I. Design preparation
1. Confirmation of the necessary drawings, contents of the gold type sample book, etc.:
Before the formal gold design, the following drawings or documents usually have:
1 part drawing;
2 gold type design and production of sample books;
3 design and production contract;
And to fully understand the above information, it is not clear that the customer should be confirmed.
2. Grasp the outline of the drawing
The part drawing determines the ultimate purpose of the gold design and must be thoroughly understood. The parts drawings provided by Japanese customers are drawn by the triangulation method according to the JIS drawing regulations, and usually consist of the following parts:
Front view, plan view, side view, sectional view, detailed view, reference drawing, annotation, tolerance list, list of official marks, title bar, other
Pay attention to the following aspects during the view process:
1 The tolerance requirements are stricter;
2 parts that have an influence on the gold structure;
2 parts of the existing drawings that are incomprehensible;
4 matters highlighted in the note
5 special materials and heat treatment requirements;
6 parts of the wall thickness is thin (t
7 parts are thicker;
8 There are no special requirements on the appearance
9 three-dimensional surface part;
10 designers, dates, deadlines, prices, etc.
3. Understanding of the three-dimensional shape of the parts
The part drawing is drawn in two dimensions, and it is converted into a three-dimensional shape in the designer's mind through the view, and the hand-drawn stereo drawing is very helpful.
Prepare paper and pencil.
First, draw the outline of the product, and then draw a cross-sectional view of each part according to your own understanding of the parts.
These are very important for the determination of the future parting surface and the division of the input. If conditions permit, it is better to use aids such as clay to help understand.
4. Review of the title bar
The title bar of the parts drawing generally indicates the tolerances in the drawing, the materials of the parts, etc., and must be carefully studied.
1 product name;
2 picture name;
4 materials (including shrinkage);
5 official sample, refers to the detailed material of the material, such as the manufacturer, trade name, resin code;
8 change column;
5. Review of the annotations section
(1) Gate type, location, quantity
If there is no special requirement, the gold designer will need the consent of the customer after making his own decision.
(2) Requirements for entering the sub-line
Since the sub-separation line will form a seam on the surface of the product, affecting the appearance, especially harmful to the folded part, the designer should follow the specifications of the part drawing.
(3) Provisions for defects such as surface scratches on molded products
Gold designers should avoid gold structure designs that may have the above defects.
(4) Requirements for no tolerances.
(5) The shape and size of the molded product need to be approved by the customer. As a gold designer, it is not a discretion.
(6) Review of the main view
The main view is where the dimensions are concentrated in the drawing. Confirm the tolerances on both sides and the tolerance on the side of the sheet, and mark the more stringent ones.
(7) Review of other views.
(8) Review of necessary type of cooperation
The molten resin produces a considerable injection pressure on the gold parting surface when injected. If the maximum force of the injection machine is less than the injection pressure, a gap will occur between the templates, and an overflow phenomenon will occur. The calculation of the necessary type of force is as follows:
F=PÃ—AF: Necessary type of force (Kg)
P: injection pressure (Kg/cm2), take 300 to 500, depending on molding conditions
A: projected area of â€‹â€‹the product in the injection direction cm2
(10) Review of the necessary injection volume
When selecting an injection machine, a review of the injection volume is required.
The total volume including the chat and the product is less than 1/2 to 2/3 of the maximum injection volume of the injection machine.
(11) Other matters
If the information provided by the customer is incomplete, you need to contact the customer to obtain all the information.
Use a marker to mark what you think is more important for the next step.
2. Design of the basic drawing of the molded product
The following picture shows the general flow of the gold design work:
Initial review â†’ basic drawing design of molded product â†’ gold structure design â†’ part drawing design â†’ inspection drawing â†’ drawing
The design of the plastic injection gold type starts from the design of the basic drawing of the molded product, and the correctness determines whether the molded product is good or bad.
The following is a description of the design method of the basic drawing of the molded product:
1. Understand the characteristics of molding materials
The most critical is the quality of the flow and the size of the shrinkage.
2. Review of fillability
The following aspects should be fully considered:
1 Whether the cavity can be completely filled;
2 the location of the splicing marks;
3 the occurrence of bubbles;
3 deformation of the molded product;
a cut mark at 5 o'clock;
In the design work, according to the working conditions, the following methods are used to analyze and verify:
1 comparison of similar gold types;
2 calculation of flow ratio (L/T);
3. Determination of gate location
4. Determination of the shape of the gate
5. Determination of the parting surface
The following principles should be referred to:
1 Try to use a plane;
2 easy to process;
3 no bad type occurs;
4 The appearance of the dividing line has no effect.
6. The decision of the gold production method
Due to the shrinkage of the plastic after cooling, the gold forming method should consider the "molding shrinkage" as follows: (for example, shrinkage rate of 0.2%)
1 Tolerance on both sides: L=25Â±0.05 â†’ L0=1.02Ã—25=25.5
2 side tolerances: L=3-0.2 â†’L0=[(3+2.8)/2]Ã—1.02=2.96
After the above method is calculated, the following two aspects must be corrected:
1 Correction of the modifiability of the gold type.
2 The even number of odd-numbered methods.
7. Decision of draft angle (fixed side)
In order to prevent the poor release, it is necessary to set the draft angle at the fixed side core, but it is generally 30' to 3Â° within the tolerance range of the molded product.
