WHAT ARE THE BASIC PROCESSES OF FREE FORGING?

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Free forging is a processing method that uses impact force or pressure to deform the metal freely in all directions between the upper and lower anvil surfaces, and obtains the required shape and size and certain mechanical properties without any restriction, which is referred to as free forging. The tools and equipment used in free forging are simple, versatile and low in cost. Compared with casting blanks, free forging eliminates shrinkage holes, shrinkage porosity, pores and other defects, so that the blanks have higher mechanical properties. Forgings are simple in shape and flexible in operation. Therefore, it has special significance in the manufacture of heavy machinery and important parts.

BASIC PROCESS OF FREE FORGING

The basic processes of free forging include upsetting, drawing, punching, bending, torsion, offset, cutting and forging.

Upsetting

A forging process that reduces the height of the blank and increases the cross-sectional area. The upsetting process is mainly used for forging gear blanks and round cake forgings. The upsetting process can effectively improve the blank structure and reduce the anisotropy of mechanical properties. Repeated upsetting and drawing can improve the morphology and distribution of carbides in high-alloy tool steels.

Agricultural machinery bearing sleeve

Upsetting mainly has the following three forms:

1. Complete upsetting. Complete upsetting is to place the blank vertically on the anvil surface, and under the hammering of the upper anvil, the blank will be plastically deformed with a height reduction and an increase in the cross-sectional area.

2, the end upsetting. After the billet is heated, one end is placed in a drain or mold to limit the plastic deformation of this part, and then the other end of the billet is hammered to make it upsetting. The upsetting method of the leaking disc is mostly used for small batch production; the method of upsetting the tire mold is mostly used for mass production. Under the condition of single-piece production, the part that needs upsetting can be heated locally, or after all heating, the part that does not need upsetting can be chilled in water, and then upsetting is performed.

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WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF FREE FORGING?

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Free forging is what we call free forging, which is completed by gradual local deformation of the blank on the flat anvil or between the tools. Because the tool is in contact with the blank part, the stagnant grid work is much smaller than the die forging bar for the production of forgings of the same size, so free forging is suitable for forging large forgings. Of course, free forging also has certain advantages and disadvantages in the forging process. Yes, let’s find out together!

Agricultural machinery lifting arm

THE ADVANTAGES OF FREE FORGING :

(1) Free forging can improve the structure and properties of metal. The quality and mechanical properties of metal free forgings are higher than those of castings, and their strength is 50% -70% higher than that of castings, so they can withstand large impact loads. Forgings can reduce the weight of the parts themselves on the premise of ensuring the design strength of the parts, which is of great significance to aerospace and transportation.

(2) Free forging can save raw materials. Parts with shapes closer to the part can be produced using the free forging method.

(3) Free forging is suitable for single-piece small batch production, and the variety is more flexible.

(4) Since there is no lateral flow in the straight shaft or curved shaft parts and annular parts, the streamline distribution is generally more reasonable than that of die forgings. It is especially suitable for straight or curved shafts, discs or rings with simple shape, small cross-section change and gentle main axis.

(5) Some special quality torsion requirements can be met by the free forging process, such as reverse upsetting can improve the quality of raw materials.

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WHAT ARE THE MAIN FACTORS AFFECTING THE QUALITY OF DIE FORGINGS?

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The die forging process has high production efficiency, low labor intensity, accurate dimensions, small machining allowance, and can forge forgings with complex shapes; it is suitable for mass production. However, the cost of the die is high, and special die forging equipment is required, which is not suitable for single-piece or small batch production. Therefore, the quality of die forgings is also more concerned by users. Correctly understand the main factors affecting the quality of die forgings. very important meaning.

THE MAIN FACTORS AFFECTING THE QUALITY OF DIE FORGINGS

Other agricultural machinery forgings

1. DEFECTS IN RAW MATERIALS

For example, there are residual shrinkage holes, bubbles, porosity, inclusions, etc. in the ingot or steel, which may cause the forging to crack. Forging cracks caused by metallurgical reasons are often accompanied by a large number of oxides, sulfides, silicates and other inclusions. The raw materials of high carbon and high alloy steel are prone to serious segregation of second phases such as carbides. If they are not crushed and evenly distributed during forging, the mechanical properties of the forgings will be reduced, and the forgings may be cracked or evenly distributed during heat treatment. distortion. If there are scratches, scars, folds and cracks on the surface of the raw material, it will bring defects to the forgings. Therefore, raw materials must be inspected in die forging production.

