CN103071751B - Forging method for six throw crankshaft - Google Patents

Abstract

The invention discloses a forging method of a six-turn crankshaft, which comprises the step of pouring a cylindrical blank. The weight percentages of chemical components in the cylindrical blank are: C 0.12-0.40%, Mn 0.42-2.0%, Si 0.7-1.5%, V 0.09 -0.15%, Ti 0.11-0.22%, Cr 0.4-1.4%, Ni 0.4-1.5%, Mo 0.15-0.30%, Li 0.4-0.8%, Nb 0.04-0.08%, Al 0.15-0.20%, Mg 0.15-0.50 %, P≤0.030%, S≤0.030%, and the balance is Fe. The invention overcomes the defects of the prior art, saves energy, improves the quality of heat treatment, shortens the production cycle, reduces the production cost and reduces the radiation pollution to the workshop environment.

Description

A method for forging a crankshaft with six turns

technical field

The invention relates to the processing field of positioning hooks, in particular to a forging method of a six-turn crankshaft.

Background technique

The six-throw crankshaft includes several sections, the crankshafts are 120°, and the included angles are evenly distributed. Large multi-turn crankshafts are mainly used in large engines. Its main function is to convert the force transmitted from the connecting rod into torque. It is the core part of the engine and is widely used in engines in large-scale machinery, chemical industry, locomotives, ships and other industries. Its forging methods include fully assembled, semi-assembled and integral forging methods. Due to the integration of the crankshaft and the curved diameter and the continuous forging fiber, the overall forging is difficult and the quality of the forging is high, so the forging is difficult, the shape is complex during the forging process, and quality problems are easy to occur (such as folding 120 ° included angle offset, etc.). At present, in the domestic overall forging of multi-turn crankshafts, misalignment and angle presets are adopted. Most of the crankshafts are forged from circle to hexagonal or octagonal to hexagonal.

Contents of the invention

The purpose of the present invention is to provide a forging method of a six-turn crankshaft, which combines high-temperature normalizing and forging organically to form a quenching and tempering heat treatment process for positioning hooks in a continuous production line, which overcomes the defects of the prior art, saves energy, and improves the heat treatment process. quality, shorten the production cycle, reduce production costs, and reduce radiation pollution to the workshop environment.

Technical scheme of the present invention is as follows:

A method for forging a crankshaft with six turns, comprising the following steps:

a. Pouring cylindrical billet step

The weight percentage of the chemical composition in the cylindrical blank is: C 0.12-0.40%, Mn 0.42-2.0%, Si 0.7-1.5%, V 0.09-0.15%, Ti 0.11-0.22%, Cr 0.4-1.4%, Ni 0.4-1.5 %, Mo 0.15～0.30%, Li 0.4-0.8%, Nb 0.04-0.08%, Al 0.15～0.20%, Mg 0.15～0.50%, P≤0.030%, S≤0.030%, the balance is Fe;

b. Forging steps

1) After upsetting the forging, pull it out to a flat square, and then press the upper and lower sides of the forging with a triangular knife according to the number of segments of the six-turn crankshaft to be forged, and stamp the forging with the same number of segments as the six-turn crankshaft;

2) According to the length of the six-turn crankshaft to be forged, use a short anvil to pre-draw the longer and shorter of them, and then draw the entire forging to the required size;

3) Twist the corresponding section of the forging after drawing to obtain the required forged six-turn crankshaft blank;

4) Perform precision forging and trimming of the six-throw crankshaft blank to obtain the required cast six-throw crankshaft;

c. Heat treatment steps

1) Normalize the workpiece after edge trimming and punching, heat it to 880±10°C in a heat treatment furnace, keep it warm for 3.5 to 4 hours, and then take it out of the furnace and cool it in air;

2) After the heat treatment, the workpiece is shot blasted, and the surface of the forging is treated by a crawler shot blasting machine until all the oxide scales on the surface fall off;

3) The workpiece after shot blasting is subjected to cold calibration, and finally the finished product is obtained.

The workpiece after trimming and punching is subjected to normalizing treatment, heated to 880° C. in a heat treatment furnace, kept for 3.7 hours, and then taken out of the furnace and cooled in air.

Compared with the prior art, the beneficial effects of the present invention are as follows:

The present invention only needs a few firing times, and the blank is turned over and elongated many times, the defects inside the steel piece can be compacted, the internal deformation of the blank is uniform, and the dead zone is not easy to appear. The forging method is used to make six crutches Crankshaft, the pass rate of the product is relatively high.

