Precautions for the design and manufacture of two-color mold of automotive lamps:

1. The flat ejector rod on the welding rib needs to be arranged densely, preferably every 50mm. In addition, because the mold temperature is required to reach 90 degrees, the flat ejector rod is easy to be roughened, so the flat ejector rod needs to be titanium plated.

2. The depth of the welding reinforcement is deep, and sometimes there will be air entrapment and poor polishing. It is made into an insert and adopts an embedded structure, which is not only conducive to the exhaust, but also conducive to the processing of the flat ejector rod hole, and more importantly, it is conducive to the welding and trimming of the orifice flash.

3. The two-color mold of the lamp adopts the rotating mold, and the accuracy of the rotary table of Taiwan's injection machine is not too high. The moving die will fall with the product when opening the die, and the product is easy to pull off the given die. Therefore, the precise positioning of the mold is very important, and a large area of precise positioning needs to be used in the design (the precise positioning area is small and easy to pull).

4. Generally, the lamps are made of PMMA and PC materials. Because the fluidity of these materials is relatively poor, if we use the side gate in our design, we need to design the side gate larger and deeper. Otherwise, it is difficult to hit enough and there are many defects at the gate, such as flow marks and shrinkage.

5. On board knowledge:

A. The size of the center distance between the two ends of the injection molding machine and the size of the locating ring. The locating ring is 15mm higher than the upper plate, and there must be a unilateral 15 degree guide chamfer at the mouth of 5mm. The size of the locating ring is 0.1-0.2mm smaller than the nominal size;

B. Upper plate die screw and center distance dimension;

C. The locating ring shall be on the axis of the rotation center. After the half die is assembled and the datum plane is straightened, the locating ring of the upper plate shall be machined on the No. 31 five axis NC milling according to the central pin hole of the die fixing plate;

6. The fixed plate of male and female die shall be designed to:

A. The center of the formwork shall be provided with a central pin hole;

B. The template guide post hole needs to be symmetrical with the central pin, because the template needs to rotate.

7. Bottom plate needs to know:

A. There are three locating rings on the bottom plate of the injection molding machine. Confirm the size of the injection molding machine. The center locating ring should not be more than 10mm higher than the bottom plate, because sometimes there is a water pipe in the center, which is easy to interfere. The locating ring on both sides is 15mm higher than the bottom plate, and there must be a unilateral 15 degree guide chamfer at the mouth of 5mm. The size of the locating ring is 0.1-0.2mm smaller than the nominal size;

B. Specification and center distance specification of bottom plate die screw;

C. The specification and size of the ejector hole of the bottom plate shall be confirmed;

D. The locating ring shall be on the axis of the rotation center. After the half punch is assembled and the datum plane is straightened, the base plate locating ring shall be milled on the No. 31 five axis NC machine according to the central pin hole of the punch fixing plate.

Note: points 5, 6 and 7 are particularly important, otherwise the normal mold test cannot be carried out Be sure to confirm it, otherwise it is very troublesome to debug the mold during the mold test (it is recommended to open two sets of molds for the two-color machine, and there will be no special restrictions at the beginning of the mold test.

8. The ejection distance shall be reduced as far as possible, as long as the ejection product is ensured, so that the effective length of the flat ejector rod can be shortened, which increases the strength of the flat ejector rod and will not cause flat bending or fracture of the flat ejector rod.

9. White sheet forming:

A. The cavity of the white sheet is 0.1mm deeper than the theoretical size, which is conducive to the secondary injection molding of the white sheet without being full. It is not only conducive to protecting the strength of the thin-walled die from the possibility of cracking of the die, but also the white sheet has a preload during the final molding of the product, so the white sheet is not easy to move and be cracked during the injection molding process;

B. The side slope of the white sheet cavity should be 10 degrees on one side as far as possible to avoid leaving a concave die for the product, but at the same time, it is necessary to consider strengthening the thin-wall strength of the parting surface;

C. The peripheral surface of the white sheet is 0.5mm away from the punch surface to strengthen the strength of the thin-wall parting surface; At this time, Gan Wan should carefully check the position of the reflective electric casting, and the height should not interfere with it, because the electric casting is higher than the surface of the punch, which is very easy to be ignored, otherwise the consequences are very serious. The general price of electric casting is 80000-100000.

