JP2012045604A - Method for manufacturing marine engine valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for providing a marine engine valve having excellent mechanical strength.
SOLUTION: It is made of a precipitation hardening type Ni-base heat-resistant alloy, and is connected while continuously increasing the shaft diameter from the shaft portion to the processing portion and the round rod-shaped shaft portion, the processing portion having a larger shaft diameter than this. A stepped round bar having a stepped portion is prepared. Also, a valve mold having a processed surface corresponding to the shape of the umbrella portion and having a central through hole is prepared. The shaft portion of the stepped round bar is inserted into the central through hole of the valve mold, is brought into contact with the machining surface from the shaft portion to at least a part of the step portion, and the shaft portion is held at least at two or more locations separated from each other. The end of the processing part of the stepped round bar is brought into contact with the anvil, the valve mold is brought close to the anvil along the axis of the stepped round bar, and the processing part is plastically deformed along the processing surface of the valve mold. . Before this upset forging, the diameter of the processed part is smaller than 1/2 of the diameter of the umbrella part, and the length of the processed part is at least 4 of the thickness at the diameter position of 1/2 of the diameter of the umbrella part. It is more than double.
[Selection] Figure 3

Description

  The present invention relates to a method for manufacturing a marine engine valve, and more particularly to a method for manufacturing a marine engine valve made of a precipitation hardening Ni-base superalloy.

  The material of engine valves such as diesel engines includes precipitation hardening type Ni-base superalloys containing about 20% Cr by mass and adding elements that form precipitates such as Al, Ti and / or Nb. For example, alloys such as NCF80A, NCF751, and Nimonic80A ("Nimonic" is a registered trademark) are used.

  In Patent Document 1, the mass elements are C: 0.1% or less, Si: 1.0% or less, Mn: 1.0% or less, Cr: 15 to 35% as a main element, Ti: 3.0% Hereinafter, a marine engine valve using a material made of a precipitation hardening type Ni-base superalloy to which at least one of Al: 2.0% or less and Nb: 3.0% or less is added is disclosed. Manufacture the engine valve formed by hot forging to a solution treatment to improve the moldability, then machine it into the shape of the engine valve, and then apply aging treatment only to the face part where mechanical strength is particularly required A method is disclosed.

  On the other hand, in the precipitation hardening type Ni-base superalloy as described above, if slip deformation is given by forging or the like, hardness according to the processing rate can be obtained. Therefore, in an engine valve provided with an umbrella part at the tip of the valve stem, between the inner peripheral side of the face part on the back side of the umbrella part and the outer peripheral side that contacts the valve seat of the engine body and requires more hardness Also known is an engine valve manufacturing method in which the processing rate is adjusted to incline the hardness.

  For example, in Patent Document 2, an umbrella-corresponding portion (substantially T-shaped horizontal portion) of an engine engine valve member made of NCF80A or NCF751 that has been cut into a substantially T-shape substantially similar to the shape of an engine valve is forged by a roll. In the manufacturing method for forming the face portion, it is disclosed that the processing rate is 20 to 80% on the outer peripheral side and 10 to 30% on the inner peripheral side.

  It is expected that an engine valve with higher mechanical strength can be obtained by using a Ni-base superalloy having higher mechanical strength at high temperatures as a material for the engine valve.

  Patent Document 3 discloses a precipitation hardening Ni-base superalloy that can be easily melted and has excellent mechanical strength and oxidation resistance at a temperature higher than 1200 ° C. Such Ni-base superalloy is added by mass%, C: 0.1% or less, Si: 2.0% or less, Mn: 2.0% or less, Cr: 30 to 45, Al: 5.0% or less It describes that it can be used in centrifugal mineral fiber manufacturing equipment and the like. In other words, it is used for applications that require high-temperature chemical reactivity and wear resistance, high-temperature strength and high-temperature oxidation resistance to molten minerals, and the Cr concentration is particularly increased compared to the Ni-base superalloy described above. ing.

