JP2006247727A - Method for correcting shape of counterweight in crankshaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for correcting the shape of a counterweight capable of obtaining the necessary and sufficient correction effect so as to realize the so-called machining-less method of the counterweight by enhancing the correction effect. <P>SOLUTION: The shape of a counterweight 3 is gradually corrected by the ironing work by relatively rocking and rotating an outer circumferential surface correction roller 11 in the direction opposite to that of the counterweight 3 while pressing a correction roller 10 arranged opposite to the counterweight against a side face of the counterweight 3. The correction quantity by the correction roller 10 is increased by the predetermined value step by step every time when the rotational direction is inverted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for correcting the shape of a counterweight in a crankshaft, and more particularly to a method for correcting the shape of a counterweight such as a counterweight with respect to a crankshaft rough material for an internal combustion engine manufactured by hot forging.

  A technique disclosed in Patent Document 1 has been proposed as a technique related to bending correction of a forged crankshaft.

For example, when a crankshaft of an in-line four-cylinder engine is subjected to a re-striking process for obtaining shape accuracy in the final step of the forging process, a punch that descends from a direction perpendicular to the axis of the crankshaft is brought into sliding contact with the crankshaft. The cam die is slid in the longitudinal direction of the crankshaft, and the counterweights are each corrected in the same direction to correct the crankshaft bending and the counterweight misalignment and tilting phenomenon in the longitudinal direction. .
Japanese Patent Laid-Open No. 2003-136181 (FIG. 4)

  In the technique described in Patent Document 1, since almost the entire side surface of the counterweight is corrected at the same time, the cam die, which is a correction jig, requires high rigidity.

  On the other hand, when the technique described in Patent Document 1 is to be applied to, for example, a crankshaft of a V-type 6-cylinder engine, as a special feature of the crankshaft of such a V-type 6-cylinder engine, an in-line 4-cylinder type crankshaft is used. Compared to the counterweight, the pitch between adjacent counterweights becomes smaller, so the cam die that inevitably goes in between adjacent counterweights is not only thin but stiff. Since the dimensions (thickness dimensions) are also different, the corrective force is different between the left and right counterweights, resulting in insufficient correction, and the variation in the position of the counterweight in the longitudinal direction is particularly large. It is difficult to expect a corrective effect. As a result, even though the counterweight can fully perform its original function even with black skin, it is necessary to perform machining in the subsequent process in order to eliminate the above-described variation in position. Increase is forced.

  The present invention has been made paying attention to such a problem, and a necessary and sufficient correction effect can be obtained in order to increase the correction effect of the counterweight as described above so as to reduce the so-called machining of the counterweight. An object of the present invention is to provide a counterweight shape correction method.

  The invention according to claim 1 is a method for correcting the shape of the counterweight in the forged crankshaft rough material, and presses the correction roller against the side surface of the counterweight, and then both are rotated around the axis of the crankshaft. It is characterized in that it is corrected by ironing with a correction roller.

  In this case, as described in claim 2, it is desirable to sandwich the counterweight between the counterweights so that the counterweight is sandwiched between the correction rollers.

  More preferably, as described in claim 3, the crankshaft supported on both ends is oscillated and rotated in the forward / reverse direction, and the correction roller is caused to follow and rotate in the forward / reverse direction along with the oscillating rotation. It shall be.

  Therefore, in the invention according to at least the first aspect, unlike the conventional method in which the jig is pressed against the entire surface of the counterweight to correct, the ironing process is performed by the correction roller, so that a so-called sequential forming form is obtained. Both the load and the rigidity required for the correction roller are small. Thereby, a necessary and sufficient correction effect for the counterweight can be obtained.

  According to the first aspect of the present invention, since a wide range of the counterweight can be reliably corrected with a small correction load, there is an effect that the number of processing steps can be reduced while the counterweight is not machined.

  FIG. 1 and the following drawings show a more specific embodiment of the present invention, and show an example in which the crankshaft of a V-type 6-cylinder engine is hot-formed as described above. Yes.

  As shown in FIG. 1, the crankshaft 1 is provided with four journal parts 2 and seven counterweights 3 in the axial direction, and the counterweights 3 and 3 are eccentric from the journal part 2. A total of six crank pin portions 4 are set at the positions.

  The rough crankshaft material 5 to be the crankshaft 1 is roughly classified as shown in FIG. 2 by forging through the first wasteland, the second wasteland, finishing, trim, twist, and wrist-like processes. Is done. The rough shape of the crankshaft 1 is finished as the crankshaft rough material 5 from the round bar-like material by passing through the first roughage, the second roughage and the finishing of the above steps, and the flash 6 is punched out in the trim step. As a result, the crankshaft rough material 5 is close to the product shape. In the twisting process, a twist of 60 ° is applied to both ends in the longitudinal direction, and in the last re-striking process, re-strike is performed to mainly correct the bending.

