Logistics crane controller cover structure is in a semi-enveloping shape, as shown in Figure 1. Plastic part structure is divided into upper and lower parts. Upper part is a semi-enclosed pointed shell, and lower part is a platform cover. There are multiple transverse reinforcing ribs in upper half-enclosed sharp-angle groove. A large undercut is formed between arc-shaped top above and top surface of lower cover. When demoulding, transverse core pulling is required for demoulding. There are side countersunk holes on both sides of cover of lower half of plastic part, and side core pulling is required to remove mold. There are 3 circles of reinforcing ribs in the center of lower half of cover, with undercuts on both sides, and side core pulling is also required for demoulding. Plastic part material is modified engineering plastic ABS, which is reinforced with 22% (mass fraction) glass fiber. After reinforcement, tensile strength, flexural strength, flexural modulus, etc. of ABS are improved, and heat deformation temperature is also significantly increased. Linear expansion coefficient is reduced, dimensional stability and accuracy can also be improved. However, impact strength decreases with increase in glass fiber content, followed by addition of flame retardant, which changes flammable properties of ABS, and material shrinkage rate is 0.58%~0.65%. Appearance of plastic part has certain requirements. It is best to set pouring point on inner wall of plastic part to be formed. Customer requires that it be set at G0 point of plastic part as shown in Figure 1.

 

Mold adopts a 1-cavity layout. As shown in Figure 2, it is necessary to arrange 2 side core-pulling slider mechanisms, 1 hydraulic cylinder to drive fixed mold first core-pulling mechanism and 2 oblique push core-pulling mechanisms located on one side of fixed mold. Mold uses 4 guide mechanisms to guide closing and opening of moving and fixed molds.

 

Mold structure layout is shown in Figure 3. Parting surface is set according to maximum outer edge contour of molded plastic part to obtain main molding parts of molded plastic part cavity: cavity insert 1 and core insert 4 are installed on fixed platen 13 and movable platen 14 respectively. The two side countersunk holes on both sides of molded plastic part use two inclined guide pillar slider mechanisms to implement side core pulling. Sliders of mechanism are right slider 2 and left slider 3 respectively.

 

1. Cavity insert 2. Right slider 3. Left slider 4. Core insert 5. Central core insert 6. Inclined push rod 7. Inclined push rod 8. Wear-resistant block 9. Inclined push seat 10 . Inclined push seat 11. Push plate 12. Fixed mold base plate 13. Fixed mold plate 14. Moving mold plate 15. Screws 16. Backing plate 17. Lower backing plate 18. Pad 19. Push rod fixed plate 20. Moving mold base plate 21.Spring
Figure 3 Mold structure layout
For three circles of reinforcing ribs on the lower cover of molded plastic part, a central core insert 5 needs to be provided, which is beneficial to exhaust of cavity and facilitates use of CNC machining without need for EDM machining. In order to facilitate installation of central core insert 5, a backing plate 16 needs to be added. For the two undercuts on inner wall of lower cover of plastic part, use oblique push component for molding and side core pulling to demould. Oblique push assembly passes through central core insert 5, backing plate 16, and lower backing plate 17. It is necessary to set a wear-resistant block 8 at the bottom of lower backing plate 17 for guidance and wear prevention. Bottom of inclined push assembly is installed on inclined push seats 9 and 10 respectively, and two inclined push seats adopt form of T-shaped guide rails. Oblique push assembly is composed of a push plate 11 and a push rod fixing plate 19 to perform pushing action.
In order to meet driving needs of demoulding mechanism of molded plastic parts, mold base is set up as a four-plate double mold opening structure, with parting surfaces being K1 and K2 respectively. When K1 side is opened, molded plastic part is demoulded from central core insert 5, and at the same time oblique push assembly completes side core pulling. Opening of K1 side is powered by spring 21, and is fixed by a pull rod. When K2 surface is opened, plastic part comes out from core insert 4, left slider 3 and right slider 2 complete side core pulling action. As shown in Figure 4, in view of design of demoulding structure in which upper part of molded plastic part half surrounds sharp angle groove, fixed mold slider 32 is used to implement side core pulling. Fixed mold slider 32 is driven by hydraulic cylinder 30, hydraulic cylinder 30 is locked and installed on support using a threaded ring 31. Fixed mold slider 32 is the first core-pulling mechanism of fixed mold, and core-pulling must be performed before parting surface K2 is opened.

 

11. Push plate 13. Fixed template 22. Inclined hot nozzle 23. Pull rod 24. Reset rod 25. Push rod 26. Magazine mechanism 27. Ejector rod 28. Travel switch 29. Push plate guide column 30. Hydraulic cylinder 31 .Threaded ring 32. Fixed mold slide 33. Positioning ring diagram
Figure 4 Mechanism installation
In order to make the overall structure of mold compact and reduce manufacturing cost, a latent gate is used for pouring. Oblique hot nozzle 22 supplies material first, then supplied to latent gate G0 through ordinary flow channel. Latent gate G0 is the only gate. Giameter of inlet gate is φ1.0mm. For cooling of mold cavity, φ8mm cooling pipes are provided in cavity insert 1 and core insert 4 for cooling.
After push plate 11 pushes out plastic part, it must be reset first before parting surface K2 can be closed. Therefore, a clip mechanism 26 is provided. In order to ensure that push plate 11 is reset accurately, a travel switch 28 is provided. Before parting surface K2 is opened, piston rod of hydraulic cylinder 30 must first drive fixed mold slide block 32 to complete side core pulling. Before parting surface K2 is closed, fixed mold slide block 32 must be reset first. Upper end of reset lever 24 is provided with a cover to ensure that push plate 11 is reset accurately and to prevent inclined push rods 6 and 7 from being damaged during reset.

As shown in Figures 2 to 4, automated injection production of plastic parts to be molded is completed in following steps: first mold is closed, injection molding machine completes melt injection process, then mold is opened. Opening step is divided into four processes. Step 1st, movable mold retreats. Under action of spring 21, mold is first opened at K1 parting surface, and central core insert 5 is pulled out first; step 2nd, hydraulic cylinder 30 piston rod drives fixed mold slider 32 to complete core pulling of fixed mold; step 3rd, movable mold continues to retreat, mold is opened at K2 parting surface, and molded plastic part is demoulded from cavity insert 1. At the same time, right slider 2 and left slider 3 complete side core pulling action; step 4th: As movable mold continues to retreat, ejector pin 27 of injection molding machine pushes push plate 11, push plate 11 pushes oblique push assembly and push rod 25 to push molded plastic part from core insert 4 to achieve complete demolding of molded plastic part. When mold is reset and closed, push plate 11 is reset first, then fixed mold slider 32 is reset, and finally mold is closed in sequence according to K2 and K1 parting surfaces to start next injection cycle.

This article introduces mold design of logistics crane controller cover. Mold is a multi-plate 2-pass hot runner injection mold and uses an oblique hot nozzle to reduce structural size of mold base and reduce mold manufacturing cost. Mold has been verified by actual production: it has a compact structure, stable and reliable movement, and has a good reference effect on molding of similar plastic parts.