JP3709786B2 - Manufacturing method of hollow shaft with protrusion - Google Patents

Description

表１に示すように、実施例では、中空素管４に第１のバルジ加工と第２のバルジ加工を行うことにより、必要な寸法精度と実用上問題のない固定強度を有するカム部材１０ａ、１０ｂを設けることができた。
【００６６】
なお、通常、カムシャフトに要求される静許容トルクは９８Ｎ・ｍと言われているが、実施例はこの値を超えた良好な値を示しており、充分に実用化可能である。
【００６７】
実施形態およびその他の実施形態の説明では、突起付き中空軸が４サイクルレシプロエンジン用のカムシャフトである場合を例にとった。しかし、本発明はカムシャフトには限定されず、中空の回転軸と、この回転軸の外周面にバルジ加工により嵌着された突起を有する突起付き中空軸であれば、等しく適用される。このような突起付き中空軸としては、４サイクルレシプロエンジン用のカムシャフト以外に、レシプロタイプのコンプレッサのカムシャフトやカム機構を有する機械部品のカムシャフト等が例示される。
【００６８】
また、実施形態およびその他の実施形態の説明では、中空体が軸受用鋼からなる場合を例にとった。しかし、本発明における中空体は、軸受用鋼に限定されず、要求される硬度を満足するとともに塑性加工可能な材料であれば、等しく適用される。塑性加工可能な材料としては、軸受用鋼以外に、機械構造用炭素鋼や機械構造用合金鋼、さらにはチタン合金等も、同様に用いることができる。
【００６９】
さらに、実施形態およびその他の実施形態の説明では、カムシャフトが２つのカム部材を有する場合を例にとった。しかし、本発明は、カム部材の数には何ら制限されず、カム部材の数が１つまたは３つ以上であっても、同様に適用される。
【００７０】
【発明の効果】
以上、詳細に説明したように、本発明により、バルジ加工後の機械加工を必要としないことから低コストに製造することができ、しかもカム部材の重量を低減できることから高速回転時のダイナミックバランスにも優れた、偏心量の大きなカム部材を有する、例えばカムシャフト等の突起付き中空軸を高い生産効率で製造することが可能な製造方法を提供することができた。
【００７１】
また、本発明では、カム部材を、焼結合金ではなく、塑性加工可能な材料により製造するため、この材料を適宜選定することにより、部品コストを低減でき、突起付き中空軸をさらに低コストで製造することができる。かかる効果を奏する本発明の意義は、極めて著しい。
【図面の簡単な説明】
【図１】実施形態の第１のバルジ加工前におけるバルジ加工型の初期セット状態と中空素管を示す模式的縦断面図である。
【図２】実施形態の第１のバルジ加工後における中空素管の状態を示す模式的縦断面図である。
【図３】実施形態の第２のバルジ加工後におけるバルジ加工型の状態とバルジ加工されたカムシャフトを示す模式的縦断面図である。
【図４】図１のイ−イ矢視によるバルジ加工型を省略した模式的横断面図である。
【図５】図３のロ−ロ矢視によるバルジ加工型を省略した模式的横断面図である。
【図６】他の実施形態の偏心部成形部材の配置態様を示す模式的横断面図である。
【図７】他の実施形態の偏心成形部材配置部分のバルジ加工後の形状を示す模式的横断面図である。
【図８】他の実施形態の固定部材の配置態様を示す模式的横断面図である。
【図９】他の実施形態の固定部材の配置部分の予成形状態を示す模式的横断面図である。
【図１０】他の実施形態の固定部材の配置部分のバルジ加工後の形状を示す模式的横断面図である。
【符号の説明】
１：バルジ加工型、
２：上型、
３：下型、
２ａ、３ａ：軸部成形用固定型、
２ｂ、２ｃ、３ｂ、３ｃ：突起部成形用可動型、
２ｄ、２ｅ、３ｄ、３ｅ：軸部成形用可動型、
４：中空素管、
５ａ、５ｂ、６ａ、６ｂ：中空体、
７ａ、７ｂ：管端拘束治具、
７ｃ、７ｄ：管路、
８ａ、８ｂ：型移動用治具、
９：カムシャフト、
１０ａ、１０ｂ：カム部材、
１１ａ、１１ｂ：ジャーナル部、
１２：回転軸、
１３：偏心部成形部材、
１４：固定部材、
１５：予成形用のプレス型、
１５ａ：予成形用のプレス型を構成する上型、
１５ｂ：予成形用のプレス型を構成する下型、
１６：中子。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a hollow shaft with protrusions, and relates to a method of manufacturing a hollow shaft with protrusions such as a camshaft to which a cam member for opening and closing an intake valve and an exhaust valve of a four-cycle reciprocating engine is attached.
