JP5252371B2 - Engine steel connecting rod - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting rod whose flexural rigidity of a broken portion and separating load can be enhanced, and a method for manufacturing the same. <P>SOLUTION: A connecting rod member is cut and divided at both side portions of a through-hole into a rod section and a cap section, and then both the sections are fastened by a fastening member after division to form the connecting rod. In the connecting rod, radial lengths H1, H2 perpendicular to an axial center of a through-hole in each of cross-sectional forms in a pair of the broken portions are set longer than widths B1, B2 in the axial direction of the through-hole. Then, an insertion hole 8 for inserting the fastening member for fastening the rod section and the cap section is formed. Further, in an inner-diameter portion in the vicinity of the insertion hole 8, a width enlarged portions E1, E2 are formed in which the widths B1, B2 in the axial direction of the through-hole are set larger than a large-diameter portion made larger than the inner-diameter portion. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a steel connecting rod of the engine, steel connecting rods of the engine being fastened integrally with particular with fastening members from ruptured both sides sites Konro' de through holes for the engine to the rod portion and the cap portion About.

  A conventional connecting rod of an engine includes a rod portion and a cap portion fastened to the rod portion with a plurality of bolts, and is generally constituted by a forged member or a sintered member. Recently, however, a connecting rod cracking technology has been adopted in which a connecting rod made of a forged member made of a ductile metal material is manufactured as an integral part, then broken using a breaking device and divided into a rod part and a cap part. It is being done. Patent Document 1 discloses a method for breaking a ductile metal part, a breaking device, and a method for producing a ductile metal part.

  The connecting rod assembled in the engine is subject to compressive and tensile loads from the piston and crankpin, and the compression stress acting on the split surface between the rod and cap tends to decrease and the split surface tends to separate. Become. Therefore, one of the performances of the connecting rod is an index called “separation load”. This is because when the large-diameter portion and the small-diameter portion of the connecting rod are pulled away from each other, until the compressive strain at the inner peripheral end (the peripheral surface of the crankpin hole) of the dividing surface becomes zero, This is the tensile load that can be added.

  When the pair of fractured portions of the large-diameter portion of the connecting rod is fractured by the cracking technique, a cleaved brittle fracture surface is generated almost entirely in the fractured portion, but the dimple-shaped ductile fracture surface is present in the fracture surface. The crankpin hole (through hole) of the large-diameter portion of the divided connecting rod becomes an oval that is slightly extended in the length direction of the connecting rod. That is, microplastic deformation has occurred in the vicinity of the fracture portion. Therefore, when the cap part is fastened to the rod part with two bolts, a part of the bolt tension is consumed to eliminate the above-mentioned microplastic deformation or to deform many microprojections, The separation load tends to decrease.

FIG. 13 shows the shape of the split surface 100 of the current connecting rod made of sintered metal adopted by the applicant of the present application, and the bolt hole 101 is also shown. FIG. 14 shows the shape of the fracture split surface 200 of the connecting rod of the current forged product adopted by the applicant of the present application, and the bolt hole 201 is also shown.
In the dividing surface 100 and the fractured dividing surface 200 of these connecting rods, the radial length H perpendicular to the axis of the crankpin is set to be about 50 to 60% of the width B in the direction parallel to the axis.
JP 2005-144560 A

  In the conventional connecting rod splitting surface and fracture splitting surface, the radial length H perpendicular to the crankpin axis is set to about 50 to 60% of the width B parallel to the axis. In the state where the cap part and the cap part are fastened with a bolt, the bending rigidity (second moment of section) in the vicinity of the pair of split surfaces (fracture parts) of the connecting rod is lowered. Therefore, when a load that causes the small-diameter portion and the large-diameter portion of the connecting rod to separate from each other acts, the inner diameter side portion of the pair of split surfaces is easily deformed in the pulling direction, so that the separating load of the connecting rod can be increased. It is difficult to improve the performance of the connecting rod.

  And since the area of a division surface is also set large, since the compressive stress when fastened with fastening members, such as a bolt, also becomes low, it is difficult to raise separation load. In particular, in the case of a connecting rod manufactured by cracking technology, it is difficult to increase the separation load as described above.

