JPH11333520A - Method for straightening bend of crankshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To straighten the bend of a crankshaft without lowering the fatigue strength in fillet parts by cold roll-working, with high dimensional accuracy, moreover, at high efficiency. SOLUTION: The expansion and contraction amount of arms is measured after cold roll-working of the fillet parts and, with the same cold working roll 5 used for cold roll-working in the case the expansion or contraction amount of the arms is larger than a prescribed amount of expansion or contraction and with the same cold working roll 5 used for cold roll-working in the case the expansion or contraction amount is smaller, when straightening roll-working is respectively executed at a high specific pressure than that at the time of cold roll-working to journal fillet parts 2 and pin fillet parts 4a, the fatigue strength in these fillet parts is not lowered, high dimensional accuracy is obtained because the expansion or contraction amount of the arms comes the prescribed expansion or contraction amount and also the setting work of straightening rolls is unnecessitated because the cold working roll is used as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of straightening a crankshaft by straightening a bend generated on a crankshaft by cold straightening roll processing by a process for improving wear resistance of a pin and a process for improving durability of a fillet portion. Belongs to the technical field.

[0002]

2. Description of the Related Art In a crankshaft of an engine, an outer peripheral surface of a pin to which a connecting rod is connected is subjected to induction hardening to improve abrasion resistance and a pin fillet portion (a portion between a pin and an arm) which is a high stress generating portion. Cold rolling is performed on the joint corner portion) to improve the fatigue strength. By performing such processing, bending occurs in the crankshaft. The bend of the crankshaft is obtained by adding the strain generated in the pin fillet portion and the journal fillet portion (joint corner portion between the journal and the arm), which are the shape discontinuous portions, by the above processing. For example, the strain in these fillet portions is as follows. Usually, since the arm and the journal have high rigidity, they appear in the form of opening and closing the gap on the connection side of the arm with the journal. Excessive bending of the crankshaft not only hinders assembly of the engine, but also increases the rotational resistance of the crankshaft, causing a reduction in engine output and abnormal wear of the bearings. May be caused.

Therefore, in order to prevent the above-mentioned problems from occurring, the crankshaft is designed so that the amount of bending generated by these processes after the above-mentioned improvement of wear resistance and fatigue strength is within a specified value. Be corrected. Conventionally, the bent portion of the crankshaft is bent back using a powerful press (conventional example 1). Particularly, in the case of a large crankshaft, each component has extremely high rigidity, and it is practically impossible to return the bent portion. For this reason, a surplus portion is provided to each part, and the surplus portion is removed by machining (conventional example 2) to absorb the bending to produce a straight crankshaft. However, in the method of bending back using the press according to the conventional example 1, there is a possibility that the fatigue strength is reduced at the time of correcting the eccentricity. There was a problem to be solved, in that cost could not be reduced.

[0004] By the way, bend straightening designed to be able to straighten a bend of a workpiece such as a crankshaft without reducing the fatigue strength of a fillet portion imparted by cold rolling and without having to add extra thickness. The method is disclosed, for example, in Japanese Patent Publication No. 3-27289 (Conventional Example 3). That is, in order to improve the durability, when correcting the bending of the work which has already been solidified and compacted in advance, it is necessary to detect where and how much compressive internal stress must be applied, and perform the test before. A part of the fret portion in the circumferential direction is rolled at a higher specific rolling pressure than in the solidification rolling action so as to reduce the bending. A relatively smaller diameter consolidation compaction roll is used.

[0005]

According to the bending correction method for the crankshaft and the like according to the above-mentioned conventional example 3 (Japanese Patent Publication No. 3-27289), the disadvantages of the conventional examples 1 and 2 can be solved. It is considered very useful. However, in the bending correction method for the crankshaft and the like according to the conventional example 3, the distance between the arms is not corrected at all. In other words, induction hardening to improve the wear resistance of the outer peripheral surface of the pin to which the connecting rod is connected,
Despite the fact that the opening / closing amount of the arm may be larger or smaller than the predetermined opening / closing amount due to the cold roll processing for improving the durability of the pin fillet portion which is a high stress generating portion, This opening / closing amount is not corrected. For this reason, the journal is inclined with respect to the rotation center line of the entire crankshaft, and the journal and the journal bearing may be abnormally worn and seizure may occur. In particular, the number of cylinders is large and the crankshaft is long. In such a case, the overall length dimension is disturbed, and the assembly of the engine is hindered.

