The dimensions of machining drawings are in millimeters, that is, mm.
The machining drawing is the design drawing of the mold design.
Design steps
1. Conduct a feasibility analysis on the designed mold product. Taking the computer case as an example, first use the design software to assemble and analyze the product drawings of each component, that is The set of drawings we call in our work ensures the correctness of each product drawing before mold design. On the other hand, we can be familiar with the importance of each component in the entire chassis to determine the key dimensions. This is very beneficial in mold design. The specific drawing method will not be introduced in detail here.
2. The work to be done after product analysis is to analyze the product and what mold structure to use, arrange the product processes, determine the punching content of each process, and use design software to develop the product , when product development is carried out, it usually starts from subsequent projects. For example, one product requires five processes.
When stamping is completed, when the product is unfolded, it starts from the product drawing to the fourth project, the third project, the second project, and the first project, and expands a graphic and then makes a copy and then expands the previous project, that is, it is completed. Start working on the products of the five projects, and then carry out detailed work. Note that this step is very important and requires special care.
If this step is completed well, it will save a lot of time in drawing the mold drawing. After the stamping content of each project is determined, including the inner and outer lines of the product material thickness in the forming mold, It is used to determine the size of the convex and concave molds. The product expansion method will not be explained here, but will be introduced in detail in the product expansion method.
3. Prepare materials according to the product expansion diagram. Determine the template size in the drawing, including each fixing plate, discharge plate, convex and concave mold, inserts, etc. Pay attention to preparing materials directly in the product expansion diagram. , which is of great benefit in drawing mold drawings. I have seen many mold designers directly perform manual calculations on product expansion drawings to prepare materials.
This method is too inefficient. Draw the template specifications and dimensions directly on the drawings and express them in the form of assembly drawings. On the one hand, you can complete the material preparation, and on the other hand, you can save the work on the various parts of the mold. A lot of work, because when drawing each component, you only need to add positioning, pins, guide posts, and screw holes to the material preparation drawings.
4. After the material preparation is completed, you can fully enter the drawing of the mold drawing. Make another copy of the material preparation drawing to draw each component, such as adding screw holes, guide post holes, positioning holes, etc. The hole position, and the various holes in the punching die need to be wire-cut. In the forming die, the forming gap between the upper and lower dies must not be forgotten. Therefore, after these tasks are completed, the mold drawing of a product has been almost completed for 80 seconds. %. In addition, when drawing the mold drawing, you need to pay attention to:
Each process refers to production, such as benchwork scribing, wire cutting, etc. Different processing processes have complete layers, so that wire cutting And drawing management has great benefits, such as color differentiation, etc. Dimension marking is also a very important task, and it is also the most troublesome task because it is too time-consuming.
5. After the above drawings are completed, the drawings cannot actually be issued. The mold drawings need to be proofread, all accessories assembled, different layers made for each different mold board, and Conduct mold assembly analysis on the same benchmarks such as guide pillar holes, etc., and insert the product expansion diagram of each process into the assembly diagram to ensure that the hole positions of each template are consistent and the clearance between the upper and lower molds at the bending position is correct.
Extended information
It is best to indicate the part number, name, material, material shrinkage, drawing scale, etc. below the process diagram. Usually the process is drawn on the mold assembly drawing.
A. Draw the general assembly structure drawing
Try to use a 1:1 ratio when drawing the general assembly drawing. Start drawing from the cavity first, and draw the main view and other views at the same time.
The mold assembly drawing should include the following contents:
①The structure of the mold forming part
②The structural form of the pouring system and exhaust system.
③Parting surface and parting pick-up method.
④The appearance structure and the position of all connecting parts, positioning and guide parts.
⑤ Mark the height of the cavity (not required, as needed) and the overall size of the mold.
⑥Auxiliary tools (piece removal and mold removal tools, correction tools, etc.).
⑦Number all parts in order and fill in the detailed list.
⑧ Mark the technical requirements and instructions for use.
B. Technical requirements for the mold assembly drawing:
① Performance requirements for certain systems of the mold. For example, there are assembly requirements for ejection systems and slider core-pulling structures.
②Requirements for mold assembly process. For example, after the mold is assembled, the fitting gap of the parting surface should be no greater than 0.05mm. The parallelism requirements on the upper and lower sides of the mold should be noted, and the size determined by assembly and the requirements for this size should be pointed out.
③Mold use, assembly and disassembly methods.
④Anti-oxidation treatment, mold number, engraving, marking, oil seal, storage and other requirements.
⑤Requirements related to mold trial and inspection.
C. Draw all parts drawings
The order of drawing parts drawings from the mold assembly drawing should be: inside first, then outside, first complex, then simple, first formed parts, then structural parts .
①Graphic requirements: Must be drawn in proportion, and enlargement or reduction is allowed. Views are well chosen, projected correctly, and laid out appropriately. In order to make the processing patent number easy to understand and facilitate assembly, the graphics should be consistent with the assembly drawing as much as possible and the graphics should be clear.