[0002]
[Prior art]
Conventionally, for example, a camshaft, which is a rotating shaft having cams for driving intake valves and exhaust valves of a 4-cycle reciprocating engine, is processed into a rough shape by casting or forging, and then processed into a final shape by machining. It was finished. However, in the above method, since the cam and the rotating shaft are integrally formed, the number of parts to be machined increases. In addition, in order to increase the hardness of the cam and improve the wear resistance, there is a need to perform carburization, heat treatment and the like after machining, and there are problems that material costs increase and manufacturing costs increase. Furthermore, this method has a problem that not only the cams that require wear resistance and the rotating shafts that require strength can be manufactured using optimum materials, but also the weight is heavy.
[0003]
For this reason, cams that require wear resistance are manufactured as a hollow cam member using a sintered alloy, and the rotating shaft is manufactured as a hollow shaft to reduce weight, and these are welded, brazed, or mechanically fixed. Developed a technology to manufacture camshafts by integrating and assembling them. However, in order to perform welding or brazing, the materials of the cam member and the rotating shaft are limited, and an optimal material cannot be used. In addition, the mechanical fixing needs to be repeatedly performed as many times as the number of cam members, and there is a problem that productivity is low.
[0004]
For this reason, as a method for improving productivity, a hollow rotary shaft is loosely fitted in the hollow portion of the cam member made of the sintered alloy and accommodated in a bulge processing die, and bulging is performed on the hollow rotary shaft. Thus, a method for fitting the cam member to the rotating shaft has been proposed (Japanese Patent Publication No. 49-28298). However, in this method, since the shape of the inner surface of the cam member changes continuously and gently, the fixing strength between the cam member and the rotating shaft is not sufficient.
[0005]
Thus, the following method has been proposed as a method for improving the fixing strength between the cam member and the rotating shaft. A method in which a fixing protrusion is provided on the inner surface of a cam member made of a sintered alloy, and this fixing protrusion is engaged with the outer surface of a hollow rotating shaft to be bulged (Japanese Patent Laid-Open No. 59-144532). A method of providing a fixing groove on the inner surface of a cam member made of a sintered alloy and bulging and filling a part of a hollow rotating shaft to be bulged in the fixing groove (Japanese Patent Laid-Open No. 60-257933).
[0006]
In addition, as a method for improving the fixed position accuracy of the cam member, a method using a bulge processing die provided with a cam positioning mechanism has also been proposed (Japanese Patent Laid-Open No. 62-97722).
[0007]
[Problems to be solved by the invention]
In any of the above conventional methods, the cam member is a sintered alloy for the following reason. That is, it has excellent wear resistance. The outer shape of the cam member having the eccentric profile can be mass-produced at a relatively low cost. However, since the cam member made of a sintered alloy breaks without plastic deformation, it cannot be plastically deformed by bulging. For this reason, in the conventional method, the final dimensional accuracy of the cam member is determined by the dimensional accuracy during sintering, but the desired dimensional accuracy cannot be obtained with the dimensional accuracy during sintering. Therefore, after the bulge processing, machining such as cutting must be performed on the high hardness cam member made of the sintered alloy. Further, the sintered alloy itself used for the cam member is also expensive. For this reason, in the conventional method, the camshaft can be manufactured with high productivity, but the manufacturing cost is significantly increased.
[0008]
Further, in the above conventional method, since the rotating shaft is hollow, an effect of weight reduction can be obtained. However, since the cam member is a heavy material made of a sintered alloy, the dynamic balance of the camshaft during high-speed rotation is poor. It was. For this reason, the reduction in the high-speed rotation performance of the camshaft due to the weight of the cam member cannot be denied.
[0009]
The object of the present invention is that it does not require machining to ensure dimensional accuracy after bulge processing, and thus can be manufactured at low cost, and has excellent dynamic balance during high-speed rotation, such as the camshaft described above. It is in providing the manufacturing method of the hollow shaft with a protrusion.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventor has made extensive studies on bulging of a steel pipe, and as a result, has obtained the findings (a) to (d) listed below.
(a) In bulging, a steel pipe is accommodated in a bulging die that determines the shape after machining, and a high-pressure fluid is introduced into the steel pipe to perform extension forming, thereby sticking the steel pipe to the die. It is formed into a predetermined shape. For this reason, if it is a steel pipe which can perform plastic working, not only a single pipe but a multilayer pipe or a composite member more than a double pipe can perform bulge processing. Therefore, if a bulge process is performed on a steel pipe made of a multi-layer pipe or a composite member that is partially a double pipe or more, a hollow shaft with protrusions can be easily formed.
(b) Forming a hollow shaft with a protrusion with a large change in outer diameter with low tube expansion rate and high accuracy by bulging a steel pipe partially having a double-pipe or more multi-layer pipe part or composite part. can do.
(c) Since bulging is performed without using a tool on the inner surface of the steel pipe, the inner shape of the steel pipe can be freely changed, and the shape of the bulging die can be set appropriately. By doing so, the extending direction of the steel pipe can be freely set. For this reason, even a double pipe in which an inner steel pipe and an outer steel pipe are arranged eccentrically can be sufficiently formed.
