Connecting Rod Forging Machine and Process - Introduction & Analysis

2019-09-12 08:57:41

Why are Connecting Rod Forged?

Connecting rod is the key part of automobile engine parts, and it is also a typical and important complex closed die forging parts. Manufacturing precision and connecting rod internal and external quality will directly affect engine performance and level. Connecting rod causes high frequency alternating stress during the high-speed rise of engine. It must withstand the impact pressure initiated by each stroke gas in the cylinder and the torsional inertial force of the crankshaft. When the engine speed is 3000-5000 rpm, the loading frequency is very high. Because the connecting rod works at high speed under fatigue load, the strength requirement of the connecting rod is very high. In addition, the weight of the connecting rod must be controlled within a certain range because the crankshaft is always running at a high speed in a balanced state. Therefore, the requirement of connecting rod forging machine is high.

The plastic forming and processing of connecting rod are very difficult. For the purpose of forging production and processing, quality problems are easy to occur. The occurrence of these quality problems involves many factors. Therefore, forging manufacturers have been constantly improving and discussing materials, forging process and mechanical processing manufacturing technology for a long time. Its purpose is to meet the technical performance and use requirements of products, while minimizing costs, improving efficiency and increasing economic benefits.

How Many Types of Forged Connecting Rod?

1) According to forging material: quenched tempered steel connecting rod and non-quenched tempered steel connecting rod

Quenched tempered steel connecting rod refers to the connecting rod which meets the performance requirements after quenching and high temperature tempering heat treatment after forging. Non-quenched and tempered steel connecting rods are those that meet the performance requirements by controlling the cooling rate after forging.

2) According to connecting rod structure: split connecting rod and integral connecting rod

Split connecting rod refers to the connecting rod that separates the main body and cover during forging. Integral connecting rod refers to the whole forging of connecting rod, main body and cover, and then separated by subsequent processing.

How Are Forged Connecting Rods Made?

With the development of automobile industry and the increase of engine power, the requirement of connecting rod quality is becoming higher and higher. Therefore, the selection of appropriate forging materials and reasonable forging process play a vital role in the performance of connecting rods.

Describe the Forging Process of Connecting Rod

The connecting rod forging process is generally as follows: blanking - heating - roll forging - closed die forging - trimming punching - heat treatment - shot blasting - correction.

Blanking

Commonly used cutting methods are cutting (bar shearing machine) and sawing (optimum sawing). The cutting size is not uniform because of the shearing method, and the connecting rod forging is better for cutting.

Bar Heating

In order to improve the working environment and the quality of billet heating, and to facilitate mechanized automation production, we usually use medium frequency induction heating. For induction heating, the consumption is low, generally less than 0.5%, and the forging flash is very thin and easy to remove. Because the production has a certain rhythm, in order to reduce the heating temperature of the billet at both ends, the billet can not exceed the opening of the cavity before it is discharged, which is usually controlled by adjusting the stroke switch. Heating temperature will directly affect the external and internal quality of forged connecting rod. Low temperature will benefit the strength of the connecting rod and subsequent heat treatment. However, too low temperature will lead to poor metal flow and rapid die wear. If the die is subjected to a greater impact force, the connecting rod is also prone to cracks. However, if the heating temperature is too high, the plasticity of the connecting rod will be too high, which will lead to defects such as excessive metal flow, partial unsatisfactory filling and serious surface oxidation. Therefore, the lower the heating temperature is, the better the quality of forged connecting rod is.

Roll Forging

The quality of roll forging billet will directly affect the quality of forged connecting rod. Therefore, in rolling and forging, the following points should be paid attention to:

• Surface quality of roll forging die: Because of the long service life of roll forging die, but after a period of time, the surface of roll forging die will not be so smooth because of metal flow, resulting in roll forging fold.
• The entry point of each roll forging is different, so the arc of transition section is very small.
• The surface of billet is uneven with scratches.The wear of roll forging dies makes the distribution of blanks uneven, with more middle and fewer sides.

How to solve problems of roll forging in connecting rod forging?

Because of these problems, they can cause defects in connecting rods, such as folding, folding lines, and incomplete filling. In order to ensure the quality of rolls and reduce rolling defects, we should pay attention to the following points:

• When designing the roll forging die, the forging shape and size of each roll should be determined reasonably.
• Rationally allocate each expansion coefficient and determine the appropriate type of slot.
• Determine the forward sliding value reasonably.
• Accurate calculation of the section size and groove size of the billet.

Closed Die Forging

The main forging machine of connecting rod are hot forging press, automatic control hammer, electric screw press and die forging electro-hydraulic hammer.

• After pre-forging, the forged connecting rod is moved to the final forging die, but the effect of removing oxide skin is obvious when moving.
• Rollers forge the flat part of the connecting rod to make it easy to locate, peel off the oxide sheet and blow off the oxide sheet at the same time.
• The production rhythm is as consistent as possible. It can ensure the trimming temperature, and is conducive to the quality control of subsequent processes, so as to improve the quality of forged connecting rods.

Cutting and Punching

Cutting and punching of connecting rod is usually carried out at high temperature. After forging, the residual heat is used and the cutting stress is small. The compound die of trimming and stamping is used in the press, which is completed at one time. In the process of trimming, the following problems are often encountered:

• uneven residual burr: caused by mismatch or excessive clearance of the die, the clearance of the die is generally 0.5-0.8 mm.
• trimming deformation: trimming die can be made into wavy shape, which can prevent deformation. In addition to the above reasons, the mismatch between forging die and trimming die is also one of the reasons.
• In order to prevent trimming deformation, high precision double-point trimming press or guide device can be used in punching die.

Shaping

The shaping of forged connecting rod is very simple, mainly to correct the flatness and thickness of the connecting rod.

How to Choose Connecting Rod Forging Machine?

To forge connecting rod, there are three kinds of closed die forging machine for you to choose. 

Hydraulic Forging Hammer 

Hydraulic forging hammer is a very common forging machine, it has the advantages of high hitting frequency, and it can make big forgings with small hitting energy. But if you want to build automatic forging line for your connecting rod, the automatic forging hammer maybe better than him to control the hitting energy automatically.

Automatic Forging Hammer for Connecting Rod Making 

Automatic forging hammer is also a hydraulic forging hammer, but as controlled by PLC, it is easier to achieve the forging automation. It can control the forging energy more precisely, and the forging process is stable. We can provide automatic closed die forging hammer with capacity from 16kj to 400kj.

Electric Screw Press

Different with forging hammer, the forging speed of press is low, but the it the shape can be pressed by once, not need be hitting by many times to form the final shape. The forging sound of electric screw press is also more quiet. Electric screw press used in forging automation is also available.

Automatic Forging Line for Connecting Rod

Automatic forging line can greatly reduce the labor cost and increase the forging efficiency. It is more suitable to produce bulk of connecting rod forgings.

 

The above three kinds of machine can all be used in forging automation, Anyang Forging Press can provide forging robot, heating treatment machine, trimming machine, forging flash remove machine, automatic graphite spray machine, induction heating machine, etc. With more than 60 years experiences in forging machine manufacture, we have the ability to provide our customer one-stop turn-key service for forging machine plant solution. If you are looking for connecting rod forging machine, please feel free to contact us!