Further, depending on the structure of the crankshaft, if the opening and closing amount of the arm is reduced, the arm may interfere with the connecting rod. According to the bending correction method for a crankshaft or the like according to the above-described conventional example 3, when the straightening roll processing is performed as described above, the solidified compaction roll used for the first solidification compaction action, that is, the fret portion Since a cold working roll with a smaller diameter than the cold working roll used to improve the fatigue life is used, a step of changing the cold working roll to a straightening roll before straightening is required, so straightening work This is not preferable for improving efficiency.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a high-efficiency straightening roll processing of a crankshaft capable of straightening the crankshaft so that the entire length of the crankshaft falls within a predetermined range. Is to provide a way.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in order to solve the above-mentioned problems, a method for correcting a crankshaft bending according to claim 1 of the present invention is employed. In addition to applying high frequency hardening to the outer peripheral surface of the pin to improve abrasion resistance, the pin fillet portion and the journal fillet portion are cold rolled by cold working rolls, and the fatigue strength of these fillet portions is improved. In the method of correcting the bending of the crankshaft due to the distortion caused after improving the, the opening and closing amount of the arm is measured with two displacement sensors after the high frequency quenching and the cold roll processing, When the opening / closing amount of this arm is larger than the predetermined opening / closing amount and the straightening is performed in a narrowing direction, the cold working roll used for the cold roll working is used to jar the arm. When the null fillet portion is rolled with a higher Hertzian surface pressure than that of the cold roll processing, and the opening / closing amount of this arm is smaller than a predetermined opening / closing amount, and when correcting in the expanding direction, the cold roll used for the cold roll processing is used. A straightening roll process is performed by rolling the pin fillet portion with a working roll at a Hertzian surface pressure higher than that of the cold roll process.

[0010] The means adopted in the crankshaft bending correcting method according to the second aspect of the present invention is to improve the wear resistance by performing induction hardening on the outer peripheral surface of the pin, and to improve the pin fillet portion by using a cold working roll. And a cold rolling process for the journal fillet portion to improve the fatigue strength of the fillet portion. After the inter-roll processing, the opening / closing amount of the arm is measured by two displacement sensors. When the opening / closing amount of the arm is larger than a predetermined opening / closing amount and is corrected in the direction of narrowing by δ, the cold roll used for the cold roll processing is used. When the straightening roll processing is performed by rolling the journal fillet portion with a higher Hertzian surface pressure than the cold roll processing by the cold working roll The correction roll processing is stopped when one displacement sensor indicates -δ / 2, and when the opening / closing amount of this arm is smaller than the predetermined opening / closing amount and correction is performed in the direction in which it is expanded by δ, a cold roll is performed. When the pin fillet portion is rolled with a higher Hertzian surface pressure than that of the cold roll processing by the cold working roll used for the roll processing to perform the straightening roll processing, and when one displacement sensor indicates δ / 2. The straightening roll processing is stopped.

According to a third aspect of the present invention, there is provided a crankshaft straightening method according to any one of the first and second aspects, wherein the crankshaft bending straightening method according to the third aspect of the present invention employs the crankshaft straightening method. When the radius of the fillet portion of the pin or the journal is R, the straightening roll processing is performed using a cold working roll having a center radius r of a center of the thickness and a tip radius r of a rolling roll of 0.6R to 0.95R. It is characterized by performing.