Japanese Patent Laid-Open No. 11-22427 JP-A-8-61028 JP 2009-299109 A

  By the way, by molding the stepped round bar into the shape of the engine valve by upsetting forging, the processing rate of the face portion can be inclined, and a marine engine valve having excellent mechanical strength can be obtained. On the other hand, a Ni-base superalloy with high mechanical strength at upsetting forging temperature requires a large load for plastic working, and it is very difficult to tilt the processing rate of the face portion accurately by upsetting forging. . In addition, it is difficult to increase the processing rate beyond a predetermined level, and there is little improvement in mechanical strength due to processing. Even if the processing rate can be increased, cracks occur at the outer peripheral portion of the thin face portion. It was getting easier.

  The present invention has been made in view of such circumstances, and an object thereof is a marine engine that is obtained by molding a stepped round bar into a predetermined shape by upsetting forging and has excellent mechanical strength. An object is to provide a manufacturing method for providing a valve.

  The present inventor can improve the processing rate even with a Ni-base superalloy having high mechanical strength at upsetting forging temperature, and without causing cracks in the outer peripheral portion of the thin face portion. Developed upset forging method that can incline the processing rate of the parts with high accuracy, and decrease the ductility of the umbrella part formed by upset forging, especially the ductility is extremely near the 1/2 position in the radial direction from the outer periphery of the umbrella part. Resolved a problem that had dropped.

  That is, the method for manufacturing a marine engine valve according to the present invention is a method for manufacturing a marine engine valve having an umbrella portion made of a precipitation hardening type Ni-base heat-resistant alloy, and includes a round rod-shaped shaft portion and a shaft diameter larger than that. Preparing a stepped round bar having a large processing portion and a step portion for continuously connecting the processing portion while continuously increasing the shaft diameter from the shaft portion toward the processing portion; Providing a valve mold having a machining surface corresponding to the shape of the valve and having a central through hole; and inserting the shaft portion of the stepped round bar into the central through hole of the valve mold from the machining surface side. A step of bringing the shaft portion into contact with the processing surface from at least a part of the step portion and holding the shaft portion at at least two spaced apart positions; and an end of the processing portion of the stepped round bar Abut the part against the anvil Upsetting forging step in which the anvil and the valve mold are relatively brought close to each other along the axis of the step and the stepped round bar, and the processing portion is plastically deformed along the processing surface of the valve mold. And before the upsetting forging step, the diameter of the processed portion is smaller than ½ of the diameter of the umbrella portion, and the length of the processed portion is the diameter of the umbrella portion. It is characterized in that it is at least four times the thickness at a half diameter position.

  According to such an invention, the shaft portion of the stepped round bar is inserted into the central through hole of the valve die from the processing surface side, and is brought into contact with the processing surface from the shaft portion to at least a part of the step portion to be stabilized. After holding the shaft at two or more places apart and stabilizing it, the end of the processed part of the stepped round bar is brought into contact with the anvil, and the valve mold is placed along the axis of the stepped round bar. When the forged forging is performed by plastically deforming the processed part of the stepped round bar along the processed surface of the valve die by bringing it close to the surface, cracks may occur even at the outer peripheral part of the thin face part The processing rate (upsetting rate) can be increased. In addition, the processing rate of the face portion can be accurately tilted. That is, a marine engine valve having excellent mechanical strength can be provided.

  Furthermore, in the above-described invention, before the upset forging step, the length of the processed portion is within a range of 4.5 to 8.0 times the thickness at a diameter position of ½ of the diameter of the umbrella portion. It may be characterized by that. According to such an invention, the mechanical strength is excellent in both the tangential direction and the radial direction in the umbrella portion, and particularly in the mechanical strength in both the tangential direction and the radial direction in the vicinity of a half position in the radial direction from the outer periphery of the umbrella portion. An excellent marine engine valve can be provided.

  Furthermore, in the above-described invention, the Ni-base heat-resistant alloy is mainly composed of C: 0.1% or less, Si: 1.0% or less, Mn: 1.0% or less, and Cr: 15 to 35% in mass%. It is good also as having the component composition which added as an element and at least any one of Ti: 3.0% or less, Al: 2.0% or less, and Nb: 3.0% or less. According to this invention, it is possible to obtain a marine engine valve that is superior in mechanical strength and can give various characteristics as marine engine valves such as corrosion resistance.

