Detailed explanation of injection mold design steps

Detailed explanation of injection mold design steps

1. Composition of injection mold. It is mainly composed of forming parts (finger moving and fixed mold parts related to forming cavity parts), pouring system (the channel through which the molten plastic enters the mold cavity from the nozzle of the injection machine), guiding parts (to make the mold fit accurately), pushing mechanism (after the mold is divided, Plastic from cavity in the launch of the device), thermal control system (to meet the requirements of injection process for mold temperature) and exhaust system (will air in the mold and plastic molding itself volatile gas discharge mode, often open exhaust slot in the parting plane) and supporting components (for mounting or support molding parts and parts of other institutions), Sometimes there are side parting and core-pulling mechanisms.

2. Design steps of injection mold

1. Preparation before design

(1) Design task book

(2) Familiar with plastic parts, including its geometry, plastic parts use requirements, plastic parts of raw materials

(3) check the molding process of plastic parts

(4) Make clear the model and specification of the injection machine

2, develop the molding process card

(1) The general situation of the product such as schematic diagram, weight, wall thickness, projected area, external size, whether there are side pits and inserts

(2) The general situation of plastics used in the product, such as product name, model, manufacturer, color and drying condition

(3) The main technical parameters of the injection machine selected, such as the relevant size, screw type and power between the injection machine and the installation mold. (4) The pressure and stroke of the injection machine

(5) Injection molding conditions such as temperature, pressure, speed, clamping force, etc

3, injection mold structure design steps

(1) Determine the number of cavity. Conditions: maximum injection volume, clamping force, product precision requirements, economy

(2) Select the parting surface. The mold structure should be simple, easy to type and do not affect the appearance and use of plastic parts for the principle

(3) determine the layout of the cavity. Use balanced arrangements whenever possible

(4) Determine the pouring system. Including the main channel, shunting channel, gate, cold hole, etc.

(5) Determine the demoulding method. According to the plastic parts left in different parts of the mold and design different demoulding way.

(6) Determine the structure of temperature regulating system. The temperature control system is mainly determined by the type of plastic.

(7) determine the concave die or core using insert block structure, proposition partition insert block and insert block at the same time, the machinability and installation fixed way.

(8) Determine the exhaust form. General exhaust can use the mold parting surface and the gap between the push mechanism and the mold, and for large and high-speed molding injection mold, must design the corresponding exhaust form.

(9) Determine the main size of the injection mold. According to the corresponding formula, calculate the working size of the molding parts and determine the thickness of the side wall of the mold cavity, the bottom plate of the mold cavity, the core plate, the thickness of the moving template, the thickness of the cavity plate of the block cavity and the closing height of the injection mold.

(10) Choose standard die frame. According to the design, the calculation of the main size of the injection mold, to choose the standard mold frame, and try to choose the standard mold parts.

(11) Draw the structural sketch of the mold. Drawing the complete structure sketch of injection mold, drawing the mold structure diagram is a very important work of mold design.

(12) Check the size of the mold and the injection machine. Check the parameters of the injection machine: including the maximum injection volume, injection pressure, clamping force, and the size of the installation part of the mold, mold opening stroke and ejection mechanism check.

(13) Review of injection mold structure design. A preliminary review shall be conducted with the consent of the user, and it shall be necessary to confirm and modify the user's request.

(14) Draw the assembly drawing of the mold. Clearly show the assembly relationship of each part of the injection mold, necessary size, serial number, list, title bar and technical requirements (technical requirements are the following: a, the performance requirements of the mold structure, such as the assembly requirements of the push mechanism, core-pulling mechanism; B. Requirements for mold assembly process, such as fitting clearance of parting surface and parallelism of upper and lower surface of mold; C. Requirements for the use of molds; D. Requirements for anti-oxidation treatment, mold number, lettering, oil seal and storage; E. Requirements on mold testing and inspection. (15) Drawing of mold parts. The order of disassembling and drawing parts drawing by mold assembly drawing or component drawing is: inside and outside first, complex and simple first, forming parts and structural parts first.

(16) Review the design drawings. The final audit of injection mold design is the final check of injection mold design, and more attention should be paid to the machining performance of parts.

3. Review of injection molds

1. Basic structure

(1) Whether the mechanism and parameters of the injection mold match the injection machine.

(2) Whether the injection mold has a clamping guide mechanism and whether the mechanism design is reasonable.

(3) parting surface selection is reasonable, there is no possibility of flapping, plastic parts are stuck in the top out of the demoulding mechanism of the moving mold (or fixed mold) side.

(4) The layout of the cavity and the design of the pouring system is reasonable. Whether the gate is suitable for plastic raw materials, whether the gate position is equal, whether the gate and runner geometry and size is appropriate, whether the flow ratio is reasonable.

(5) Molding parts design is reasonable.

(6) Ejecting demoulding mechanism and lateral male type. Or core-pulling mechanism is reasonable, safe and reliable. With or without interference and occlusion. (7) Whether there is an exhaust mechanism, and whether the form is reasonable. (8) Whether the temperature regulation system is required. Its heat source and cooling method is reasonable.

(9) whether the structure of supporting parts is reasonable.

(10) Whether the external dimension can ensure the installation, whether the fixing method is reasonable and reliable, and whether the bolt hole used for installation is consistent with the screw hole position on the injection mechanism and the fixed mold fixing plate.

2. Design drawings

(1) Assembly drawing

Whether the assembly relationship of parts is clear, whether the matching code is properly and reasonably marked, whether the parts are fully marked, whether they correspond to the serial number in the list, whether the relevant instructions are clearly marked, and how standardized the whole injection mold is.

(2) Parts drawing

Part number, name, machine number whether hu exact annotation, size tolerance and multifarious tolerance is reasonable is complete, the molding parts is easy to wear parts are reserved grinding capacity, which parts with high precision, this request is reasonable, appropriateness of cushion for leaning on of the various parts of the material, heat treatment and surface roughness requirements is reasonable.

(3) Cartographic methods

Whether the drawing method is correct, whether it conforms to national standards, and whether the geometric figures and technical requirements expressed on the drawing surface are easy to understand. 3. Quality of injection mold design

(1) the design of injection mold, whether the correct consideration of the process characteristics of plastic raw materials, molding performance, injection machine type may affect the quality of molding, on the molding process may occur in the design of injection mold has taken the corresponding preventive measures.

(2) whether the plastic parts of the injection mold guidance accuracy requirements, guide structure design is reasonable.

(3) The working size calculation of the molding parts is correct, can ensure the accuracy of the product, and whether it has enough strength and stiffness.

(4) Whether the supporting parts can ensure that the mold has enough overall strength and stiffness.

(5) Whether the requirements of mold trial and mold repair have been considered

4. Whether there are grooves and holes for convenient assembly and disassembly and handling conditions, and whether they have been marked.