  In such a forging process of the crankshaft rough material 5, as shown in FIG. 3, the counterweight 3 has a draft angle (draft angle or draft angle) θ as well as misalignment and excessive burr height. As described above, the phenomenon such as the positional deviation in the longitudinal direction and the falling of the counterweight 3 often occurs, and the synergistic effect thereof tends to increase the variation in the position of the counterweight 3 in the longitudinal direction. .

  Therefore, in the present embodiment, it is assumed that the shape of the counterweight 3 is corrected in the form of hot forging following the restructuring process shown in FIG.

  4 and 5 show an outline of the process of correcting the shape of the counterweight 3. Both the gear shaft portion 7 and the rear flange portion 8 (see FIG. 1) at both ends of the cranshaft coarse material 5 are both supported by a chuck (not shown). On the other hand, a pair of correction rollers 10 supported by the roller arms 9 are arranged opposite to each other on both sides of the counterweight 3, and the counterweight 3 is sandwiched between each pair of correction rollers 10. Then, the crankshaft coarse material 5 is swung and rotated alternately in the forward / reverse direction, and each correction roller 10 is rolled in the forward / reverse direction so as to follow it, and both sides of the counterweight 3 are ironed. The shape of each counterweight 3 is corrected or shaped in the form of so-called sequential molding. At this time, the rotation angle of the crankshaft coarse material 5 is set in advance so that two correction rollers 10 arranged on one side of the counterweight 3 do not come off from the counterweight 3, and at most, the sector angle of the counterweight 3 itself. It shall be within the range of α. Further, every time the rotation direction of the counterweight 3 is reversed, the correction cost exerted on the counterweight 3 by each of the correction rollers 10 is increased stepwise by a predetermined amount, and is adjusted so as to always have a uniform correction load.

  In addition to the correction rollers 10 that are pressed against both side surfaces of the counterweight 3, an outer peripheral surface correction roller 11 is used in combination as an outer peripheral surface restraining means for constraining the cylindrical outer peripheral surface 3a of the counterweight 3. It restrains so that the shape of the outer peripheral cylindrical surface 3a of the counterweight 3 may not collapse with ironing.

  In this case, instead of the outer peripheral surface correction roller 11 shown in FIGS. 4 and 5, a so-called outer peripheral surface correction jig 12 as shown in FIG. 6 may be used.

  In this way, each counterweight 3 is applied under a relatively small correction load by performing the ironing process by the relative rotation using the outer peripheral surface correction roller 11 or the outer peripheral surface correction jig 12 in addition to the respective correction rollers 10. It is possible to reliably and accurately correct the shape.

  7 and 8 show a second embodiment of the present invention, in which the counterweight 3 on the crankshaft coarse material 5 side is fixed, and only the correction roller 13 is moved relative to the counterweight 3. An example of the case is shown.

  As shown in FIGS. 7 and 8, the counterweight 3 is sandwiched by placing two sets of two correction rollers 13 facing each other on both sides of the counterweight 3. Each straightening roller 13 is supported by a roller arm 14 and is directed from the vicinity of a center line C that bisects the counterweight 3 that forms a fan shape in a side view toward the end side of the counterweight 3 (in FIG. Direction), and ironing is performed so that the counterweight 3 is extended in the vertical direction in the figure. However, in order to avoid interference between the correction roller 13 and elements such as the journal portion 2 other than the counterweight 3 in the crankshaft 3, the movement locus of each correction roller 13 is positively shown as shown by a solid line M in FIG. Machining is performed while controlling the machine.

  Once the ironing process is completed, the respective correction rollers 13 are returned to their original positions, and each time the above operation is repeated a plurality of times while increasing the correction allowance by a predetermined amount step by step.

  In addition to the correction roller 13, a pair of halved outer peripheral surface correction jigs 15 are used together, and ironing is performed while correcting or shaping the outer peripheral surface shape or contour shape of the counterweight 3. In this case, it is possible to contribute to the improvement of the material yield by forming the shape of the counterweight 3 in a small size in anticipation of the coarse material volume corresponding to the increase in the contour shape accompanying the ironing process. It becomes like this.

  FIGS. 9 and 10 show modified examples of FIGS. 7 and 8. As is apparent from comparison with FIGS. 7 and 8, only one pair of correction rollers 23 supported by the roller arm 14 is used to move the other end of the counterweight 3 to the other. In order to make a so-called full stroke up to the end, FIGS. 9 and 10 are reciprocated in the vertical direction to perform ironing.

  Also in this case, every time the moving method of the correction roller 23 is reversed, the correction allowance is increased by a predetermined amount stepwise, which is particularly effective for eliminating the so-called draft angle θ as shown in FIG. .

  In this way, according to each embodiment, the shape of the counterweight 3 is corrected by ironing with the correction rollers 10, 13, and 23, so that the draft as shown in FIG. It becomes possible to reliably correct the angle θ, the mold deviation, the excess burr height, the longitudinal position deviation, the falling of the counterweight 3, and the like.