It is a figure which shows the marine engine valve member and the stepped round bar before a process. It is a figure which shows the component composition of the Ni-base heat-resistant alloy of an Example. It is a figure which shows the mode of upset forging. It is a figure which shows the tensile strength of the tangential direction in the outer periphery vicinity of the umbrella part of the engine valve member for ships. It is a figure which shows the tensile strength of the tangent direction in the 1/2 diameter position of the umbrella part of the engine valve member for ships. It is a figure which shows the tensile strength of the radial direction in the outer periphery vicinity of the umbrella part of the engine valve member for ships. It is a figure which shows the tensile strength of the radial direction in the 1/2 diameter position of the umbrella part of the engine valve member for ships.

  One embodiment of the present invention will be described in detail with reference to FIGS.

As shown in FIG. 1, the marine engine valve member 1 is obtained by upsetting a stepped round bar 5 as will be described later, and has a round bar-shaped shaft portion 2 and an umbrella portion formed on one end thereof. 3. The umbrella part 3 has a face part 4 having a diameter larger than the diameter of the shaft part 2 and continuously reducing the diameter from the outer periphery to the shaft part 2. Here, the outer diameter of the umbrella part 3 is D ₁ , and the thickness in the axial direction X at a position of a half of the outer diameter is H ₁ .

The stepped round bar 5 has a processing portion 6 having a diameter larger than that of the shaft portion 2 for processing the umbrella portion 3 at the tip of the shaft portion 2. Between the shaft portion 2 and the processing portion 6, there is a step portion 7 that connects them while continuously increasing the diameter from the shaft portion 2 toward the processing portion 6. Here, the outer diameter of the processed portion 6 is D ₀ and the length is H ₀ .

  Next, an upset forging method for obtaining the engine valve member 1 from the stepped round bar 5 will be described with reference to FIG.

  For example, a steel material made of a Ni-base heat-resistant alloy having a component composition as shown in FIG. 2 is roughly forged into a stepped round bar 5 as shown in FIG. In such rough forging, the stepped portion 7 is provided by using an anvil having a curved surface corresponding to the curved surface of the valve mold 11 described later.

  Next, as shown in FIG. 3, a valve mold 11 having a processed surface 11a corresponding to the shape of the face portion 4 of the umbrella portion 3 of the marine engine valve member 1 and having a central through hole 11b is prepared.

  When the shaft portion 2 of the stepped round bar 5 is inserted into the central through hole 11b of the valve die 11 from the processing surface 11a side, it contacts the processing surface 11a of the valve die 11 from the shaft portion 2 to at least a part of the step portion 7. Touch. Thereby, the mutual positional relationship between the valve die 11 and the stepped round bar 5 is stabilized. Further, the shaft portion 2 is held by the holding jig 12 at at least two positions separated along the shaft portion 2. As a result, the stepped round bar 5 can be firmly fixed, and stable without being shaken during upset forging described later. On the other hand, the end of the stepped round bar 5 on the processed portion 6 side is brought into contact with the anvil 13.

  The anvil 13 is brought close to the valve mold 11 along the axis of the stepped round bar 5, and the processing section 6 is slowly plastically deformed along the processing surface 11 a of the valve mold 11 to perform upset forging so that the umbrella section 3 is moved. The marine engine valve member 1 is obtained. By performing upsetting forging while firmly fixing the stepped round bar 5 in this way, even at the outer peripheral portion of the thin umbrella portion 3, cracking does not occur, and a high processing rate can be obtained with high accuracy. Can give a slope.

Here, the length H ₀ of the processed portion 6 of the stepped round bar 5 with respect to the thickness H ₁ of the umbrella portion 3 at the diameter position ½ of the diameter D ₁ of the umbrella portion 3 of the marine engine valve member 1, that is, , H ₀ / H ₁ is defined as the upsetting rate. According to the method for manufacturing the marine engine valve member 1 described above, the upsetting rate can be significantly increased.

