JP4063703B2 - Crankshaft manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crankshaft used in a reciprocating pump or the like, and more particularly to a manufacturing method thereof.
[0002]
[Prior art]
A conventional general reciprocating pump for transporting liquid by reciprocating movement of a piston or plunger (hereinafter collectively referred to as “piston”) includes a cylinder, a piston that reciprocates in the cylinder, and a drive unit that drives the piston. I have. A so-called pump chamber is formed at the end of the cylinder opposite to the drive unit. Moreover, the drive part is provided with the crankshaft for receiving the motive power from motors, such as an electric motor and an internal combustion engine, and rotating and converting into the reciprocating linear motion of a piston.
[0003]
The crankshaft in the reciprocating pump as described above is composed of a hollow shaft-like connecting portion connected to the output rotation shaft of the prime mover and a crank portion having a crankpin eccentric from the central axis of the connecting portion. .
[0004]
As conventional crankshaft manufacturing methods, the following three methods are known.
[0005]
The first method is to obtain a predetermined shape by machining a crank part and a connection part using a round bar of alloy steel subjected to quenching and tempering as a raw material.
[0006]
The second method is to forge a portion corresponding to the crank part to a non-tempered alloy steel round bar to obtain an approximate shape, and after using this as a raw material, the crank part and the connecting part are machined. Processing to obtain a predetermined shape.
[0007]
A third method is a method disclosed in the following Patent Document 1, and after joining a material corresponding to the connecting portion and a material corresponding to the crank portion to each other by welding, a predetermined shape is formed by machining. Is to get.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 50-133364
[Problems to be solved by the invention]
However, the conventional crankshaft manufacturing method as described above has various problems.
[0010]
That is, in the first and second methods described above, the machining of the connecting portion is performed on the bottomed hole having a certain depth formed by the hole and the key groove portion that are aligned with the output rotation shaft of the prime mover. Since this is a process, there is a problem that it takes time and costs to process the key groove.
[0011]
Further, the third method has a problem that slag entrainment and other welding defects are likely to occur in the welded portion.
[0012]
Accordingly, an object of the present invention is to provide a manufacturing method capable of solving the conventional technical problems and manufacturing a crankshaft having a desired shape easily and inexpensively.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a key groove portion having a hole (38) into which the rotating shaft (24) is fitted and connected, and into which a fastening key (40) with the rotating shaft (24) is inserted. A crank part having a crank pin (44) formed integrally with the connection part (34) in which (42) is formed and the connection part (34) and being eccentric from the central axis (C) of the connection part (34) ( 36), a hollow shaft-shaped connecting portion material (134) serving as the connecting portion (34) is prepared, and a round bar-shaped crank portion material serving as the crank portion (36) is prepared. (136) is prepared, and the hole (38) and the key groove portion (42) are processed in the portion (46) on one end side with respect to the connection portion material (134), and the inner diameter is the hole (38) on the other end side. Forming an enlarged diameter part (48) larger than the inner diameter of the connecting part material (134) The end face of the other end side (50) against the one end surface of the crank portion material (136) and friction welding, after friction welding the definitive, the outer shape of the crank portion material to form a crank pin (44) (136) And the outer shape of the connection portion material (134) is processed to adjust the outer diameter of the connection portion material (134) .
[0014]
In this method, a non-heat treated steel material can be used as the connecting portion material (134) and the crank portion material (136). Since the means for joining both materials (134, 136) is friction welding, the reliability of the joint (52) is high.
[0015]
In addition, in order to increase the surface pressure at the start of friction welding and to enable friction welding with certainty, it is effective to make the end surface (50) of the connecting portion material (134) a tapered surface.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 is a cross-sectional view showing a reciprocating pump 10 for transporting liquid by reciprocating pistons according to an embodiment of the present invention. The reciprocating pump 10 shown in the figure is basically of a general triple type known from the past, and three cylinders 12 are arranged in parallel to each other, and a piston ( Plunger) 14 is provided so as to be able to reciprocate. A drive unit 16 for reciprocating the piston 14 is provided on one end side of the cylinder 12, and a pump chamber (not shown) is provided on the other end side. The pump chamber includes a valve device for sucking the liquid into the pump chamber and discharging the liquid from the pump chamber to the outside when the piston 14 is reciprocated in the cylinder 12.
[0018]
The drive unit 16 includes a crankcase 20 constituting a part of the pump casing 18 and a prime mover 22 such as an electric motor or an internal combustion engine disposed outside the crankcase 20. Further, in the crankcase 20, a crankshaft 26 connected to the output rotary shaft 24 of the prime mover 22 and rotationally driven, a piston base 30 integrally fixed to the piston 14 via a piston rod 28, and a piston A connection rod 32 that connects the base 30 and the crankshaft 26 is provided. When the prime mover 22 is driven and the crankshaft 26 is rotated in a predetermined direction, the rotational force is transmitted through the connection rod 32, the piston base 30 and the piston rod 28, and the piston 14 reciprocates in the cylinder 12. Has been.