D. Put a 0.1M, m gap between the white side and the punch face to face, which is not easy to be too large, and do a good job in the figure;

Otherwise, the thin wall will be broken by pressure injection After the mold is too small, the outer parting surface of the white sheet is easy to rub the forming surface of the red sheet, which increases the product tightening force and causes the product to crack;

E. The corners of the side and periphery of the white sheet cannot be cleared, and the R angle should be increased by 10.5 as much as possible to improve the strength of the thin wall.

10. Punch part:

A. All rib mouths cannot be chamfered, r<0.3mm, (the wall thickness of the product is generally 2.5mm. At the same time, it is easy to produce stress and crack the product during ejection. If the product is allowed, communicate with the customer and confirm that the rib at the white sheet can be 0.5 to 1mm lower than that at the red sheet, so as to increase the wrapping force of the product on the side of the punch, so as not to leave the die for the product;

B. When there is no flat ejector rod at the white sheet, the punch needs to be tilted by 1 degree, and the draft should be gradually increased according to the mold test If there is a flat ejector rod, do not put the slope, but under normal circumstances, the customer is not allowed to have a ejector rod here, otherwise it will affect the appearance of the product;

C. With the permission of the customer, add a flat ejector rod to facilitate ejection and exhaust, and change the white punch into an insert, using an embedded structure;

D. The peripheral fusion reinforcement shall be drawn as much as possible, and one side shall be greater than or equal to 3 degrees (but the large end of the reinforcement shall not exceed 1.80mm, otherwise it will cause shrinkage;

E. The size of the flat ejector rod shall be 1.2mm (not less than 1.0mm), and the length of the fitting section on the punch is generally 20mm, so as to increase the strength of the flat ejector rod and prevent it from bending or breaking;

F. For red and white products, the gate position must be analyzed to confirm the melting line and gas trace position, and then communicate with customers and confirm the position of flat ejector rod and exhaust insert;

G. The parting surface on the side of the die must be densely covered with exhaust slots, because in principle, the parting surface of the die cannot be moved, and one cavity is equipped with two punches).

11. Cooling:

A. The concave die has four inlets and four outlets, and the single cavity is cooled separately. The high temperature resistant O-ring and gate have separate cooling water path as far as possible, and the water path is added;

B. Punch 4 in 4 out, separate cooling single punch High temperature resistant O-ring;

C. The water inlet and outlet holes on the side of the female mold face the ground, and the water pipe holes cannot be countersunk. Use oil pipe joints. All the water pipe connection holes, the hole diameter is as large as possible, generally 15mm. The water pipe leaves the mold surface twice the hole diameter, so as to avoid the possibility of cracking. The cooling water must be connected in the mold to prevent the possibility of water leakage and scald;

D. The O-ring in the air valve control port must be a high-temperature resistant O-ring, and the connecting pipe must be connected with a high-temperature oil pipe, otherwise the air valve controller will be easily damaged by scalding The air valve controller needs to add a protective device to enlarge the template if allowed (enlarge the opposite side of the operator as much as possible, and it is not allowed to put it on the top, which is inconvenient to operate. At the same time, when the external air source enters the air valve controller, a filter must be added, otherwise the air circuit and valve core of the air valve controller will be blocked.

12. The guide sleeve must be added, and the cover plate of the guide sleeve (because the upper and lower molds are not concentric on the injection molding machine, it is easy to pull the guide sleeve out of the fixed plate.