(d) However, if the amount of eccentricity of the protrusion is extremely large, the inner steel pipe is likely to break, making it difficult to form. As a countermeasure, as a bulge processing mold, a mold part that molds the outer steel pipe to be a protrusion into a predetermined shape, and one of the mold parts located on both sides of this mold part, separately, A bulging die that is divided so as to be movable in the longitudinal direction of the steel pipe to be accommodated is used. Then, the inner steel pipe portion corresponding to the protruding portion is preformed in advance wider than the width of the protruding portion to be obtained, and then expanded and expanded to a predetermined width. Thereby, the inner steel pipe is not broken, and even a hollow shaft with a projection having a large eccentricity of the projection can be formed.
[0011]
The gist of the present invention based on the above knowledge resides in the following method for producing a hollow shaft with protrusions.
[0012]
The hollow shell inserted inside the hollow body made of a plastically deformable material is accommodated in the bulge processing mold, and the hollow body is bulged to form the outer shape of the hollow body. A method for producing a hollow shaft with protrusions that undergoes the following steps (1) to (4) when the hollow shell and the hollow body are fitted together.
[0013]
(1) As a bulge processing mold, a protruding part forming movable mold for forming the outer shape of the hollow body into a predetermined shape, a shaft part forming movable mold located on one side of the protruding part forming movable mold, and the other side Prepared is a bulging die that is divided into a fixed shaft forming mold and that is movable separately from the protruding mold forming mold and the shaft forming movable mold. Process,
(2) Protruding part forming movable mold and shaft part such that the prepared bulge processing mold shaft part forming fixed mold, protrusion part forming movable mold and shaft part forming movable mold have a predetermined interval. A step of setting a movable mold for molding, and housing a hollow shell inserted with a gap inside a hollow body made of a plastically deformable material in the bulge processing mold after the setting,
(3) bulging the hollow shell accommodated in the bulging mold and bringing the inner surface of the hollow body into contact with the outer surface of the hollow shell;
(4) The bulging process is continued by pressing the movable mold for shaft molding in the direction of the fixed mold for molding the shaft, and the hollow body is stretched on the inner surface of the hollow body molding bulge mold defined by three molds. A step of forming the outer shape of the hollow body into a predetermined shape and fitting the hollow shell and the hollow body.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a method for producing a hollow shaft with projections according to the present invention will be described below in detail with reference to the accompanying drawings. In the following description of the embodiments, the case where the hollow shaft with protrusions is a camshaft for a 4-cycle reciprocating engine is taken as an example.
[0015]
FIG. 1 is a schematic longitudinal sectional view showing a bulge forming die 1 used in the method of the present invention and a hollow shell before the bulge processing accommodated in the bulge processing die. 2 is a schematic longitudinal sectional view showing a state after the first bulge processing, and FIG. 3 is a schematic longitudinal sectional view showing a state after the second bulge processing. Further, FIG. 4 is a cross-sectional view taken along arrow II in FIG. 1, and FIG. 5 is a cross-sectional view taken along arrow II in FIG.
[0016]
As shown in FIGS. 1 to 3, in this embodiment, a bulge processing die 1 divided into an upper die 2 and a lower die 3 is used. On the inner surfaces of the upper mold 2 and the lower mold 3 constituting the bulge processing mold 1, hole molds having the same shape as the final finished shape of the camshaft 9 to be manufactured are respectively engraved.
[0017]
Each of the upper mold 2 and the lower mold 3 includes a shaft-forming fixed mold 2a, 3a that molds the central portion in the longitudinal direction of the inner hollow shell 4 serving as a hollow shaft, and an outer hollow shell. Protruding part forming movable molds 2b, 3b and 2c, 3c for forming the hollow bodies 5a, 5b to be the cam members 10a, 10b into a predetermined outer shape, and both end portions of the hollow shell 4 to a predetermined shape It is divided into movable parts 2d, 3d and 2e, 3e for forming the shaft part.
[0018]
Further, the protruding portion forming movable molds 2b, 3b and 2c, 3c and the shaft portion forming movable molds 2d, 3d, 2e, and 3e are, for example, different from the shaft portion forming fixed molds 2a and 3a. It is mounted so as to be slidable in the left-right direction in the drawing by appropriate means such as a groove mechanism.
[0019]
Both the upper mold 2 and the lower mold 3 configured as described above are pressed by a press mechanism (not shown) from above and below in order to withstand a splitting force caused by internal pressure during bulge processing. The upper mold 1 and the lower mold 2 are also moved up and down by the vertical movement, whereby the hollow bodies 5a and 5b to be the cam members 10a and 10b and the hollow bodies 6a and 6b to be the journal portions 11a and 11b are externally inserted. Carrying in the hollow shell 4 into the mold and carrying out the camshaft 9 out of the mold after completion of processing are performed.
[0020]
Furthermore, between the upper mold 2 and the lower mold 3, both ends of the hollow shell 4 are airtightly held, and the hollow shell 4 or the camshaft 9 at the time of bulging is connected to the inside of the upper mold 2 and the lower mold 3. Tube end restraining jigs 7a and 7b are arranged to be supported at predetermined positions.