[0019]
2 and 3 show a crankshaft 26 manufactured according to the manufacturing method of the present invention. As understood from FIGS. 1 to 3, the crankshaft 26 includes a hollow shaft-shaped connection portion 34 and a crank portion 36 integrated with the connection portion 34. The connecting portion 34 has a hole 38 into which the output rotary shaft 24 of the prime mover 24 is fitted and connected, and a key 40 for fastening the output rotary shaft 24 and the crankshaft 26 to the inner peripheral surface of the hole 38. A key groove portion 42 is formed in which is inserted. The crank portion 36 has three crank pins 44 that are rotatably engaged with the respective connection rods 32. The three crank pins 44 are eccentric from the central axis C of the connecting portion 36 by the same eccentric amount. Further, these crank pins 44 are formed at equal angular intervals (120-degree intervals) so that the three pistons 14 are reciprocated while deviating at a constant period.
[0020]
Next, a procedure for manufacturing such a crankshaft 26 will be described with reference to FIGS.
[0021]
First, a hollow shaft-shaped member made of non-heat treated steel is prepared as the connection portion material 134 that becomes the connection portion 34. Further, as the crank part material 136 to be the crank part 36, a solid round bar made of non-heat treated steel is prepared. The outer diameter of the crank part material 136 is preferably substantially the same as the outer diameter of the connection part material 134. As will be described below, the connecting portion material 134 and the crank portion material 136 are joined to each other by friction welding.
[0022]
Here, non-tempered steel is steel that has not been tempered (quenched / tempered), and is strengthened by precipitation of fine carbonitriding additives such as vanadium during the cooling operation after hot forging. Say. Non-tempered steel has the characteristics that it can reduce the costs associated with tempering and has excellent uniformity in mechanical properties such as hardness.
[0023]
Next, as shown in FIG. 4, the connecting portion material 134 is machined so that a hole 38 having an inner diameter substantially the same as the outer diameter of the output rotary shaft 24 of the prime mover 22 is formed. This processing is performed on a portion 46 having a certain length from the end opposite to the crank portion 36. Further, a key groove portion 42 that receives a key 40 for fastening the output rotary shaft 24 and the crankshaft 26 of the prime mover 22 is machined on the inner peripheral surface of the portion 46. Since the machining of the hole 38 and the key groove portion 40 is performed on the connection portion material 134 that is hollow over the entire length, it is not much laborious as compared with the case of performing the processing on the bottomed hole. Accordingly, the processing time can be shortened, and the processing cost can be reduced. Furthermore, since it can process easily, it contributes also to the improvement of a processing precision.
[0024]
Further, the connecting portion material 134 is processed to have an inner diameter larger than that of the portion 46 in the portion 48 within a predetermined length from the end portion on the side where the crank portion material 136 is friction-welded. When this portion 48 is referred to as an enlarged diameter portion because the inner diameter is enlarged, the length of the enlarged diameter portion 48 is long enough to perform friction welding, and storage of burrs caused by friction welding is performed. The size should be a part. The inner diameter of the enlarged diameter portion 48 is larger than the maximum length from the central axis C of the connecting portion material 134 to the outer end of the key groove portion 42. Thereby, the inner periphery and the outer periphery of the cross-sectional shape of the enlarged diameter portion 48 are always circular over the entire length of the enlarged diameter portion 48, and no depression or the like by the key groove portion 42 is formed.
[0025]
Further, machining is performed so that the end surface 50 on the diameter-enlarged portion 48 side is inclined with respect to the central axis C of the connecting portion material 134, that is, a tapered surface. It is preferable that the inner peripheral edge of the tapered surface 50 protrudes more than the outer peripheral edge.
[0026]
When the machining for the connecting portion material 134 is completed, the connecting portion material 134 and the crank member 136 are set in a known friction welding apparatus (not shown), and the friction welding is performed. Here, the friction welding refers to a technique in which two members are butted while rotating and both the members are joined by applying frictional heat to the abutting surfaces and applying a strong pressure.
[0027]
Since it is joining by such friction welding, high reliability is obtained in the joining part 52. Moreover, since the end surface 50 of the connection part material 134 is a taper surface, a contact area is small at the time of the start of friction welding, a surface pressure can be raised, and friction welding can be performed reliably. In addition, in this embodiment, the part where the crank part material 136 first contacts the connection part material 134 is the inner peripheral edge of the end surface 50 of the connection part material 134, and the inner diameter of the enlarged diameter portion 48 of the connection part material 134 is other than that. Therefore, as the friction welding progresses, the burr 54 is stored in the enlarged diameter portion 48 as shown in FIG. 5, and the burr 54 enters the portion 46 of the connecting portion material 134. Thus, problems such as preventing insertion of the output rotating shaft 24 of the prime mover 22 are prevented. Further, since the diameter-enlarged portion 48 absorbs the influence of heat at the time of friction welding, it is possible to prevent a change in the hole machining size of the portion 46 and maintain high accuracy.
