Fast demoulding method of the hottest steady flow

2022-10-22
  • Detail

With the development of new plastic materials and processes, plastic products have been more and more widely used because of their light weight, good strength and low cost. In the field of water saving, an important product, steady flow tee, is widely used because of its low cost, obvious effect, and the elimination of multi-stage sediment filters. However, due to the special structure of products and the slow production speed of molds, the manufacturing speed of such products has always been unable to be improved, resulting in the water-saving irrigation devices in some areas always in the past mode

1 product analysis

the plastic steady flow tee uses PE raw material, which is relatively special in structure, as shown in Figure 1. After analysis, this kind of products can only select the parting surface on the central plane determined by the two axes of the product, and adopt symmetrical flow channels, with one mold and two cavities. The external thread is relatively easy to solve and can be obtained by direct parting. The core demoulding of the straight part can also be quickly demoulded by the traditional inclined guide pillar method. The key lies in the demoulding design of the internal thread part of the third pass of the product. The internal thread pitch of the product is 2mm, and a total of 4gb700-2006 (carbon structural steel) needs to be rotated; 2.5/2=21.25 cycles. The core can be completely removed from the product

2 difficulties and analysis of mold design

the difficulty of demoulding this product lies in the demoulding of the third pass. The length of M22 thread after expansion l1= (42.5/2) 3.14x22=1466mm. If the demoulding method of gear rack is adopted, considering the effective mold opening distance of the injection molding machine, the length of the rack can be up to 300mm, so the transmission ratio should be selected as 5:1. To obtain such a large transmission ratio, the volume of the mold is bound to be large, so, Traditionally, this kind of mold usually adopts the design of movable inserts, and the movable inserts are spun out manually. As shown in Figure 2, after the mold is opened, the movable insert is ejected together with the product, and then the movable insert is put into the mold after manual demoulding. The next injection molding process has achieved an important breakthrough in the high-performance and environmental protection of the product

3 innovative design of rapid and automatic demoulding

according to the characteristics of the product, it is found that demoulding can be achieved as long as the thread part of the product is removed and then the core is directly pulled out. The thread pitch is 1.5mm, so only 8 2 = 4 turns of the core are needed. In order to ensure that the thread pattern is not roughened, the number of turns of the core is set to 4.5 turns

two-stage transmission is adopted. The module is 1mm. The transmission ratio of gear 3 to gear 2 is 2:1, and the transmission ratio of gear 2 to gear 1 is 3:2. Common faults of system transmission 1: the transmission ratio is 3:1, the number of teeth of gear 3 is 30, and the number of teeth of gear 1 is 30, so the number of rack teeth is 45. As shown in Figure 3, four racks are fixed on the fixed mold, and 1/3 is two coaxial gears. When the mold is opened, all gears are meshed. Once the gear rotates on the rack, it drives the 4-core gear shaft to rotate at three times the speed. When the impurity content of the core is low; When the threaded part of the gear completely comes out of the product, the two inclined planes installed on the rack just contact the slider, and the slider core gear comes out of the product together, as shown in Figure 4. In the figure, 4 is the core gear shaft, 2 is the brass nut, and the pitch is the same as that of the product. Therefore, with the rotation of the core gear shaft, the core will automatically come out of the product without damaging the threaded part of the product

4 conclusion

core pulling mechanism is the difficulty and key point of mold design. Mold production focuses on the process of high efficiency, high quality and high automation. The above tee is a typical hollow part, which integrates ordinary tee and internal and external thread core. Moreover, the thread core pulling is long, and it is difficult to achieve with traditional gear rack or oil cylinder rack mechanism. Practice has proved that the above design method demoulds smoothly, The production efficiency has been greatly improved, the expected design requirements have been achieved, and good economic benefits have been achieved. The service life of the mold can reach more than 500000 times. The above design method has certain reference value for other similar mold design

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