13. The water in and out of the punch side is close to the operator side and faces the ground side. The non operator side is facing the sky. Because the water temperature is high to prevent scalding, the water pipe cannot be countersunk. Use the oil pipe connector. The hole diameter of all the water pipe connector holes is as large as possible, generally 15mm. The water pipe is 2 times the hole diameter away from the profile, so as to avoid the possibility of cracking. The cooling water must be connected in the mold to prevent water leakage and scalding.

14. The punch is all quenched parts, so there should be no corner clearing on the parting surface, and the product corner clearing is connected with a small R. this point must be considered in the design.

15. All wear-resistant plates and fine positioning on the side of the punch and die must be embedded, and they must not be stuck flat when dry. (because of the high temperature of the die, it is easy to tighten and the screws are easy to break.

16. The upper and lower baseplates shall be added with heat insulation panels according to the situation. (because the mold temperature is high, but a few two-color injection molding machines have heat insulation panels attached to the front and rear wallboards.

17. The front face of the cavity and core should avoid adding a water pipe bulkhead as far as possible (to prevent water leakage and corrosion of the cavity and core).

18. The outlet of all white and red needle valve gates is generally 2mm, otherwise the product appearance will be affected. Carefully check the version finally confirmed by the hot runner company. If it is out of tolerance, we must communicate with the customer, otherwise the die will be scrapped.

Manufacturing precautions

1. At present, the precision positioning designed by the company is not satisfactory in the manufacturing process. They are all put on the mold and do not play the role of precision positioning (the gap of some precision positioning is about 0.2mm). The accuracy of the two-color rotating meme machine tool is a problem, and it must be accurate in the future.

2. The flat ejector rod on the welding rib is best to be flat and must not be lower than the punch groove. If it is lower than the punch groove, the flat ejector rod will be higher than the welding rib, causing cracking during welding. It can also be less than 0.2mm lower than the welding reinforcement. The molten plastic parts are generally about 0.8mm during welding. Too much lower will cause insufficient strength and water leakage during welding.

3. The forming part of the edge mouth of the electric casting needs to be polished to 2000 pieces of sandpaper, and the forming part of the fixed frame mouth also needs to be polished, otherwise the product is easy to crack.

4. All ribs and sides shall be polished carefully. During polishing, attention shall be paid to the demoulding slope and the surface shall be leveled.

5. Because the mold adopts high temperature, the heat rise factor should be considered in the process of matching the mating surface, and it can be loosened.

6. When assembling the mold, the inserts and flat ejector rods must be free of oil, and must be wiped clean with alcohol during assembly Because the mold temperature is high, after being heated, the oil melts and enters the product. It needs dozens of molds and will not be cleaned up, which is a serious waste of raw materials.

7. Two screws are used to connect the ejector plate and the punch fixing plate, because there is a return spring between the top plate and the punch fixing plate, and the fitting section of the flat ejector rod is relatively short, and sometimes it may not be able to lift out smoothly when removing the ejector rod fixing plate in the future. In the process of up and down, the flat ejector rod is easy to disengage from the fitting section of the punch, and the angle of the flat ejector rod collides with the step, resulting in the collapse of the ejector rod.

8. The hot melt reinforcement on the side of the punch can be punched individually during rough punching, but it must be punched together with the flat ejector rod during fine punching, otherwise the orifice of the flat ejector rod will not collapse and the bottom surface is easy to break.

9. When the hot melt rib on the side of the punch is polished, be careful of the collapse of the flat top rod mouth. It is best to combine the flat top rod on the bottom and polish it together.

10. When the white sheet is not surrounded by the red sheet but fused, the position of the flat ejector rod of the red sheet and white sheet must be close to the fusion edge, because the connection strength of the fusion edge of this type of product is poor. If it is far from the fusion edge, the product is easy to crack.

11. The punch has the same two cavities, so all parting surfaces, especially the depth and side of the white sheet parting surface, must be consistent. When processed on the same Shamir machine tool, the error is controlled within 0.02mm. If there is any difference, it will directly affect the fitter's mold matching and cannot be repaired at all.

What aspects should be paid attention to in the design and manufacture of two-color mold for automotive lamps?