JPH01257502A - Center hole machining device for crankshaft - Google Patents

Abstract

PURPOSE:To form a center hole with high precision, by a method wherein when a crankshaft is rotationally driven around the axis of a journal part, a rotary tool is pressed against the end surface of the crank shaft to drill the center hole. CONSTITUTION:A crankshaft 8 is rotatably supported by a support device, and center hole correction machining is applied on two end surfaces in a way that a cutter 66 for correcting a center and a combination tool 94 are moved forward as the crankshaft 8 is rotated around the axis of a journal part by means of a rotational drive means. Thus, even if the axis of the journal part is displaced from the central lines of the cutter 66 for correcting a center and the combination tool 94 due to the size error of the journal part, machining thereof is effected around the axis of the journal part. This constitution enables the corrected two holes to coincide with the axis of the journal part with high precision, and permits improvement of stroke precision of a crank pin 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a center hole machining device for machining a center hole in the end face of a crankshaft with high precision.

Conventional technology A crankshaft is connected to a piston through a crank pin and a connecting rod that are eccentrically provided with respect to the journal portion, and is rotated by the reciprocating motion of the piston to extract the shaft output of the engine. Therefore, high strength, rigidity, wear resistance, etc. are required. Therefore, when manufacturing such crankshafts, the mechanical strength of the crankshaft is generally improved by subjecting the crankshaft made of mechanical structural carbon steel or the like that has been forged into a predetermined shape to heat treatment through quenching and tempering. After that, it is normal to remove the distortion caused by heat treatment and then grind the journal part, crank pin, etc. However, as the crank pin is ground, the crankshaft deforms and the end face There was a problem in that the center hole previously provided in the crankshaft and the axis of the journal part were misaligned, causing errors and variations in the stroke of the crank pin, and vibrations in various parts. In addition, such deformation of the crankshaft is
This is thought to be because residual stress generated during heat treatment is released by scraping off the surface layer of the crank pin.

On the other hand, after grinding the crank pin, that is, after the crankshaft is deformed, the center hole, which is the reference for grinding the journal part, must be re-machined so that it matches the axis of the journal part. is considered. This is done by fixing the crankshaft in the journal section and moving a rotary tool such as a center drill installed opposite the end surface relatively close to each other, similar to when a center hole is first formed on the end surface of the crankshaft. This is to correct the center hole.

Problems to be Solved by the Invention However, when fixing the journal part and correcting the center hole as described above, the journal part may be damaged due to dimensional errors or deviations from a perfect circle. If the axial center of the rotary tool deviates from the center line of the rotary tool, the center hole also deviates from the axial center of the journal portion, resulting in a problem in that it is not always possible to obtain sufficiently satisfactory accuracy.

The present invention has been made against the background of the above-mentioned circumstances, and its purpose is to make it possible to machine a center hole that coincides with the axis of the journal portion with high precision.

Means for Solving the Problems In order to achieve the object, the present invention provides an apparatus for machining a center hole of a crankshaft, which includes: (a) supporting a journal portion of the crankshaft so as to be rotatable about an axis; (b) a rotary drive means for rotationally driving the crankshaft supported by the support device around the axis; and (C) a rotary drive means for rotating the crankshaft supported by the support device; and a rotary tool disposed so as to be relatively movable in the axial direction, and machining the center hole by being pressed against the end face of the crankshaft when the crankshaft rotates.

In the crankshaft center hole machining device as described above, the crankshaft whose journal portion is rotatably supported by the support device is rotationally driven around the axis of the journal portion by the rotational drive means. At this time, a center hole is machined by pressing a rotary tool against the end face of the crankshaft. Therefore, even if the axial center of the journal deviates from the center line of the rotary tool due to dimensional errors in the journal, machining with the rotary tool will be performed centering on the axial center of the journal, and Center holes that match with precision are now formed.

This center hole processing device is preferably used when correcting the center hole after grinding the crank pin, but it can also be used similarly when forming the center hole on the end face of the crankshaft for the first time. It is something.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, the crankshaft 8 shown in FIG. 1 is used in a four-cylinder automobile engine, and has five journal parts 10a, 10b, 10C, 10d, and 10e, and four crank pins 12a, 12. b, 12
c, 12d, and each crank pin 12a, 12b, 12c.

