Category: Chains and sprockets

The national standard for sprockets (GB1244-85) does not specify a concrete tooth profile, only the maximum and minimum tooth groove shapes and their limiting parameters. Currently, a commonly used tooth profile is the three-circular-arc straight-line tooth profile (as shown in the right figure). In the right figure, the aa, ab, and cd segments on the tooth profile are three circular arcs with radii r1, r2, and r3 respectively; the bc segment is a straight line. II. Sprocket Structure and Materials Depending on the sprocket diameter, sprockets can be manufactured as integral, perforated, or assembled types (see structural diagram). The axial tooth profile and dimensions of the sprocket should conform to the provisions of national standard GB1244-85. The sprocket material should ensure sufficient wear resistance and strength of the teeth; different materials are suitable for different applications.

Standardized sprocket production is a primary focus in industrial machinery manufacturing. With a focus on practical applications, rational design and production are crucial, and achieving standardized specifications is paramount. In the process of rational development, sprocket manufacturers continuously pursue higher product quality, selecting high-quality materials, and ultimately producing standardized products. Standardized products are easier to install and use on more equipment, truly meeting diverse production needs, offering wide adaptability, and thus better sales. In actual production, sprocket manufacturers ensure higher production levels, achieving a highly professional level of practicality. Emphasizing practicality, improving product quality, and focusing on material selection are the most important basic development goals for modern sprocket manufacturers, achieving a more scientifically sound development approach. The key lies in the development process itself…

The relationship between the number of sprocket teeth and the number of chain links is generally considered to be related to the number of teeth and links between the sprocket and chain, as well as the overall power of the vehicle and the gear ratios of each gear. These relationships are meticulously designed before leaving the factory for optimal parameter matching and should not be altered. However, if the chain stretches beyond its adjustable length and must be replaced, it's because the length of each link increases, exceeding the distance between the teeth on the sprocket. Forcibly removing a link and installing it will result in poor meshing with the sprocket, causing the chain to "bite" during rotation. This not only increases noise but also accelerates wear. Furthermore, the tooth pitch between the new chain and the old sprocket will not match well, causing the new chain to wear out quickly. Therefore, it's best to replace the sprocket and chain together. Besides chain quality issues, improper adjustment is also a major factor in rapid chain stretching. Overly tight chain adjustments or frequent poor lubrication will shorten its lifespan. The relationship between the number of sprocket teeth and the number of chain links…

When designing the chain drive structure, what should be paid attention to when oiling the chain (1) When oiling the chain, the oil should be injected into the gap between the movable joints of the chain and evenly distributed over the width of the chain. (2) The lubricant should be added to the loose side because the chain links are in a loose state and the lubricant can easily enter between the friction surfaces.

Chain drive components: 1—Driving sprocket; 2—Chain; 3—Driven sprocket. 2. Working principle: Relying on the meshing force between the chain 2 and the two sprockets, the driven sprocket 1 rotates, thereby realizing the transmission of motion and/or power. 3. Characteristics: 1) Advantages: ① Accurate average transmission ratio, no slippage ② Compact structure, low shaft pressure Q ③ High transmission efficiency η=98% ④ High load capacity P=100KW ⑤ Can transmit long distances (amax=5～6m), suitable for high-temperature and harsh environments ⑥ Low cost. 2) Disadvantages: ① Instantaneous transmission ratio is not constant ② Unstable transmission ③ Noise and impact during transmission. 4. Application scope: Suitable for two shafts far apart, harsh working conditions, such as agricultural machinery, construction machinery, petroleum machinery, mining, hoisting, metal cutting machine tools, motorcycles, bicycles, etc. Medium and low speed transmission: Transmission ratio ≤8, P≤100KW, V≤1…

The tooth profile of the sprocket should ensure smooth and free engagement and disengagement of the chain links, preventing chain slippage, and should have a simple shape for easy machining. GB/T1243-97 specifies the end face tooth profile (Table 9-3) and shaft face tooth profile (Table 9-4) for roller chain sprockets. Since the roller surface tooth profile and the sprocket tooth profile are non-conjugate, the sprocket tooth profile design has considerable flexibility, meaning it can be used within both maximum and minimum ranges. If the sprocket uses a standard tooth profile, the end face tooth profile does not need to be drawn on the sprocket working drawing; it is only necessary to indicate that it is manufactured according to GB/T1243-97. However, the shaft face tooth profile must be drawn for machining the blank.

When designing a chain drive structure, what should be noted when applying oil to the chain? (1) When applying oil to the chain, the oil should be injected into the gaps between the moving joints of the chain and evenly distributed across the chain width. (2) The lubricating oil should be applied to the slack side, as the chain links are in a relaxed state at this time, and the lubricating oil can easily enter between the friction surfaces. Types of Chain Drives There are many types of chain drives. According to their uses, chains can be divided into three main categories: lifting chains, traction chains, and transmission chains. ① Lifting chain (also known as traction chain) - mainly used in lifting machinery to lift heavy objects, mainly used to transmit force, to traction and suspend items, and to make slow movements. Its working speed V≤0.25m/s; ② Traction chain (also known as conveyor chain) - mainly used in chain conveyors to move heavy objects, to transport workpieces, items and materials, can be directly used on various machines, or can be used as a unit in a chain conveyor. Its working speed V≤4m/s...