[0021]
Furthermore, between the upper mold 2 and the lower mold 3, the protruding part forming movable molds 2b, 3b and 2c, 3c and the shaft part forming movable molds 2d, 3d and 2e, 3e, respectively, For example, mold moving jigs 8a and 8b composed of an appropriate pressing mechanism such as a hydraulic cylinder, which are moved toward the shaft-forming fixed molds 2a and 3a, and are fixedly supported at predetermined positions as necessary. Has been placed.
[0022]
In the method of the present invention, the upper mold 2 and the lower mold 3 configured as described above are opened by operating the press mechanism, and the protrusion forming movable molds 2b, 3b and 2c, 3c, and the hollow shaft As shown in FIG. 1, the shaft-forming movable dies 2d, 3d and 2e, 3e for forming both end portions into a predetermined shape are respectively spaced apart from the shaft-forming fixed dies 2a, 3a. It is initially set across.
[0023]
Next, the hollow bodies 5a and 5b to be the cam members 10a and 10b that are externally inserted are located at the center of the protrusion forming movable molds 2b, 3b and 2c and 3c, and become the journal parts 11a and 11b. The hollow shell 4 is inserted into the bulge processing die 1 so that 6a and 6b are located in the central part of the journal die part engraved on the movable molds 2d, 3d and 2e and 3e for forming the shaft part. Close the mold 2 and the lower mold 3.
[0024]
Through the above operation, as shown in FIG. 1, the hollow shell 4 is formed inside the hollow bodies 5a and 5b that become the cam members 10a and 10b having the hollow holes and the hollow bodies 6a and 6b that become the journal portions 11a and 11b. The bulge processing mold 1 is housed in a state where gaps are provided.
[0025]
Since the hollow shell 4 forms the rotation axis of the camshaft 9, which is a product, sufficient strength is required. In this embodiment, the hollow shell 4 is a STKM13A steel pipe defined in a general JIS standard.
[0026]
Further, in the present embodiment, the hollow bodies 5a and 5b are cams having a final shape as shown in FIG. 4 in order to arrange the hollow bodies 5a and 5b in the protrusion forming movable molds 2b, 3b and 2c, 3c. It is preliminarily eccentrically formed into a shape similar to the members 10a and 10b. In addition, between the outer peripheral surface of the hollow bodies 5a and 5b and the inner peripheral surface of the protrusion forming movable molds 2b, 3b and 2c and 3c, and the outer peripheral surface of the hollow bodies 6a and 6b to be the journal portions 11a and 11b As shown in FIG. 1, according to the overhang amount at the time of bulge processing, between the inner peripheral surfaces of the journal forming hole molds engraved in the movable molds 2d, 3d and 2e, 3e for the shaft forming There is a gap.
[0027]
Further, for the hollow bodies 5a, 5b and 6a, 6b, bearing steel pipes were used as materials that can be plastically processed. That is, in the above-described conventional method, not only is the wear resistance excellent, but the outer shape of the cam member having an eccentric profile can be mass-produced at a relatively low cost. Therefore, a sintered alloy is used for the cam member. On the other hand, in the present embodiment, the cam members 10a and 10b that can satisfy the required performance of wear resistance and have a predetermined outer shape can be plastically processed by being easily formed by bulge processing described later. Use materials. For this reason, in this embodiment, the steel pipe for bearings was used for hollow body 5a, 5b and 6a, 6b.
[0028]
Next, in the present invention, a bulge process in the first step and a bulge in the second step described below are inserted into the hollow shell 4 inserted into the hollow bodies 5a, 5b and 6a, 6b with a gap between them. Processing.
[0029]
That is, in the bulge processing in the first step, the positions of the protruding portion forming movable molds 2b, 3b and 2c, 3c and the shaft portion forming movable molds 2d, 3d, 2e, 3e are set to the mold moving jigs 8a, 8b. To fix and hold in the state shown in FIG. Then, high-pressure bulge processing liquid is injected into the hollow shell 4 from the pipes 7c and 7d provided at the shaft centers of the tube end restraining jigs 7a and 7b, and the hollow shell 4 is expanded and expanded. Then, as shown in FIG. 2, a part of the outer peripheral surface of the hollow shell 4 in the axial direction is brought into contact with the inner peripheral surfaces of the hollow bodies 5a and 5b to be the cam members 10a and 10b.
[0030]
Next, in the bulge processing of the second step, the mold moving jigs 8a and 8b are operated, and the shaft part forming movable molds 2d, 3d and 2e and 3e are directed to the shaft part forming fixed molds 2a and 3a, respectively. While continuing to inject the liquid for high-pressure bulge processing from the conduits 7c and 7d provided at the axial centers of the tube end restraining jigs 7a and 7b, further expanding and deforming the hollow shell 4 to expand and deform, When the state shown in FIG. 3 is reached, the bulge processing is finished.