On the opposite side of 12d are counterweights 14a,
14b, 14c, and 14d (hereinafter, unless otherwise distinguished, each will simply be referred to as journal portion 10.
Crank pin 12. counterweight 14). Further, a front shaft 16° and a rear flange 18 are provided at both ends of the crankshaft 8, respectively, and a screw hole 20 is provided at the center of both end faces. Pilot hole 22
is formed. The front shaft 16 has a pair of pulleys in contact with the thrust surfaces 24 and 26, respectively, and the screw holes 20 and 20 are prevented from relative rotation by locking keys fitted in the key grooves 28 and 30. The flywheel is attached to the rear flange 18 by tightening bolts on the thrust surface 32.
The bolts are tightened into the screw holes 34 in a state where they are in close contact with each other, so that they are integrally fixed. Further, a bearing is arranged in the pilot hole 22. Drill hole 2 above
0. The openings 36 and 38 of the pilot hole 22 are both tapered and used as a center hole. Furthermore, four flat surfaces 40 are formed at 90° intervals on the outer peripheral surface of the base end of the front shaft 16.

The crankshaft 8 is made of a material such as carbon steel for mechanical structure and has a desired shape, that is, the journal portion 10. Crank pin 12. Counterweight 14. Front axis 16. After forging into a shape having a rear flange 18 and a rear flange 18, it is processed according to the processing steps shown in FIG.

That is, the forged crankshaft 8 is
First, heat treatment by induction hardening and tempering is performed to obtain the desired mechanical strength, and then strain measurement and strain relief due to the heat treatment are performed. Next, using the journal parts 10a and 10e at both ends as a reference, that is, by fixing the journal parts 10a and toe, the threaded hole 20. A pilot hole 22 is formed. Further, the rear flange 18 is machined with screw holes 34, and the base end of the front shaft 16 is chamfered at 90° intervals to form the four flat surfaces 40.

Next, the screw hole 20 formed above. While rotating the crankshaft 8 with the openings 36.38 of the pilot hole 22 as a reference, that is, with the pair of centers engaged with these openings 36.38, the journal portion 10 is grooved and rolled. After doing so, remove the journal parts 10 at both ends.
Semi-finishing grinding is performed only on a and 10e. This semi-finishing grinding is to improve the processing accuracy of the subsequent grinding of the crank bin 12, correction of the center hole, and finishing of the pilot hole 22.
0a and 10e serve as standards when such processing is performed.

That is, in the next grinding process of the crank bin 12, the journal parts IQa, 10e are fixed, and the grinding process is performed on the crank bin 12 at a position spaced apart by half the stroke of the crank bin 12 from their axes. In addition, in the subsequent correction of the center hole and finishing of the pilot hole 22, the journal portion 10a.

10e, the crankshaft 8 is rotatably supported, and while the crankshaft 8 is being rotated, the openings 36 and 38 are modified using a rotary tool provided opposite to the end face, and the pilot hole 22 is finished. be. This modification of the openings 36, 38 causes their center lines to coincide with the axes of the journals 10a, 10e.

Here, the center hole is corrected following the grinding of the crank bin 12 because the crankshaft 8 is deformed by the grinding of the crank bin 12, and the previously machined screw hole 20. Center line of pilot hole 22 and journal part 1
0 will be misaligned, so leave those screw holes 20. This is because if post-process processing is performed using the openings 36 and 38 of the pilot hole 22 as a reference, processing errors will occur. According to experiments conducted by the present inventors, the crankshaft 8 is deformed due to the grinding process of the crankshaft 12, and the central portion curves upward in FIG. by crankbin 1
This phenomenon is thought to occur because the residual stress generated in No. 2 is released by removing the surface layer by grinding.

Thereafter, while rotating the crankshaft 8 with reference to the modified opening 36, 38, the front shaft 1
6. Rear flange 18. and central journal part 10
Grinding is performed on the pair of thrust surfaces 42 facing each other with C in between, and finishing grinding is performed on all journal parts 10. Furthermore, the rotation of the crankshaft 8 is stopped and the grooves of the keyways 28 and 30 are ground. I do. Finally, the counterweight 14 is balanced and the balance is adjusted to complete the series of machining operations.

As a result, the crankshaft 8 shown in FIG. 1 is obtained.