The beneficial effects of the present invention are as follows: the forging method of the above-mentioned six-turn crankshaft has simple process and simple operation, its corresponding forging time is reduced from the original 440-550 minutes to 220-250 minutes, and the reject rate of the product is reduced by 20%, thus It can save energy and cost required for production.

Detailed ways

A method for forging a crankshaft with six turns, comprising the following steps:

a. Pouring cylindrical billet step

The weight percentage of the chemical composition in the cylindrical blank is: C 0.12-0.40%, Mn 1.42-1.8%, Si 0.7-1.5%, V 0.09-0.15%, Ti 0.11-0.22%, Cr 0.9-1.4%, Ni 0.9-1.5 %, Mo 0.15～0.30%, Li 0.4-0.8%, Nb 0.04-0.08%, Al 0.15～0.20%, Mg 0.15～0.50%, P≤0.030%, S≤0.030%, the balance is Fe;

b. Forging steps

1) After upsetting the forging, pull it out to a flat square, and then press the upper and lower sides of the forging with a triangular knife according to the number of segments of the six-turn crankshaft to be forged, and stamp the forging with the same number of segments as the six-turn crankshaft;

2) According to the length of the six-turn crankshaft to be forged, use a short anvil to pre-draw the longer and shorter of them, and then draw the entire forging to the required size;

3) Twist the corresponding section of the forging after drawing to obtain the required forged six-turn crankshaft blank;

4) Perform precision forging and trimming of the six-throw crankshaft blank to obtain the required cast six-throw crankshaft;

c. Heat treatment steps

1) Normalize the workpiece after trimming and punching, heat it to 880°C in a heat treatment furnace, keep it warm for 3.7 hours, and then take it out of the furnace and cool it in air;

2) After the heat treatment, the workpiece is shot blasted, and the surface of the forging is treated by a crawler shot blasting machine until all the oxide scales on the surface fall off;

3) The workpiece after shot blasting is subjected to cold calibration, and finally the finished product is obtained.

Main mechanical performance indicators:

Tensile strength ≥ 854 Mpa

Yield strength ≥ 646 Mpa

Elongation ≥ 14%

Reduction of area ≥ 35%

Brinell hardness HB=237—259.

Claims (2)

1. a forging method for six throw crankshaft, is characterized in that comprising the following steps:

A, cast cylinder blank step

In cylinder blank, chemical component weight percentage is: C 0.12-0.40%, Mn 0.42-2.0%, Si 0.7-1.5%, V 0.09-0.15%, Ti 0.11-0.22%, Cr 0.4-1.4%, Ni 0.4-1.5%, Mo 0.15 ~ 0.30%, Li 0.4-0.8%, Nb 0.04-0.08%, Al 0.15 ~ 0.20%, Mg 0.15 ~ 0.50%, P≤0.030%, S≤0.030%, surplus is Fe;

B, forging step

1), will after forging jumping-up pulling to flat side, then according to the hop count triangular knife of the six throw crankshaft of required forging to the impression up and down of forging, forging is impressed out the hop count identical with six throw crankshaft;

2), according to the length of the six throw crankshaft of required forging, first comparatively length is wherein pulled out in advance with short anvil, and then whole forging is carried out entirety pulling to required size;

3), the six throw crankshaft blank obtaining required forging is reversed to the corresponding section of forging after pulling;

4), to six throw crankshaft blank carry out finish forge finishing, obtain the six throw crankshaft of required casting;

C, heat treatment step

1), by the workpiece after trimming, punching carry out normalized treatment, in heat-treatment furnace, be heated to 880 ± 10 DEG C, and air cooling of coming out of the stove after being incubated 3.5 ~ 4 hours;

2), by the workpiece Shot Blasting after heat treatment, apron type airless shot blasting machine is adopted to carry out surface treatment to forging, until the oxide skin that its surface produces all comes off;

3), by the workpiece after ball blast carry out the process of cold school, finally obtain finished product.

2. the forging method of six throw crankshaft according to claim 1, is characterized in that: described workpiece after trimming, punching is carried out normalized treatment, is heated to 880 DEG C in heat-treatment furnace, and air cooling of coming out of the stove after being incubated 3.7 hours.