8. Decision of the draft angle (movable side)
If necessary, the movable side can also be added with the draft angle, but generally it is not added. If there is a bad ejection, it can be solved by adding a ejector.
9. Configuration of the ejector
Follow the following principles:
1 The ejection area is as large as possible, because the small ejector holes are difficult to machine.
2 Try to use the dome rod, because the square top hole is difficult to machine (but it is easier to use the insert dividing line).
3 The ram should be placed near the core.
4 Minimum 1mm wall thickness around the ejector hole is guaranteed.
10. Recording of production quantities
3. Gold structure design
After the basic drawing of the molded product is completed, the most important work can be carried out - the design of the gold-type structural drawing. This part of the work accounts for 80% of all research work on gold design. The following is the specific design process:
1. Confirmation of the gold type of the molding machine:
1 Confirmation of the distance between the sliders
The size of the gold type should not exceed the distance between the sliders, and a safety distance of 20 mm or more is usually required.
2 The most small and thick confirmation
The thickness of the gold type is greater than the minimum thickness of the injection machine.
3 Confirmation of the maximum mold opening stroke
4 Confirmation of maximum clamping force
5 Confirmation of theoretical injection capacity
6 Confirmation of the diameter of the positioning ring (to select the positioning ring model)
7 Confirmation of the tip shape of the nozzle of the injection machine (to select the sprue cover model)
8 maximum thickness calculation
T = minimum thickness + maximum mold opening distance - S1-S2-S
2. Review of the cavity configuration method
For multi-cavity molds, the cavity position should be properly arranged so that the projection center is completely centered on the mold base and the flow path is minimized to achieve a balanced feed.
3. Determination of cavity wall thickness
4. Selection of formwork
For plastic injection molds, the formwork has been standardized. Our company uses the Japanese FUTABA (double leaf) formwork. When selecting a formwork, in addition to the size specifications, the following aspects should be confirmed:
1 Guide post guide sleeve position, some guide posts are on the fixed side, and some are on the movable side. Choose according to your needs.
2 The thickness of each template should be confirmed in conjunction with the basic drawing of the molded product. Generally, it is preferred that the length of the non-formed portion of the insert be about 30 mm.
3 Currently we have FUTABA's standard formwork CAD library, which can be used to quickly generate formwork drawings.
5. Decision of the type action
After the template thickness is determined, a review of the typing action is performed.
1 The mold opening distance between the fixed side plate and the flow channel plate S1
S1=point sprue sleeve length + sprue sleeve length +10~20
2 Opening distance S2 between the flow channel plate and the fixed side seat plate
S2= Pulling hook hook length + 3mm safety distance
3 The length of the stop bolt is determined
L=fixed side profile thickness + S1
4 The length of the stop bolt head is determined
5 support guide column length decision
L=fixed side plate thickness + S1 + flow channel thickness + S2+ fixed side seat plate thickness
6 Pulling hook length determines
7 runner ejector decision
8 The surrounding mechanism of the sprue sleeve is decided
9 The mold layout to make the molded product fall naturally after it is ejected
6. The sprue sleeve is made of PUNCH city goods.
7. Determine the order of the mold opening and use the appropriate mechanism to ensure the realization of this mold opening sequence.
8. The method for the smooth exit of the runner from the runner plate:
Adopt RUNNER EJECTING SET (MISUMI)
9. Review of support column configuration
At the time of injection, the injection opportunity generates an instantaneous injection pressure at the bottom of the movable side plate, causing the deformation of the template. To prevent this from happening, a support column can be placed in the mold frame so as not to hinder the ejector and force. Arranged around each cavity as a principle.
10. Decision to cool the water hole
In order to maintain a constant mold temperature, a cooling water hole must be opened for cooling water.
The size of the cooling water hole has little to do with the cooling efficiency. Medium-sized molds generally use Ñ„8.5 water holes, and the interface uses PT1/8 pipe threads.
The location and number of cooling water holes are closely related to the cooling effect. When determining, it should be as close as possible to the cavity and as much as possible, but no interference should occur.
11. The configuration of the ejector part
According to the basic drawing of the molded product, the position of the ejector pin should be reasonably arranged, and be careful not to interfere with the components such as the cooling water hole and the support column.
12. Configuration of the sprue bushing
The sprue sleeve head SR inch method is about 1 mm larger than the SR inch method of the injection nozzle.
The opening method of the sprue sleeve is about 0.5mm larger than the Ï† inch method of the nozzle of the injection machine.
For taper, it is better to use 1Â° on the side of the sheet.
13. Positioning ring configuration
In combination with the molding machine, the PUNCH market is used.
