What problems can not be ignored in mold design process?
Posted on 2020-11-17 15:11:32
With the advent of the intelligent era, many things are automated. Whether it is mechanical equipment or the products we need to use in our daily life, they are all intelligent, mainly convenient and convenient. Now mold design can be displayed in front of us by simulation, so as to get some pattern effect faster. However, mold design is different now.
1、 Problems to be considered in mold design
The design of the die must meet the calculation requirements of stiffness and strength, so as to reduce the elastic deformation of the die under compression. When determining the working belt, the length of the working belt, the form of the empty knife, the die neck and the welding chamber should be considered to select the best parameters. In order to reduce the pressure, a larger value should be selected as far as possible in the allowable range for the selection of the coefficient of the guide hole and the diversion hole of the die. Aluminum template is generally produced with 6061 hard alloy, which makes the production technology more difficult. In extrusion production, there are often some problems such as the material is dragged away, the pressure is not moving, and the discharge is too slow. Therefore, the design of the die plays a key role in the production process.
mould design
1. Design of diversion hole and diversion hole
When designing the die, the position of the diversion hole and the diversion hole should be evenly distributed, so that each part of the profile can absorb the same amount of metal. The size of diversion hole and diversion hole is in positive proportion to the area of profile. Under the condition that the die strength and profile surface quality are not affected, the diversion hole and diversion hole shall be maximized as far as possible. When the metal flows into the welding chamber during extrusion, the larger the diversion hole and the diversion hole, the smaller the stress on the bridge area. The metal flow from the bridge displacement reduces the resistance and increases the discharge speed, but does not affect the die strength. Therefore, the die with small feed hole and large bridge position may not be better than the mold with large feed hole.
Dongguan mold design, Dongguan mold design should pay attention to what
2. Bridge location design
The bridge position is an important part of the die structure. It is the supporting bridge of the mold. When designing the bridge position of the mold, it must be considered that it has enough support force for the mold. In order to meet the support strength of the die, the bridge position angle is generally designed between 18 ~ 25 ℃. If the angle is too large, the friction force between metal flow and bridge position will be increased, and the flow of metal flow will be slowed down. The smaller the angle is, the easier the metal is to be welded, and the discharge speed will be increased. At the same time, the design of bridge position angle joint should be smooth and excessive as far as possible to avoid or reduce the welding dead angle.
3. Welding room design
The welding chamber should not be too deep. If the welding chamber is too deep, the metal volume in the welding room will be increased. When the volume of the welding chamber increases, the welding process will be lengthened, and the extrusion pressure will be increased.
4. Working belt desig
Mold work belt polishing should be careful to ensure flatness, perpendicularity, no turtle back or uneven, reasonable calculation of the working belt length, uniform metal flow.
2、 Extrusion process
1. Process flow:
The aluminum rod is heated (440-460 degrees) to the mold, heated (420-460 degrees, 3-6h), extruded (outlet temperature 530-570 degrees), spray cooled by air quenching, then heated by the spindle (410-420 degrees), self inspected (410-420 degrees below), self leveled (below 200 degrees Celsius), then stretched straightened (below 70 degrees, tensile rate is less than 1.5%). Aluminum rod heating for 6061 alloy, must be heated to 500 ℃ above, Mg and Si can be completely solid solution, before extrusion ingot above 440 ℃, due to the role of extrusion deformation heat temperature rise, through the die hole metal temperature reaches 530-570 ℃, to achieve solution treatment state, therefore, aluminum rod must be heated to 440 ~ 460 ℃ before extrusion.
2. Mold heating
The temperature regulation of die before heating: flat die 410-440 ℃, split die 430-460 ℃; mold heating time in the furnace is not allowed to exceed 10 h, too long, the die hole working belt is easy to produce corrosion spots.
3. Extrusion
The extrusion speed must be controlled carefully in the extrusion process. Extrusion speed has an important influence on the deformation heat effect, deformation uniformity, recrystallization and solution process, mechanical properties and surface quality of products. In order to improve the production efficiency, according to many years of production discussion and experience accumulation, at present, our main extrusion methods follow the "low temperature and high speed" production process, that is, the aluminum bar temperature is inversely proportional to the extrusion speed, the extrusion speed is appropriately slowed down when the aluminum bar temperature is high, and the extrusion speed is appropriately accelerated when the aluminum rod temperature is low. Through this adjustment mode, the extrusion production is adjusted to the best The status shall prevail. Generally speaking, the cooling can be accelerated when the upper die is produced to the third bar, and the best temperature for the flat die aluminum bar is 390 ~ 410 ℃, and the best temperature for the aluminum bar in the split die is 410 ~ 430 ℃.
4. On line quenching
The purpose of quenching is to keep the Mg2Si which is dissolved in the base metal at high temperature after rapid cooling to room temperature. 6061 contains mg2si0.6-0.9%, from about 500 ℃ to 204 ℃. The minimum cooling rate is not less than 180 ℃ / min. water cooling can be used. The aluminum template hardness of 6061 alloy is required to be ≥ 15hw, and its large section quenching cooling is recommended to be 549 ℃ / min. During on-line quenching by extrusion, the cooling rate should be based on the principle that the supersaturated solid solution can be condensed. For the products that can be straightened, the warpage caused by quenching should be limited to that which can be corrected.
