U型槽模具硬度不足的原因和预防措施如下：炉或进入冷却槽方法不当等原因造成，应该修正工艺温度，检修校核控温系统，装炉时，工件间隔合理摆放均匀，分散入槽，禁止堆积或成捆入槽冷却。淬火温度过高，这是由工艺设置温度不当或控温系统误差造成，应当修正工艺温度，检修校核控温系统。过回火，这是由回火温度设置过高、控温系统故障误差或炉温过高时入炉造成，应当修正工艺温度，检修校核控温系统，不高于设置炉温装入。
The reasons and preventive measures for the lack of hardness of the U-groove die are as follows: the process temperature should be corrected, the temperature control system should be checked and checked, and the workpiece interval should be reasonably arranged evenly, dispersed into the groove and stacked or bundled into the groove for cooling should be prohibited. The quenching temperature is too high, which is caused by improper process setting temperature or temperature control system error. The process temperature should be corrected, and the temperature control system should be checked and checked. Overtempering is caused by over tempering temperature setting, fault error of temperature control system or charging when the furnace temperature is too high. The process temperature should be corrected, the temperature control system should be checked and checked, and the charging temperature should not be higher than setting the furnace temperature.