Product Description

A:company profile

 L.T Group has a comprehensive product and technology portfolio that focuses on 4 field of graphite – ultrafine particle graphite mould,graphite electrode, graphite crucible, as well as other products mainly made of graphite.

 Graphite materials exhibit unique properties such as good electrical and thermal conductivity, heat and corrosion resistance, low friction, and reduced weight while at the same time maintaining high strength. Due to the shortage of energy and raw materials, our high performance products made from graphite are in increasingly high demand in industries. They also play a progressively important role in everyday life, thereby substituting traditional materials.
 

B:Pantograph skateboard application

 The electrical equipment used by electric traction locomotives to obtain electrical energy from the catenary is installed on the roof of the locomotive or motor car. The pantograph can be divided into single-arm bow and double-arm bow, both of which are composed of a skateboard, upper frame, lower arm rod (lower frame for double-arm bow), underframe, bow lifting spring, transmission cylinder, support insulator and other components. The diamond-shaped pantograph is also called the CZPT pantograph. The smoothness of the load current passing through the contact surface of the contact wire and the pantograph slide is related to the contact pressure, transition resistance, and contact area between the slide and the contact wire, and depends on the interaction between the pantograph and the contact net.
 

C: Advantages of pantograph skateboard

 The pantograph is to get electricity through the contact between the sliding plate and the contact net. The sliding plate is generally made of graphite and other materials, so the contact net wear is relatively small, and the sliding plate is easy to replace after it is worn, and the cost is low. The cycle is generally about 2 weeks, and it can be replaced once a month if the quality is good. However, the high-speed rail speed is 300 kilometers per hour, and the wind resistance of the pantograph is very large, so the design is very particular, not only to make it solid and reliable, but also to make it as light as possible.

D:Classification of pantograph charcoal skateboard

 The pantograph sliding plate is a part of the pantograph head and directly contacts the contact wire. According to the material, it can be divided into pure metal sliding plate, powder metallurgy sliding plate, pure carbon sliding plate and immersed metal sliding plate.

 Where the pantograph of electric locomotive contacts the wire, there are currently 3 materials in use in our country: 1. Pure carbon graphite slide plate 2. Metal-impregnated carbon slide plate 3. Powder metallurgy slide plate. However, due to the powder metallurgy sliding plate, the copper wire is seriously worn. Therefore, it has been basically replaced by the first 2 skateboards.
 

 (1) Pure carbon graphite slide
A certain proportion of pitch coke, petroleum coke, graphite powder, carbon black or hard carbon is mixed with each other, and then pressed into a high-temperature sintering CZPT for roasting. The product can be applied after reprocessing. Although pure carbon slides are hard, brittle and easy to break, they are widely used because of their self-lubricating ability and good anti-wear properties.

 (2) Metal-impregnated carbon skateboard
This type of skateboard not only combines the high mechanical strength and low resistance of powder metallurgy skateboards, but also combines the self-lubricating ability of pure carbon skateboards and the characteristics of less wear on overhead contact nets. In theory, it is the most ideal material for skateboards.

 (3) Powder metallurgy skateboard
Using metal (iron, copper) raw materials and non-metallic powders (carbon, lead, molybdenum disulfide, etc.) as auxiliary lubricants, they are mixed with each other and then pressed into shape. After high temperature sintering, they are immersed in lubricating oil, and finally machined into shape. The processing process is similar to Ceramic firing, the surface hardness of the pantograph produced by it is high, and it is not easy to appear fracture and uneven wear. Compared with pure metal skateboards, it has its own lubrication effect.
 

Worm Shafts and Gearboxes

If you have a gearbox, you may be wondering what the best Worm Shaft is for your application. There are several things to consider, including the Concave shape, Number of threads, and Lubrication. This article will explain each factor and help you choose the right Worm Shaft for your gearbox. There are many options available on the market, so don’t hesitate to shop around. If you are new to the world of gearboxes, read on to learn more about this popular type of gearbox.

Concave shape

The geometry of a worm gear varies considerably depending on its manufacturer and its intended use. Early worms had a basic profile that resembled a screw thread and could be chased on a lathe. Later, tools with a straight sided g-angle were developed to produce threads that were parallel to the worm’s axis. Grinding was also developed to improve the finish of worm threads and minimize distortions that occur with hardening.
To select a worm with the proper geometry, the diameter of the worm gear must be in the same unit as the worm’s shaft. Once the basic profile of the worm gear is determined, the worm gear teeth can be specified. The calculation also involves an angle for the worm shaft to prevent it from overheating. The angle of the worm shaft should be as close to the vertical axis as possible.
Double-enveloping worm gears, on the other hand, do not have a throat around the worm. They are helical gears with a straight worm shaft. Since the teeth of the worm are in contact with each other, they produce significant friction. Unlike double-enveloping worm gears, non-throated worm gears are more compact and can handle smaller loads. They are also easy to manufacture.
The worm gears of different manufacturers offer many advantages. For instance, worm gears are 1 of the most efficient ways to increase torque, while lower-quality materials like bronze are difficult to lubricate. Worm gears also have a low failure rate because they allow for considerable leeway in the design process. Despite the differences between the 2 standards, the overall performance of a worm gear system is the same.
The cone-shaped worm is another type. This is a technological scheme that combines a straight worm shaft with a concave arc. The concave arc is also a useful utility model. Worms with this shape have more than 3 contacts at the same time, which means they can reduce a large diameter without excessive wear. It is also a relatively low-cost model.