[0028]
When the friction welding is completed, machining for adjusting the outer diameter of the connection material 134 based on the central axis C of the connection material 134, machining for forming the crank pin 44 on the crank material 136, or the like. Perform external processing. Thus, the crankshaft 26 having the shape shown in FIGS. 2 and 3 is manufactured.
[0029]
In this way, since the crankshaft 26 is manufactured by joining the two materials 134 and 136 made of non-heat treated steel by friction welding, the strength of the entire crankshaft 26, particularly the crank portion 36, becomes uniform, and the tempered alloy There is no worry that the hardened layer disappears due to cutting as in the case of using steel as a material. 2, reference numeral 56 indicates a screw hole into which a screw 58 (see FIG. 1) for fixing the key 40 to the key groove portion 42 is screwed.
[0030]
According to the manufacturing method according to this embodiment described above, it is possible to easily manufacture a highly accurate crankshaft, but it goes without saying that the present invention is not limited to the above-described embodiment.
[0031]
For example, in the said embodiment, although the connection part raw material and the crank part raw material are the same alloy steel, since the friction welding method is utilized, the raw materials of a different material can be joined.
[0032]
Moreover, in the said embodiment, although the taper end surface 50 has taken the form in which the inner periphery protrudes from the outer periphery, conversely, the form in which the outer periphery protrudes from the inner periphery may be sufficient.
[0033]
Furthermore, the crankshaft manufactured by the method of the present invention is not limited to a triple reciprocating pump, but may be used for other multiple reciprocating pumps, a single reciprocating pump, or other mechanisms.
[0034]
【The invention's effect】
As described above, according to the manufacturing method of the present invention, a crankshaft having a predetermined shape can be manufactured easily and with high accuracy. Since the manufacturing is easy, the cost required for the manufacturing can be reduced. In addition, since the two materials are joined by friction welding, the performance and reliability of the reciprocating pump using the crankshaft manufactured by the method is combined with the high reliability and high precision of the joint. It will also contribute to the improvement of performance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a triple reciprocating pump to which a crankshaft manufactured by the method of the present invention can be applied.
FIG. 2 is a partial sectional side view showing an embodiment of a crankshaft manufactured by the method of the present invention.
FIG. 3 is a view taken along the line III-III in FIG. 2;
4 is a partial cross-sectional side view showing a connecting portion material and a crank portion material used in manufacturing the crankshaft shown in FIGS. 2 and 3. FIG.
5 is a partial cross-sectional side view showing a state in which the connecting portion material and the crank portion material of FIG. 4 are friction-welded. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Reciprocating pump, 12 ... Cylinder, 14 ... Piston, 16 ... Drive part, 22 ... Motor | power_engine, 24 ... Output rotary shaft, 26 ... Crankshaft, 34 ... Connection part, 36 ... Crank part, 38 ... Hole, 40 ... Key, 42 ... Key groove, 44 ... Crank pin, 48 ... Expanded diameter part, 50 ... End surface (tapered surface), 52 ... Junction, 54 ... Burr.

Claims (2)

A connecting portion (34) having a hole (38) into which the rotating shaft (24) is fitted and connected, and having a key groove portion (42) into which a fastening key (40) with the rotating shaft (24) is inserted. ) And a crank part (36) provided integrally with the connection part (34) and having a crank pin (44) eccentric from the central axis (C) of the connection part (34). In the method of producing
Prepare a hollow shaft-shaped connecting portion material (134) to be the connecting portion (34),
Prepare a round bar-shaped crank part material (136) to be the crank part (36),
The hole (38) and the key groove part (42) are processed in the part (46) on one end side with respect to the connection part material (134), and the inner diameter on the other end side is larger than the inner diameter of the hole (38). Forming a larger diameter expansion part (48),
The end surface (50) on the other end side of the connection portion material (134) and one end surface of the crank portion material (136) are brought into contact with each other and friction-welded,
After the friction welding, the outer shape of the crank part material (136) is processed to form the crank pin (44), and the outer diameter of the connection part material (134) is adjusted to adjust the outer diameter of the connection part material (134). A method of manufacturing a crankshaft characterized by machining an outer shape.   The method of manufacturing a crankshaft according to claim 1, wherein the end surface (50) of the connecting portion material (134) is a tapered surface.

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