14. Exhaust duct configuration
In order to smoothly discharge the air in the cavity, an exhaust passage is sometimes required. However, it is not considered in the general design. If there is a bad exhaust in the production, it will be solved.
15. Design of the ejection guide and the ejection guide
In order to improve the accuracy of the movement of the ejection member, thereby extending the life of the ejector pin and the core, and preventing the ejector strain from being pulled, the ejection guide post and the ejection guide sleeve can be designed.
16. Determination of the product number
The company has established a naming rule for the use of the part number of the gold type, and determines it according to this rule.
At this point, the structural design of the gold type is basically completed.
After the structural design is completed, the gold part drawing design is performed according to the basic drawing of the molded product and the gold type structural drawing, including the following contents:
(1) Design the parts drawing to be processed.
(2) The outer part is chased by the processing part.
(3) Purchase a sample of the department.
1. Design of the cavity part:
(1) The shape of the cavity portion is extracted from the gold type structure diagram. The XY direction is fitted to the template, paying attention to tolerances and fits. The Z direction can be fixed by screws or hooks or keys.
(2) Forming part shape and inch method
Determine according to the basic drawing of the molded product, and consider the following aspects:
1 Forming tolerances.
2 Relationship with other parts (coordination), etc.
3 Easy to correct the gold type.
4 Machining methods can achieve the processing capacity.
5 Processing costs.
(3) The cores are matched with the cavity parts in the form of hooks, and the XY directions are strictly controlled by tolerances.
(4) Gate design
(5) Fixed method
(6) Determination of material and hardness
Consider the following:
1 The shape and the precision of the molded product maintain the function.
2 The surface quality of the molded product determines its function.
3 Impact resistance, rigidity and strength should be sufficient.
4 Corrosion resistance.
5 wear resistance.
7 Mirror characteristics.
8 Thermal conductivity.
9 heat treatment.
10 material prices.
2. Design of fixed side core
The shape and inch method are determined based on the basic drawing of the molded article.
Refer to the above for the material selection.
The movable side core and cavity design are roughly the same as the fixed side, but the design content of the ejector portion is more.
At this point, the part related to the forming in the gold part drawing has been completed, and the part design of the gold type structural part is performed below.
After the design of the part drawing is completed, it is necessary to carry out the inspection, which is as important as the design work. Finding errors before putting them into production is more costly and energy-saving than finding them in production or after completion.
The drawing work can be undertaken by the designer himself or by a third party. The following principles should be grasped in the inspection:
(1) When designing detailed and important design inspections, it is best to carry out when you are energetic.
(2) For 1 to 2 hours of continuous work, rest for 10 to 15 minutes to keep your head clear.
(3) Don't be afraid of failure, gain experience in growth in failure.
(4) Do not start with detailed design. It should start with the overall plan, so it is easy to find big principle errors.
(5) It can investigate the problems that occur in the use of similar gold types and compare them with their own design work.
The main contents of the map work are as follows:
1. Important principle projects
(1) According to the core and cavity schedule, there is no missing design part.
(2) Is the gold type appropriate?
(3) Is the setting of the parting surface correct? Does it meet the requirements of the gold type sample book?
(4) Can the cavity be completely filled?
(5) Is the production cost within the budget?
(6) Is the production cost of the molded product within the budget?
(7) Can the gold type payment period be completed?
(8) Have you taken reasonable measures to guarantee the payment period?
(9) Can the molded cavity be smoothly removed?
(10) Can the molded product core be smoothly removed?
(11) Is there any improper arrangement of gates and runners?
(12) Is there any interference in the cooling channel?
(13) Does the support column, the ejector pin, and the guide column have interference?
(14) Is the calculation of the forming shrinkage ratio correct?
(15) Is the insert division method correct?
(16) Is the design of the components that match each other correctly?
(17) Does the forming machine meet the requirements?
(18) Are other special requirements met?
2. Review of gold structure
(1) Is the current design correct or not, is there any improvement?
(2) Is the expectation of resin flow correct?
(3) Is the core and cavity release countermeasure correct or not?
(4) Is the design of the slider and the sliding core correct?
(5) Is the tolerance of the fitting part correct?
(6) Is the exhaust passage suitable?
(7) Is the fit clearance appropriate? CAD/CAM/CAE
(8) Is it difficult to assemble?
(9) Is it convenient to disassemble?
(10) Is there any prevention of bleaching?
(11) Is there any interference between the components on both sides?
3. The part of the detailed review:
(1) Are there any inconsistencies in size?
(2) Is the shape of the section correct or not?
(3) Is the number of parts correct?
(4) Is the part material correct?
(5) Does the rigidity of the profile meet the requirements?
(6) Does the cavity rigidity and strength meet the requirements?
(7) Is the gate shape suitable?
(8) Has the processing method been properly considered?
(9) Is the electrode design correct?
(10) Is there any mistake in the standard part of the note?
(11) Has the customer's official sample change part been changed?
(12) Has the scrap image been replaced?
(13) Is the tolerance of the inch method and the surface roughness too strict?
(14) Is the machinability appropriate?
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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