2. HEATING SPECIFICATION

When forging large die forgings and alloy steel die forgings, if the heating speed is too fast, the temperature difference between the inner and outer layers will be large, and the central part will be cracked due to temperature stress and structural stress.
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When the heating temperature is too high and the holding time is too long to cause slight overheating, a lustrous, crystalline, and intergranular fracture will be produced. Coarse grains that are slightly overheated can be corrected by annealing or normalizing, followed by recrystallization. In severe overheating, fractures or stone fractures will occur. The characteristics of the fracture are fish-scale bright spots and transgranular fracture; the reason for the fracture is that the coarse austenite grains form an intragranular texture with extremely high stability. Texture characteristics are preserved.

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What are the manufacturing process of slewing bearing?

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The slewing bearing structure includes: inner ring, outer ring, rolling elements and cage guided by rolling elements. It is an important transmission component in mechanical equipment and has been widely used in construction machinery, light industrial machinery, metallurgical machinery, medical machinery, marine equipment and other industries. Application, then the excavator slewing bearing manufacturer will take you to understand the manufacturing process and detailed steps of the slewing bearing.

1. Cutting of slewing bearing steel raw materials

The commonly used raw materials for slewing ring bearings are carbon-chromium bearing steel that is hardened as a whole, and the slewing ring is made of surface-hardened steel, generally made of 50Mn steel, such as: S48C, 42CrMo, 5CrMnMo. The cylindrical raw material billets transported from the steel mill are cut according to the size required for processing the bearing. Generally, the carbide saw blade should be used for cutting bearing steel, which has high hardness, wear resistance, good strength and toughness, heat resistance, corrosion resistance, etc. A series of excellent properties.

2. Slewing bearing billet forging

In a heating furnace, the billet is heated and forged into a round cake shape. The forging link is an important link to ensure the reliability and life of the bearing. After the raw material is forged, the bearing ring blank is formed. At the same time, the organizational structure of the raw material becomes denser and the flow line becomes better, which can improve the reliability and service life of the bearing. In addition, the quality of the forging process will directly affect the utilization rate of raw materials, thereby affecting the production cost.

3. Forging ring of slewing bearing

The billets are forged into ring-shaped steel rings using a ring mill. Forging can improve the internal structure of steel and improve the strength, plasticity, impact toughness and other mechanical properties of steel.

4. Rough turning

The steel ring after the ring is put into the machine tool, rough machining is performed, various groove raceways are turned, the steel ring is fixed on the gear milling machine, and the teeth are cut. The main purpose is to make the finished ferrule the same shape as the final product, to create conditions for post-grinding machining.

slewing bearing

5. Slewing bearing quenching (heat treatment)

After machining, through the quenching operation, the strength and hardness of the steel are improved, and the wear resistance, fatigue strength and toughness of the metal are improved. The heat treatment process is to carry out high temperature treatment on the bearing ring after forging and turning, which directly affects the uniformity of carburization in the bearing ring, which can improve the wear resistance and hardness of the bearing, and also affects the reliability and life of the bearing important part.

6. Slewing bearing opening processing

Drill the mounting hole on the end face of the steel ring. When opening the slewing bearing, the center and cutting angle should be determined, and the drilling machine, hand-held electric drill and hand drill should be selected for operation.

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For details, please visit:https://www.excavatorbearing.com/a/bearing-knowledge/manufacturing-process-of-slewing-bearing.html

What are the factors that affect the life of the slewing bearing?

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In fact, when it comes to the factors that affect the life of the slewing bearing, there are many factors that work together to affect the life of the bearing. Many of these factors are difficult to express in a quantitative way and have a direct relationship with the bearing life, but in most cases, it also has a more or less impact on the bearing life from the side. For this problem, slewing bearing manufacturers start from the production and use of bearings. A detailed analysis of the factors affecting the life of the slewing bearing.

Production

slewing bearing

1. Structural design

The design structure of the slewing bearing includes rolling elements, inner and outer rings, and cages. In the design, the diameter of the rolling elements, the number of rolling elements, the wall thickness of the ring, the effective length of the rolling contact, the tightness and the convexity of the contact surface of the raceway should be considered. shape and size. At the same time, the chemical composition of bearing production materials, oxides, impurities, gases and other factors have an impact on bearing performance and life.

