Design of injection mold for the nozzle body of th

2022-10-19
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Design of injection mold for sanitary ware nozzle body Abstract: the design and manufacturing method of injection mold for sanitary ware nozzle body are introduced. The injection mold adopts the hydraulic buckle gear rack core pulling mechanism to complete the thread demoulding, and uses the bending plate core pulling mechanism to realize the core demoulding

key words: nozzle body hydraulic core pulling gear tooth Nai injection mold

1 characteristics of plastic parts

plastic parts are sanitary ware nozzle bodies, as shown in Figure 1. The material is POM, and the shape is relatively complex. There are mutually perpendicular external thread m18mm and internal thread m24mm in the axis direction, and a long internal hole is connected with the internal thread m24mm. When in use, the external thread m18mm is connected with the water pipe, the rest is stuck in the shell of the nozzle body, the ∮ 30mm part is the exposed surface, and the m24mm is connected with a water separator

2 mold design

the mold assembly drawing is shown in Figure 2, 1 horizontal and 2 cavities. This pair of molds requires both internal hole lateral core pulling and thread rotation core pulling. The structure is complex. Considering comprehensively, the placement position of plastic parts in the mold is the most reasonable at present. In the design, the hydraulic cylinder is used to remove 1. After receiving the fault report, the thread and the bending method are used to realize the lateral core pulling of the inner hole

it can be seen from Figure 2 that the lateral core pulling distance of the inner hole is long. Because a set of hydraulic system has been used for demoulding the threaded core 12, the sample clamping length is short, which cannot be used here. Considering that the cross-sectional area of the side pull core 11 is very small and does not require a large clamping force, a bending side pull method is adopted. The guide pin 29 passes through the bending plate 30 and is fixed on the slider 31. The sliding of the guide pin 20 in the groove of the dome plate 30 drives the core pulling of the slider 31. At the same time, the bending plate 30 also undertakes the work of the locking block. Compared with the previous side pulling methods such as inclined guide pillars and hydraulic cylinders, it has the characteristics of small mold volume and low cost

the stripping movement of the threaded core 12 is completed by the hydraulic system. Because the thread diameter is relatively large and it is fine thread (M24 × 1mm), therefore, the required demoulding distance is relatively long. Therefore, a group of gear speed increasing mechanisms are used to shorten the core pulling stroke of the hydraulic cylinder. Due to the speed increasing mechanism, the torque borne by rack 20 is relatively large. In order to keep the rack 20 in a good motion state, its two cuts are machined with tooth shape, and a set of no-load gear shafts are set on the non working side, as shown in Figure 2; The rack 20 can move smoothly during the core pulling process. In order to prevent its deflection, guide blocks 21 made of brass are arranged on the upper and lower sides of the rack 20

3 key points of mold manufacturing

the structural characteristics of the mold determine that the mold base is self-made, and the guide post 22 with centering plug is used to connect the fixed chess base plate 2 and the fixed template 3, so as to ensure the coaxiality of the hole system between the two plates, especially the bearing seat hole, during the processing and assembly process

first grind the locking surface between the bending plate 30 and the sliding block 31, and then process the guide groove on the bending plate 30 and the hole for fixing the guide pin 29 on the sliding block 31. The guide pin 29 and the guide groove of the bending plate 30 can be matched with a large gap (o.mm) to avoid over positioning. In order to ensure sufficient strength, the chute of the bending plate 30 is made into a closed shape. 4. The working process of the mold

(1) after the injection, pressure maintaining and cooling are completed, and before the mold is opened, the hydraulic cylinder drives the rack 20 to move in a straight line through the transmission between the rack 20 and the gear shaft 17. The big tooth stem 19 on the gear shaft 17 drives the thread core 12, so that the thread core 12 rotates and the cutting tool moves back axially to complete the thread demoulding

(2) when the mold is opened, the fixed template 3 is separated from the moving template 4, the guide pin 29 slides along the guide groove of the bending plate 30, and the driving slider 31 drives the cutting core 11 to pull out. The plastic part stays on the cavity plate 9 of the moving model (Note: the opening stroke should be accurately controlled to prevent the bending plate 30 from being broken or damaged due to the excessive opening stroke). It has strong applicability

(3) the push rod of the injection machine moves forward, pushes the push rod to take grids 25 and 27 to the right, and pushes down the plastic parts to complete the mold opening process

(4) when closing the mold, push out the optical reset of the mechanism, and then close the fixed and moving mold, although the rear hydraulic system is reset

5 Conclusion

the combination of hydraulic core pulling and bending core pulling mechanism realizes the core demoulding in two directions, which makes the mold design more compact and reduces the processing cost. The mold has been verified by production practice for several times, and the opening and closing action of the mold is stable and reliable, the demoulding of plastic parts is smooth, and the quality meets the design and use requirements. (end)

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