[0031]
Specifically, the protrusion-forming movable molds 2b, 3b, 2c, and 3c are in contact with the shaft-forming fixed molds 2a and 3a, and the protrusion-forming movable molds 2b, 3b, 2c, and 3c are in contact with each other. On the other hand, the outer peripheries of the hollow bodies 5a, 5b and 6a, b are in contact with the inner surface of the hole of the bulge forming die 1 in which the movable molds 2d, 3d and 2e, 3e come into contact with each other. The bulging process is terminated when the entire outer surface of the hollow shell 4 comes into contact with the entire inner surface of these hollow bodies.
[0032]
As described above, when the bulging process is performed in two stages on the hollow shell 4 to which the hollow bodies 5a, 5b and 6a, 6b are fitted, the cam members 10a, 10b in the first bulging process. The expanded tube bulge area in the tube axis direction of the hollow shell 4 corresponding to the hollow bodies 5a and 5b becomes longer than that in the case of using a conventional bulge processing die that is only divided vertically. Further, when the internal pressure applied to the hollow shell 4 is the same, the bulge amount and the material volume also increase.
[0033]
The expanded tube bulge region of the hollow shell 4 which is long in the tube axis direction and has a large bulge amount and material volume is the movable part 2d, 3d and 2e for forming the shaft part in the second bulge processing step, With the movement of 3e, the pipes bulge and deform while undergoing bending in the tube axis direction on both side portions thereof, and the protruding mold forming movable molds 2b, 3b of the bulge mold 1 in which the molds come into contact with each other, and The outer peripheral surfaces of the hollow bodies 5a and 5b are in full contact with the inner peripheral surfaces of 2c and 3c, and the outer peripheral surfaces of the hollow bodies 6a and 6b are also engraved on the movable molds 2d, 3d and 2e and 3e for forming the shaft portion. The entire surface contacts the inner peripheral surface of the journal forming hole mold portion, and the bulge processing is completed. At this time, the inner peripheral surfaces of the hollow bodies 5a, 5b and 6a, 6b naturally contact the outer peripheral surface of the hollow shell 4 as a matter of course.
[0034]
As described above, when the hollow shell 4 is expanded and deformed without bending in the tube axis direction during the bulge processing of the hollow shell 4, the expanded tube bulge deformation proceeds smoothly, The tube 4 is not broken. Therefore, the camshaft 9 having the cam members 10a and 10b having a large eccentricity can be molded.
[0035]
Here, between the shaft-forming fixed molds 2a and 3a and the protrusion-forming movable molds 2b, 3b and 2c and 3c, and the protrusion-forming movable molds 2b, 3b and 2c at the time of the first bulge processing, The initial set interval between the movable molds 2d, 3d and 2e, 3e and the internal pressure applied to the inside of the hollow shell 4 is determined according to the required eccentric amount of the cam members 10a, 10b. Of these, the initial set interval is usually increased as the amount of eccentricity increases.
[0036]
Further, the internal pressure applied to the inside of the hollow shell 4 at the time of the second bulge processing is the outer shape of the cam members 10a, 10b and the extension portion of the expanded portion of the hollow shell 4 after the first bulge processing. Although determined by the shape and the like, in the second bulge processing, the higher the internal pressure applied, the better the shape after molding. For this reason, the internal pressure applied to the inside of the hollow shell 4 in the second bulge processing should be as high as possible.
[0037]
In addition, at the time of the 2nd bulge process, it is based on the following reason that the bending process of a pipe-axis direction is provided to the both-sides part of a pipe expansion area. That is, at the time of the second bulge processing, the protrusion forming movable molds 2b, 2c and 3b, 3c are the high pressure bulge processing in which the hollow shell 4 and the hollow bodies 5a, 5b are injected into the hollow shell 4. Of the movable portion 2d, 3d and 2e, 3e for forming the shaft portion with respect to the protruding portion forming movable molds 2b, 3b and 2c, 3c without being displaced in the tube axis direction. This is because the protrusion forming movable molds 2b, 3b and 2c, 3c approach the shaft forming fixed molds 2a, 3a by the same amount as the approaching amount.
[0038]
In the present embodiment, as described above, the outer surfaces of the hollow bodies 5a, 5b and 6a, 6b are attached to the hole molds engraved in the bulge processing mold 1, thereby allowing the hollow bodies 5a, 5b and 6a, The outer shapes of 6b are respectively formed according to the final finished shapes of the cam members 10a and 10b and the journal portions 11a and 11b of the camshaft 9 to be manufactured.
[0039]
In this embodiment, the hollow shell 4 is expanded and deformed by the above-described two-stage bulge processing so that the hollow shell 4 is brought into contact with the inner surfaces of the hollow bodies 5a, 5b and 6a, 6b with a high surface pressure. Can be brought into close contact with each other. Thereby, the hollow shell 4 and the hollow bodies 5a, 5b and 6a, 6b are fitted with a practically sufficient fixing strength (static permissible torque).