According to a fourth aspect of the present invention, there is provided a method of correcting a crankshaft according to any one of the first, second, and third aspects. When the shaft is made of a material having a tensile yield point of 35 to 90 kgf / mm ² , the pin or journal fillet of this crankshaft is
A straightening roll process is performed by pressing the fillet portion with a pressing force that generates a Hertzian surface pressure of 300 to 600 kgf / mm ² .

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a crankshaft correcting method according to an embodiment of the present invention.
FIG. 1 is a perspective view showing a portion, FIG. 2A is an external view of a crankshaft showing an open state of an arm, and FIG. 2B is an explanatory view showing an arrangement state of cold working rolls used for straightening roll working. )When,
FIG. 3 of an external view of a crankshaft showing a narrowed state of an arm.
(A), FIG. 3 (b) showing the arrangement of cold working rolls used for straightening roll processing, and FIGS. 4 (a) (b) and 5 (a) showing straightening roll processing explanatory views. (B) and FIGS. 6 and 7 (a) and (b) of an opening and closing start position explanatory view of the arm.
And FIG. 8 of the explanatory diagram showing the fatigue strength improvement rate.

As a result of a two-dimensional FEM deformation analysis as shown in FIGS. 6 and 7A and 7B, the inventors found that the bending of the crankshaft 1 was caused by a discontinuity in the crankshaft shape immediately below the cold roll working. The opening and closing of the arm 3 with the weakest portion or the free surface on the extension of the cold roll processing angle as the opening / closing start position is caused by opening and closing of the crankshaft 1.
It is found that the weakest portion due to the discontinuity of the crankshaft shape has a large effect on the bending of the pin fillet portion 4a, and further cold rolling is performed on the pin fillet portion 4a in order to improve the fatigue strength of the pin fillet portion 4a. The arms 3 and 3 are opened to increase the opening and closing amount, and the journal fillet portion 2a
It has been found that when cold rolling is performed on the journal fillet portion 2a to improve the fatigue strength of the arm, the arms 3 and 3 close and the opening / closing amount decreases. Therefore, the inventors have found that, in order to correct the bending of the crankshaft 1, for example, if the plate material is locally dented, if the pressing force is removed, the residual bending deformation centered on the depression becomes The present invention is based on the consideration that the phenomenon that occurs in the above-mentioned case should be utilized.

The present invention will be described in detail below. Reference numeral 1 shown in FIG. 1 indicates a well-known structure including a journal 2, arms 3, 3 and a pin 4 having an end connected to the arms 3, 3. The crankshaft has the following configuration.
Induction hardening is performed on the outer peripheral surface of the armature to improve abrasion resistance, and a journal fillet portion 2 which is a corner portion between the journal 2 and the arm 3 which is a high stress generating portion.
a and the pin fillet portions 4a, 4a, which are the corner portions of the arm 3 and the pin 4, are rolled by cold working rolls to improve the fatigue strength. By such a process, the interval on the opening side of the arms 3, 3, that is, the opening / closing amount becomes wider than the predetermined opening / closing amount, or conversely, becomes narrower. The measurement is performed by the two displacement sensors 11, 11.

As a result of measuring the opening / closing amount of the arms 3, 3 by the displacement sensors 11, 11, as shown in FIG. 2A, the opening / closing amount of the arms 3, 3 is larger than the predetermined opening / closing amount and only δ If the distance must be reduced, as shown in FIG. 2 (b), the interval between the arms 3 and 3 is reduced by δ so that a predetermined opening / closing amount is set in the journal fillet portion 2a.
To use the cold work roll 5 used for improving the fatigue strength of these fillet portions as it is, to generate a depression in the journal fillet portion 2a after the fatigue strength is improved, and to cause residual deformation to the arms 3 and 3. A higher Hertzian surface pressure is applied than in the case of cold roll processing, and a stronger pressing force is applied to the journal fillet portion 2a to perform straightening roll processing. One of the displacement sensors 11 indicates -δ / 2. Then, the straightening roll working by the cold working roll 5 is stopped. Next, the other journal fillet part 2
For a, the same straightening roll processing is performed,
When −δ / 2 is indicated on the other one of the displacement sensors 11, the straightening roll working by the cold working roll 5 is stopped.