Therefore, the marine engine valve member 1 is changed by changing the upsetting rate H ₀ / H ₁ from 3.7 to 7.3 for the stepped round bar 5 made of a Ni-base heat-resistant alloy having the composition shown in FIG. It manufactured by the above-mentioned manufacturing method and measured the mechanical strength of the umbrella part. In the measurement, test pieces were cut out in the tangential direction and the radial direction from the vicinity of the outer peripheral part of the umbrella part 3 and the diameter position of 1/2 of the diameter D ₁ of the umbrella part 3, respectively, and a tensile test was performed at room temperature and 500 ° C. . Regarding the results of the room temperature tensile test and the high temperature tensile test, FIG. 4 and FIG. 5 show the tangential elongation (El) and the drawing (RA), and FIG. 6 and FIG. 7 show the radial elongation (El) and drawing (RA). It was shown to.

As shown in FIG. 4, in the tangential direction in the vicinity of the outer peripheral portion of the umbrella portion 3, as the upsetting rate H ₀ / H ₁ is increased in both the room temperature tensile test and the high temperature tensile test, the elongation (El) and the restriction (RA) ) Both tended to increase.

Further, as shown in FIG. 5, in the tangential direction of the diameter position ½ of the diameter D ₁ of the umbrella portion 3, the upsetting rate H ₀ / H ₁ is increased in both the room temperature tensile test and the high temperature tensile test. Accordingly, both the elongation (El) and the aperture (RA) increase significantly, and eventually become constant. That is, as compared with FIG. 4, when the upsetting ratio H ₀ / H ₁ is 4 or less, the elongation (El) and the restriction (RA) are significantly increased at the diameter position ½ of the diameter D ₁ of the umbrella portion 3. It will fall. However, by increasing the upsetting rate H ₀ / H ₁ , it is possible to prevent such a decrease in elongation (El) and restriction (RA) at the same position.

On the other hand, as shown in FIG. 6, in the radial direction in the vicinity of the outer peripheral portion of the umbrella portion 3, in both the room temperature tensile test and the high temperature tensile test, as the upsetting rate H ₀ / H ₁ is increased, the elongation (El) and Both of the apertures (RA) rise once, but eventually become constant except for the aperture (RA) of the room temperature tensile test.

Further, as shown in FIG. 7, in the radial direction of the diameter position of ½ of the diameter D ₁ of the umbrella portion 3, as the upsetting ratio H ₀ / H ₁ is increased, the elongation (El) and the restriction (RA) are increased. Both rise once, but eventually become constant.

As described above, according to the manufacturing method described above, the upsetting rate H ₀ / H ₁ can be set to 4.0 or more. In such a case, the upsetting rate H ₀ / H ₁ smaller than 4.0 is set. Compared with the conventional manufacturing method, the elongation (El) and the aperture (RA) can be greatly improved. This is particularly noticeable at a diameter position of ½ of the diameter D ₁ of the umbrella portion 3. That is, by making the diameter D ₀ of the processed portion 6 smaller than ½ of the diameter D ₁ of the umbrella portion 3, a large plastic deformation is caused by upset forging at a position ½ of the diameter of the umbrella portion 3. This can result in a significant improvement in the extension of the same position and of the aperture.

From FIG. 4 to FIG. 7, as the upsetting rate H ₀ / H ₁ is increased, the elongation (El) rises significantly and becomes constant over about 15%. Similarly, in the room temperature tensile test, the restriction (RA) increases substantially as the upsetting rate H ₀ / H ₁ is increased and becomes constant over about 25%. That is, the preferable upsetting ratio H ₀ / H ₁ is in the range of 4.5 to 8.0 at which high values of elongation and restriction can be obtained, and in such a case, in particular, the engine valve member for boats having excellent mechanical strength. 1 is given.

  Here, the component composition of the Ni-base heat-resistant alloy having the component composition as shown in FIG. In this embodiment, even a Ni-base superalloy having high mechanical strength at upsetting forging temperature can apply a sufficient load to plastic working. As a result, in mass%, C: 0.1% or less, Si: 1.0% or less, Mn: 1.0% or less, Cr: 15 to 35% as a main element, Ti: 3.0% or less, If it is a component composition which added at least any one of Al: 2.0% or less and Nb: 3.0% or less, the marine engine which is excellent in the same mechanical strength by applying the manufacturing method of a present Example The valve member 1 is provided.

