Knowledge about tube sheet drilling
Introduction to tube sheet drilling:
Tube sheet drilling is a key process in industrial manufacturing, mainly used in the production of heat exchangers, boilers, steam turbines and other equipment. As the core component for supporting and fixing metal tubes, tube sheets need to be accurately processed into hundreds or thousands of holes on thick steel plates. The precision requirements include hole size, position, verticality and surface roughness, which is especially challenging in the processing of large diameter, high thickness and strong metal materials. With the increasing demand for large tube sheets in nuclear power, seawater desalination, power plants and other fields, tube sheet drilling services have gradually become an important link in the high value-added industrial chain.
tube sheet drilling
1. Technology:
1. Drilling method
Traditional mechanical drilling
Equipment: radial drilling machine, vertical drilling machine
Features: suitable for small batch production, flexible operation, but accuracy and efficiency depend on operator experience.
Steps: marking positioning → pre-drilling center hole → drilling in stages (such as step drilling) → reaming finishing.
CNC drilling
Equipment: CNC drilling machine, machining center
Features: high degree of automation, suitable for mass production, hole position accuracy can reach ±0.05mm, support complex hole types (such as inclined holes, threaded holes).
Advantages: automatic generation of drilling paths through programming, reducing human errors, and supporting multi-axis linkage.
Laser drilling
Equipment: high-power laser cutting machine
Features: suitable for thin plates or special materials (such as titanium alloys, composite materials), no tool wear, but high equipment cost.
Water jet drilling
Equipment: high-pressure water jet cutting machine
Features: no heat-affected zone, suitable for heat-sensitive materials, but slightly lower aperture accuracy.
2. Drilling tools
Drill bit type
Twist drill: general-purpose drill, suitable for carbon steel, stainless steel, etc., the material can be high-speed steel (HSS) or carbide (such as tungsten steel).
Deep hole drill: used for deep hole processing with aspect ratio > 10, with internal cooling structure to reduce chip removal problems.
Step drill: form multiple diameter holes in one go, reducing tool change time.
Reamer: used for fine processing to improve the finish of the hole wall (Ra≤1.6μm).
Chamfering tool: deburr the hole mouth and form a guide bevel.
Auxiliary tools
Fixture: hydraulic or mechanical fixture to fix the tube sheet to prevent vibration deviation.
Cooling system: inject cutting fluid (such as emulsion, oil-based coolant) by internal cooling/external cooling to reduce temperature and lubricate.
Guide sleeve: ensure the verticality of the drill bit and reduce runout error.
Detection tools
Measuring tools: digital caliper, height gauge, plug gauge (check hole diameter), three-coordinate measuring machine (CMM).
Centering tools: edge finder, laser centering instrument (for CNC equipment).
2. Industry applications:
1. Energy and power
Nuclear power plant steam generator: Because the tube sheet needs to withstand high temperature and high pressure, laser-mechanical composite processing is used to ensure the consistency of the aperture and reduce residual stress.
Offshore wind power heat exchanger: 316L stainless steel tube sheet needs to resist seawater corrosion, and electrolytic polishing is required after drilling.
2. Chemical and petrochemical
Hydrogenation reactor: After drilling the duplex steel tube sheet, penetration testing (PT) and ultrasonic testing (UT) are required to ensure that there are no crack defects.
3. Emerging fields
Hydrogen energy storage and transportation equipment: Drilling of composite tube sheets needs to avoid stratification, and ultrasonic vibration assisted processing technology is used to reduce cutting force.
3. Application fields and market demand
1. Core application scenarios
Energy industry: Nuclear power, thermal power and petrochemical equipment have a large demand for tube sheets, especially high temperature and high pressure resistant alloy material processing
Environmental protection field: Tube sheets in seawater desalination equipment need to be corrosion resistant, and the environmental protection of drilling processes (such as reducing waste emissions) is required to be higher
High-end manufacturing: The demand for micro-hole and special-shaped hole processing in the aerospace and precision instrument fields has increased, promoting the application of laser and EDM technology
2. Market driving factors
Infrastructure construction: The global urbanization process has accelerated, and the demand for heat exchangers and pressure vessels in water conservancy, transportation and other fields has surged
Policy support: Chinas "14th Five-Year Plan" emphasizes high-end equipment manufacturing and green industry, promoting drilling technology upgrades and environmental protection equipment investment.