[0040]
Thus, as shown in FIG. 3, the engine on which the hollow rotating shaft 12, the cam members 10 a and 10 b fitted on the outer peripheral surface of the rotating shaft 12 by bulge processing, and the camshaft 9 are mounted. There is provided a camshaft 9 having journal portions 11a and 11b for pivotal support by bearings provided in the cylinder head, and the outer shapes of the cam members 10a and 10b are formed by bulging. That is, in this embodiment, the cam members 10a and 10b and the journal portions 11a and 11b all correspond to the protrusions in the present invention.
[0041]
Then, after completion of the second bulge processing, the press is operated to open the upper mold 2 and the lower mold 3, and the bulged camshaft 9 is carried out of the bulge processing mold 1.
[0042]
In addition, it is desirable to quench the surface of each of the cam members 10a and 10b and the journal portions 11a and 11b with a high frequency with respect to the camshaft 9 carried out of the bulge processing die 1. Thereby, while giving desired hardness, all are prevented that the cam members 10a and 10b and the journal parts 11a and 11b which are fitting parts by bulge processing loosen by thermal expansion.
[0043]
Further, compared to the cam members 10a and 10b, a large torque does not act on the journal portions 11a and 11b, and a large pipe expansion rate is not required. For this reason, bulging for the journal portions 11a and 11b is easier than bulging for the cam members 10a and 10b.
[0044]
Further, in the present embodiment, the journal portions 11a and 11b are also formed by bulge processing. However, as described above, since a large torque does not act on the journal portions 11a and 11b, the cam members are not formed by bulge processing. After the bulging of only 10a and 10b, the separate parts forming the journal portions 11a and 11b may be fixed by appropriate means such as welding, brazing, or mechanical fixing.
[0045]
In this embodiment, the cam members 10a and 10b and the journal portions 11a and 11b all have sufficient dimensional accuracy, and therefore need not be cut after bulging. Moreover, the steel pipe for bearings used for cam member 10a, 10b and journal part 11a, 11b is cheaper than a sintered alloy. For this reason, according to this embodiment, even if the camshaft 9 has the cam members 10a and 10b with large eccentricity, it can be manufactured with high production efficiency and at low cost.
[0046]
In the present embodiment, the cam members 10a and 10b are manufactured by expanding and hollowly deforming the hollow bodies 5a and 5b, which are bearing steel pipes, and are practically solid made of a conventional sintered alloy. It is lighter than the cam member. For this reason, the dynamic balance of the camshaft during high-speed rotation becomes good, and the maximum allowable rotational speed of the camshaft can be increased as compared with the conventional one. Thereby, the rotation speed of a 4-cycle reciprocating engine can also be raised.
[0047]
FIGS. 6 to 10 are schematic cross-sectional views showing other embodiments. In the case of the embodiment shown in FIGS. 6 and 7, the camshaft 9 having cam members 10a and 10b having larger eccentric amounts. 8 to 10, the camshaft has a stronger fitting strength between the hollow shell 4 and the hollow bodies 5a, 5b and 6a, 6b and a higher static permissible torque. 9 can be manufactured. Hereinafter, these will be described in detail.
[0048]
As shown in FIG. 6, in this embodiment, the hollow shell 4 has a substantially circular cross section, and before the first bulge processing, the hollow shell 4 has a substantially circular cross section. An eccentric portion forming member 13 is disposed in the gap between the hollow body 5 and the hollow bodies 5a and 5b. The eccentric portion forming member 13 is disposed in order to sufficiently secure the bulging deformation amount of the hollow bodies 5a and 5b in a state where the bulging deformation amount of the hollow shell 4 is kept low.
[0049]
The eccentric part forming member 13 is preferably easily deformed by the bulging deformation of the hollow shell 4 in order to fill the gap between the hollow shell 4 and the hollow bodies 5a and 5b, and is also reduced in weight. Therefore, a lightweight one is desirable.
[0050]
The material of the eccentric part forming member 13 may be set as appropriate in consideration of these requirements, ease of handling in the processing step, and further, for example, cost. For example, it is desirable to use pure aluminum or an alloy thereof.
[0051]
In addition, the shape, size, etc. of the eccentric portion forming member 13 can be inserted into the gap between the hollow shell 4 and the hollow bodies 5a, 5b and have a volume capable of forming the cam members 10a, 10b. It doesn't need any limitation. In other words, the eccentric part forming member 13 may be disposed at least in a part between the hollow shell 4 and the hollow bodies 5a and 5b, and the shape thereof is not limited to the solid body shown in the figure, and is a hollow body. There may be.
[0052]
As shown in FIG. 6, when the eccentric part forming member 13 is disposed in the gap between the hollow shell 4 and the hollow bodies 5a and 5b and bulging is performed, as shown in FIG. And the eccentric part shaping | molding member 13 contact | abuts to the internal peripheral surface of hollow body 5a, 5b, and bulges and deforms hollow body 5a, 5b. At this time, since the eccentric portion forming member 13 is made of pure aluminum or an alloy thereof as described above, the eccentric portion forming member 13 is deformed so as to fill the gap between the hollow shell 4 and the hollow bodies 5a and 5b. Suppresses local bulging deformation. For this reason, even if the expansion ratio of the hollow shell 4 is small, a large amount of eccentricity can be obtained, and the hollow shell 4 can be prevented from breaking.
