flange 51 is changed. In the structure that is joined to the circular opening 51 b, it is necessary to form the bent portion 52 a in the pipe 52 and then to process the end portion to form the shape change section P, and the portion where the pipe 52 starts to be bent is the flange 51. This causes a problem that the bending radius R of the bent portion 52a must be reduced.
[0005]
In addition, as shown in FIG. 16, when the bent portion 55b and the shape change section P are formed in the casting flange 55, the bent radius of the bent portion 55b can be increased, but a core is required at the time of molding. In addition, there is a problem that the inner surface roughness of the bent portion 55b increases due to the core, and the pipe resistance increases.
[0006]
FIG. 17 is a front configuration diagram of the oval openings 51b and 55c in FIGS. 15 and 16. The oval openings 51b and 55c have a dimension D2 in the height direction with respect to the diameter D1 of the perfect pipe 52. It is small and has a large lateral dimension D3.
[0007]
[Means for Solving the Problems]
The present invention has been devised in view of the above-mentioned conventional problems, and it is a first object of the present invention to provide a method for manufacturing a pipe flange having a bent portion with a high degree of design freedom without increasing pipe resistance. The second purpose is to provide an inexpensive pipe flange manufacturing method that uses die-casting and has a small machining cost without using a core. The first gist is that the two main types are combined. A step of forming a casting space, and a linear slide mold in the casting space with a predetermined angle at a projecting portion projecting linearly from one of the two main molds into the casting space And a flange having a flow path composed of a first straight pipe portion and a second straight pipe portion connected with a bent portion of the predetermined angle inside by pouring hot water into the casting space. Step of bending and inner side of the bent portion The cutting dimension is the same as the maximum distance between the contact point of the outer bent portion of the bent portion and the virtual arc that continuously connects the first straight pipe portion and the second straight pipe portion in a round shape, or And a step of cutting the inner bending point so as to be about 1.2 times the maximum distance .
The second gist is that the flow path is formed with a shape change section that changes from a perfect circle to an ellipse or an ellipse, and the shape change section is cut in a process of cutting the inner bending point. It is set in .
The third gist is that the correction of the change in the cross-sectional area accompanying the change in the shape of the flow path is supplemented by a process of cutting a bending point inside the bending portion .
The fourth gist has a step of cutting the end side of the flow path into a straight line to form a joint for pipe joining, and pouring hot water into the casting space to form the flange. The casting burr generated at the time of forming is generated at a site that can be removed by the process of cutting the bending point inside the bent part and the process of forming the joint part.
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram of a flange-pipe joint structure. The flange 1 is formed by die casting without using a core, and the flange 1 is directly connected from the right side to the downstream side. The pipe part 5 is formed, the joining side straight pipe part 4 is formed from the other side, and both the straight pipe parts 4 and 5 are configured to form a contact at the outer bending point 6 and the inner bending point 7. . That is, the internal flow path is formed in a shape in which two straight pipes are connected at an angle θ from the upstream side and the downstream side, and the end of the joint-side straight pipe part 4 is A straight joint insertion portion 3 is formed, and a perfect circular pipe 2 having a diameter D is inserted from the outside into the joint insertion portion 3 and joined by brazing or welding.
[0009]
In FIG. 1, the maximum distance between the outer bending point 6 and a virtual arc 9 in which two straight pipes constituted by the joining-side straight pipe part 4 and the downstream straight pipe part 5 are continuous in a round shape. The dimension of t2 corresponding to t1 is scraped off at the inner bending point 7 to form a cutting part 8, and as shown in FIG. 2, this cutting part 8 is smaller than the inner diameter of the flow path after die casting. The shaft 10a of the small cutting tool 10 is rotated, and the inner bending point 7 is cut by the rotating cutting tool 10 and cut off.
[0010]
If the cutting part 8 is formed in this way, as shown in FIG. 3, the actual flow line 11 of the fluid flowing into the flow path in the flange 1 from the pipe 2 side is larger than the virtual arc 9 outside the flow path. Does not develop, a turbulent flow region does not occur in the cutting part 8 inside the flow path, the actual flow path diameter D is substantially the same as the inner diameter D of the pipe 2, and the fluid flows from upstream to downstream, An increase in pipe resistance due to bending can be suppressed.
[0011]
If the cutting portion 8 is not present, as shown in FIG. 4, an inner turbulent flow region 12a due to fluid viscosity or the like is formed downstream of the inner bending point 7, and the actual flow path diameter D4 becomes smaller. . Similarly, when the cutting amount of the cutting portion 8 is too small, the inner turbulent flow region 12a develops and the actual flow path diameter becomes small.
On the other hand, if the cutting amount of the cutting portion 8 is too large, as shown in FIG. 5, the portion of the cutting portion 8 becomes a tube expanding portion, and after the flow path diameter is expanded, the portion of the downstream straight tube portion 5 is expanded. Therefore, the outer turbulent flow region 12c is formed following the turbulent flow region at the outer bending point 6, and the inner turbulent flow region 12b is also continuous with the inner turbulent flow region 12a. As a result, the pipe resistance increases.
