什么时候选拉杆液压缸，什么时候选焊接液压缸？两者的区别是什么？

我们先来看一个液压油缸分类表：

■ 拉杆液压缸 Tie rod cylinder 

拉杆液压缸靠螺丝杆连接前后缸盖，小缸径时为四根螺丝杆，大缸径会加多螺丝杆的数量来保证油缸的耐压性，比如6根、16根，甚至20根。

不同的使用压力，螺丝杆的材质不同，可能为A3、45号、合金钢。

Tie rod style hydraulic cylinders use high strength threaded steel rods to hold the two end caps to the cylinder barrel. This method of construction is most often seen in industrial factory applications. Small bore cylinders usually have 4 tie rods, while large borecylinders may require as many as 16 or 20 tie rods in order to retain the endcaps under the tremendous forces produced.

拉杆液压缸优势 Advantages：

1）易于拆装、维修；

2）多为标准系列，半成品或成品有库存，交期较短。

Tie rod style cylinders can be completely disassembled for service and repair, and they are not always customizable.

■ 焊接液压缸 Welded cylinder

焊接液压缸的后盖焊接在缸筒上，油口焊接在缸筒上，前盖与缸筒通常使用螺纹或螺栓固定。

Welded body cylinders have no tie rods. The barrel is welded directly to the end caps. The ports are welded to the barrel. The front rod gland is usually threaded into or bolted to the cylinder barrel. This allows the piston rod assembly and the rod seals to be removed for service.

焊接液压缸的优势 Advantages：

1）整体的安装尺寸小于拉杆油缸；

2）比拉杆油缸能够承受更大的压力；

3）更容易定制，比如特殊油口、特殊安装方式、加装锁紧阀等

Welded cylinders have a narrower body and often a shorter overall length enabling them to fit better into the tight confines of machinery. Welded cylinders do not suffer from failure due to tie rod stretch at high pressures and long strokes. The welded design also lends itself to customization. Special features are easily added to the cylinder body, including special ports, custom mounts, valve manifolds, and so on.

总结：

1）安装空间够，压力小，行程短，选拉杆液压缸；

2）安装空间有限制，压力大，选焊接液压缸；

3）使用压力大，工况比较恶劣，可能需要定期更换密封件，选拉杆液压缸；

4）油口位置有特殊要求，或需加装液压锁或平衡阀等，选焊接油缸。