[0053]
Further, as shown in FIG. 8, in this embodiment, before the first bulge processing is performed on the hollow shell 4, a fixing member 14 for fixing the hollow shell 4 and the hollow bodies 5a and 5b is disposed. Is done. As will be described later, since the fixing member 14 needs to be recessed into both the hollow shell 4 and the hollow bodies 5a and 5b, it is preferable to use a high-hardness member. It is desirable to use a polygonal CrMo steel wire or the like.
[0054]
That is, as shown in FIG. 9, as a pre-molding, the fixing member 14 is disposed between the core 16 and the hollow bodies 5a and 5b, and the press body 15 including the upper mold 15a and the lower mold 15b is used to form the hollow body. Press in a direction to reduce the diameter of 5a and 5b. As a result, the fixing member 14 plastically deforms the vicinity of the abutting portion of the hollow bodies 5a and 5b and sinks into the hollow bodies 5a and 5b. Since the fixing member 14 needs to be recessed into the hollow shell 4 by the first bulge processing and the second bulge processing performed subsequently, in this press, about half the diameter of the fixing member 14 is required. It is desirable that the hollow bodies 5a and 5b are recessed by the depth of.
[0055]
And after performing this preforming, the hollow shell 4 is accommodated in the bulge processing mold 1 initially set in the state shown in FIG. 1, and the first bulge processing and the second bulge processing are performed. According to this embodiment, as shown in FIG. 10, the fixing member 14 fitted into the hollow bodies 5 a and 5 b is in the vicinity of the contact portion of the hollow shell 4 as the hollow shell 4 bulges and deforms. Is plastically deformed and embedded in the hollow shell 4.
[0056]
For this reason, the fixing member 14 has the same fixing action as the key between the hollow shell 4 and the hollow bodies 5a and 5b, and a high surface pressure between the hollow shell 4 and the hollow bodies 5a and 5b by bulge processing. Combined with the contact at, extremely high static permissible torque can be secured.
[0057]
It goes without saying that the fixing member 14 may be disposed with respect to the journal portions 11a and 11b.
[0058]
【Example】
A camshaft for a four-cycle reciprocating engine is manufactured by the method proposed in Japanese Patent Application Laid-Open No. 60-257933 described above, in which a camshaft for a four-cycle reciprocating engine is manufactured according to the embodiment shown in FIGS. Taking the case where the shaft was manufactured as a comparative example, the static permissible torque, the degree of freedom of the cam shape and the manufacturing cost of the camshaft obtained by each were evaluated.
[0059]
In the example, a short steel pipe made of high carbon Cr bearing steel subjected to spheroidizing annealing was used for the hollow bodies 5a and 5b, and the axial length of the short steel pipe was matched with the required cam width. The hollow shell 4 was a general STKM 13A steel pipe.
[0060]
Further, in the first bulge processing of the example, the initial set interval between the fixed molds 2a and 3a for forming the shaft part and the movable molds 2b, 3b and 2c and 3c for forming the protruding part is 6 mm, and the movable part for forming the protruding part The initial set interval between the molds 2b, 3b and 2c, 3c and the shaft forming movable molds 2d, 3d and 2e, 3e was set to 4 mm.
[0061]
This is because the movement of the movable mold in the second bulge processing is performed from the outside, so that the amount of bulging deformation accompanying bending of the bulged portion formed by the first bulge processing is fixed to the shaft portion molding fixed mold. This is because the shaft forming movable molds 2d, 3d and 2e, 3e side are more in number than the 2a, 3a side. With this setting, the expansion expansion of the hollow shell 4 in the cam members 10a, 10b is prevented. The protrusion-forming movable molds 2b, 3b and 2c, 3c were deformed almost symmetrically with the center in the width direction as the axis of symmetry.
[0062]
Furthermore, both the first bulge processing and the second bulge processing for the hollow shell 4 of the example were performed by applying an internal pressure of 250 MPa to the hollow shell 4.
[0063]
The camshaft after the bulge processing of the example was subjected to induction hardening on the surfaces of the cam members 10a and 10b to adjust the surface hardness to a desired value.
[0064]
The production conditions and evaluation results are shown together with the comprehensive evaluation in Table 1.
[0065]
[Table 1]

As shown in Table 1, in the embodiment, by performing the first bulge processing and the second bulge processing on the hollow shell 4, the cam member 10a having a necessary dimensional accuracy and a fixing strength with no practical problem, 10b could be provided.
[0066]
Normally, the static permissible torque required for the camshaft is said to be 98 N · m, but the example shows a good value exceeding this value and can be sufficiently put into practical use.
[0067]
In the description of the embodiments and other embodiments, the case where the hollow shaft with protrusions is a camshaft for a 4-cycle reciprocating engine has been taken as an example. However, the present invention is not limited to a camshaft, and can be equally applied to a hollow shaft with a protrusion having a hollow rotating shaft and a protrusion fitted on the outer peripheral surface of the rotating shaft by bulging. Examples of such a hollow shaft with a projection include a camshaft for a reciprocating compressor, a camshaft for a machine part having a cam mechanism, and the like in addition to a camshaft for a four-cycle reciprocating engine.
