RU2247623C2 - Crank shaft forming method - Google Patents

Abstract

FIELD: machine engineering, namely process for making crankshaft by hot die forging.

SUBSTANCE: method comprises steps of forming crank pins of crankshaft and further bending of them. Crank pins are formed at imparting to fibers of their surface material finally oriented position parallel relative to axes of journals. Crankshaft is bent at closing crank pins by means of surfaces of clamping members. After bending operation, jaws and counter-balances are formed in open die sets while holding finally formed crank pins of crankshaft and preventing material yielding in direction normal relative to outer surface of jaws.

EFFECT: improved strength of crankshaft.

6 dwg

Description

The invention relates to the field of engineering and, in particular, to a technology for manufacturing a crankshaft by hot forging.

A known method of manufacturing a crankshaft by hot die forging from rolling by bending a workpiece with upsetting in a sectional stamp at separate transitions with shaft calibration in a common stamp. See, for example, EI Semenov et al. Handbook “Forging and Punching”, Vol. 2 Hot Punching. M., Mechanical Engineering, 1986, pp. 31-33.

The disadvantage of this method is the impossibility of its application in large-scale and mass production, typical of the automotive industry, a significant overspending of the starting material and the uncertain orientation of the surface fibers of the material of the connecting rod journals, which leads to their earlier wear due to the release of fibers to the surface, since the connecting rod journals work in plain bearings.

A known method of hot volumetric stamping of the crankshaft of a car, described in the book Semendiy V.M., Akaro I.L., Volosov N.N. “Progressive technology, equipment and automation of forging and stamping production of KAMAZ”, M., Mechanical Engineering, 1989, pp. 215-255. The stamping method consists in dividing the initial rolled products into measured billets, heating the billets, distributing the material by rolling on the forging rollers, followed by preliminary and final stamping in open dies, trimming, dressing and calibration.

The disadvantage of this method also lies in the absence of a certain controlled orientation of the surface fibers of the connecting rod journal material, the exit of the fibers to the surface due to trimming of the crankshaft, the earlier appearance of pitting on the surface of the connecting rod journals during operation, the unfavorable appearance of hubs and, as a result, the shorter crankshaft life.

The closest method for stamping a crankshaft, adopted as a prototype, is a method of hot volumetric stamping of a crankshaft of a car, described in an article by Adolf W.W. "Neuere Entwicklungen bei geschmiedeten Kraftfahrzeug-Kurbenwellen" in Schmiede-Joumal, September 2001, S 14-17.

The method consists in cutting, forging on rollers, preliminary, final forming of the shaft and trimming.

The prototype has the same drawbacks as its analogues, namely, the randomly oriented, uncontrolled during stamping arrangement of surface fibers of the neck material, their exit to the outside and, as a result, accelerated wear of the material in the form of pitting along the necks and, as a result, earlier wear of the crankshaft.

The disadvantages of the method of manufacturing the crankshaft, characteristic of the prototype, are eliminated by the fact that the crankshaft connecting rods are enclosed in closed surfaces and the crankshaft is bent, then the cheeks and balances are molded in open dies, while the crankshaft is also held by the finally formed connecting rods in closed surfaces and exclude the outflow of material in a direction perpendicular to the outer surface of the necks.

A comparative analysis of the manufacturing method of the crankshaft with the well-known adopted for the prototype showed that the claimed method, providing an oriented, controlled position of the surface fibers of the connecting rod journal material parallel to their axes, as well as bending the shaft to form cranks, significantly increases the crankshaft strength in the direction of application of force and thereby increases durability.

The set of essential features of the method providing the technical result includes holding the shaft in the stamp by placing the connecting rod journals in a closed volume formed by the stamp elements eliminating the outflow of the neck material in an uncontrolled direction.

The invention is illustrated by drawings, where:

figure 1 - the original workpiece;

figure 2 - the formation of the connecting rod necks;

figure 3 - clamp connecting rod journals and bending of the crankshaft;

figure 4 - preliminary molding of the cheeks and crankshaft balances;

figure 5 - the final molding of the crankshaft;

6 is a cropping.

The method is implemented as follows.

As shown in FIG. 1, the initial rolled stock 1 has the position of the fibers 2 parallel to its axis. The blank 1 is installed in a deep rolling mill (not shown) and the crankshaft 4, 5, 6, 7 of the crankshaft 8 are rolled by tool 3, forming them into the final dimension “d”, obtaining the arrangement of surface fibers 2 parallel to the axis of the connecting rod necks and crankshaft, as shown in figure 2. Another way of forming necks is also possible.

Then the semi-finished product from the workpiece 1 is placed in the bending tool 9 of the stamp 10 and the press is moved (not shown). During the slide of the press down, the bending tool 9 with its punches 11, 12, 13, 14 and movable power clamps 15, 16, 17, 18 with rigidly lockable surfaces covers the connecting rod journals 4, 5, 6, 7 in outer diameter, closes them and bends the core of the workpiece 1 with punches in the semi-matrices 19, 20, forming sections 21, 22, 23, 24, 25 for the subsequent molding of the cheeks and balances of the crankshaft.

The resulting semi-finished product 26 is placed in subsequent tools 27, 28 for molding the cheeks 29 and counterweights 30 in an open die, while the crankshaft is held in tools 27, 28 in the rigidly closing surfaces of the movable power clamps 15, 16, 17, 18 by the connecting rod journals 4, 5, 6, 7.

Excess material from open tools 27, 28 expires in the flush 31 and is removed in the cutting tool.

This ends the hot stamping of the crankshaft. The stamping method can be performed both in a multi-position stamp and in separate stamps.

Thus, the stamping method provides constant control of the location of the surface fibers of the starting material of the connecting rod journals and the crankshaft of the car as a whole and eliminates the outflow of material perpendicular to the outer surfaces and interruption of the surface fibers in a controlled orientation, thereby increasing its strength and durability.

Claims (2)

1. A method of manufacturing a crankshaft by hot forging from rolled metal, including forming a crank pin of the crankshaft and subsequent bending, characterized in that the formation of the crank journals is carried out to give the surface fibers of their material an oriented final position parallel to the axes of the crank journals, the crankshaft is bent with closure of the connecting rod journals by the surfaces of the clamping elements, after which the cheeks and balances are molded in open dies while holding the crankshaft shaft for the finally formed connecting rods with the help of the aforementioned closed surfaces with the exception of the outflow of material in the direction perpendicular to the outer surface of the cheeks. 2. The method according to claim 1, characterized in that the formation of the connecting rod journals of the crankshaft is carried out by transverse deep rolling.

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