On the other hand, as a result of measuring the opening and closing amounts of the arms 3 and 3 by the displacement sensors 11 and 11, as shown in FIG. 3A, the opening and closing amounts of the arms 3 and 3 are smaller than a predetermined opening and closing amount. When it is necessary to increase by δ, FIG.
As shown in the figure, the pin fillet portions 4a, 4a
Then, using the cold working roll 5 used for improving the fatigue strength of the fillet portion as it is, a straightening roll working is performed by applying a rolling pressure described later, and one of the displacement sensors 11 is used.
When + δ / 2 is shown in FIG. 5, the straightening roll working by the cold working roll 5 is stopped. Next, the same straightening roll processing is performed on the other pin fillet portion 4a, and when + δ / 2 is indicated on the other one displacement sensor 11, the straightening roll by the cold working roll 5 is used. Processing is stopped.

In this embodiment, a dial gauge is used as a displacement sensor. However, in consideration of unmanned measurement and shortening of processing time, for example, a non-contact type displacement sensor of a laser type or an eddy current type is used. It is preferably used.

FIGS. 4A and 4B and FIG.
As shown in (a) and (b), r is the radius of the tip end of the compacting roll surface with the center of the thickness of the cold working roll 5 as the radius, and R is the radius of the pin fillet portion 4a of the crankshaft 1. Then, the ratio r / R is 0.6 to 0.95 (r = 0.6R
０．９0.95R). The cold work rolls 5 are set 4a and 4a in these pin fillet portions such that the roll work angle α between the axis passing through the center in the width direction and the vertical axis is 35 to 60 °. As shown in FIG. 3B, a backup roll 6 receiving the reaction force of the cold working roll 5 is set on the opposite side of the pin 4 from the cold working roll 5.

FIGS. 4A and 4B and FIG.
The definitions of the symbols shown in (a) and (b) are as follows, respectively. R: radius of the fillet portion of the crankshaft r: tip radius of the rolling surface of the cold working roll α: roll working angle P: pressing force of the cold working roll δ / 2: arm opening amount θ: arm opening angle S: distance from opening and closing start position of the arm to the rolling surfaces tip cold work rolls L: distance from the opening and closing start position of the arm to the tip of the arm R _1: radius of the pin R _2: radius R ₁ of the cold-working rolls': R ₁ / cosα d: Permanent deformation amount of fillet portion Hereinafter, all the symbols used in the description are defined as above.

As described above, in both cases where the opening and closing amount of the arms 3 and 3 is larger than the predetermined opening and closing amount, the bending of the crankshaft 1 is caused by the straightening roll processing by the cold working roll 5 as described above. It was confirmed that the straightness was corrected and the degree of bending of the crankshaft 1 was within an allowable range. By the way, by correcting the bending of the crankshaft 1 by such straightening roll processing using the cold working roll 5, if the fatigue strength of the journal fret portion 2a and the pin fillet portion 4a of the crankshaft 1 is reduced by the cold roll processing. If something lowers than the secured fatigue strength,
This method of straightening the crankshaft cannot be applied.

Therefore, each fillet portion 2 of the crankshaft 1
In order to confirm the fatigue strength of a and 4a, the base material of the crankshaft (document 1), the cold-rolled crankshaft (document 2, bending correction by straightening roll processing is not performed), and straightening roll processing were performed. A bending fatigue test was performed on each of the bent crankshafts (Document 3), and the fatigue strength improvement rate of Material 3 (the fracture strength of the fillet portion of the crankshaft when the fatigue strength of the crankshaft base material was set to 1) Index). The fatigue test results are shown in FIG.
As shown in FIG. The test piece in FIG. 8 has a diameter of 291.5 mm, an arm thickness of 92 mm, and a tensile yield point of 76 kgf / mm ² (tensile strength of 96 kgf / mm ² ).
The material is JIS SCM440 equivalent steel.