2. Processing technology

The impact of bearing processing technology on bearing performance and life is a more critical part. In the process of bearing manufacturing and processing, the hardness, metallographic structure, burn, bump and surface roughness of the working surface of the bearing, the shape of the surface busbar, the thickness of the ring wall, the poor grouping of parts, the accuracy of the roller guide surface, the bearing clearance, the parts Cracks, residual magnetism and residual stress on the surface of the parts will also affect the life of the bearing.

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For details, please visit:https://www.excavatorbearing.com/a/bearing-knowledge/factors-affecting-the-life-of-slewing-bearing.html

How to maintain the slewing bearing of the truck-mounted crane?

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The truck-mounted crane is a carrier vehicle with both hoisting and cargo-carrying functions. The slewing bearing plays a very critical role in the middle as an accessory of the truck-mounted crane. The accessory of slewing bearing is not only used on truck-mounted cranes, but also used on construction machinery models such as flatbed trucks. Next, the following detailed introduction is given to the maintenance methods of truck-mounted slewing bearings and the precautions for use. Let’s understand together. Just a moment.

Maintenance method of slewing bearing of truck mounted crane

slewing bearing of the truck-mounted crane

1. Regularly add grease

When the product is put into use, it should be filled with new grease according to different working conditions. The slewing bearing should be filled with grease regularly. According to different types of slewing bearings, the specific filling time of grease is as follows:

(1) Ball type: add grease every 100 hours of operation;

(2) Roller type: add grease every 50 hours of operation;

If it is in a special working environment, such as: tropical, high temperature, dusty, high temperature, and continuous work, the grease filling cycle should be shortened, and it should be ensured that it should be filled every 50 hours; Apply detergent once every 150 hours. When working vigorously, apply detergent every 75 hours. Note that the teeth must be wiped clean before applying detergent.

The machine must be filled with new grease before and after the machine has been stagnant for a long time. Each time the grease is added, the raceway must be filled until it overflows from the sealing device. When adding grease, the slewing bearing should be slowly transferred. Fill the raceway with grease evenly.

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For details, please visit:https://www.excavatorbearing.com/a/bearing-knowledge/truck-mounted-crane-slewing-bearing-maintenance.html

How to improve the service life of robot bearings

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Robot bearing is an important part of mechanical equipment. If you want to improve the service life of robot bearing, it is necessary to select the size and accuracy according to the location of use, use conditions and environmental conditions. Matching suitable bearings is the premise to ensure the life and feasibility of robot bearings.

1. Parts of use: Robot bearings are suitable for bearing combined radial and axial loads mainly based on radial loads. They are usually used in pairs with two sets of bearings, mainly for front and rear wheel hubs, driving bevel gears, differentials, etc. of automobiles. Transmission parts such as reducer.

2. Allowable rotational speed: In the environment of correct installation and good lubrication, it is allowed to be 0.3-0.5 times the limited rotational speed of the robot bearing. Under normal circumstances, 0.2 times the speed limit is appropriate.

Robot-bearing

3. Allowable inclination angle: Robot bearings generally do not allow the shaft to be inclined relative to the housing hole. If there is an inclination, it should not exceed 2′.

4. Allowable temperature: Under normal load, and the lubricant has high temperature resistance and sufficient lubrication, the general bearing is allowed to work at an ambient temperature of -30°C to 150°C.

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For details, please visit:https://www.prsbearings.com/a/news/improve-the-service-life-of-robot-bearings.html

What are the effects of heat treatment on crossed roller bearing materials?

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Crossed roller bearings are a kind of bearings that are used more in machinery, especially in industrial machines. Of course, when we use them, we want to have better performance of crossed roller bearings and ensure that the crossed roller bearings have better performance. Various properties, then we need to heat treatment its processing materials, why heat treatment, and what is the effect of heat treatment on crossed roller bearing materials? Let’s find out together!

1. Surface residual stress

The distribution of residual stress on the surface of bearing steel after quenching is largely affected by the cooling rate and quenching medium. For the material used in crossed roller bearings, after heating to 840 ° C and quenching in oil, the axial stress and shear stress The distribution characteristics of the stress along the section are roughly the same, and the magnitudes are similar. There is tensile stress near the inner and outer surfaces, and compressive stress at the center of the section. If the material and quenching process are different, the surface stress distribution law is different, or even reversed.

2. Quenching cracks

(1) Two types of quenching cracks will appear after the bearing is quenched: deep cracks and surface cracks. Deep cracks are caused by stresses related to temperature gradients; surface cracks are related to surface decarburization. Another reason for cracks is mainly due to the reduction of the brittle fracture strength of the formed martensite due to the higher quenching temperature. Increasing the quenching temperature will reduce the number of quenching cracks; ℃, can make it more stable.

