A Shape Correction Method for Complex Crankshafts with Large Length-to-diameter Ratio

Abstract

The invention discloses a method for correcting shape of a complex crankshaft with a large length-diameter ratio. The method for correcting the shape of the complex crankshaft with the large length-diameter ratio comprises the following steps that firstly, dimension scribing is carried out on the bent crankshaft with the large length-diameter ratio, the shape run-out amount and the lowest point position of the crankshaft in the axial direction are checked, and the shape correction amount range is calculated according to the recorded data. The crankshaft is heated to the stress relief aging temperature in a local and sectional mode, the crankshaft is placed on a shape correction workbench in a hoisted mode, the two ends of the crankshaft are restrained through a special W-shaped tool, thena mechanical press is adopted to perform single-point shape correction from the calculated minimum deformation amount according to the parameters calculated through the shape correction force, the overall straightness of the crankshaft is checked after each shape correction, so that the dimension is ensured to meet the product requirements. According to the method, the problems that the complex crankshaft with the large length-diameter ratio is scrapped due to bending deformation, a special complex tool needs to be developed if a traditional shape correction means is adopted, and the "opening"of the crankshaft in the shape correction process cannot be avoided are solved.

Description

technical field

[0001] The invention relates to the technical field of precision plastic forming, in particular to a method for correcting the shape of a complex crankshaft with a large aspect ratio. Background technique

[0002] The crankshaft is one of the most important parts of the engine. Its main function is to collect the reciprocating work of each cylinder of the diesel engine and transmit it in the form of rotary motion. Its structure is complex, the working load is heavy, and it bears the effects of periodically changing bending stress, torsional stress, inertial force, and additional stress caused by vibration. In order to ensure the wear resistance and fatigue performance of the crankshaft, forging blanks are usually used and then machined. No matter what kind of forging process is used, due to the large length-to-diameter ratio, the force of the wrong turn is uneven, and some processes even require forging. Adding the twisting process afterward will often cause...

Examples

Embodiment 1

[0028] A method for rectifying the shape of a complex crankshaft with a large length-to-diameter ratio, comprising the following steps:

[0029] Step 1. Draw a line

[0030] Carry out dimensional scribing on the three-throw crankshaft with a large aspect ratio of φ160mm in the warped main journal, and record the dimensional tolerance along the axial direction as -2.5;

[0031] Step 2. Heating

[0032] The three-throw crankshaft that has completed step 1 is heated in local sections. The heating area is the three crank parts. The heating temperature of the high-temperature section is 250°C, the stress-relief aging temperature of the material 34CrNiMo6 steel, and the heating temperature of the low-temperature section is 220°C.

[0033] Step 3. Installation

[0034] Hoist the crankshaft with three crankshafts into the form-shaping workbench, and restrain the second crankshaft with a special W-shaped tooling.

[0035] Step 4. Single point pressing

[0036] Use a mechanical pres...

Embodiment 2

[0041] A method for rectifying the shape of a complex crankshaft with a large length-to-diameter ratio, comprising the following steps:

[0042] Step 1. Draw a line

[0043] Carry out dimensional scribing on the crankshaft with a large length-to-diameter ratio of φ150mm in the warped main journal, and record the dimensional tolerance along the axial direction as -1.5;

[0044] Step 2. Heating

[0045] The five-bend crankshaft that has completed step 1 is heated in local sections, and the heating area is the third crank and the adjacent second and fourth cranks; the heating temperature of the high-temperature section is the stress relief aging temperature of the material 34CrNiMo6 steel 250 ° C, The heating temperature of the low temperature section is 220°C.

[0046] Step 3. Installation

[0047] Hoist the crankshaft with five crankshafts into the form-shaping workbench, and restrain the third crankshaft with a special W-shaped tooling.

[0048] Step 4. Single point pressi...

