硬岩复合地层中，滚刀刀圈常见的问题与应对方案——梯度硬度

Common Issues and Solutions for Roller Cutter Rings in Hard Rock Composite Formations - Gradient Hardness

城市地铁隧道的埋深大多是在地下十几米至二三十米不等，在这种埋深区间中，遇到不同风化强度的岩层概率较高，因此，城市盾构隧道的施工，往往遇到上软下硬、软硬不均的岩层，对施工中使用的盾构刀具产生较大且不均匀冲击，导致刀具的异常损坏率增加。其中滚刀刀圈的崩刃与断裂情况最为明显。

The depth of urban subway tunnels is mostly between ten to twenty meters underground, and within this depth range, it is quite likely to encounter rock layers with varying degrees of weathering. Therefore, during the construction of urban shield tunnels, it is common to encounter rock layers that are soft on top and hard underneath, with uneven hardness. This can cause significant and uneven impacts on the shield tunneling tools used in construction, leading to an increased rate of abnormal damage to the tools. Among these, the chipping and breaking of the rolling cutter rings are the most noticeable.

在所有的异常损坏形式中，刀圈断裂对盾构掘进的影响最为严重，断裂的刀圈随着刀盘的继续转动，对周边连续轨迹有可能产生不好的影响，卡住刀体、挤压刀圈和端盖（俗称刀打刀）的现象。 

产生这种现象的主要原因是刀圈的冲击韧性较差。一般来说，不论是碳钢还是合金钢，淬火、回火后的冲击值和洛氏硬度HRC大致成反比例。

通常提升冲击韧性的解决方案是降低刀圈的硬度，但从市场的反馈来看，绝大多数刀圈采用的整体降低硬度的方案，这种方案对刀圈韧性的提升有限，在强冲击下仍然会断裂。

经过采纳与收集各项目的经验，多次实践与调整刀圈内部金属微量元素的比例，增加深冷、多次回火等特殊热处理工艺，形成独特的梯度硬度刀圈。

Among all forms of abnormal damage, the breakage of the cutter ring has the most severe impact on shield tunneling. The broken cutter ring, as the cutter head continues to rotate, may have a negative effect on the surrounding continuous trajectory, leading to phenomena such as jamming the cutter body, squeezing the cutter ring and end cover (commonly referred to as "knife hitting knife").

The main reason for this phenomenon is the poor impact toughness of the cutter ring. Generally speaking, for both carbon steel and alloy steel, the impact value and Rockwell hardness HRC after quenching and tempering are roughly inversely proportional.

The common solution to improve impact toughness is to reduce the hardness of the cutter ring. However, based on market feedback, the majority of cutter rings adopt an overall reduction in hardness, which has limited improvement in toughness and can still break under strong impacts.

After adopting and collecting experiences from various projects, and through multiple practices and adjustments of the ratio of trace metal elements inside the cutter ring, as well as incorporating special heat treatment processes such as deep cryogenic treatment and multiple tempering, a unique gradient hardness cutter ring has been formed.

（梯度硬度刀圈横截面的各部位洛氏硬度值）

梯度硬度刀圈可以做到刃部25mm-30mm的洛氏硬度HRC57-59，顺延至中部过渡区洛氏硬度HRC50-57，内圈洛氏硬度HRC40-50，且刀圈检测冲击功最高可达200J以上。刀圈的硬度从刃口到肩部呈现梯度下降的趋势，这样既保证了刃口处的破岩需要的高硬度，又增加了刀圈根部防断裂的韧性。

梯度硬度刀圈刃口硬、其余部位软的特点，能有效避免刀圈在上软下硬、溶洞、基岩凸起、孤石、破碎带等复杂地况刀圈整体断裂的情况。如图所示，

The gradient hardness cutter ring can achieve a Rockwell hardness HRC of 57-59 for the cutting edge within 25mm-30mm, transitioning to a hardness of HRC 50-57 in the middle zone, and an inner ring hardness of HRC 40-50. Moreover, the impact energy of the cutter ring can reach up to over 200J. The hardness of the cutter ring decreases gradually from the cutting edge to the shoulder, ensuring both the high hardness required for rock breaking at the cutting edge and the toughness needed to prevent breakage at the root of the cutter ring.

The characteristic of the gradient hardness cutter ring, with a hard cutting edge and softer other parts, can effectively prevent the overall breakage of the cutter ring in complex ground conditions such as soft upper and hard lower strata, karst caves, bedrock protrusions, boulders, and fractured zones. As shown in the figure,

（弱冲击与强冲击下的刀圈效果对比）

Comparison of the cutter ring performance under weak and strong impact.