  In particular, by using the outer peripheral surface correction roller 11 or the outer peripheral surface correction jigs 12 and 15 together, the outer peripheral cylindrical surface or contour shape of the counterweight 3 can be finished with high accuracy by improving the correction effect.

  Further, as shown in FIGS. 7 and 9, it is possible to correct a wider range of the counterweight 3 by positively controlling the movement trajectory M of the correction rollers 13 and 23.

  Further, as shown in FIGS. 7 and 9, the contour shape of the counterweight 3 itself is forged and made smaller in advance than the contour shape corrected by the outer peripheral surface correcting jigs 12 and 15, thereby reducing the amount of material input. It is also possible to improve the material yield.

The perspective view which shows an example of the crankshaft for V type 6 cylinder engines. Process explanatory drawing of the forge molding process of the crankshaft shown in FIG. Explanatory drawing of the malfunction of the counterweight which generate | occur | produces in the forge forming process shown in FIG. Explanatory drawing which shows the outline of a counterweight shape correction process as embodiment of this invention. FIG. 5 is an explanatory plan view of a main part of FIG. 4. Explanatory drawing which shows the modification of FIG. Explanatory drawing which shows the outline of a counterweight shape correction process as the 2nd Embodiment of this invention. Explanatory drawing of the vertical cross section of FIG. Explanatory drawing which shows the outline of a counterweight shape correction process as the 3rd Embodiment of this invention. FIG. 10 is a vertical cross-sectional explanatory diagram of FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Crankshaft 3 ... Counterweight 3a ... Cylindrical outer peripheral surface 5 ... Crankshaft rough material 10 ... Correcting roller 11 ... Outer peripheral surface correcting roller (outer peripheral surface restraining means)
DESCRIPTION OF SYMBOLS 12 ... Outer surface correction jig 13 ... Correction roller 15 ... Outer surface correction jig 23 ... Correction roller

Claims (14)

A method for correcting the shape of the counterweight in the forged crankshaft rough material,
A method for correcting the shape of a counterweight in a crankshaft, wherein the straightening roller is pressed against the side surface of the counterweight, the two are rotated relative to each other around the axis of the crankshaft, and correction is performed by ironing with the straightening roller.   2. The method for correcting the shape of a counterweight in a crankshaft according to claim 1, wherein the counterweight is sandwiched between the counterweights so that the counterweight is sandwiched between the correction rollers.   3. The crank according to claim 2, wherein the crankshaft supported on both ends is oscillated and rotated in the forward / reverse direction, and the correction roller is corrected by following and rotating in the forward / reverse direction along with the oscillating rotation. A method for correcting the shape of the counterweight on the shaft.   4. The method for correcting the shape of a counterweight in a crankshaft according to claim 3, wherein the swing rotation range of the crankshaft is set within a sector shape of the counterweight.   5. The method for correcting the shape of a counterweight in a crankshaft according to claim 3 or 4, wherein the amount of correction by the correction roller is increased each time the rotation direction of the crankshaft is reversed.   6. The method for correcting the shape of a counterweight in a crankshaft according to claim 2, wherein two sets of correction rollers are arranged in parallel in the rotational direction of the counterweight.   The shape correction of the counterweight in the crankshaft according to any one of claims 1 to 6, wherein the outer peripheral surface restraining means is pressed against the cylindrical outer peripheral surface of the counterweight, and the cylindrical outer peripheral surface is corrected in parallel. Method. A method for correcting the shape of the counterweight in the forged crankshaft rough material,
The counterweight is sandwiched between at least a pair of straightening rollers arranged on both sides of the counterweight, and the straightening roller is moved along the side surface of the counterweight while avoiding interference with elements other than the counterweight forming the crankshaft rough material. And correcting the shape of the counterweight in the crankshaft, which is corrected by ironing with the correction roller.   Two sets of straightening rollers are placed opposite each other on both sides of the counterweight, and each pair of straightening rollers is moved synchronously from the center position that bisects the fan-shaped counterweight in a side view toward both ends of the counterweight. 9. The method of correcting the shape of the counterweight in the crankshaft according to claim 8, wherein the correction is performed by ironing with the correction roller.   The method for correcting the shape of the counterweight in the crankshaft according to claim 9, wherein a correction jig for correcting the contour shape of the counterweight is used in combination.   The pair of correction rollers are reciprocated between one end of the counterweight having a fan shape in a side view and the other and corrected by ironing with the correction roller. Counterweight shape correction method for crankshaft.   12. The method for correcting the shape of a counterweight in a crankshaft according to claim 11, wherein a correction allowance by the correction roller is increased each time the moving direction of the pair of correction rollers is reversed.   13. The method for correcting the shape of a counterweight in a crankshaft according to claim 12, wherein a correction jig for correcting the contour shape of the counterweight is used in combination.   14. The method for correcting the shape of a counterweight in a crankshaft according to claim 10, wherein the contour shape of the counterweight itself is forged and formed in advance smaller than the contour shape to be corrected by a correction jig.

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