An object of the present invention is an engine steel connecting rod that is split into a rod portion of a steel connecting rod and a cap portion of a steel connecting rod by breaking and then fastened with a fastening member, and increases the bending rigidity of the breaking portion, An object of the present invention is to provide a steel connecting rod for an engine capable of increasing the separation load.

Steel connecting rod of claim 1 engine is divided by breaking both sides site of the through holes of the steel connecting rod of the engine and the rod portion and the cap portion of the steel connecting rod of the steel connecting rods, they rod after split In a steel connecting rod for an engine in which a part and a cap part are fastened by a fastening member, a radial direction orthogonal to the axis of the through hole in each cross-sectional shape of the pair of fractured parts divided into the rod part and the cap part The length is set to be longer than the axial width of the through-hole, and in order to insert the fastening member that fastens the rod portion and the cap portion, an insertion hole is formed that penetrates each fractured portion orthogonally, A width expanding portion in which the axial width of the through-hole is set larger than the large-diameter side portion larger than the inner-diameter side portion is formed in the inner-diameter side portion in the vicinity of the insertion hole of each broken portion. Of this width extension Is characterized in that width is smaller than the radial width of the larger-diameter portion.

According to the present invention, is divided by fracture both sides site of the through holes of the steel connecting rod of the engine and the rod portion and the cap portion of the steel connecting rods steel connecting rods, after split and their rod portion In a steel connecting rod of an engine in which a cap part is fastened by a fastening member, a radial length perpendicular to the axis of the through hole in each cross-sectional shape of the pair of fractured parts divided into the rod part and the cap part because There is set longer than the axial width of the through hole, wherein the fastening condition by the fastening member, since the flexural rigidity of the breaking portions on both sides of the through-hole (second moment) is high, the rod portion and the cap portion bets can be increased remarkably the separation load when the load is applied to a direction to phase separation, the high-performance metal part.

In order to insert a fastening member that fastens the rod portion and the cap portion , insertion holes are formed through the respective fractured portions orthogonally, and an inner diameter side portion of each fractured portion in the vicinity of the insertion hole is formed. The width-expanded portion with a larger diameter in the axial direction of the through hole is formed than the large-diameter side portion, which is larger than the inner-diameter side portion, so that the bending rigidity of the fractured portion is prevented from being lowered by the insertion hole. Thus, it is advantageous in increasing the bending rigidity of the fractured portion. And it becomes possible to make the cross-sectional area of a fracture | rupture part small by making the width | variety of a large diameter side part small. Therefore, in a state where the rod portion and the cap portion are fastened by the fastening member, it is possible to increase the compressive stress acting on the fracture portion, and as a result, it is possible to increase the separation load, and to the steel connecting rod . The manufacturing cost can be reduced by reducing the amount of metal material used.
Further, since the radial width of the width expanding portion is formed smaller than the radial width of the large diameter side portion, the area in the vicinity of the insertion hole can be reduced, so that the surface pressure in the vicinity of the insertion hole can be increased. Since the fastening force can be increased, the separation load can be increased.

  Hereinafter, the best mode for carrying out the present invention will be described based on examples.

First, a steel connecting rod which is a metal part will be described.
As shown in FIGS. 1 and 2, the connecting rod is manufactured by forging using a ductile forging steel. The connecting rod 1 includes a rod portion 2, a cap portion 3, and these rod portions 2. And a pair of bolts 4 as fastening members for fastening the cap part 3 to each other.
As shown in FIGS. 1 and 2, when the cap portion 3 is fastened to the rod portion 2 by a pair of bolts 4 inserted through the insertion hole 8 and the fracture portion 6 is brought into close contact with each other, the large-diameter portion of the connecting rod 1 is used. A circular through hole 5 is formed in 1 a, and a pin hole 9 is formed in the small diameter portion 1 b of the connecting rod 1.

  When the connecting rod 1 is manufactured, the connecting rod member 1A (see FIG. 3) is manufactured as an integral product by forging, and then the boundary between the rod portion 2 and the cap portion 3 is broken to break the rod portion 2 and the cap portion 3. And split. In such a divided state, the rod portion 2 corresponds to the first divided component, and the cap portion 3 corresponds to the second divided component.