In this way, following the grinding of the crank bin 12, the opening 36° 38 is corrected so that the axes of the journal portions 10a, 10e at both ends coincide with the center hole, and the corrected opening 36 Since the finish grinding of the journal portions 10 is performed with reference to .degree. Since the bar journal portion 10 is ground after the grinding of the bottle 12, the runout of each part is also reduced.

11, j, bj When the crankshaft 8 with the crank bin 12 still subjected to the grinding process is driven to rotate, for example, with reference to the journal parts 10a and 10e at both ends, the crankshaft 8 due to the grinding process of the crank bin 12 is rotated. Due to the deformation of the shaft 8, the other journal parts 10b, 10c
, 10d, and the front shaft 16, vibration occurs in all of them. again.

The center hole of the crankshaft 8, that is, the opening 3
6. If you grind the journal part 10 using those as a reference without modifying 38, the crank shirt)
Due to the misalignment caused by the deformation of -8, the grinding allowance becomes uneven and the stroke of the crank bin 12 changes.

By the way, the modification of the -1-2 center hole and the finishing of the pyro-seat hole 22 are suitably performed, for example, by the center hole machining 1 shown in FIG. Such a center hole machining device constitutes one embodiment of the present invention, and the center hole machining device will be described in detail below.

In FIG. 3, on the base 44, there is a support device 46 that rotatably supports the crank shirt l-8, a front rotary processing device 4 disposed on the left side of the support device 46, and a right side of the support device 46. A rear rotary processing device 50 is provided. The support device 46 includes a pair of fixed R brackets 52 and 54 fixed to the base 44 and the fixed R brackets 5.
Movable R shafts 56 and 58 are disposed above 2 and 54 so as to be movable in the vertical direction, and a drive cylinder 60 that drives the movable R shafts 56 and 58 in the vertical direction.
．． 62. The ends of the fixed R shaft 52° 54 and the movable R shafts 56 and 58 are both arcuate surfaces with approximately the same curvature as the journal portion 10, and between them the journal portion 10a of the crankshaft 8, 10e
is supported rotatably around an axis. In addition, R Yagen 52.54°56.58 and journal parts 10a, 10e
Lubricant is supplied to the sliding parts.

Furthermore, a positioning device 64 is disposed at an intermediate position of the support device 46. The positioning device 64 positions the crankshaft 8 in the axial direction by being engaged with the crank arm on the outside of the journal portion 10e.

On the other hand, as shown in an enlarged view in FIG. 4, the front rotary processing device 48 has a spindle 68 with a center correction cutter 66 as a rotary tool attached to its tip.
and a sleeve 74 having a pair of kelets 70 and 72 attached to its tip. The spindle 68 is located on the rotation center line of the crankshaft 8 rotatably supported by the support device 46, that is, on the journal portion 10a.
.

The center correction cutter 66 is disposed on an extension of the axis of the crankshaft 10e so as to be movable in the axial direction and rotatable about the axis, and the center correction cutter 66 is opposed to the front end surface of the crankshaft 8. Further, a pulley 76 is connected to the intermediate portion of the spindle 68 via spline fitting so as to be relatively movable in the axial direction but not relatively rotatable around the axis. A piston 82 of a cylinder 80 is fixed to the pulley 76 and rotatably supported by the case 78. The pulley 76 is rotationally driven by a drive motor 84 shown in FIG. By being driven forward by the crankshaft 8, center correction machining is performed on the opening 36 of the screw hole 20 formed in the front end surface of the crankshaft 8. The case 78 is integrally fixed to the base 44.

Further, the sleeve 74 is fitted to the outside of the spindle 68 so as to be relatively movable in the axial direction and relatively rotatable around the axis, and also connects the case 86 fixed to the base 44 to the cylinder. Cylinder 8 serving as a housing
The piston 90 is disposed within the piston 90 of No. 8 so as to be relatively movable in the axial direction and relatively rotatable around the axial center. The sleeve 74 is driven forward by the cylinder 88, and a pair of keleys 70 are attached to the tip end thereof.
72 is the front shaft 1 as shown in FIG.
6 is engaged with a flat surface 40 provided at the left end portion of 6.

Further, a gear 92 is connected to the rear end of the sleeve 74 through spline fitting so as to be relatively movable in the axial direction but not relatively rotatable around the axis. By being rotationally driven,
The crankshaft 8 engaged with the above-mentioned keleys 70, 72 is driven to rotate around the axes of the journal parts 10a, 10e supported by the support device 46. The above Kelley 70.72. Sleeve 74. Cylinder 88, gear 92. A front-side rotary drive means 93 includes a drive motor (not shown) that rotationally drives the gear 92.