5. Limitation of time
The mechanical properties of 6061 alloy aluminum template profiles generally require tensile strength of 265 (σ ь) MPa and Vickers hardness of ≥ 15hw. Therefore, the aging temperature is generally 180-200 ℃ and the aging time is 5-6h; sometimes (170-180) ℃× (6-8) H process can be used to improve the strength properties.
1、 Problems to be considered in mold design
The design of the die must meet the calculation requirements of stiffness and strength, so as to reduce the elastic deformation of the die under compression. When determining the working belt, the length of the working belt, the form of the empty knife, the die neck and the welding chamber should be considered to select the best parameters. In order to reduce the pressure, a larger value should be selected as far as possible in the allowable range for the selection of the coefficient of the guide hole and the diversion hole of the die. Aluminum template is generally produced with 6061 hard alloy, which makes the production technology more difficult. In extrusion production, there are often some problems such as the material is dragged away, the pressure is not moving, and the discharge is too slow. Therefore, the design of the die plays a key role in the production process.
mould design
1. Design of diversion hole and diversion hole
When designing the die, the position of the diversion hole and the diversion hole should be evenly distributed, so that each part of the profile can absorb the same amount of metal. The size of diversion hole and diversion hole is in positive proportion to the area of profile. Under the condition that the die strength and profile surface quality are not affected, the diversion hole and diversion hole shall be maximized as far as possible. When the metal flows into the welding chamber during extrusion, the larger the diversion hole and the diversion hole, the smaller the stress on the bridge area. The metal flow from the bridge displacement reduces the resistance and increases the discharge speed, but does not affect the die strength. Therefore, the die with small feed hole and large bridge position may not be better than the mold with large feed hole.
Dongguan mold design, Dongguan mold design should pay attention to what
2. Bridge location design
The bridge position is an important part of the die structure. It is the supporting bridge of the mold. When designing the bridge position of the mold, it must be considered that it has enough support force for the mold. In order to meet the support strength of the die, the bridge position angle is generally designed between 18 ~ 25 ℃. If the angle is too large, the friction force between metal flow and bridge position will be increased, and the flow of metal flow will be slowed down. The smaller the angle is, the easier the metal is to be welded, and the discharge speed will be increased. At the same time, the design of bridge position angle joint should be smooth and excessive as far as possible to avoid or reduce the welding dead angle.
3. Welding room design
The welding chamber should not be too deep. If the welding chamber is too deep, the metal volume in the welding room will be increased. When the volume of the welding chamber increases, the welding process will be lengthened, and the extrusion pressure will be increased.
4. Working belt desig
Mold work belt polishing should be careful to ensure flatness, perpendicularity, no turtle back or uneven, reasonable calculation of the working belt length, uniform metal flow.
2、 Extrusion process
1. Process flow:
The aluminum rod is heated (440-460 degrees) to the mold, heated (420-460 degrees, 3-6h), extruded (outlet temperature 530-570 degrees), spray cooled by air quenching, then heated by the spindle (410-420 degrees), self inspected (410-420 degrees below), self leveled (below 200 degrees Celsius), then stretched straightened (below 70 degrees, tensile rate is less than 1.5%). Aluminum rod heating for 6061 alloy, must be heated to 500 ℃ above, Mg and Si can be completely solid solution, before extrusion ingot above 440 ℃, due to the role of extrusion deformation heat temperature rise, through the die hole metal temperature reaches 530-570 ℃, to achieve solution treatment state, therefore, aluminum rod must be heated to 440 ~ 460 ℃ before extrusion.
2. Mold heating
The temperature regulation of die before heating: flat die 410-440 ℃, split die 430-460 ℃; mold heating time in the furnace is not allowed to exceed 10 h, too long, the die hole working belt is easy to produce corrosion spots.
3. Extrusion
The extrusion speed must be controlled carefully in the extrusion process. Extrusion speed has an important influence on the deformation heat effect, deformation uniformity, recrystallization and solution process, mechanical properties and surface quality of products. In order to improve the production efficiency, according to many years of production discussion and experience accumulation, at present, our main extrusion methods follow the "low temperature and high speed" production process, that is, the aluminum bar temperature is inversely proportional to the extrusion speed, the extrusion speed is appropriately slowed down when the aluminum bar temperature is high, and the extrusion speed is appropriately accelerated when the aluminum rod temperature is low. Through this adjustment mode, the extrusion production is adjusted to the best The status shall prevail. Generally speaking, the cooling can be accelerated when the upper die is produced to the third bar, and the best temperature for the flat die aluminum bar is 390 ~ 410 ℃, and the best temperature for the aluminum bar in the split die is 410 ~ 430 ℃.
4. On line quenching
The purpose of quenching is to keep the Mg2Si which is dissolved in the base metal at high temperature after rapid cooling to room temperature. 6061 contains mg2si0.6-0.9%, from about 500 ℃ to 204 ℃. The minimum cooling rate is not less than 180 ℃ / min. water cooling can be used. The aluminum template hardness of 6061 alloy is required to be ≥ 15hw, and its large section quenching cooling is recommended to be 549 ℃ / min. During on-line quenching by extrusion, the cooling rate should be based on the principle that the supersaturated solid solution can be condensed. For the products that can be straightened, the warpage caused by quenching should be limited to that which can be corrected.
5. Limitation of time
The mechanical properties of 6061 alloy aluminum template profiles generally require tensile strength of 265 (σ ь) MPa and Vickers hardness of ≥ 15hw. Therefore, the aging temperature is generally 180-200 ℃ and the aging time is 5-6h; sometimes (170-180) ℃× (6-8) H process can be used to improve the strength properties.