Principles and requirements of injection mold design for UG mold design
1. General principles of mold design
1. Reasonable mold design is mainly reflected in the quality of the molded plastic products (appearance quality and dimensional stability); the processing and manufacturing are convenient, rapid, and concise, that is, saving money and manpower, leaving room for correction and improvement; when using It is safe, reliable and easy to maintain; it has a short molding cycle and a long service life during injection molding, as well as reasonable mold manufacturing technology.
2. Several aspects that should be paid attention to in mold design:
1) At the beginning of the mold design, you should pay more attention to several options, weigh the advantages and disadvantages of each option, and choose one of them, and take the T mold seriously. Because of the time, you thought that a reasonable design at that time would definitely be possible to improve after production and use.
2) After handing over the design plan, communicate more with the factory to understand the processing process and manufacturing usage in China and Germany. Each set of molds should have a fixed analysis experience and sum up the process of gains and losses in order to continuously improve the level of mold design;
3) When designing, refer to similar drawings designed in the past to learn from its experience and lessons;
4) The mold design department should be a whole, and each design member cannot work independently. Especially in terms of mold design conclusions, there must be a style.
3. Mould design basis
The main basis is the product drawings and samples provided by the customer. Designers must carefully analyze and digest the products and samples. At the same time, during the design process, all items must be checked one by one;
- The correctness of dimensional accuracy related dimensions;
A. The appearance requirements are high, and the dimensional accuracy requirements are low. Clinker products, such as toys, etc., except for the specific dimensions, as long as the other dimensions are in good agreement;
B. Functional plastic products have strict size requirements and must be within the allowable tolerance range, otherwise it will affect the performance of the entire product;
C. Products with strict requirements for onlookers size.
2) Whether the draft angle is reasonable;
3) Product wall thickness and uniformity;
4) Plastic types. (Plastic types want to steal the choice of mold steel and determine the shrinkage rate.)
5) Surface requirements.
6) Product color. (Generally, the color has no direct influence on the mold design. However, when the product wall is thick and the appearance is larger, the color is easy to be uneven; and the darker the color, the more obvious the product defects are exposed).
- Whether there is post-treatment after the product is formed. (If there are products with surface electroplating, and a mold with multiple cavities, you must consider setting up auxiliary runners to connect the products together, and then separate them after the electroplating process is completed).
8) The batch of products, (the batch of products is an important basis for mold design, and the customer must provide a range to determine the number of mold cavities, size, mold material selection and life).
9) Specifications of injection molding machine.
10) Other requirements of customers. The designer must carefully consider and check to meet the compatibility requirements.
4. General process of mold design:
<1> Analyze and digest products and templates.
<2> It should be understood whether the customer has requirements for the specifications of the injection machine to determine the size of the mold.
<3> Determine and rank the number of cavities.
<4> The parting surface is determined.
<5> If there are row positions and oblique square structures, they should be understood first.
<6> Gating system design.
<7> Confirmation of mosaic structure.
<8> Ejection. Reset system design.
<9> Cooling and heating system design.
<10> Guiding. Positioning device.
<11> Determine the mold base and select standard parts.
<12> Mold steel selection.
<13> Complete the structure drawing, mold embryo drawing, and cutting.
<14> Print out the drawing, check it, and submit it to the mold design team leader and supervisor.
2. Mold requirements
- Rank
<1> The position of the inner mold of the product should be discharged in the best effect form, and the water inlet position and parting surface factors should be considered. It should be proportional to the size and depth of the product.
<2> The distance from the product to the edge of the fine frame:
A) Small products: the distance is between 25mm and 30mm, the distance between the finished products is 15mm 20mm, if there is, it is about 25mm, and the minimum distance between the finished products is 15mm.
B)Large products: the distance between the edges is 35~50mm, and the minimum inlay is 35mm. If multiple small products are produced from one steel part, the distance between them should be about 12~15mm. The length of the finished product is more than 200mm, and the width The product should be no less than 35mm from the edge above 150mm.