Further, as shown in an enlarged view in FIG. 6, the rear rotary processing device 50 has a spindle 9 to which a combination tool 94 is attached at its tip.
6, and a sleeve 100 having a plurality of engagement pins 98 protruding from its tip.

The spindle 96 is located on the rotation center line of the crankshaft 80 rotatably supported by the support device 46, within the piston 106 of the cylinder 104 whose cylinder housing is the case 102, and which is not relatively movable in the axial direction and is not relatively movable in the axial direction. The combination tool 94 is arranged to be relatively rotatable, and is opposed to the rear end surface of the crankshaft 8. Further, a pulley 10 is connected to the rear end of the spindle 96 through spline fitting.
8 are connected to each other such that they can move relative to each other in the axial direction and cannot rotate relative to each other around the axis, and this pulley 108 is rotationally driven by a drive motor 110 shown in FIG. 3. As a result, the spindle 96 and furthermore the combination tool 94 are rotationally driven, and in this state they are driven forward by the cylinder 104 to finish the pilot hole 22 formed on the rear end surface of the crankshaft 8 and to open the opening 38. Center correction machining is performed continuously. The combination tool 94 integrally includes a cutting tool for processing the inner surface of the pilot hole 22 and a cutting tool for processing the tapered surface of the opening 380. Further, the case 102 is integrally fixed to the base 44.

On the other hand, the sleeve 100 is held in a case 112 so as to be rotatable about the same axis as the spindle 96, and the case 112 is held in the front-rear direction parallel to the axis of the spindle 96 by a guide iron 114, that is, in the sixth direction. It is supported so as to be movable in the left and right directions in the figure. An output rond of a cylinder 116 is connected to this case 112, and as the case 112 is driven forward by the cylinder 116, a plurality of retaining bins 98 protruding from the tip of the sleeve 100 are connected to the crankshaft. It is inserted into a screw hole 34 formed in the rear flange 18 of the shaft 8. The engagement pin 98 is provided in a protruding manner corresponding to the screw hole 34. In addition, a gear 118 is integrally provided on the sleeve 100, and a gear 120. The connecting rod 122 is rotationally driven by a drive motor 128 via gears 124 and 126. As a result, the crankshaft 8 engaged with the engagement pin 98 is moved to the journal portions 10a, 1 supported by the support device 46.
Rotationally driven around the axis 0e.

Said engagement bin 98. Sleeve 100. cylinder 116,
Gears 118, 120, 124, 126. Connecting rod 12
2. A rear rotation drive means 130 includes the drive motor 128 and the drive motor 128.

The connecting rod 122 and the gear 124 are connected through spline fitting, and relative movement in a direction parallel to the axis of the spindle 96 is permitted.

When performing center correction machining on both center holes of the crankshaft 8 using the center hole machining device configured as described above, first, the journal portions 10a, 10e of the crankshaft 8 are moved by the support device 46. Rotation drive means 93 or 130 disposed at the end opposite to the end on which center correction processing is performed while rotatably supported.
While rotating the crankshaft 8, the combination tool 94 or the center correction cutter 66 is rotated.
advance and process. That is, when performing center correction machining on the 3rd day of the opening of the pilot hole 22, which is the center hole on the rear side, while rotating the crankshaft 8 with the rotation drive means 93 on the front side, the combination tool 94 is used to correct the opening. 38, and when performing center correction processing on the opening 36 of the screw hole 20, which is the center hole on the front side, while rotating the crankshaft 8 by the rotation drive means 130 on the rear side, The center correction process is performed on the opening 36 using the center correction cutter 66. Note that when the combination tool 94 performs center correction machining on the opening 38, which is the center hole on the rear side, finishing machining is also performed on the pilot hole 22 at the same time.

In this way, the center hole machining device of this embodiment rotatably supports the crankshaft 8 by the support device 46, and rotates the crankshaft 8 around the axes of the journal portions 10a, 10e by the rotation drive means 93, 130. Since the center correction cutter 66 and the combination tool 94 are moved forward while rotating to perform center correction processing on both end faces, due to dimensional errors in the journal parts 1°a and 10e, the axis Even if the center lines of the center correction cutter 66 and the combination tool 94 deviate from each other, the machining by the center correction cutter 66 and the combination tool 94 will be performed on the journal portion 10a.
, 10e, and both center holes corrected in this way are aligned with the journal portion 10a.
, 10e with high accuracy. This further improves the stroke accuracy of the crank pin 12.