[0012]
Therefore, the cutting dimension t2 of the cutting part 8 is preferably the same as t1 or about 1.2 times t1, and when the cutting part 8 is cut and set in this way, as shown in FIG. It is possible to reduce the pipe resistance without generating a turbulent flow region in the portion 8.
[0013]
The flange 1 as shown in FIG. 1 can be die-casted without using a core by using a split-type die casting mold 15 composed of main molds 16 and 17 and a slide mold 18 as shown in FIG. Is.
That is, a portion for forming the outer bending point 6 is provided in the main mold 17, and a portion of the inner bending point 7 is formed by a joint surface M 1 between the main mold 17 and the slide mold 18, and the inner casting is performed. The flange 1 can be manufactured by pouring hot water into the space S, the main mold 17 can be pulled out by moving in the direction of the arrow, and the slide mold 18 can also be pulled out in the direction of the arrow. If the die-cast mold 15 is of the type, the flange 1 can be formed by drawing it straight without requiring a core.
[0014]
At the time of molding the flange 1, as shown in FIG. 7, a burr 19b is formed at the inner bending point 7 of the joint surface M1 of the main mold 17 and the slide mold 18, and a burr 19c is formed outside. In addition, the burrs 19a and 19a are formed at the joint surfaces M2 and M3 of the main mold 16 and the slide mold 18, and all of the cast burrs 19a, 19b and 19c generated during such die casting are It can be removed by subsequent cutting.
[0015]
That is, as shown in FIG. 7, the burr 19 b is removed when the inner bending point 7 is cut with the blade 10 to form the cutting portion 8, and the pipe 2 is joined. The burrs 19a, 19a, 19c are removed when the joint insertion portion 3 is cut with the joint insertion portion machining blade 20, and no burrs remain in the flow path. It is not necessary to perform the removal work of 19b and 19c, and the number of processing steps is reduced.
[0016]
If the cast burrs 19b, 19c, etc. remain in the flow path, they drop due to fluid pressure or vibration and flow into the flow path, and in the case of an intake pipe of an engine, they are caught by the valve portion and sealed. The casting burrs 19b, 19c and the like had to be carefully removed because they would cause serious problems such as defects, valve damage, engine stalls, etc. In this example, the part of the cutting part 8 and the joint insertion part Since the burrs 19b and 19c are set in advance so that the burrs 19b and 19c are generated in the third processed portion, the burrs 19a, 19b and 19c in the flow path can be surely deleted by cutting after die casting.
[0017]
FIG. 8 is a modification of FIG. 6. In the die casting mold 15 of FIG. 8, the outer bending point 6 is set in advance to the round shape of the virtual arc 9, and the main mold 17 is formed. is there.
Next, the die casting mold 15 shown in the longitudinal cross-sectional view of FIG. 9 and in the cross-sectional view of FIG. 11 can form the shape change sections P1 to P2 in the flow path inside the flange 1, and slides. The mold 18 is formed to have a diameter D1, and on the side of the main mold 17, the vertical dimension is D2 as shown in FIG. 10 as a sectional view taken along line AA in FIG. Thus, an elliptical or elliptical shape portion having a lateral dimension of D3 is provided.
[0018]
In such a die casting mold 15, the main mold 17 is provided with shape change sections P1 to P2 in which the diameter is changed from D1 to D2 (D1 to D3) in the section of the cutting allowance t2 of the cutting portion 8, and the cutting allowance t2 is set. By increasing the maximum distance t1 between the outer bend point 6 and the virtual arc 9 by adding the change in the cross-sectional area due to the shape change, it is possible to prevent an increase in pipe resistance due to the turbulent flow region at the bend. Thus, the processing for correcting the cross-sectional area is not required, and the flange 1 can be formed at low cost without using a core.
Moreover, the burr | flash which generate | occur | produces in the surface which the main type | molds 16 and 17 and the slide type | mold 18 join is set so that it may become the position of the cutting part 8 and the joining insertion part 3, and the subsequent cutting part 8 and joining insertion part The burrs can be removed by the cutting process 3, and it is not necessary to perform a deburring process separately, and the flange 1 can be manufactured at low cost.
[0019]
【The invention's effect】
The manufacturing method of the pipe flange of the present invention includes a step of forming a casting space by combining two main molds, and a linear slide mold from one main mold of the two main molds into the casting space. A step of joining the projecting portion projecting linearly at a predetermined angle in the casting space, and a first straight pipe portion in which hot water is poured into the casting space and connected with the bent portion of the predetermined angle inside Forming a flange having a flow path composed of a second straight pipe portion, an inner bending point of the bent portion, a cutting dimension of the bent portion and a contact point of the outer bent portion of the bent portion, and the first The step of cutting the inner bending point so as to be the same as the maximum distance from the virtual arc that makes the straight pipe part and the second straight pipe part continuous in a round shape, or about 1.2 times the maximum distance. and, by having a, low cost die-without the core The pipe flange can be formed by the strike molding, and the molded pipe flange does not generate a turbulent flow region and has a low pipe resistance.