<3> Principles for selecting benchmarks when ranking products:
A) The part with obvious characteristics (such as column position, perforation, bone position) is selected first.
B) If PRO/E 3D benchmark is selected, the name of CSO or CSI or DTM should be indicated.
C) For products with special shapes and difficult to determine benchmarks, discuss with CAM to determine the benchmarks.
D) The product reference and the center of the mold base must be integers, and add a box to the number to show the difference when marking the size.
<4> The principle of determining the X and Y coordinate directions of the inner mold fine frame during ranking: If the length and width dimensions of the inner mold fine frame are significantly different, the longer side must be taken as the X axis to place the mold blanks to match the workshop The machining direction of the machine tool reduces the chance of error.
2. Order mold embryo
<1> Try to use standard mold embryos (LKM standard or Hongfeng standard).
A) When changing from an I-shaped mold to a straight mold, do not move the square iron, but directly place the gong on the square iron.
B) Non-standard molds must be approved by the supervisor and indicated on the ranking chart.
<2> Use CH and CT mold blanks to make code mold pits, the height and width are about 25~35mm, and the length is determined by the height of the mold blank.
<3> The top stick hole should be processed with 1 or 2 or 4 holes according to the large slender width of the mold base (when processing more than one top stick hole, make a long top stick, not the top stick hole in the center of the mold base) ). The hole diameter is 35mm ~ 40mm. The height of the mold base is below 400mm (including 400mm) to make 1 top stick hole; the height of the mold base is above 400mm to make 2 or 4 top stick holes, and the hole distance is processed according to the data.
<4> The diameter of the slingshot hole should be 1~2mm larger than the diameter of the slingshot, and the depth of the slingshot hole should be at least 20 to 30mm.
<5> The mold blank processing drawing must be processed by the mold blank supplier to process the pump hole (flange), spring hole, square auxiliary device installation recess or side nail hole, etc.; large mold blank (800X800) needs Processing support holes (including the screw holes at the bottom), oblique avoidance holes, oblique bronze inserts, oblique colors, row positions, row position pressure plates, water transportation, water transportation buckets, etc.; fine nozzle mold blanks must be processed Nozzle rods, slingshot plastic holes, plastic holes, plug screw holes, etc.; please consult the factory requirements before the mold blank processing drawing, and determine the objects to be processed according to the actual workload of the factory.
<6> The large nozzle mold blank is a mold blank above 2730. The thickness of the A plate should be between the depth of the fine frame and 25mm and 35mm, and the thickness of the B plate should be between the depth of the fine frame and 50mm and 70mm; the mold blank is below 2525, The thickness of the A plate is about 25mm 30mm plus the depth of the frame , and the B plate is between 40mm and 50mm.
<7> The thickness of the A plate of the thin nozzle mold blank is between the depth of the frame and 30 to 40mm, and the thickness of the B plate is between the depth of the frame and 50 to 60mm. (For the specifications of large and thin nozzle molds, please refer to the information of Longji mold blanks)
3. Order materials
- Ordering principle:
A) The cutting size of the insert that does not require fine grinding = actual number + 3~5mm (this number should be as consistent with the steel supplier's specifications as possible).
B) Cutting size of fine grinding = actual number + margin
C) Y-CUT insert size = actual number + 5mm (one side) + 5mm (adjacent side) + 20mm (opposite side) + 20mm (opposite side adjacent side).
D) The cutting size of the insert to be hardened = actual number + >10mm. (except for fine grinding).
- The mold steel materials should be ordered according to the plastic properties of the products (including beer plastic materials) as follows:
A) Depending on the pattern structure, GS083H, S136, S136H, and beryllium copper can be used as inner mold materials for beer PVC products.
B) Beer transparent material, POM material, nylon material, ABS material, K lined material and other internal mold materials are GS083HS136, S136H and other steel materials. Note: molds made of S136H, GS083H and S136 steel materials, except under special circumstances It is better not to solder, if solder, you need to burn the same material and temper.
C) Except for beer that has acidic or transparent rubber, the inner mold materials of other products are P5, P20, 738, and 718 steels.
