Because the particle machine ring mold finished product has high surface hardness and certain toughness. At the same time, because some feeds and additives have corrosive effects on the ring mold under high temperature and high pressure, and the ring mold material is required to have corrosion resistance,
Chapter III Test Results and Discussion
3.1 Effect of particle machine ring mold material on the quality of ring mold
3.1.1 Influence of different materials on the service life of ring mold
Granulator pellet machine ring die
Because the particle machine ring mold finished product has high surface hardness and certain toughness. At the same time, because some feeds and additives have corrosive effects on the ring mold under high temperature and high pressure, and the ring mold material is required to have corrosion resistance, several factors are mutually restricted. 4Cr13 material has good stiffness and toughness, heat treatment hardness of 52 ~ 55HRC, and has good wear resistance and corrosion resistance. Long service life. According to the statistics of the use of a large number of feed manufacturers, the 4Cr13 ring mold material has the lowest cost of the ring mold, which is a ring mold material that is completely suitable for the use of the granulator.
3.1.2 Effect of C content and Cr content on the performance of ring mode
(1) Effect of C content on material hardness
Granulator pellet machine ring die
As can be seen from the figure, as the carbon content increases, the hardness of the ring mold increases. When the C content is ≤0.42% to 0.50%, the hardness of the ring die blank is 170-220HB.
(2) Effect of Cr content of 4Cr13 material on ring mold hardness
After many tests, the Cr content in the 4Cr13 material is from 12% to 14%, and the hardness of the ring mold is basically unchanged.
(3) Effect of Cr content of 4Cr13 material on service life of ring mold
Granulator pellet machine ring die
It can be seen from Fig. 3-2 that the service life of the ring mold containing about 12% of Cr in actual use is less than 1/3 of the service life of the ring mold containing 14% of Cr under the same conditions as other treatments: Therefore, the source of the ring mold is from the ingot, and the Cr content is required to be more than 12.5%.
3.2 Influence of forging temperature on 4Cr13 ring mold material
Granulator pellet machine ring die
It can be seen from the above figure that the heating temperature is too high and the time is too long when the ring blank is forged, the forging blank is yellowish white, and the temperature exceeds 1200 °C. At this time, the forging blank is prone to surface over-burning, the overall overheating, the coarse grain of the structure is not Uniform phenomenon. During the heating process, the forging is overheated or partially over-burned due to uneven temperature, resulting in coarse grain and poor homogeneity of the forging blank. The larger the forging size, the more serious this phenomenon is. It is difficult to eliminate such defects in the subsequent heat treatment process, and is also a common cause of ring splitting.
3.3 Influence of cold working process on the quality of ring die hole
The cutting speed directly affects the surface roughness of the ring mold. The higher the cutting speed, the better the surface quality. The effect of ring die aperture and speed on surface roughness when using a gun drill to drill a die hole:
It can be seen from the figure that the ring die hole is machined with a gun drill. When the die diameter is Ø5mm, the surface roughness is 1.6 um when the spindle speed is 3000r/min, and the surface roughness can be reached when the speed is 5000r/min. 0.8 μm.
Granulator pellet machine ring die
The ring die hole is machined by a gun drill. When the die hole diameter is Ø1. 6mm, the surface roughness is 1.6 um when the rotation speed is 9000r/min, and the surface roughness can reach 0.8 pm when the rotation speed is 13000r/min.
For ordinary drilling machines, the maximum speed is generally 3000~5000r/min, and the surface quality of the machine is poor. When the small-aperture ring mold is processed, the roughness is unqualified, and the material can not be discharged during the strip test of the ring mold.
3.4 Effect of heat treatment process on the quality of ring mold
3.4.1 Effect of quenching temperature on hardness and impact toughness of ring die
(1) The austenitizing temperature of the 4Cr13 material is about 1000 °C, and the final heating temperature (gas quenching temperature) of the ring mold should be higher than this value to form an austenite structure. If the vacuum gas quenching temperature of the ring mold is high, the hardness after heat treatment is high, but quench cracks are also easily formed. Moreover, in a high-temperature vacuum environment, the evaporation of alloying elements such as Cr, Mn, etc. in the high chromium stainless steel may increase, which may reduce the mechanical properties of the bad mold. Therefore, the vacuum gas quenching temperature of the ring mold cannot be too high.
The effect of quenching temperature on the hardness of the ring mold is shown in the figure below.
Granulator pellet machine ring die
It can be seen that the quenching temperature of the 4Cr13 ring mold is increased from 1020 ° C to 1060 ° C, and its hardness increases as the heating temperature increases.
Granulator pellet machine ring die
The quenching temperature is from 1030. C rises to 1050 and the hardness can be increased by 1 to 1.5 HRC.
(2) Effect of austenitizing temperature on impact toughness
Granulator pellet machine ring die
The quenching temperature is increased from 1040 ° C to 1060 ° C. Although the hardness is high, the impact toughness is obviously decreased, the thermal stress is too large, and quenching microcracks are easily generated. Therefore, quenching at 1040 ° C is most suitable.
3.4.2 Effect of vacuum quenching on the roughness of ring die hole
The roughness of the ring die hole is basically not reduced after vacuum gas quenching, and the roughness of the material after the gun drilling is 0.8 μm. After inspection, the roughness after heat treatment is still 0.8 μm; the roughness after the gun drill is 1. 6 μm, after inspection, the roughness after heat treatment was still 1.6 μm. The Ra value is not substantially lowered as compared with that before the heat treatment.
3.4.3 Effect of tempering temperature on ring hardness and impact toughness
The performance of the ring mold is a comprehensive problem, such as the hardness is too high, although the wear resistance is very good, but the brittleness is very large, it is easy to smash in use. However, the hardness is too low, which is easy to cause the hole of the die hole to be formed and the wear of the bad die and the working surface of the pressure roller to affect the service life. The 4Cr13 ring mold has high strength and high wear resistance, but also has a large crack sensitivity, so tempering after quenching is very important.
(1) Effect of tempering temperature on the hardness of the ring mold
High temperature tempering, the comprehensive mechanical properties are improved, but the hardness is lower than before tempering; the medium temperature tempering, the hardness is slightly lower than before tempering, but the high yield ratio, elastic limit and toughness are obtained; low temperature tempering can maintain The high hardness and high wear resistance of the quenched martensite while reducing the quenching stress and brittleness.
Sanmenxia Futong New Energy sells biomass fuel feed molding machinery such as pellet machine, straw pellet machine, straw briquetting machine, feed pellet machine, etc. At the same time, we also sell pellet machine ring and other accessories.
Information from: manufacturing process of pellet machine ring mold (7) http://
Http://news.chinawj.com.cn Submission:
PPGI And PPGL With Normal Colors
PPGL Roofing Sheet,PPGI Roofing Sheet,Galvanized Sheet Price,PPGI Colour Coated Sheet
SHAOXING YOTO IMPORT&EXPORT CO., LTD , https://www.sxyotoes.com