  As described above, the manufacturing method of the marine engine valve member 1 according to the present embodiment is made of a precipitation-hardening Ni-base heat-resistant alloy having a predetermined component composition, and has a round rod-shaped shaft portion 2 and a shaft diameter larger than that. Providing a stepped round bar 5 having a large processing portion 6 and a step portion 7 for continuously connecting the processing portion 6 while continuously increasing the shaft diameter from the shaft portion 2 to the processing portion 6; A step of preparing a valve die 11 having a machining surface 11a corresponding to the shape of the portion 3 and having a central through hole 11b; and a stepped round bar 5 from the machining surface 11a side to the central through hole 11b of the valve die 11 A step of inserting the shaft portion 2 into the processing surface 11a from the shaft portion 2 to at least a part of the step portion 7, and holding the shaft portion 2 with at least two holding jigs 12 spaced apart from each other; The end of the processed part 6 of the round bar 5 with an anvil 1 And the anvil 13 and the valve die 11 are relatively brought close to each other along the axis of the stepped round bar 2, and the processing portion 6 is plastically deformed along the processing surface 11 a of the valve die 11. An upset forging step. Here, before the upset forging step, the diameter of the processed portion 6 is smaller than ½ of the diameter of the umbrella portion 3 and the length of the processed portion 6 is 1 / diameter of the diameter of the umbrella portion 3. 2 at least four times the thickness at the radial position.

  The stepped round bar 5 is stably fixed by contacting the processing surface 11a from the shaft portion 2 to at least a part of the stepped portion 7 and holding the shaft portion 2 at at least two separated positions. Thereby, even if it is the outer peripheral part of the thin umbrella part 3 by upsetting forging, a processing rate (upsetting rate) can be raised, without producing a crack. On the other hand, although the processing rate of the portion of the stepped round bar 5 in contact with the processing surface 11a is lowered, the ratio of the diameter of the processing section 6 and the diameter of the umbrella section 3 is set to a predetermined ratio or less. The processing rate (upsetting rate) of the entire portion 3 can be increased, and the processing rate of the face portion of the umbrella portion 3 can be accurately inclined. That is, the marine engine valve 1 having excellent mechanical strength can be provided.

  So far, representative embodiments and modifications based on the embodiments have been described. However, the present invention is not necessarily limited thereto, and those skilled in the art will not depart from the scope of the appended claims. Various alternative embodiments and modifications may be found.

1 Engine valve member 2 Shaft portion 3 Umbrella portion 5 Stepped round bar 6 Processing portion 11 Valve mold 11a Processing surface

Claims (3)

A method for manufacturing a marine engine valve having an umbrella portion made of a precipitation hardening type Ni-base heat-resistant alloy,
A stepped portion having a round bar-shaped shaft portion, a processing portion having a larger shaft diameter, and a step portion for continuously connecting the shaft portion to the processing portion while continuously increasing the shaft diameter. Preparing a round bar;
Preparing a valve mold having a processed surface corresponding to the shape of the umbrella part and having a central through hole;
The shaft portion of the stepped round bar is inserted from the processing surface side into the central through hole of the valve mold, and is brought into contact with the processing surface from the shaft portion to at least a part of the step portion. Holding the shaft at at least two spaced apart positions; and
Abutting an end of the processed portion of the stepped round bar with an anvil;
An upset forging step of relatively bringing the anvil and the valve mold close to each other along the axis of the stepped round bar, and plastically deforming the processed portion along the processed surface of the valve mold, Including
Before the upset forging step, the diameter of the processed portion is smaller than ½ of the diameter of the umbrella portion, and the length of the processed portion is ½ of the diameter of the umbrella portion. A method for manufacturing a marine engine valve, wherein the thickness is at least four times the thickness at a radial position.   Before the upsetting forging step, the length of the processed portion is in the range of 4.5 to 8.0 times the thickness at a diameter position of ½ of the diameter of the umbrella portion. A method for manufacturing a marine engine valve according to claim 1.   The Ni-base heat-resistant alloy is, in mass%, C: 0.1% or less, Si: 1.0% or less, Mn: 1.0% or less, Cr: 15 to 35% as main elements, Ti: 3. 3. The marine engine valve according to claim 1, comprising a component composition to which at least one of 0% or less, Al: 2.0% or less, and Nb: 3.0% or less is added. Production method.