D) The commonly used steel for inner mold runner iron is yellow-label material.
E) The row material, oblique pillow material and row pressure plate are usually 738 material (except for the row position without inserts).
F) All alloy molds are made of 8407 materials (including inner mold materials), which is convenient for hardening.
G) When hardware needs to be mounted at the bottom of the row or the oblique position, the material should be 738 steel.
- Communicate with the workshop, fill in the material opening form carefully and check and submit it.
4. Parting surface
<1> Selection principle of parting surface:
A) It does not affect the appearance of the product, especially for products with clear requirements on the appearance, and more attention should be paid to the effect of the parting on the appearance;
B) It is helpful to ensure the accuracy of products;
C) It is conducive to the processing of molds, especially the processing of parisons;
D) Conducive to the design of the gating system, exhaust system, and cooling system;
E) Facilitate the demoulding of the product and ensure that the product is left on the side of the movable mold when the mold is opened;
F) Facilitate the installation of metal inserts;
<2> When the parting surface is a large curved surface or the height of the parting surface is large, the upper and lower mold materials can be considered as a tiger mouth. The size of the tiger mouth depends on the mold material. The length and width are less than 200mm, and 4 tiger mouths with a height of 15mmX8mm are made , The slope is about 10%%d. If the length and width are more than 200mm, the mouth should be 20mmX10mm and the degree should be about 10%%d. If the length and width are more than 200mm, the mouth should be 20mmX10mm The number of tiger's mouths high or above depends on the ranking (can be set or left in place).
<3> When drawing, it is necessary to clearly express the position of the mold opening line, whether the sealing surface is extended, etc.
5. Other design and processing requirements
<1> The clearance between plate A and plate B is 0.1mm (that is, the total height of the inner mold material is greater than the sum of the depths of the A and B plates by 0.1mm). The clearance between the medium and large molds A and B is 0.5mm. The height should be 0.05 0.2mm smaller than the clearance of the AB board . (i.e. the height of the stool + the height of the B board + the clearance height-the clearance 0.05 0.2mm-the height of the bottom needle board and the garbage nail = the length of the back stitch.)
<2> The top surface of the mold blank (the pull hole is the hanging mold hole) should be marked with the number of the "factory and customer number comparison table>>, and the typing mark must be at least 12mm, and the marked lettering must be neat.
<3> All the pry angles are on the four corners of the B board, making an equilateral triangle with a depth of 4~5mm and inverted R or chamfer.
<4> All water inlets and outlets on the mold blank must be marked with 1 IN----1 OUT ~ 2 IN----2 OUT, etc.
<5> The distance of the code mold hole and the specifications of the teeth are determined according to the specifications of the injection molding.
<6> The requirements for upper and lower mold materials and mold blanks are as follows:
A) The bottom of the mold material and the four sides of the mold frame are chamfered with 45%%d of about 1mmX1mm.
B) The mold surface of A and B plates should be 5mm gongs on the side of the frame according to the number of inner mold materials, a circle with a diameter of 1/2"mm and a depth of 0.5mm. 1, 2, 3-mark with the word, B board press 01, 02, 03-mark with the word. The upper and lower mold materials face the A board, the position of the B board should be marked with the factory number (XXXX ), the upper mold number is XXXX----1,2,3----, the lower mold number is XXXX----01, 02, 03----. The upper and lower mold numbers must be symmetrical (that is, the upper mold is 1. The lower mold is 01 as a box). The upper and lower molds are 30mm long, 8mm wide, and 0.5mm deep. The gong is marked with a 5.0mm word mark, and the inner mold number should be engraved or marked according to the customer. Numbering.
C) The allowable difference between the upper and lower mold frame is %%p0.02mm, the allowable tolerance of the upper and lower mold material curved scale is %%p0.02mm, and the upper and lower mold material size tolerance is %%p0.02mm.
<7> When moving the mold, the exterior should be clean, and the inner mold should be sprayed with anti-rust oil.
<8> Except for the special requirements of customers, the factory must follow the above methods for processing.