Thread pattern

A good worm gear requires a perfect thread pattern. There are a few key parameters that determine how good a thread pattern is. Firstly, the threading pattern must be ACME-threaded. If this is not possible, the thread must be made with straight sides. Then, the linear pitch of the “worm” must be the same as the circular pitch of the corresponding worm wheel. In simple terms, this means the pitch of the “worm” is the same as the circular pitch of the worm wheel. A quick-change gearbox is usually used with this type of worm gear. Alternatively, lead-screw change gears are used instead of a quick-change gear box. The pitch of a worm gear equals the helix angle of a screw.
A worm gear’s axial pitch must match the circular pitch of a gear with a higher axial pitch. The circular pitch is the distance between the points of teeth on the worm, while the axial pitch is the distance between the worm’s teeth. Another factor is the worm’s lead angle. The angle between the pitch cylinder and worm shaft is called its lead angle, and the higher the lead angle, the greater the efficiency of a gear.
Worm gear tooth geometry varies depending on the manufacturer and intended use. In early worms, threading resembled the thread on a screw, and was easily chased using a lathe. Later, grinding improved worm thread finishes and minimized distortions from hardening. As a result, today, most worm gears have a thread pattern corresponding to their size. When selecting a worm gear, make sure to check for the number of threads before purchasing it.
A worm gear’s threading is crucial in its operation. Worm teeth are typically cylindrical, and are arranged in a pattern similar to screw or nut threads. Worm teeth are often formed on an axis of perpendicular compared to their parallel counterparts. Because of this, they have greater torque than their spur gear counterparts. Moreover, the gearing has a low output speed and high torque.

Number of threads

Different types of worm gears use different numbers of threads on their planetary gears. A single threaded worm gear should not be used with a double-threaded worm. A single-threaded worm gear should be used with a single-threaded worm. Single-threaded worms are more effective for speed reduction than double-threaded ones.
The number of threads on a worm’s shaft is a ratio that compares the pitch diameter and number of teeth. In general, worms have 1,2,4 threads, but some have three, five, or six. Counting thread starts can help you determine the number of threads on a worm. A single-threaded worm has fewer threads than a multiple-threaded worm, but a multi-threaded worm will have more threads than a mono-threaded planetary gear.
To measure the number of threads on a worm shaft, a small fixture with 2 ground faces is used. The worm must be removed from its housing so that the finished thread area can be inspected. After identifying the number of threads, simple measurements of the worm’s outside diameter and thread depth are taken. Once the worm has been accounted for, a cast of the tooth space is made using epoxy material. The casting is moulded between the 2 tooth flanks. The V-block fixture rests against the outside diameter of the worm.
The circular pitch of a worm and its axial pitch must match the circular pitch of a larger gear. The axial pitch of a worm is the distance between the points of the teeth on a worm’s pitch diameter. The lead of a thread is the distance a thread travels in 1 revolution. The lead angle is the tangent to the helix of a thread on a cylinder.
The worm gear’s speed transmission ratio is based on the number of threads. A worm gear with a high ratio can be easily reduced in 1 step by using a set of worm gears. However, a multi-thread worm will have more than 2 threads. The worm gear is also more efficient than single-threaded gears. And a worm gear with a high ratio will allow the motor to be used in a variety of applications.

Lubrication

The lubrication of a worm gear is particularly challenging, due to its friction and high sliding contact force. Fortunately, there are several options for lubricants, such as compounded oils. Compounded oils are mineral-based lubricants formulated with 10 percent or more fatty acid, rust and oxidation inhibitors, and other additives. This combination results in improved lubricity, reduced friction, and lower sliding wear.
When choosing a lubricant for a worm shaft, make sure the product’s viscosity is right for the type of gearing used. A low viscosity will make the gearbox difficult to actuate and rotate. Worm gears also undergo a greater sliding motion than rolling motion, so grease must be able to migrate evenly throughout the gearbox. Repeated sliding motions will push the grease away from the contact zone.
Another consideration is the backlash of the gears. Worm gears have high gear ratios, sometimes 300:1. This is important for power applications, but is at the same time inefficient. Worm gears can generate heat during the sliding motion, so a high-quality lubricant is essential. This type of lubricant will reduce heat and ensure optimal performance. The following tips will help you choose the right lubricant for your worm gear.
In low-speed applications, a grease lubricant may be sufficient. In higher-speed applications, it’s best to apply a synthetic lubricant to prevent premature failure and tooth wear. In both cases, lubricant choice depends on the tangential and rotational speed. It is important to follow manufacturer’s guidelines regarding the choice of lubricant. But remember that lubricant choice is not an easy task.