In process of work, analyzing causes of mistakes made and summarizing lessons are important ways to improve work ability.
Failure case: A Corinthian pillar of a certain model of Haitian injection molding machine broke. Corinthian pillar was replaced and balance was adjusted without professional tools.
Generation of clamping force: The four Gorin columns of injection molding machine penetrate crank arm base, fixed platen to position base and moving direction of platen. Parallelism between base and fixed mold plate is determined by position of nuts on both ends of Corinthian column. In process from movable mold plate contacting mold to curved arm straightening, due to obstruction of mold, movable mold plate cannot move forward, base tends to move backward, making Corinthian column in a stretched state. Tensile force * 4 corresponding to deformation variable of a single Corinthian column is clamping force. It is equal to pressure of movable mold plate on mold, also equal to pressure between movable mold and fixed mold of mold.
Force balance of Corinthian pillars means that when mold is closed, pulling forces generated by four Corinthian pillars are equal, or deformation amount of Corinthian pillars is equal. Accurate installation is impossible without professional tools.
Author's thoughts before taking action: Front-end fixed baffle and fixing nut of Corinthian column are not installed. Mold is closed so that base drives Corinthian column to retreat, so that force on base is balanced; front fixing nut is tightened with mold adjustment to complete balanced installation.

 

Expected plan:
1. Remove Corinthian column and screw rear mold adjustment nut to same position.
2. Return Corinth plunger to same distance (measure distance between adjusting nut and base or runner)
3. Install front and rear nuts, front and rear fixing plates of Corinthian column so that distance between four corners of base and fixed mold plate is approximately equal.
4. Install mold and adjust mold to normal. Make mold close and in a state of no high pressure. Remove front fixing nut and front fixing plate of Corinthian column, and only remove rear fixing plate.
5. Let four Corinthian pillars move forward at the same distance to create high pressure. At this time, Corinthian pillars will move back, and this will be repeated to make force even.
6. Install front fixing nut and front fixing plate. This step is very important. Do not tighten nuts. Tighten fixing nut by adjusting mold and complete.
Follow above operations and analyze them one by one below:
1. Mold adjustment nut does not need to be positioned accurately on Corinthian column. And it should be determined according to previous distance, it may be adjusted later. In actual operation, a caliper was used to measure relative position of die-adjusting nut, Corinthian column, base, and runner, which was accurate to level of one tooth. A lot of time was wasted in process.
2. Relative position of mold adjusting nut and base is fixed. There is only a gasket in the middle, which is tightened by rear fixed plate. No adjustment or measurement is required.
3. When adjusting position of mold adjusting nut, it must be same as previous position. Otherwise, due to fixed base position and Corinthian column extending more or less from fixed mold plate, front fixed plate cannot be installed. In actual debugging, it was determined according to one of positions, resulting in inconsistent lengths of Corinthian columns in front of fixed mold plate (lengths of Corinthian columns were inconsistent or base was skewed). After fixing Corinthian column mold adjusting nut and rear fixing plate, it is hoped that force will be consistent by closing or adjusting mold. Actual situation is: due to inertia during mold opening and closing process, base vibrates, retreats and drives Corinthian pillars to retreat together; when adjusting mold, Corinthian pillars can move forward and backward. Since front of Gorin pillars is not fixed, some parts are rotated. Plan is declared failed here!
4. Before completing balance, it is harmful to use high pressure. Adjust mold to less than thickness of mold, but effect will be same.
5. If everything was normal before, remove front fixing plate and nuts, and use mold to balance force. After analysis, it is concluded that if front fixing nut and front fixing plate are not installed, are not subject to pulling force of Corinthian column, base and Corinthian column will retreat together so that protruding distance is less than installation distance, front fixing plate and front fixing nut cannot be installed. However, this action can reduce skew of base. Before this action, there must be room for the front end of Corinthian pillar to extend.
6. If fixing nut is manually tightened too tightly, it will cause base to be pulled askew, and it cannot be guaranteed that force of Gorin column will be consistent when mold is closed. This is true. During subsequent debugging process, because fixing nut was too tight, one corner of pull base tilted and force was uneven, making it impossible to adjust mold.
Summary plan:
1. After Gorin Pillar is roughly installed, adjust mold thickness to less than mold thickness, bend crank arm as much as possible, and mold is in a closed state.
2. Remove all front fixing plates, front fixing nuts, and rear fixing plates, adjust position of mold adjustment nut appropriately, compare protrusion distance of front end of corin column, and make protrusion distance convenient for installation.
3. Loosen all mold adjusting nuts same distance backward and install rear fixing plate. At this time, protruding distance of Gorin column is greater than installation distance. This margin cannot be too small or too large. If it is too small, subsequent movement of base will be less, and base cannot be guaranteed to be parallel; if it is larger than movement distance of base, it will not move back in place, front fixing nut and front fixing plate cannot be installed.
4. Reduce mold closing speed and perform mold closing action. Movement is smooth. During mold closing process, since front of Gorin pillar is not fixed, movable mold plate and mold are in contact, curved arm gradually becomes straight, and base drives Gorin pillar to retreat. At this time, base gradually becomes parallel to fixed mold plate, reducing skew, and adjusts it to installation position. Tighten front fixing nut until it is in contact (important), and fix baffle before installation.
5. Adjust mold to normal state, close mold and lock it so that fixing nut is in a tight state, and tighten front fixed baffle again to prevent corin column from loosening when mold is loose. During operation, tighten positioning screw to prevent Corinthian column from rotating.