  When the connecting rod member 1A is divided, the breaking device 10 shown in FIG. 3 is used. At the time of this breakage, a pair of notches 7 is formed in a portion corresponding to the breakage portion 6 (see FIGS. 1 and 2) on the inner peripheral surface of the through hole 5. Thereafter, as shown in FIG. 3, a pair of mandrels 11 (expansion tools) positioned on both sides of the notch 7 are set in the through hole 5, and a V-shaped gap 12 formed between the mandrels 11 is set. The wedge member 13 is inserted, the wedge member 13 is connected to the tip of the output rod 15 of the hydraulic cylinder 14, and the wedge member 13 is instantaneously forcibly inserted into the V-shaped gap 12 by the hydraulic cylinder 14. A break is generated with the pair of notches 7 as the starting point of the break, and the rod portion 2 and the cap portion 3 are divided. Most of the fracture surface 6 (divided surface) is a fracture surface such as a cleaved brittle fracture surface, and this fracture surface includes a dimple-shaped ductile fracture surface having a large number of microprojections.

  By the way, in the case of the connecting rod 1 manufactured by cracking as described above, a small plastic strain is generated in the outer peripheral side wall portion of the through hole 5, the roundness of the through hole 5 is reduced, and the through hole 5 is longer than the length of the connecting rod 1. The shape is distorted in the vertical direction. However, the roundness of the through hole 5 is ensured by polishing the inner surface of the through hole 5 in a state where the rod part 2 and the cap part 3 are fastened by the fastening member (bolt 4).

  Here, the small diameter portion 1b of the connecting rod 1 is connected to the piston of the engine via a pin member, the large diameter portion 1a of the connecting rod 1 is connected to the crank pin of the crankshaft, and the cap portion from the rod portion 2 during operation of the engine. A large separation load acting to separate 3 acts. Therefore, the maximum separation load that the connecting rod 1 can withstand is an important index for evaluating the performance of the connecting rod 1.

  When measuring the separation load of the connecting rod 1 manufactured by cracking, a fastening member (bolt 4) is set in a predetermined state with a strain gauge attached to a portion corresponding to the fracture surface 6 of the inner peripheral surface of the through hole 5. By tightening strongly with the fastening force of, the broken portion 6 and the wall portion in the vicinity thereof are compressed, and in that state, a “tensile load” is applied to separate the large diameter portion 1a and the small diameter portion 1b from each other. The tensile load when the strain of the strain gauge becomes zero while reducing the compressive strain of the fracture surface 6 and the wall portion in the vicinity thereof is defined as “separation load”. Hereinafter, the “separation load” described in this specification refers to the above-described separation load.

  By the way, in the case of the connecting rod 1 manufactured by cracking, there is a ductile fracture surface in which a large number of microprotrusions as described above are present on the fracture surface 6, and a minute plastic strain is generated on the outer peripheral side wall portion of the through hole 5. In addition, a part of the fastening force by the fastening member 4 is absorbed (consumed) there, so that the separation load tends to decrease.

  Therefore, the inventors of the present application develop based on quality engineering to determine a desirable sectional shape of the fractured surface (that is, a desirable sectional shape appearing in the XX section of FIG. 1) using a quality engineering technique. It was. The contents and desirable cross-sectional shape will be described below.

  As shown in FIGS. 4 and 5, as a quality engineering control factor for the connecting rod 1, a reference length, an aspect ratio, a vertical step ratio, a reference seat R and the like for securing a bolt seat were selected. For these control factors, three levels of levels 1, 2, and 3 were set. Level 2 shows an average value, level 1 shows a lower value than level 2, and level 3 shows a higher value than level 2. In FIG. 4, 12 models having 4 factors × 3 levels are set.

  As shown in FIG. 6, as a quality engineering error factor for the connecting rod 1, a cross-sectional area, a middle concave amount, and a middle convex amount are selected, and N1 (advantage) and N2 (disadvantage) are selected as shown in FIG. Various quantities of error factors were set. As shown in FIG. 7, the center recess is a state in which a gap is generated between the fractured surfaces 6 a without being fastened by a fastening member on the inner peripheral surface of the through hole 5 </ b> A. State.

