Introduction
Finishing the surface with a whetstone, also known as a honing stick, that is embedded in the honing head.
Also known as honing.
This machine is primarily used for processing cylindrical holes with a diameter of 5-500mm or more, and the ratio of hole depth to hole diameter can be 10 or greater. However, under certain conditions, it can also process planes, outer surfaces, spherical surfaces, tooth surfaces, etc.
The honing head’s outer circumference is equipped with 2-10 oil stones with a length of about 1/3-3/4, which rotate and move back and forth during the boring process. The honing head is evenly raised by a spring or hydraulic control. This results in a large contact area with the surface of the hole, ensuring high processing efficiency. After honing, the dimensional accuracy of the hole is IT70.04 microns.
The honing allowance amount depends on the hole diameter and the workpiece material. Typically, the honing allowance for cast iron pieces is 0.02 to 0.15 mm, and for steel pieces, it is 0.01 to 0.05 mm.
The honing head speed is typically 100-200 rpm, and the speed of the reciprocating motion is generally 15-20 m/min. To improve the surface roughness and lower the temperature of the cutting zone while washing away the chips and abrasive grains, a large amount of cutting fluid, such as kerosene or a small amount of spindle oil, is often necessary. Sometimes an extreme pressure emulsion may be used.
Method
① During honing, the workpiece is typically secured on a boring machine table or within a fixture. An honing head, equipped with several oil stone strips, is then inserted into the machined hole and rotated by the machine tool spindle for axial reciprocation. The oil stone strip applies pressure against the hole wall, removing a very thin layer of metal.
The honing head is typically connected to the main shaft in a floating manner.
② There are various types of honing head pressure systems available, including mechanical, air pressure, or hydraulic pressure regulators. The honing head illustrated in the figure is mechanically pressurized, though the hydraulic pressure regulating type is more commonly used in production settings.
Process characteristics
- Honing is an efficient processing method that enables achieving high precision, high surface quality, and long life. It can effectively improve dimensional accuracy, shape accuracy, and reduce the Ra value, but it cannot improve the positional accuracy of the hole and other surfaces.
- It is suitable for machining cast iron parts, both hardened and non-hardened steel parts, bronze parts, etc. However, it is not recommended to use for processing non-ferrous metal parts with high toughness.
- Honing is mainly used for hole machining, where the center of the original machined hole is guided. The processing aperture range is from φ5 to φ500, and the aspect ratio can reach up to 10.
- Honing is widely used in large batch production of cylinder bores, cylinders, valve bores, and various barrels. It can also be used in single-piece or small-batch production.
- Coaxiality cannot be determined when honing.
- Honing has the characteristics of reducing labor, high productivity, and easy automation, compared to grinding.
