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What are the problems encountered in the trial of automotive molds?

1. Insufficient plastic parts: mainly due to insufficient feeding, poor melt filling flow, excessive inflation and poor exhaust, etc., which cause the filling cavity to be dissatisfied, and the shape of the plastic parts is incomplete or the cavity of the cavity is not full.

2, the size is unstable: mainly due to poor mold strength, poor precision, the injection machine is unstable and the forming conditions are unstable, etc., so that the dimensional changes of the plastic parts are unstable.

3, air bubbles: due to excessive inflation or poor exhaust gas in the melt, resulting in residual gas in the plastic parts, and a small volume or a series of holes (note that should be distinguished from vacuum bubbles).

4, collapse pits (dents) or vacuum bubbles: due to poor pressure feeding, plastic parts cooling uneven, uneven wall thickness and plastic shrinkage.

5, the flashing edge is too large: due to poor clamping, the gap is too large, the plastic fluidity is too good, too much feeding causes the plastic parts to extrude excess flakes along the edge.

6. Poor welding: Due to the low material temperature during the confluence of the melt, the resin and the adduct are incompatible, and the fusion is poor at the confluence, resulting in obvious fine seam lines along the surface or inside of the plastic part.

7. Surface corrugation of plastic parts: As the melt does not flow neatly along the surface of the mold, it fills the cavity, but becomes semi-cured and fluctuates in the cavity surface or the stagnation of the melt.

8. Poor mold release: Due to excessive filling effect and poor mold release performance, it is difficult to demould the plastic parts or the plastic parts are deformed or broken after demolding, or the residual direction of the plastic parts does not meet the design requirements.

9. Mica flaky peeling: Due to the mixed foreign material or low mold temperature, the shearing effect of the melt flowing along the surface of the mold is too large, so that the material is peeled off in a thin layer and the physical properties are degraded.

10. Gate sticking mode: Due to mechanical resistance in the sprue bushing, the cooling is not enough or the pulling bar is out of order, so that the gate sticks in the sprue bushing.

11. Poor transparency: Due to poor contact between the melt and the surface of the mold, there are small pockets on the surface of the plastic part to cause radiation or plastic decomposition, foreign matter impurities, or the surface of the mold is not bright, making the transparent plastic poor or uneven.

12, silver silk marking: due to moisture or aeration in the material, and excessive volatiles, the melt is too shearing, the melt and the mold surface is poorly sealed, or rapidly cooled or mixed with foreign materials or decomposition and deterioration, and Silver-white lustrous acicular streaks or mica flakes appear in the surface of the plastic part.

13. Warpage, deformation: internal stress caused by residual stress, shear stress, cooling stress and uneven shrinkage during forming; poor mold release, insufficient cooling, insufficient strength of plastic parts, deformation of the mold, etc. Shape distortion, uneven warp or hole orientation, uneven wall thickness.

14. Crack: Due to excessive stress in the plastic part, poor mold release, uneven cooling, poor plastic performance, poor design of plastic parts and other defects (such as deformation), fine cracks appear on the surface of the plastic part and near the feed opening. , or cracking or cracking in the load and solvent.

15. Black spots and black bars: Due to the decomposition of plastics or flammable volatiles in the material, the air is decomposed and burned under high temperature and high pressure, and the combustion products are injected into the plastic cavity with the melt, and black spots, black stripes, or The surface of the plastic part is charred.

16. Uneven color or discoloration: Due to poor distribution of pigments or fillers, plastic or pigment discoloration is uneven on the surface of plastic parts. The unevenness of color is different depending on the phenomenon of appearance. The pigment is distributed unevenly near the feed port. If the color of the whole part is uneven, it is caused by poor thermal stability of the plastic. When the color of the welded part is uneven, the pigment property is different. related.

The system hardware design in the stamping die; the CNC unit die is mounted on the crank press, and the stamping principle of the machine tool is unchanged. What needs to be controlled is two aspects: firstly, the zero point and the position of each work point are determined; secondly, in the start and stop of the reciprocating action of the upper die, the fast feeding feed motion of the workpiece in the X, Y direction is encoded and this Coordination of two actions. That is, synchronous control of stamping and feeding operations is achieved. 
     The man-machine interface of the numerical control system adopts the keyboard input LED to display the function keys of the keyboard with number keys, setting, modification, search, X and Y direction adjustment, execution, etc., which can be used to complete the input, modification and control operation of the machining program. And adjustments, etc. The operator encodes the computer according to the shape of the workpiece, automatically generates a machining program, and downloads the machining program to the MCU through the serial port and saves it in the FLASH ROM. Manually adjust the zero position after the mold is installed. 
      After entering the execution, the MCU obtains the machining program from the FLASH ROM, and calculates the step distance in the X and Y directions, and then converts it into the corresponding step pulse number to control the number of rotation steps of the stepping motor in the X and Y directions. When the photoelectric signal detects that the upper mold is in the open position, the numerical control system quickly positions the workpiece to be processed to the processing position, and starts pressing on the punching die to realize one punching. When the punching machine drives the upper die to open, the numerical control system quickly moves the workpiece to the next processing position and waits for the next punching until the machining is stopped to stop the punching motion.

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