② Dimensions must be unified, centralized, orderly and complete. The order of marking dimensions is: first mark the dimensions of the main parts and the draft angle, then mark the matching dimensions, and then mark all dimensions. On non-main parts drawings, mark the matching dimensions first and then all dimensions.
③Surface roughness. Mark the most commonly used roughness in the upper right corner of the drawing, such as "Other 3.2." Other roughness symbols are marked on each surface of the part.
④ Other contents, such as part name, mold drawing number, material grade, heat treatment and hardness requirements, surface treatment, graphic proportions, free-size processing accuracy, technical description, etc. must be filled in correctly.
D. Proofreading, reviewing drawings, tracing and sending for printing
The contents of self-proofreading are:
①The relationship between the mold and its parts and the plastic part drawings, Whether the material, hardness, dimensional accuracy, structure, etc. of the mold and mold parts meet the requirements of the plastic part drawings.
②Plastic parts
Whether the flow, shrinkage holes, weld marks, cracks, demoulding slope, etc. of the plastic material flow affect the performance, dimensional accuracy, etc. of the plastic parts. Surface quality and other aspects of requirements. Is there any deficiencies in the pattern design, is the processing simple, and is the shrinkage rate of the molding material selected correctly?
③In terms of molding equipment
Whether the injection volume, injection pressure, and clamping force are sufficient, whether there are any problems with the installation of the mold, the core of the plastic parts, and the demoulding, and whether the injection machine Whether the nozzle and the mouthpiece are in correct contact.
④Mold structure
a. Whether the parting surface position and finishing accuracy meet the requirements, will overflow occur, and whether the plastic parts can be ensured to remain in place after the mold is opened. The side of the mold with the ejection device.
b. Whether the demoulding method is correct, whether the size, position and quantity of the extension rod and push tube are appropriate, whether the push plate will be stuck by the core, and whether it will cause scratches on the molded parts.
c. Mold temperature adjustment. The power and quantity of the heater; whether the location, size and quantity of the flow line of the cooling medium are appropriate.
d. How to deal with undercuts in plastic parts, and whether the mechanism for removing undercuts is appropriate, such as whether the slider and push rod in the inclined guide column core-pulling mechanism interfere with each other.
e. Whether the location and size of the pouring and exhaust systems are appropriate.
f. Design drawings
g. Whether the placement of each mold part on the assembly drawing is appropriate, whether the representation is clear, and whether there are any omissions
h. Parts drawing The part number, name, production quantity, whether the part is made in-house or outsourced, whether it is a standard part or a non-standard part, the processing accuracy of the parts, the correction processing and allowance of high-precision dimensions of the molded plastic parts, and the material of the mold parts , whether the degree of heat treatment, surface treatment, and surface finishing is clearly marked and described.
⑤Main parts, working dimensions and matching dimensions of molded parts. Size figures should be correct and do not require manufacturer conversions.
⑥ Check the view positions of all parts drawings and assembly drawings, whether the projection is correct, whether the drawing method complies with the national drawing standards, and whether there are any missing dimensions.
⑦Check the machining performance: (whether the geometric structure, view drawing, size marking, etc. of all parts are conducive to processing)
⑧Recalculate the main working dimensions of the auxiliary tools
p>Professional proofreading is in principle carried out as a designer's self-checking project; however, it should focus on structural principles, process performance and operational safety. When tracing, you must first digest the graphics, draw them according to the national standard requirements, and fill in all dimensions and technical requirements. After tracing, self-correct and sign. Submit the traced base drawing to the designer for proofreading and signature. The common practice is for the relevant technical personnel of the tool manufacturing unit to review, countersign, and check the manufacturing process before sending it to the public.
⑨Write the manufacturing process card
The technical staff of the tool manufacturing unit will write the manufacturing process card and prepare it for processing and manufacturing. In the manufacturing process of mold parts, inspection should be strengthened and the focus of inspection should be on dimensional accuracy. After the mold assembly is completed, the inspector will inspect it according to the mold inspection form. The main thing is to check whether the performance of the mold parts is good. Only in this way can the manufacturing quality of the mold be known.
⑶ Mold trial and mold repair
Although the mold design is carried out under the expected process conditions when selecting molding materials and molding equipment, people's understanding is often imperfect Therefore, after the mold processing is completed, a trial mold test must be carried out to see the quality of the formed parts. After the discovery is made, the mold will be repaired to eliminate the error.
There are many types of defects in plastic parts, and the reasons are also very complicated. There are reasons for molds and process conditions, and the two are often combined.
Before mold repair, careful analysis and research should be conducted based on the actual adverse phenomena of the plastic parts, and the causes of the defects in the plastic parts should be found out and remedies should be proposed. Because the molding conditions are easy to change, the general approach is to change the molding conditions first. When changing the molding conditions cannot solve the problem, repair the mold is considered.
You should be more cautious when repairing molds, and do not act rashly if you are not very sure. The reason is that once the mold conditions are changed, major modifications and restoration to the original state cannot be made.
Baidu Encyclopedia - Mechanical Processing Drawings
Baidu Encyclopedia - Mold Design