The structures of sprockets generally fall into three categories: 1. Integral structure. This is generally used for machining single and double-row, single and double-flange sprockets with standard chain P=38.1 or less. 2. Welded structure. This is mainly used for machining medium and large-sized single and double-flange sprockets. During machining, the flange part is machined from bar stock into a convex shape. The gear ring part can be machined from sheet metal, with the outer diameter and shaft hole machined. A welding bevel is machined at one end of the hole to fit the flange part for welding. Welding is done at both ends using low-hydrogen welding rods such as T506. 3. Cast sprockets. This is mainly used for machining large sprockets. During machining, only the gear ring, the two end faces of the flange, the outer and inner diameters, and the keyway are machined, and then the tooth profile is machined. Ring sprockets are all cast. Cast sprockets are generally made of two materials: cast iron and cast steel, such as HT15O, HT2O0, and ZG310-570 (ZG45). 4. Forged sprockets. It is mainly used in the production of medium and large-sized sprockets subjected to significant forces.

Gear failure modes: 1. Tooth surface wear: In open gear drives or closed gear drives containing unclean lubricating oil, the relative sliding between the meshing tooth surfaces allows some harder abrasive particles to enter the friction surface, thus changing the tooth profile, increasing backlash, and eventually causing excessive thinning of the gear and tooth breakage. Generally, abrasive wear on the tooth surface will only occur during operation when abrasive particles are mixed in the lubricating oil. 2. Tooth surface scuffing: In high-speed, heavy-load gear drives, the friction between the tooth surfaces is large, and the relative speed is high, resulting in excessively high temperatures in the meshing area. If lubrication conditions are poor, the oil film between the tooth surfaces will disappear, causing the metal surfaces of the two gears to come into direct contact and stick together. When the two tooth surfaces continue to move relative to each other, the harder tooth surface tears off some material from the softer tooth surface along the sliding direction, forming grooves. 3. Fatigue pitting: When two meshing gears come into contact, the action and reaction forces between the tooth surfaces cause…

1. Geometric shape of sprocket teeth: Common sprocket geometric shapes include three-circular-arc straight-line shape, two-circular-arc straight-line shape, two-circular-arc convex tooth shape, one-circular-arc straight-line shape, straight tooth shape with offset tooth groove center, and straight tooth shape. 2. Design principles: The design of sprocket teeth should mainly meet three requirements: meshing requirements, usage requirements, and processability and precision requirements. (1) Ensure that the chain can smoothly mesh in and out without interference. (2) Have sufficient capacity to accommodate chain pitch elongation. (3) Have a reasonable operating angle. (4) The tooth profile curve is adapted to the chain drive working conditions. (5) Facilitate meshing and prevent chain drop due to chain jumping. (6) Have good processability. Currently, the sprocket standard implemented in my country is GB1244-85 tooth shape.

The tooth profile of a sprocket should ensure smooth and free engagement and disengagement of the chain links, prevent chain slippage, and have a simple shape for easy machining. GB/T1243-97 specifies the end face tooth profile (Table 9-3) and shaft face tooth profile (Table 9-4) for roller chain sprockets. Since the roller surface tooth profile and the sprocket tooth profile are non-conjugate, the sprocket tooth profile design has considerable flexibility, meaning it can be used within both maximum and minimum ranges. If the sprocket uses a standard tooth profile, the end face tooth profile does not need to be drawn on the sprocket working drawing; it is only necessary to indicate that it is manufactured according to GB/T1243-97. However, the shaft face tooth profile must be drawn for machining the blank.

At present, the most widely used car trolley in my country's coal mines is the electric circular chain trolley. This type of trolley uses a high-strength circular chain as the traction mechanism, has a simple structure, reliable operation, wear resistance, and long service life. The maximum stroke of the trolley currently in use can only reach the edge of the cage, which cannot meet the requirements of all working conditions [3]. In the transportation operation of mine cars, in order to load, lift and unload the mine cars, it is often necessary to use a trolley to move the position of the mine cars within a short distance, such as pushing the mine cars into and out of the cage or tipper, which plays an important role in improving the automation level of mine hoisting and reducing the labor intensity of workers [1]. According to their location of use, trolleys can be divided into the following categories: (1) Trolleys set in front of the cage. The characteristic of this type of trolley is that it pushes one or two mine cars into the cage and pushes out the empty cars in the cage at the same time. Therefore, only a small thrust is needed, but the action is required to be relatively fast, so as not to prolong the hoisting work...

First, the chain pitch is too large or the sprocket teeth are too small. Too large a pitch leads to poor matching between the roller and the gear, easily causing the roller to break; too small a tooth count prevents the roller from being fully engaged, also easily causing cracks. Repair: Select a chain with a smaller pitch or increase the number of teeth on the sprocket, depending on the actual situation. Second, debris in the sprocket teeth grooves causes the roller to be squeezed and break. Repair: Remove the debris from the tooth grooves or replace the chain. Third, the chain creeps too high on the sprocket teeth. This is due to a mismatched chain or being too loose, resulting in excessive creep. Repair: Replace the chain or, depending on the situation, appropriately tension the chain. Fourth, the chain is subjected to excessive impact force, exceeding its maximum load. Repair: Reduce the load to decrease the impact on the chain.