  Four models of the N1 and N2 connecting rod models for the 12 models shown in FIG. 4, that is, a total of 24 connecting rod models are machined to deform the bolt seat angle, the amount of the center recess, the amount of the center protrusion, etc. Was made by folding. FIG. 7 is a perspective view of the connecting rod model 1M. The connecting rod model 1M includes a rod portion substitute portion 3B as a substitute for the rod portion, a cap portion 3A, a bolt hole 8A, a through hole 5A, and the like.

  Next, for each of a total of 24 connecting rod models 1M, in a state where the fastening member 4 is fastened with three fastening forces (10KN, 25KN, 40.8KN), the rod part substitute part 3B and the cap part 3A are The separation load was measured when a load in the separation direction to be separated was applied. Although the measurement results are omitted, FIG. 8 shows the “S / N ratio” obtained from the measurement results, and FIG. 9 shows the “sensitivity” obtained from the measurement results.

  The “S / N ratio” is an index indicating a property that depends on an error, and is preferably as large as possible. “Sensitivity” is proportional to “SNR” and is an index indicating a property that depends on an error. 8 and 9, A1, A2, A3,... Shown on the horizontal axis indicate connecting rod models 1M classified by control factors A to D and levels 1, 2, and 3. In FIG. A connecting rod model indicated by “double circle” is desirable for each control factor.

As can be seen from FIGS. 8 and 9, the control factor A (reference length) has a desirable result for the A1 model, and therefore “14.5” mm is a desirable value for the “reference length”.
As for the control factor B (aspect ratio), the B3 model had a desirable result, and it was found that “1: 1.2” is a desirable value for the “aspect ratio”. With respect to the control factor C (vertical step ratio), the model C1 had desirable results, and it was found that “1: 2” was a desirable value for the “vertical step ratio”. For the control factor D (reference locus R), the model D3 has a desirable result, and therefore, it was found that “0” is a desirable value for the “reference locus R”.
The optimum shape of the fracture surface 6a (divided surface) of the connecting rod model 1M obtained as described above is as shown in FIG. However, the numerical values in FIG. 10 are not strictly limited.

In consideration of the above examination results, the shape of the desired fracture surface (divided surface) of the connecting rod 1 manufactured by the cracking technique will be supplementarily described.
FIG. 11 shows the shape of a particularly desirable fracture surface 6A (divided surface) that the applicant intends to adopt in the future. In the shape of the fracture surface 6A (divided surface), the width B1 in the direction parallel to the axis of the through hole is B1 = 14.5 mm, and the length H1 in the direction orthogonal to the axis of the through hole is H1 = width B1 × (1.1 to 1.2), the vertical step ratio h1: h2 is 1: 2, the reference seat R is 0, and the cross-sectional area of the fracture surface 6A is, for example, 260 mm ² .

  In the fracture surface 6A, an insertion hole 8 (bolt hole) that penetrates the fracture surface orthogonally is formed, and the inner diameter side portion in the vicinity of the insertion hole 8 of each fracture surface 6A is larger than the inner diameter side portion. A width expansion portion E1 is formed in which the axial center width C of the through hole is set larger than that of the large diameter side portion.

  FIG. 12 shows the shape of a particularly desirable fracture surface 6B (divided surface) that the applicant intends to adopt in the future. In the fracture surface 6B, a width expansion portion E2 similar to the width expansion portion E1 is formed, and the length H2 in the direction orthogonal to the axial center of the through hole is set to be larger than the width B2 in the direction parallel to the axial center of the through hole. Has been. Further, in the large diameter side portion larger than the inner diameter side portion, a wall portion 8a having a predetermined thickness is formed on the outer peripheral side of the insertion hole 8, and the axial parallel direction width b of the large diameter side portion is set small. ing.