(2) If it is taken out from the hot oil and cleaned immediately, it will induce cracks, and even the mixture of a small amount of water in the quenching oil will significantly increase the risk of cracks; if there is insufficient intermediate annealing, or decarburization is not removed. The layer is subjected to secondary quenching, which also increases the possibility of cracks. Surface quenching cracks caused by decarburization are largely related to the depth of the tool marks on the surface after machining, which causes stress concentration. The greater the depth of the tool marks before quenching, the longer the cracks after quenching.

Crossed Roller Bearings

3. Surface oxidation and decarburization

During heat treatment, oxidation and decarburization on the surface of the ferrule are inevitable, and the thickness of these oxidation and decarburization layers is called the heat treatment metamorphic layer. However, by using the protective atmosphere heat treatment method, the thickness of the metamorphic layer can be minimized, thereby reducing metal waste and grinding consumption.

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For details, please visit:https://www.prsbearings.com/a/news/effect-of-heat-treatment-on-crossed-roller-bearing-materials.html

Causes and detection methods of abnormal noise of crossed roller bearings

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A crossed roller bearing is a special type of bearing in which the inner ring is divided and the outer ring rotates. Compared with conventional models, the rigidity of crossed roller bearings is increased by 3 to 4 times. At the same time, since the inner ring or outer ring of the crossed roller bearing is divided into two structures, the bearing clearance can be adjusted, and even if a preload is applied, high-precision rotational motion can be obtained.

In our daily life, the bearing will encounter the problem of abnormal bearing noise after three or two years of normal use. The following are several methods for detecting abnormal noise of bearings summarized by crossed roller bearing manufacturers. Let’s take a look.

Cause of abnormal noise

There are many kinds of abnormal sounds during the operation of crossed roller bearings, the formation mechanism is relatively complex, and the factors are multi-faceted, and various abnormal sounds are often superimposed together, which is difficult to distinguish. The main reasons are as follows:

(1) There are periodic vibration pulses caused by bumps, scratches or serious defects in the inner and outer raceways of the bearing.

(2) Non-periodic vibration pulses caused by defects such as bumps and scratches on the surface of the rolling element.

(3) Periodic or aperiodic vibration pulses caused by the presence of residual magnetically adsorbed iron powder on raceways or rolling elements.

(4) The pulse of aperiodic vibration caused by impurities or dust entering the running area of the bearing raceway.

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For details, please visit:https://www.prsbearings.com/a/news/causes-and-detection-methods-of-abnormal-noise-of-crossed-roller-bearings.html

Precautions for the replacement of tractor clutch friction discs

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Tractor clutch friction discs are divided into inner friction discs and outer friction discs, which are usually installed inside the tractor clutch. The clutch of the tractor is mainly composed of clutch piston, end plate, drum, disc drum, outer friction plate, inner friction plate, pressure plate and spring, etc. There are three wet shift clutches in total (two for shifting, one for for reversing), which are hydraulically engaged.

Tractor clutch friction plate

1. Transmission of rotational torque. The tractor engine flywheel is the driving part of the clutch, and the driven disc and driven hub with friction discs are connected with the driven shaft (ie, the driving shaft of the transmission) by sliding splines. The compression spring presses the driven disc against the end face of the flywheel.

2. The torque of the tractor engine is transmitted to the driven disc by the friction between the flywheel and the contact surface of the driven disc, and then transmitted to the driving wheel through the driven shaft and a series of components in the drive train. The greater the compression force of the compression spring, the greater the torque that the clutch can transmit.

Precautions for the replacement of tractor clutch friction discs

1. The driven disc assembly should be kept clean, and the tractor clutch friction plate must be dust-proof, anti-fouling and oil-proof. Before assembling on the engine, the surface of the pressure plate and flywheel should be wiped clean to remove oil stains to prevent the clutch from slipping.

2. The tractor clutch has been adjusted before leaving the factory under normal circumstances, and it does not need to be adjusted during installation.

3. In order to ensure the smooth operation of the clutch, the clutch pressure plate assembly and the driven plate assembly have been balanced before leaving the factory. Do not replace the spare parts at will during use. When the tractor clutch must be disassembled for repair, mark it first, then assemble and rebalance according to the original mark after repair.

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For details, please visit:https://www.syclutch.com/news/precautions-for-replacement-of-clutch-friction-discs.html