[0020]
Further, the flow path has a shape change section that changes from a perfect circle to an ellipse or an ellipse, and the shape change section is set in a portion that is cut in the step of cutting the inner bending point. The pipe flange to be molded can be formed with a shape change section with little pipe resistance, and cast burrs can be removed well by subsequent cutting, and there is a shape change section in the flow path. The flange to be manufactured can be manufactured at low cost without using a core.
[0021]
Further, the correction of the change in the cross-sectional area due to the change in the shape of the flow path is supplemented by the process of cutting the bending point inside the bent portion, so that the cutting allowance of the cut portion is changed by the change in the cross-sectional area due to the change in shape. By adding the above, processing for correcting the cross-sectional area becomes unnecessary, and the flange can be formed at a low cost.
[0022]
Further, it has a step of cutting the end side of the flow path into a straight line to form a joint portion for pipe joining, and casting that occurs when hot water is poured into the casting space to form the flange. Since burrs are generated in the part that can be removed by the process of cutting the bending point inside the bent part and the process of forming the joined part, the casting burr generated at the time of die casting is cut inside the bent part. Since it occurs in the machining area and in the cutting area for pipe joining, the casting burr can be surely removed by subsequent machining, and the occurrence of defects due to the dropping of the casting burr can be reliably prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of a state in which a straight pipe is joined to a flange having a curved flow path.
FIG. 2 is an operation explanatory diagram in a state where the inside of a bent portion is cut with a cutting tool after molding of the flange of FIG. 1;
FIG. 3 is an explanatory configuration diagram showing the actual flow path diameter of the fluid flowing in the flow path when the cutting amount of the inner bending point is an appropriate value.
FIG. 4 is an explanatory configuration diagram of a state in which a turbulent flow region is generated when an inner bending point is not cut.
FIG. 5 is an explanatory configuration diagram illustrating a state in which a turbulent flow region increases when the cutting amount of an inner bending point is large.
6 is a cross-sectional configuration diagram of a die casting mold for forming the flange of FIG. 1. FIG.
FIG. 7 is a schematic configuration diagram showing a position of a casting burr generated on a flange formed by a die casting mold.
FIG. 8 is a cross-sectional configuration diagram showing a modification of the die casting mold.
FIG. 9 is a longitudinal sectional view of a die casting mold for forming a flow path having a shape change section into a flange.
FIG. 10 is an end view taken along line AA in FIG.
11 is a cross-sectional configuration diagram of FIG. 9;
12 is an end view taken along line BB of FIG.
FIG. 13 is a cross-sectional configuration diagram of a configuration in which a conventional pipe side is bent.
FIG. 14 is a cross-sectional configuration diagram in a state in which a bent flow path is formed on the conventional flange side.
FIG. 15 is a cross-sectional configuration diagram in the case where a shape change section is formed on the conventional pipe side.
FIG. 16 is a cross-sectional configuration diagram in which a shape change section is formed in a flow path in a conventional flange.
17 is a front view of the oval opening in FIGS. 15 and 16. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flange 2 Pipe 3 Joining insertion part 4 Joining side straight pipe part 5 Downstream side straight pipe part 6 Outer bending point 6a Bending part 7 Inner bending point 8 Cutting part 9 Inscribed circular arc 10 Cutting tool 11 Fluid actual flow line 12a, 12b inside Turbulent flow region 12c Outer turbulent flow region 15 Die casting mold 16, 17 Main mold 18 Slide mold 19a, 19b, 19c Casting burr 20 Cutting tool for joint insertion part M1, M2, M3 Joint surface S Casting space P1-P2 Shape change section

Claims (4)

Forming a casting space by combining two main molds;
Joining a linear slide mold in the casting space at a predetermined angle to a projecting portion projecting linearly into the casting space from one of the two main molds;
Pouring hot water into the casting space and forming a flange having a flow path composed of a first straight pipe part and a second straight pipe part connected with the bent part of the predetermined angle inside;
An internal bending point of the bent portion, and a cutting dimension thereof is a virtual arc that connects the contact point of the outer bent portion of the bent portion with the first straight pipe portion and the second straight pipe portion in a round shape. Cutting the inner bending point to be the same as the maximum distance or about 1.2 times the maximum distance;
A method for manufacturing a pipe flange. The flow path is formed with a shape change section that changes from a perfect circle to an ellipse or an ellipse,
2. The method for manufacturing a pipe flange according to claim 1, wherein the shape change section is set in a portion to be cut in the step of cutting the inner bending point. The method for manufacturing a pipe flange according to claim 2, wherein the correction of the change in the cross-sectional area accompanying the change in the shape of the flow path is supplemented by a step of cutting a bending point inside the bending portion. A step of cutting the end side of the flow path into a straight line to form a joint for pipe joining,
Cast burrs that are generated when hot water is poured into the casting space to form the flange are generated at a part that can be removed by the process of cutting the bending point inside the bending part and the process of forming the joint part. The pipe flange manufacturing method according to any one of claims 1 to 3, wherein the pipe flange is manufactured.

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