The operation and effect of the connecting rod 1 shown in FIGS. 10 to 12 described above will be described.
In the connecting rod 1 shown in FIG. 11, the radial length H <b> 1 perpendicular to the axis of the through-hole 5 in each cross-sectional shape of the pair of fractured portions 6 divided into the rod portion 2 and the cap portion 3 is the through-hole 5. Since it is set to be longer than the axial center direction width B1, the bending rigidity at the fracture portions on both sides of the through hole 5 is increased in the state of being fastened by the fastening member 4, so that the rod portion 2 and the cap portion 3 are separated from each other. The separation load when the load acts on the rod can be significantly increased, and the connecting rod 1 with high performance is obtained.

  Since the width expansion portion E1 is formed, it is advantageous in preventing the bending rigidity of the fracture portion from being lowered by the insertion hole 8 and increasing the bending rigidity in the fracture portion. In addition, since the axial center parallel direction width B1 of the outer diameter side portion on the outer diameter side of the width expansion portion E1 can be reduced and the cross-sectional area of the fracture portion can be reduced, the fastening member 4 is fastened. Since the compressive stress in can be set large, it is advantageous in increasing the separation load.

In addition, since the radial width of the width expanding portion E1 is smaller than the radial width of the large diameter side portion, the area in the vicinity of the insertion hole 8 can be reduced. Since the fastening force can be increased, the separation load can be increased.
In the connecting rod of FIG. 12, since the same operation and effect as described above are achieved, the width b of the outermost diameter side portion of the outer diameter side portion on the outer diameter side of the width expanding portion E2 is reduced. The cross-sectional area of the fracture portion can be further reduced, and the weight can be reduced.

  The manufacturing method of the connecting rod 1 of the present application is such that the radial lengths H1 and H2 perpendicular to the axial center of the through hole 5 in each cross-sectional shape of the pair of fractured parts divided into the rod part 2 and the cap part 3 are formed as through holes. 5 is set to be longer than the axial center widths B1 and B2, thereby increasing the bending rigidity at the fracture portion and increasing the separation load at the fracture portion.

It In the above embodiment has described the case of applying the present invention to forging steel connecting rod of the engine as an example, the present invention is applicable to a variety of steel connecting rod other than forging steel connecting rod of the engine Of course.

It is a front view of the connecting rod which concerns on the Example of this invention. It is the II-II sectional view taken on the line of FIG. It is a principal part sectional view of a breaking device and a connecting rod member which breaks a connecting rod member. It is explanatory drawing which shows 12 models divided according to the control factor and the level. It is a graph which shows the content of a control factor and a level. It is a graph which shows the content of an error factor and advantage / disadvantage. It is a perspective view of a connecting rod model. It is a diagram which shows the S / N ratio about 12 models. It is a diagram which shows the sensitivity about 12 models. It is a graph which shows the optimal value of the control factor regarding the fracture surface of a connecting rod. It is a top view of the desirable torn surface shape of a connecting rod. It is a top view of the desirable torn surface shape of another connecting rod. It is a top view of the division surface of the conventional sintered metal connecting rod. It is a top view of the torn surface shape of the connecting rod of the conventional forged product.

1 Connecting rod 2 Rod part 3 Cap part 4 Bolt (fastening member)
5 Through-hole 6 Breaking part 8 Insertion hole H1, H2 Radial length B1, B2 Axial width E1, E2 Width expansion part

Claims (1)

It is divided by breaking both sides site of the through holes of the steel connecting rod of the engine and the cap portion of the rod and steel connecting rod of steel connecting rod, the cap portion and their rod portion after divided is fastened by a fastening member In steel connecting rods for engines ,
The radial length orthogonal to the axial center of the through hole in each cross-sectional shape of the pair of fractured portions divided into the rod portion and the cap portion is set longer than the axial width of the through hole ,
In order to insert a fastening member that fastens the rod part and the cap part, an insertion hole is formed that penetrates each fractured part orthogonally,
A width expanding portion in which the axial width of the through-hole is set larger than the large-diameter side portion larger than the inner-diameter side portion is formed in the inner-diameter side portion in the vicinity of the insertion hole of each broken portion. A steel connecting rod for an engine, wherein the radial width of the widened portion is smaller than the radial width of the large-diameter side portion .