JPH03149139A - Work method for crankshaft - Google Patents

Abstract

PURPOSE:To greatly improve the working efficiency by using the same tool in a single set of work machine to perform milling work and turning work, in the case of preliminary work of fillet roll work in a crankshaft. CONSTITUTION:A milling cutter 6, in which many chips 7 having a circular arc-shaped protrusion are mounted in the corner part, is rotated, and milling work in a polygonal shape is applied to the peripheral surface of a journal 2 or a pin 3 of a crankshaft 1 rotated at a low speed. Next in a condition that rotation of the milling cutter 6 is stopped with the crankshaft 1 rotated, turning work of a smooth circular arc-shaped groove is applied to a corner thickness part 5 of the journal 2 or the pin 3 by the circular arc-shaped protrusion in the corner part of the chip 7 similarly to a tool, so that fillet roll work can be immediately performed. By using the same tool in a single set of work machine for preliminary work of the fillet roll work, work efficiency can be remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for machining a crankshaft journal or pin and its corner portion before fillet rolling the engine crankshaft.

[Conventional technology]

Conventionally, engine crankshafts have been subjected to fillet roll processing in order to improve their fatigue strength. As shown in Figures 6 and 7,
Crank journal 2 and arm 4 of crankshaft L
A small-diameter roller 11 supported by a holder IO is pressed against the corners 5, 5, and work hardening is caused in the corners 5, 5.
This is a method to improve fatigue strength. In this case, work hardening in the fillet is caused by the Hertzian stress determined from the diameter of the fillet roller 11 and its pressing force, the diameter of the workpiece, and the radius R of the arc of the fillet, so the arc of the fillet is It must be formed smoothly.

Conventionally, the arcuate grooves 5a, 5a having a radius of R are formed in the fillet portion 5.5 before the fillet roll processing by turning using a lathe. The same applies to the pre-processing for filleting the corners of the pins 3 of the crankshaft l.

On the other hand, milling is used to process the outer periphery of the journal or pin of the crankshaft before finishing the grinding in order to shorten the processing time.

(Problems to be Solved by the Invention) Conventional machining of crankshafts before fillet roll machining involves machining the outer periphery of journals and pins using mirrors;
Two steps are required: machining the arcuate groove in the fillet using a lathe.

Therefore, two different machines are required, and workpieces must be attached to and removed from these machines, resulting in very poor work efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a crankshaft machining method that allows pre-machining of fillet roll machining to be performed using one machining machine and the same tool.

[Means and effects for solving the problem] The present invention involves milling the outer periphery of a journal or pin of a crankshaft by rotating a milling cutter equipped with a large number of tips having arc-shaped projections at the corners and rotating at a low speed. This is a method for machining a crankshaft, which comprises the steps of: stopping the rotation of the milling cutter, rotating the crankshaft, and turning the corner of the journal or pin.

In the milling process, the tip of the tip cuts the outer circumferential surface of the journal or pin, but since the rotation of the crankshaft is slow, the outer circumferential surface of the journal or pin is milled into a polygonal shape rather than a cylinder, and is milled into the next process. When the rotation of the milling cutter is stopped, the arcuate protrusion at the corner of the tip cuts an arcuate groove at the corner of the journal or pin, similar to a cutting tool, and this arcuate groove is formed smoothly. Fillet rolling processing can be performed immediately.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of an embodiment of the present invention for machining the journal of a crankshaft, and FIG. 2 is a side view showing the machining state.

A crude crankshaft material l formed by forging or the like is supported so as to be rotatable around the central axis of the journal. On the other hand, a disc-shaped milling cutter main body 6 supported by a rotating sleeve 8
A large number of chips 7, to 7H made of carbide material and having protruding corners are fixed at predetermined intervals on the outer periphery of the chip. As shown in FIG. 5, each chip 7 is formed into an arc-shaped protrusion whose corner portion has a radius of approximately the same radius.

Next, the outer peripheral surface of the journal 2 and the arms 4.4 on both sides thereof.
The case of processing the fillet portion 5.5 will be explained.

The crankshaft rough material l is rotated at low speed as the rotating shaft that is the axis of the journal 2, and the milling cutter is rotated with the arm 4, while rotating the shaft 8 of the milling cutter at high speed.
4 in the direction of journal 2. As shown in Fig. 2, the tip of the tip 7 cuts the outer peripheral surface of the journal 2, but since the rotation of the crankshaft rough material l is slow, the outer peripheral surface of the journal 2 is not cylindrical but milled into a polygonal shape 2a. In this state, the machining of the outer peripheral surface of the journal 2 is completed.

Next, as shown in FIG. 3, the crankshaft rough material 1 is rotated at high speed, and the milling cutter is sent in the direction of the journal 2 between the arms 4, 4 while the rotation of the shaft 8 of the milling cutter is stopped.

The protrusion R at the tip corner of the tip 7, which is located at the lower end in the figure of the milling cutter, turns the fillet portion 5.5 of the journal 2 in the same way as a cutting tool in a lathe, and as shown in FIG. Grooving is performed to form a smooth arcuate groove 5a of approximately radius.

The journal 2 milled into a polygonal shape 2a is finished into a cylindrical shape by grinding in a subsequent process.

When performing pre-fillet processing on the corner of the pin 3 of the crankshaft 1, by rotating the crankshaft rough material l with the center of the pin 3 as the rotation axis, one Milling and turning can be performed with this processing machine.

By providing protrusions with a radius R on both diagonal corners of each tip 7, both sides can be used by changing the attachment to the milling cutter body 6.

〔Effect of the invention〕

The present invention provides pre-processing for fillet roll processing.

Milling and turning are performed using the same tool on one processing machine, which has the effect of greatly improving work efficiency.

[Brief explanation of the drawing]

Figure 1 is a front view of an embodiment of the present invention for machining the journal of a crankshaft, Figure 2 is a side view showing the machining state, Figure 3 is a front view of corner turning, and Figure 4 is turning. Fig. 5 is an enlarged perspective view of the chip after processing, Fig. tJ6 is a front view of conventional fillet roll processing, and Fig. 7 is an enlarged view showing the state of fillet roll processing. l: Crankshaft 2: Journal 3: Bin
4: Arm 5 two fillets 5a two circular arc grooves 6: milling cutter body ani tip

Claims (1)

[Claims] A step of milling the outer periphery of a journal or pin of a crankshaft rotated at low speed by rotating a milling cutter equipped with a large number of tips having arcuate protrusions at the corners; A method of machining a crankshaft comprising the steps of rotating and turning the corners of the journal or pin.