As a core connecting element in mechanical engineering, the design, machining, and standardized application of internal threads are crucial for industrial manufacturing. This article will conduct an analysis from aspects such as the definition, machining methods, application scenarios, and standard dimensions of internal threads to help readers systematically master relevant knowledge.

Internal Grinding Machine

I. Definition and Core Functions of Internal Threads

An internal thread refers to a helical structure formed on the inner surface of a cylindrical or conical hole. It is usually used in conjunction with external thread fasteners such as bolts and screws to achieve the functions of fixing, connecting, and supporting. Its design needs to meet the requirements of high precision and high strength to ensure the stability and reliability of mechanical components.

II. Five Major Machining Methods for Internal Threads

1. Tapping

Tapping is the most commonly used method for machining internal threads, which forms threads by cutting inside a pre - drilled hole with a tap.

- Operation Essentials:

  - Calculate the bottom hole diameter according to the material (such as steel, cast iron). For ductile materials, the bottom hole diameter ≈ nominal diameter - pitch; for brittle materials, the hole diameter needs to be appropriately reduced.

  - Keep the tap vertical during tapping and reverse it periodically to break chips to avoid tool jamming. For blind hole machining, additional depth (usually 0.7 times the nominal diameter) needs to be reserved.

  - Lubricant selection: Use machine oil for steel parts and kerosene for cast iron.

※ Feed and dressing movements are controlled by means of two independent driving systems.Size-metric grinding is adopted.Feed movement can be caried out both manually and hydraulically.
※ Because the machine is quipped with jumping mechanism,it is unnecessary to reset the tool after returning grinding wheelfor measurement or dressing.
※ The machine is equipped with a hydraulic switch valve to ensure safety during loading and unloading workpieces
※ A grinding spindle with 18,000 r/min.is optional for grinding bore diameter ranging from 20 to 50mm.
※ An endface grinding device is provided on the top of the workhead.There is a hydraulic interlock system between the swivel of the endface grinding device and the longitudinal movement of the worktable.