According to FIG. 8, in the document 3, the fatigue strength of the fillet portion is improved by the straightening by the straightening roll process, and the fatigue strength of the fillet portion by the cold roll process is higher than that of the straight roll process. Does not decrease.

Incidentally, as described above, r / R is 0.6.
The roll processing angle α of the cold working roll 5 is set to be in the range of 35 to 60 °. Thus, r / R is 0.6
R / R is set to fall within the range of 0.95.
Is less than 0.6, the thickness of the cold working roll 5 is too thin to be corrected by one compaction, and 0.95
Exceeding the thickness, the thickness is too thick, and a strong pressurizing device is required. In addition, the outer circumference of the pin or the journal is formed due to the formation of the unstable rolling surface and the roll processing effect by being equal to the radius R of the fret portion. This has an adverse effect on the surface.

The range of the roll working angle α is the range in which the angle can be deflected due to the limitations of the apparatus (cold working roll storage cassette). Part α = 45 ° ± 10 °
This range is set in the vicinity because it is possible to perform processing that sufficiently satisfies this angle range. The Hertz surface pressure is 300 to 600 kgf / mm ^{2 in} terms of Hertz surface pressure.
Is selected. The range of the Hertzian surface pressure is set by the following procedure. In the present embodiment, the tensile yield point 7
A steel equivalent to JIS SCM440 of 6 kgf / mm ² was used, but a tensile yield point of 35 to 90 kgf / mm ² and a tensile strength of 6
It was confirmed that the same effect can be obtained for a material in the range of 0 to 105 kgf / mm ² .

The cold working roll 5 is used under various roll working conditions under a Hertzian surface pressure conversion of 300 to 600 kgf / m.
A hertzian surface pressure in the range of m ² is applied and both arms open and closed (δ /
The pressing force P required to correct 2) is determined by the following procedure using the concept of Hertzian surface pressure. _{A = 1/2 (1 /} R 1 '-1 / R + 1 / R 2 + 1 / r) ‥‥‥‥‥‥‥‥ B = 1/2 _{[(1 / R 1' + 1} / R) 2 + (1 / R ₂ -1 / r) ² +2 (1 / R ₁ '+ 1 / R) (1 / R ₂ -1 / r)] ^1/2 {cos} = B / A} In the Hertzian contact theory, the major and minor radii “a” and “b” of the contact ellipse with the fillet due to contact with the roll are the same for both the crankshaft and the roll. Longitudinal modulus of elasticity is 21000kgf
/ Mm ² and a Poisson's ratio of 0.3, a = 0.04 m (P / A) ^1/3 ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ b = 0. 04n (P / A) ^1/3 }, and the relationship between the pressing force P and the Hertzian surface pressure P ₀ is P = 2P ₀ πab / 3 ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥.

By the way, as shown in FIG. 4B, in order to open and close the arm by δ / 2, δ / 2 = d sin α · L / S ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥. ‥‥‥‥‥ In other words, permanent deformation of d = δ / 2 · S / (L sinα) ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ on the roll processing bottom of the fillet after the roll processing Must be given. The pressing force P that gives the permanent deformation amount d to the roll processing bottom of the fillet portion is P = [1 / A · (5000 d / k) ³ + (80πab) ² ] ^1/2 ‥‥‥‥. The pressing force P obtained by the above expression is 300 to 300 obtained from the above expression on the roll processing bottom of the fillet portion.
It is a pressing force for generating a Hertzian surface pressure of 600 (upper limit of the device capacity) kgf / mm ² , and it has been confirmed that it is effective to apply the pressing force P within this range to perform the straightening roll working. In addition, if the fillet portion has been subjected to cold roll processing for improving fatigue strength at the stage prior to the straightening roll processing, the cold roll processing has already been applied to the fillet roll processing bottom by cold roll processing. Since the permanent deformation processing is performed, the difference is selected as a necessary correction pressing force.

The above-mentioned m, n and k when cosＢ = B / A are known values given in Table 1 below, and are described in, for example, the Japan Society of Mechanical Engineers, Mechanical Engineering Handbook, etc. I have.

