Technology frontier: Save time and save material 3D printing new ways to facilitate 4D printing
Recently, a group of researchers have developed a new 3D printing method to create objects that respond to heat and can be permanently converted into different shapes. The team created objects by printing shape memory polymers, each designed to react differently when exposed to heat. Jerry Qi, a professor at the George Woodwood School of Mechanical Engineering, said: "This new method greatly simplifies 4D printing and increases its potential by directly incorporating machine programming post-processing steps into the 3D printing process. This allows computer simulations, 3D Print design High-resolution 3D printing components, then directly and quickly converted to a new permanent configuration with simple heating." It is reported that the research team published the research results in the magazine "Scientific Progress." The new 3D printed objects they developed follow the team's early work with smart shape memory polymers (SMPs) that have the ability to record a shape and fold along hinges when uniform heat is applied. Change to another programming shape. "This approach can reduce the printing time and save up to 90% of the material, while completely eliminating the time-consuming mechanical programming in the design and manufacturing workflow." Qi said. To demonstrate the capabilities of the new process, the team created several objects that, when immersed in hot water, can be quickly bent or expanded, including true daisies mimicking petal curvature, true daisies that respond to sunlight, and grid-like objects to expand the original scale Eight times. Zhen Ding, a postdoctoral researcher at the Singapore University of Technology and Design, said: “Our composite material at room temperature is a soft material that can be programmed to contain internal stresses, and another material is rigid.†"We use computational simulations to design composite parts where the shape and size of the rigid material prevents programmed internal stresses from being released from the soft material after 3D printing. When heated, the hard material softens and the soft material releases its pressure. Changes in product shape." Researchers say that new 4D objects can implement a series of new product features, such as allowing flat or rolling products to be stacked, and then expanding the use once. Ultimately, this technology can enable the creation of spatial structures in response to components such as temperature, humidity, or light stimulation in a precisely timed manner that can be deployed to a range of medical devices, robots, toys, and other structures. Martin L. Dunn, director of digital manufacturing at the Singapore Institute of Technology and Design, said: "The major advancement in this work is 4D printing, which greatly simplifies and enables the creation of high-resolution, complex 3D reprogrammable products." This technology promises to achieve numerous applications in biomedical devices, 3D electronics and consumer products, and even opens up new paradigms for product design, where components go from service to configuration.
Tungsten carbide roller has characteristics of good wear resistance, high temperature red hardness, thermal fatigue resistance and thermal conductivity and high strength , have been widely used in high-speed wire rod, bar, rebar, seamless steel tubes, etc. Domestic production of tungsten carbide roller materials mostly WC- Co, WC- Co- Ni- Cr two series, and the content of Co, Co- Ni - Cr is in the range of 6wt% ~ 30wt%. From the use of perspective, tungsten carbide rollers has good mechanical properties, its flexural strength up to 2200 MPa or more, shock toughness up (4 ~ 6) × 10^6 J/ m^2, Rockwell hardness (HRA) is up to 78 to 90, widely in the high-speed wire rod rolling process, which is much higher than single-slot chilled cast steel or high speed steel rolls.Tungsten carbide is made of Tungsten Carbide Powder and binder phase (such as drilling, nickel, etc.), and then pressing and sintering, regardless of the conditions under cold rolled or hot rolled has excellent wear resistance, tungsten carbide rollers has been widely used in pre-finishing mill and finishing of high-speed wire rod currently. On the performance of tungsten carbide roller in hot-rolling wire rod , the material must meet the following requirements:
Tungsten carbide roller material design
Tungsten carbide roller category
Tungsten carbide roller production process control Carbide Roller,Carbide Ring,Mill of Rolling Line,Steel Wire Rod,Mill Rolling Finish Stand,Mill Roller Groove Type Luoyang Golden Egret Geotools Co., Ltd , https://www.xtccarbide.com
1. Sufficient anti-fracture strength;
2. Good abrasion resistance;
3. The smooth surface finish;
4. Excellent corrosion resistance, thermal fatigue, thermal cracking performance.
Tungsten carbide roller rings can working in bad conditions , small profile rolling (especially rebar rolling) process conditions is harsher than the high-speed wire rod, and therefore corresponds to the profile rolling ,tungsten carbide rollers recommend using high binder phase carbide.
Pre-finishing all vehicles roller should ensure its high toughness, strength, rigidity and thermal conductivity, followed before considering its wear resistance. When designing each vehicles roller, pre-finishing materials should choose carbide grades of Co, Co- Ni- Cr binder content is high (greater than or equal to 25wt%) , requiring an average WC grain size of coarse (5μm ~ 6μm), to obtain a higher shock toughness, proper strength and hardness. For the finishing of the roller movements, particularly the last two rollers of the finish rolling, which suffered load is small, and high relative velocity of the material to be pressed (80 m / min ~ 120 m / min). In this case, the wear resistance of the roller to be the most important requirements, and must ensure the strength , timpact toughness and hardness of a reasonable match, so the binder of Co / Ni content ratio and the average grain WC control of particle size and other factors must have greater control in front of different pre-finishing rolling roll.
According to the structure of tungsten carbide rollers, it can be divided into solid tungsten carbide roller and composite tungsten carbide roller. Solid tungsten carbide rollers have been widely used in pre-finishing and finishing stands high speed wire rod mill (including fixed reducing the rack, pinch roller rack). Composite tungsten carbide roller is made of cemented carbide and other materials, and it can be divided into tungsten carbide composite roll rings and solid tungsten carbide composite roller. Tungsten carbide composite roll rings mounted on the roller shaft; solid tungsten carbide composite roller will be directly cast in the roll axis to form a whole, a large load is applied to the rolling mill.
Tungsten carbide rollers produced by powder metallurgy method, the key to its process control is the chemical composition of the material and the mixture was prepared, pressed molding, sintering and deep processing and other preparation process parameters.
1. Preparation of starting material (WC focus quality): As the WC raw material and quality control of the use of different levels of quality may fluctuate, resulting in adverse effects on microstructure.
2. Preparation of the mixture: Mixture preparation is the key to the production process of the roller, the roller of failure modes - trachoma, mainly generated by this procedure.
3. Pressing: roller pressing is an important process of the roller mill.
4. Sintering: roller sintering is to determine the final quality of the roller production processes, use of advanced low-pressure sintering technology, HIP sintering technology can greatly improve the performance of roller.
5. Deep processing: deep processing rollers have a greater impact on the quality and accuracy of the roller surface.