Finishing of the finished surface with a whetstone (also known as a honing stick) embedded in the honing head.
Also known as honing.
It mainly processes various cylindrical holes with a diameter of 5-500 mm or more, and the ratio of the hole depth to the hole diameter can be 10 or more.
Under certain conditions, planes, outer surfaces, spherical surfaces, tooth surfaces, etc. can also be processed.
The outer circumference of the honing head is set with 2-10 oil stones with a length of about 1/3-3/4, which rotates and moves back and forth during the boring. At the same time, it is evenly raised by the spring or hydraulic control in the honing head.
Therefore, the contact area with the surface of the hole is large, and the processing efficiency is high. The dimensional accuracy of the hole after honing is IT7~4, and the surface roughness can reach Ra0.32~0.04 microns.
The amount of honing allowance depends on the hole diameter and the workpiece material. Generally, the cast iron piece is 0.02 to 0.15 mm, and the steel piece is 0.01 to 0.05 mm.
The speed of the honing head is generally 100-200 rpm, and the speed of the reciprocating motion is generally 15-20 m/min.
In order to wash away the chips and abrasive grains, improve the surface roughness and lower the temperature of the cutting zone, it is often necessary to use a large amount of cutting fluid, such as kerosene or a small amount of spindle oil, and sometimes an extreme pressure emulsion.
① During honing, the workpiece is mounted on a boring machine table or in a fixture. A honing head with a number of oil stone strips is inserted into the machined hole and rotated by the machine tool spindle for axial reciprocation.
The oil stone strip is in contact with the wall of the hole at a certain pressure to cut off a very thin layer of metal.
The honing head is generally in floating connection with the main shaft.
② The honing head has several types of mechanical pressure, air pressure or hydraulic pressure regulator.
The honing head shown in the figure is mechanically pressurized, and the hydraulic pressure regulating type is often used in actual production.
① Honing processing is an efficient processing method to achieve high precision, high surface quality and long life.
It can effectively improve the dimensional accuracy, shape accuracy and reduce the Ra value, but it can not improve the positional accuracy of the hole and other surfaces.
② Machinable cast iron parts, hardened and non-hardened steel parts and bronze parts, etc., but it is not suitable to process non-ferrous metal parts with high toughness.
③ Honing is mainly used for hole machining.
In the hole honing process, the center of the original machined hole is guided.
The processing aperture range is from φ5 to φ500, and the aspect ratio is up to 10.
④ Honing is widely used in large batch production of cylinder bores, cylinders, valve bores and various barrels.
Can also be used in single-piece small batch production.
⑤ Coaxiality cannot be determined when honing.
⑥ Compared with grinding, honing has the characteristics of reducing labor, with high productivity and easy automation.