[Table 1]

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A crankshaft 1 used for straightening after cold roll processing has a single pin 4 as shown in FIG. 12, that is, a single cylinder, and is a so-called test piece. Therefore, a method of correcting the bending of the crankshaft confirmed from the bending correction result by such a test piece is described in, for example, a side view of a crankshaft for a multi-cylinder in FIG.
9 (a) and FIG. 9 (b) in the view of the arrow A in FIG. 9 (a) (this crankshaft is used for six cylinders). Or not.

The crankshafts used for confirming the applicability of the above-described method for correcting the bending of the crankshaft are denoted by reference numerals J1 to J7.
The diameter of the journal is 291.5 mm, the thickness of the arm is 92 mm, and the distance from the journal center to the pin center of the arm, that is, the piston stroke is 180 mm.
mm, the diameter of the pins indicated by reference symbols P1 to P6 is 271.5 m
m, the total length is 4055 mm, and the tensile yield point of each part is 76 kgf / mm ² (tensile strength 96 kgf
/ Mm ² ). The amount of bending of the crankshaft after the process of improving the wear resistance of each pin indicated by P1 to P6 and the fatigue strength of each fillet portion is described by the description of the amount of runout of the journal of the multi-cylinder crankshaft after the bending correction processing. As shown in FIG. 14 of the drawing, the maximum value was 0.56 mm.

First, the crankshaft shown in FIGS. 9A and 9B is converted into a wire model as shown in FIG. 10 showing the configuration of a wire model of a crankshaft for a multi-cylinder. The arm 3 is bent from the end of the pin 4 and the journal 2 and the arm 3 as shown in FIG. 11 showing the open state of the arm according to the wire model because the pin and the arm of the crankshaft are extremely rigid. And that the length of the pin 4, the journal 2, the arm 3 is invariable and that the single-throw crank as shown in FIG. Using a shaft (test piece), as shown in FIG. 13, the horizontal axis represents the pressing force P (ton) of the cold working roll, and the vertical axis represents the bending amount of the arm and the opening / closing angle θ of the arm. Against pressure The relationship between the bending amount of the arm and the opening / closing angle θ of the arm is obtained, and from this relationship, the straightening roll processing is performed so that the opening / closing amount of the arm is set to the predetermined opening / closing amount. The amount of shake in the Z direction was determined by calculation.

Next, the pin fret portion and the journal are cold-rolled so that the opening and closing amount of each arm of the multi-cylinder crankshaft having the structure shown in FIGS. 9A and 9B becomes a predetermined opening and closing amount. After correcting the bending by performing a straightening roll process on the fillet portion, the Z direction of each journal of the crankshaft (see FIGS. 9A and 10). The runout of｝ was measured. The straightening roll processing range between the pin fillet and the journal fillet by the cold working roll is ± 90 degrees at the pin fillet and ± 90 ° at the journal fillet with the center line of the arm passing through the center of the pin and the journal in the radial direction interposed therebetween. The range is 180 degrees.

That is, as shown in FIG. 10, a calculated value of the runout of the journal of the crankshaft (shown by a solid line and a white circle) and a measured value of the runout of the journal of the crankshaft (shown as a solid model) The solid lines and black circles are as shown in FIG. In this figure, the horizontal axis indicates journal numbers J1 to J7, and the vertical axis indicates the amount of run-out in the Z direction of each journal in mm. According to FIG. 14, the calculated value and the measured value are extremely similar. Then, the run-out amount of the journal of the crankshaft after the straightening roll processing is about 0.1 mm at the maximum, and is corrected so as to be within 0.5 mm which can sufficiently satisfy the user. It has been confirmed that the method for correcting the curvature can be sufficiently applied to practical use.

