Correct choice and use of mold spring - mold parts for plastic molding manufacturing

Time:2019-07-17 08:48:37 / Popularity: / Source:

mold parts 

First, basic knowledge of spring

In a set of plastic molding, more elastic materials are needed, including various springs, superior rubber, and nitrogen springs. Different elastic materials are used in different plastic molding manufacturing according to different needs. For example, bending and punching can be done with ordinary flat wire springs, such as brown springs, also known as brown springs; excellent glue is generally used for drawing molds, shaping molds, or flatness.
Spring includes flat wire spring, wire spring, etc. Purpose of spring is to remove and press material in plastic molding, magnitude of spring force is related to whether mold production is smooth and whether product is qualified or not. Spring force is small, which may cause various problems in plastic molding manufacturing such as product deformation, mold not to be stripped, products not good to be taken out from mold, strips, knife edges, and punches.
Flat wire springs are generally divided into: brown, green, red, blue, and yellow. Strength is also weakened in turn. Colors are different, strength is different, and compression is different.
There is a soil method to calculate compression of spring in plastic molding manufacturing: measure the total height of spring beforehand, put spring in vise, lock it, then use a caliper to measure length remaining after spring is clamped, and then subtract the total length from spring and divide it by total length. This method is universal for any spring in plastic molding manufacturing. For example, length of brown spring is 60mm. After being clamped by vise, there should be about 45.6mm. Then you subtract 60 from 45.6 to 14.4, divide 14.4 with 60. Result is equal to 0.24, which is amount of compression.
According to different production times, such as 1 million times, 500,000 times, 300,000 times, the larger compression amount, the shorter spring life, the shorter life of plastic molding (of course, spring can be replaced if it is broken). If mold is produced for a period of time, spring may be weak, and spring with a poor quality may break in the mold. Generally compression amount of spring is calculated according to 300,000 times, that is to say, mold may be incapable of hitting 300,000 times of springs. Of course, general plastic molding life is not so long, and it can also be calculated according to maximum compression amount. If calculated according to maximum compression amount, it can only guarantee that spring does not explode inside mold. Mold is pressed a little and it is good for product flatness.
Maximum compression (how much this spring can be pressed), maximum compression of spring is equal to free height of spring multiplied by maximum compression ratio of spring. For example, a brown spring with a length of 60mm, then its maximum compression is 60*24% (maximum compression ratio), is approximately equal to 14, this spring can be pressed down to 14 mm, its maximum stroke is 14 mm, stroke of mold must be less than 14 mm. If more than 14 mm, spring may fail, deform, and may break in the mold, or explode mold, and can not be pressed.

Second, attention points of spring use

1. Specifications of each spring are different. It has been determined at the time of design. Springs should not be easily replaced with each other mold parts during use, nor can they be modified at will.
2. Selection of spring mounting socket and diameter of central shaft is essential for normal use of spring, and these two play a stable and guiding role for spring in plastic molding manufacturing.
3. Guiding length of spring refers to length of central axis of spring and depth of socket. If length of guiding is insufficient, and spring is subjected to side bending or tilting, which causes spring to collide with socket and central shaft, resulting in early failure of spring. When spring travel is guaranteed, guide length is greater than 1/2 of free length.
4. Upper and lower mounting faces of spring must be parallel to each other. Upper and lower ends of standard spring are very flat for equipment, but if a sheared spring is used, joint cannot be flush with end face.
5. When plastic molding is being repaired and maintained, old and new springs should not be mixed together, which will cause spring to bear uneven load, and it is the early failure of spring with large load in plastic molding manufacturing.
6. Prevent spring from mixing iron scraps, scraps and other debris. Debris will reduce effective number of turns of spring, causing high stress in the spring to be destroyed. In the use, it is necessary to check whether there is any foreign matter in the spring.
7. Maintenance personnel of plastic molding often modify standard springs due to absence of suitable springs. For example, truncating, grinding inner and outer diameters or series springs can cause spring to fail to retain its originnal characteristics, causing early failure.

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