Further, in this embodiment, rotation drive means 93° 130 are provided on the front side and rear side of the crankshaft 8, respectively, and when performing center correction processing on the front side, the rotation drive means 130 on the rear side is used. When carrying out center correction machining on the side, the crankshaft 8 is rotationally driven by the front side rotation driving means 93, so that the center of rotation of the end on the side where the center correction machining is performed is the same as above. Due to the engagement with the rotation drive means 93, 130, there is no fear that the journal portion 10a and the toe will be deviated from the axis, and center correction processing can be performed with high accuracy.

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can also be implemented in other embodiments.

For example, in the embodiment described above, rotation drive means 93, 130 are provided at both ends of the crankshaft 8, but as in the center hole machining device shown in FIG.
It is also possible to remove the rear rotary drive means 130 consisting of the drive motor 16 and the drive motor 128, and rotate the crankshaft 8 only with the front rotary drive means 93, so that center correction machining can be performed on both end surfaces at the same time. It is possible.

Conversely, it is also possible to remove the front side rotational drive means 93 and rotate only the rear side rotational drive means 130. In the above embodiment, the front side rotation drive means 93 is used when performing the front side center correction process, and the rear side rotation drive means 130 is used when performing the rear side center correction process. It is also possible to drive the shaft 8 in rotation.

Further, in the above embodiment, the kelleys 70 and 72 are engaged with the flat surface 40 provided on the front shaft 16, and the engagement pin 98 is engaged with the screw hole 34 formed in the rear flange 18. Although the crankshaft 8 is rotationally driven, other parts such as the crank pin 12 can also be used to rotate the crankshaft 8.

Further, the support device 46 of the above embodiment has R Yagen 52.54.
．． Using 56.58, journal parts 10a, 10 at both ends
Although it is designed to rotatably support the journal portions 10a and 10e, other types of support devices may be used, such as one in which rollers are provided at the contact portions with the journal portions 10a and 10e. Further, it is also possible to support other journal parts 10 such as journal parts 10b and 10d and perform center correction processing.

Further, in the above embodiment, a center hole machining device for a crankshaft 8 used in a four-cylinder engine of an automobile was explained, but the present invention can also be applied to a center hole machining device for a crankshaft used in other multi-cylinder engines such as a six-cylinder engine. may be applied as well.

Furthermore, the machining steps for the crankshaft 8 shown in FIG. 2 are merely examples, and some of the machining steps may be omitted or replaced.

Although other examples are not provided, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an example of a crankshaft whose center has been corrected by a crankshaft center hole processing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of the processing steps in manufacturing the crankshaft shown in FIG. 1. FIG. 3 is a front view of a crankshaft center hole machining device according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing the front side rotary drive means and rotary tool in the center hole machining apparatus of FIG. 3. FIG. 5 is a sectional view showing a state in which the rotation drive means shown in FIG. 4 is engaged with the crankshaft. FIG. 6 is a cross-sectional view showing the rear rotary drive means and rotary tool in the center hole machining apparatus of FIG. 3. FIG. FIG. 7 is a front view showing another embodiment of the present invention. 8: Crankshafts 10a, 10b, 10c, 10d, 10e: Journal portion 36.38: Opening (center hole) 46: Support device 66: Center correction cutter (rotary tool) 93.130:
Rotation drive means 94: combination tool (rotary tool) applicant
Toyota Motor Corporation Fujikoshi Co., Ltd. Figure 2

Claims (1)

[Scope of Claims] An apparatus for machining a center hole of a crankshaft, comprising: a support device that supports a journal portion of the crankshaft so as to be rotatable about an axis; and a support device that supports the crankshaft supported by the support device. a rotational drive means that rotates around the axis; and a rotational drive means that is disposed so as to be relatively movable in the axial direction opposite to the end face of the crankshaft supported by the support device, and that rotates the end face when the crankshaft rotates. A crankshaft center hole machining device comprising: a rotary tool that machins the center hole by being pressed by a rotary tool.