Of course, although not shown, the X and Y directions of the crankshaft (see FIGS. 9A and 10). ｝
It was confirmed that the run-out amount of each journal was the same as the run-out amount of each journal in the Z direction, and that all the bends of the crankshaft were corrected to be within 0.5 mm that could sufficiently satisfy the user. Thus, according to the method of straightening the crankshaft according to the present invention, the straightening roll working is performed by the cold working roll used for improving the durability of the fillet portion, and the bending of the crankshaft can be reduced in a short time. Could be corrected.

Therefore, according to the method for correcting the bending of the crankshaft according to the present invention, unlike the method for correcting the bending of the crankshaft or the like according to the above-described conventional example 3 in which the interval between the arms is not corrected at all, the journal is provided at the center of rotation of the entire crankshaft. Long cranks with a large number of cylinders, in addition to the excellent effect of not only causing the journal and journal bearings to wear abnormally, but also eliminating the risk of seizure, as well as reducing the inclination of the crank with respect to the line. Even if the shaft is used, since the overall dimensional accuracy is further improved, it can be easily incorporated into the engine.

Further, since the opening / closing amount of the arm is corrected to the predetermined opening / closing amount, there is no possibility that the arm will interfere with the connecting rod, and when performing the correction roll processing,
Conventional example 3 using a cold working roll smaller in diameter than the cold working roll used to improve the fatigue life of the fret portion
Unlike the method for straightening a crankshaft or the like according to the above, the straightening of the crankshaft is straightened by using the cold-working roll as it is for straightening roll processing, so that there is no need for a step of changing the set of rolls, greatly contributing to improvement of straightening work efficiency. can do.

In the above, as well understood from the above description and the accompanying drawings, the case where the crankshaft whose bending is corrected is formed integrally by forging has been described as an example. The technical idea according to the present invention can also be applied to a crankshaft having a configuration in which a pin and a pin are shrink-fitted, respectively. The range is not limited.

[0037]

As described above, according to the method for correcting the bending of the crankshaft according to the present invention, the method for correcting the bending of the crankshaft and the like according to the above-mentioned conventional example 3 in which the interval between the arms is not corrected at all. In contrast, the journal does not tilt with respect to the rotation center line of the entire crankshaft, not only does the journal and journal bearings wear abnormally, but also there is no danger of seizing, and a long crankshaft with a large number of cylinders is used. Even so, the overall dimensional accuracy is improved, and it can be easily incorporated into the engine. Furthermore, since the opening and closing amount of the arm is corrected to a predetermined opening and closing amount, there is no risk of the arm interfering with the connecting rod, and the cold working used to improve the fatigue life of the fret portion when performing straightening roll processing. Unlike the bending straightening method for a crankshaft or the like according to Conventional Example 3 using a cold working roll having a smaller diameter than a roll, the cold working roll is used for straightening roll working as it is, so that a roll change process is not required, and the crank There is an extremely excellent effect that it can greatly contribute to the improvement of the efficiency of the operation of straightening the shaft.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a part of a crankshaft for describing a method for correcting a crankshaft according to an embodiment of the present invention.

2 (a) is an external view of a crankshaft showing an opened state of an arm, and FIG. 2 (b) is an arrangement of a cold working roll used for straightening roll working according to the embodiment of the present invention. It is an explanatory view of a state.

FIG. 3A is an external view of a crankshaft showing a narrowed state of an arm according to the embodiment of the present invention.
(B) is an explanatory view of an arrangement state of a cold working roll used for straightening roll working.

FIG. 4 relates to the embodiment of the present invention, and FIG.
(B) is an explanatory view of straightening roll processing.

FIG. 5 relates to the embodiment of the present invention, and FIG.
(B) is an explanatory view of straightening roll processing.

FIG. 6 is an explanatory diagram of an opening / closing start position of an arm according to the embodiment of the present invention.

7A and 7B according to an embodiment of the present invention.
(B) is an explanatory diagram of the opening / closing start position of the arm.

FIG. 8 is an explanatory diagram showing a fatigue strength improvement rate according to the embodiment of the present invention.

