Glass bottle mold quenching cracks

by:Lisson     2020-11-11
Mould quenching crack

the mold after quenching crack is the biggest flaw in the process of mould heat treatment, will make the processed mold scrapped, make production and economy caused great loss.

( 1) The causes of

1) Mold material exists serious meshy carbide segregation.

2) In mould machining and cold plastic deformation stress.

3) Mould improper heat treatment operation ( Heating or cooling too quickly, improper selection, cooling quenching cooling medium temperature is too low, the cooling time is too long, etc. ) 。

4) Die complex shape, thickness, Angle and threaded hole, etc. , make the thermal stress and organization stress is too large.

5) Die quenching heating temperature is too high cause overheating or burnt.

6) Die after quenching tempering time insufficient tempering heat preservation time.

7) Mold repair quenching heating, without intermediate annealing and quenching again.

8) Mold heat treatment, improper grinding technology.

9) Mold edm after heat treatment, have higher tensile stress exist in the hardening layer and microscopic cracks.

( 2) Preventive measures

1) Strictly control the immanent quality of mold material

2) Improve forging and spheroidizing annealing process, eliminate mesh, belt, chain carbide, improve the uniformity of spheroidizing organization. 、

3) After machining or after cold plastic deformation of mould should be to stress annealing ( > 600℃) After quenching.

4) Of complicated shape mould should use asbestos jams threaded hole, bandaging dangerous section and the thin wall, and USES the hierarchical quenching and isothermal quenching.

5) Repair or refurbish the mould need to annealing or high temperature tempering.

6) Mould preheating, should be taken in quenching heating cooling precooling measures, and select suitable quenching medium.

7) Should strictly control the quenching heating temperature and time, to prevent overheating and burnt mould.

8) Mould should be timely after quenching tempering, heat preservation time to fully, high alloy complex mould should be 2 - tempering 3 times.

9) Select the correct grinding process and the appropriate grinding wheel.

10) Improve the mold edm process, and to stress tempering.
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