[0068]
In the description of the embodiments and other embodiments, the case where the hollow body is made of bearing steel is taken as an example. However, the hollow body in the present invention is not limited to bearing steel, and can be equally applied as long as it satisfies the required hardness and can be plastically processed. As materials that can be plastically processed, carbon steel for machine structure, alloy steel for machine structure, titanium alloy, and the like can be used in the same manner in addition to bearing steel.
[0069]
Furthermore, in the description of the embodiments and other embodiments, the case where the camshaft has two cam members is taken as an example. However, the present invention is not limited to the number of cam members, and is similarly applied even when the number of cam members is one or three or more.
[0070]
【The invention's effect】
As described above in detail, according to the present invention, since machining after bulge processing is not required, it can be manufactured at low cost, and the weight of the cam member can be reduced, so that dynamic balance during high-speed rotation can be achieved. In addition, it was possible to provide a manufacturing method capable of manufacturing a hollow shaft with a projection such as a cam shaft having high eccentricity with high production efficiency.
[0071]
Further, in the present invention, the cam member is manufactured not by a sintered alloy but by a material that can be plastically processed. By appropriately selecting this material, the cost of parts can be reduced, and the hollow shaft with protrusions can be further reduced. Can be manufactured. The significance of the present invention having such an effect is extremely remarkable.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing an initial set state of a bulge processing mold and a hollow shell before first bulge processing according to an embodiment.
FIG. 2 is a schematic longitudinal sectional view showing a state of the hollow shell after the first bulge processing of the embodiment.
FIG. 3 is a schematic longitudinal sectional view showing a state of a bulge processing die and a bulged cam shaft after the second bulge processing of the embodiment.
4 is a schematic cross-sectional view in which a bulge processing die as viewed in the direction of arrows in FIG. 1 is omitted.
FIG. 5 is a schematic cross-sectional view in which a bulge processing die as viewed in the direction of arrows in FIG. 3 is omitted.
FIG. 6 is a schematic cross-sectional view showing an arrangement mode of an eccentric portion molding member according to another embodiment.
FIG. 7 is a schematic cross-sectional view showing a shape after bulging of an eccentric molded member arrangement portion according to another embodiment.
FIG. 8 is a schematic cross-sectional view showing an arrangement mode of fixing members according to another embodiment.
FIG. 9 is a schematic cross-sectional view showing a pre-formed state of an arrangement portion of a fixing member according to another embodiment.
FIG. 10 is a schematic cross-sectional view showing a shape after bulging of an arrangement portion of a fixing member according to another embodiment.
[Explanation of symbols]
1: Bulge processing mold,
2: Upper mold,
3: Lower mold,
2a, 3a: Shaft part forming fixed mold,
2b, 2c, 3b, 3c: movable mold for forming projections,
2d, 2e, 3d, 3e: movable mold for forming the shaft part,
4: hollow shell,
5a, 5b, 6a, 6b: hollow body,
7a, 7b: tube end restraining jig,
7c, 7d: pipeline,
8a, 8b: Mold moving jig,
9: Camshaft
10a, 10b: cam members,
11a, 11b: Journal part
12: rotating shaft,
13: Eccentric part molding member,
14: fixing member,
15: Press mold for preforming,
15a: upper mold constituting a press mold for preforming,
15b: lower mold constituting a press mold for preforming,
16: Core.

Claims (1)

The hollow shell inserted inside the hollow body made of a plastically deformable material is accommodated in the bulge processing mold, and the hollow body is bulged to form the outer shape of the hollow body. A method for producing a hollow shaft with protrusions that undergoes the following steps (1) to (4) when the hollow shell and the hollow body are fitted together.
(1) As a bulge processing mold, a protruding part forming movable mold for forming the outer shape of the hollow body into a predetermined shape, a shaft part forming movable mold located on one side of the protruding part forming movable mold, and the other side Prepared is a bulging die that is divided into a fixed shaft forming mold and that is movable separately from the protruding mold forming mold and the shaft forming movable mold. Process,
(2) Protruding part forming movable mold and shaft part such that the prepared bulge processing mold shaft part forming fixed mold, protrusion part forming movable mold and shaft part forming movable mold have a predetermined interval. A step of setting a movable mold for molding, and housing a hollow shell inserted with a gap inside a hollow body made of a plastically deformable material in the bulge processing mold after the setting,
(3) bulging the hollow shell accommodated in the bulging mold and bringing the inner surface of the hollow body into contact with the outer surface of the hollow shell;
(4) The bulging process is continued by pressing the movable mold for shaft molding in the direction of the fixed mold for molding the shaft, and the hollow body is stretched on the inner surface of the hollow body molding bulge mold defined by three molds. A step of forming the outer shape of the hollow body into a predetermined shape and fitting the hollow shell and the hollow body.

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