9 (a) is an explanatory diagram of a configuration of a multi-cylinder crankshaft, and FIG. 9 (b) is a diagram of FIG. 9 (a) according to the embodiment of the present invention.
FIG.

FIG. 10 is a configuration explanatory diagram of a wire model of a multi-cylinder crankshaft according to the embodiment of the present invention.

FIG. 11 is an explanatory diagram of an open state of an arm based on a wire model according to the embodiment of the present invention.

FIG. 12 is a configuration explanatory view of a test piece of a crankshaft according to the embodiment of the present invention.

FIG. 13 is a diagram illustrating a relationship between a pressing force of a cold working roll and a bending amount of an arm according to the embodiment of the present invention.

FIG. 14 is a diagram illustrating a run-out amount of a journal of a multi-cylinder crankshaft after a straightening process according to the embodiment of the present invention.

[Description of Signs] 1 ... Crankshaft 2 ... Journal, 2a ... Journal fillet 3 ... Arm 4 ... Pin, 4a ... Pin fillet 5

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideaki Nagasaka 2-3-1, Shinhama, Arai-machi, Takasago-shi, Hyogo Inside Kobe Steel, Ltd. Takasago Works

Claims (4)

[Claims] An outer peripheral surface of a pin is subjected to induction hardening to improve abrasion resistance, and a cold roll is applied to a pin fillet portion and a journal fillet portion by a cold roll process, so that the fatigue of the fillet portion is reduced. In the crankshaft bending correcting method for correcting the bending of the crankshaft caused by the strain generated after improving the strength, the opening and closing amount of the arm is measured by two displacement sensors after the high frequency quenching and the cold roll processing. When the opening / closing amount of the arm is larger than a predetermined opening / closing amount and straightening is performed in a narrowing direction, the journal fillet portion is formed by the cold working roll used for the cold roll working at a higher Hertzian surface pressure than the cold roll working. Rolling, and when the opening / closing amount of this arm is smaller than the specified opening / closing amount, and cold-rolling when straightening in the expanding direction A straightening roll process by rolling the pin fillet portion with a higher Hertzian surface pressure than the cold roll process using the cold working roll used in (1). 2. An outer peripheral surface of a pin is subjected to induction hardening to improve abrasion resistance, and a pin work portion and a journal fillet portion are cold-rolled by a cold working roll, so that the fatigue of these fillet portions is reduced. In the crankshaft bending correcting method for correcting the bending of the crankshaft caused by the strain generated after improving the strength, the opening and closing amount of the arm is measured by two displacement sensors after the high frequency quenching and the cold roll processing. When the opening / closing amount of the arm is larger than a predetermined opening / closing amount and is corrected in the direction of narrowing by δ, the journal fillet portion is formed by the cold working roll used for the cold roll working so that the hertz surface is higher than that of the cold roll working. Rolling is performed by pressing with pressure, and when one displacement sensor indicates -δ / 2, the straightening roll processing is stopped. Also, when the opening and closing amount of the arm is smaller than a predetermined opening and closing amount and is corrected in the direction of expanding by δ, the pin fillet portion is higher in hertz than the cold roll working by the cold working roll used for the cold roll working. A straightening method of a crankshaft, characterized in that a straightening roll is performed by rolling with a surface pressure and the straightening roll is stopped when δ / 2 is indicated by one displacement sensor. 3. When the radius of the fillet portion of the pin or journal of the crankshaft is R, the tip radius r of the compacting roll surface centered on the center of the thickness is 0.6R-0.
The straightening process of a crankshaft according to any one of claims 1 and 2, wherein straightening roll working is performed using a 95R cold working roll. 4. The engine according to claim 1, wherein said crankshaft is 35 to 90 kgf / m.
When made of a material having a tensile yield point of m ² , the fillet portion of the pin or journal of the crankshaft is attached to the fillet portion at 300 to 600 kgf / m.
Claim is pressed under a pressure which generates a hertz surface pressure m ² and performing straightening rolled 1, 2 or 3
The method of straightening a crankshaft according to any one of the above items.