Embodiment 3

[0054] A method for rectifying the shape of a complex crankshaft with a large length-to-diameter ratio, comprising the following steps:

[0055] Step 1. Draw a line

[0056] Carry out dimensional scribing on the warped main journal of φ180mm four-flip crankshaft with large length-to-diameter ratio, and record the dimensional tolerance along the axial direction as -2.0;

[0057] Step 2. Heating

[0058] The four-bend crankshaft that has completed step 1 is heated in local sections, and the heating area is the second crank and the adjacent first and third cranks; the heating temperature of the high-temperature section is the stress relief aging temperature of the material 40CrNiMoA steel 250 ° C, The heating temperature of the low temperature section is 220°C.

[0059] Step 3. Installation

[0060] Hoist the crankshaft with four crankshafts into the form-shaping workbench, and restrain the second crankshaft with a special W-shaped tooling.

[0061] Step 4. Single point press...

technical field

[0001] The invention relates to the technical field of precision plastic forming, in particular to a method for correcting the shape of a complex crankshaft with a large aspect ratio. Background technique

[0002] The crankshaft is one of the most important parts of the engine. Its main function is to collect the reciprocating work of each cylinder of the diesel engine and transmit it in the form of rotary motion. Its structure is complex, the working load is heavy, and it bears the effects of periodically changing bending stress, torsional stress, inertial force, and additional stress caused by vibration. In order to ensure the wear resistance and fatigue performance of the crankshaft, forging blanks are usually used and then machined. No matter what kind of forging process is used, due to the large length-to-diameter ratio, the force of the wrong turn is uneven, and some processes even require forging. Adding the twisting process afterward will often cause...

Examples

Embodiment 1

[0028] A method for rectifying the shape of a complex crankshaft with a large length-to-diameter ratio, comprising the following steps:

[0029] Step 1. Draw a line

[0030] Carry out dimensional scribing on the three-throw crankshaft with a large aspect ratio of φ160mm in the warped main journal, and record the dimensional tolerance along the axial direction as -2.5;

[0031] Step 2. Heating

[0032] The three-throw crankshaft that has completed step 1 is heated in local sections. The heating area is the three crank parts. The heating temperature of the high-temperature section is 250°C, the stress-relief aging temperature of the material 34CrNiMo6 steel, and the heating temperature of the low-temperature section is 220°C.

[0033] Step 3. Installation

[0034] Hoist the crankshaft with three crankshafts into the form-shaping workbench, and restrain the second crankshaft with a special W-shaped tooling.

[0035] Step 4. Single point pressing

[0036] Use a mechanical pres...

Embodiment 2

[0041] A method for rectifying the shape of a complex crankshaft with a large length-to-diameter ratio, comprising the following steps:

[0042] Step 1. Draw a line

[0043] Carry out dimensional scribing on the crankshaft with a large length-to-diameter ratio of φ150mm in the warped main journal, and record the dimensional tolerance along the axial direction as -1.5;

[0044] Step 2. Heating

[0045] The five-bend crankshaft that has completed step 1 is heated in local sections, and the heating area is the third crank and the adjacent second and fourth cranks; the heating temperature of the high-temperature section is the stress relief aging temperature of the material 34CrNiMo6 steel 250 ° C, The heating temperature of the low temperature section is 220°C.

[0046] Step 3. Installation

[0047] Hoist the crankshaft with five crankshafts into the form-shaping workbench, and restrain the third crankshaft with a special W-shaped tooling.

[0048] Step 4. Single point pressi...

Embodiment 3

[0054] A method for rectifying the shape of a complex crankshaft with a large length-to-diameter ratio, comprising the following steps:

[0055] Step 1. Draw a line

[0056] Carry out dimensional scribing on the warped main journal of φ180mm four-flip crankshaft with large length-to-diameter ratio, and record the dimensional tolerance along the axial direction as -2.0;

[0057] Step 2. Heating

[0058] The four-bend crankshaft that has completed step 1 is heated in local sections, and the heating area is the second crank and the adjacent first and third cranks; the heating temperature of the high-temperature section is the stress relief aging temperature of the material 40CrNiMoA steel 250 ° C, The heating temperature of the low temperature section is 220°C.

[0059] Step 3. Installation

[0060] Hoist the crankshaft with four crankshafts into the form-shaping workbench, and restrain the second crankshaft with a special W-shaped tooling.

[0061] Step 4. Single point press...

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