reaming
Reamers are used to remove thin layers of metal from machined hole walls for precise hole diameter and geometry and low surface roughness machining. Reaming is generally carried out after drilling, reaming or boring. It is used to process precise cylindrical and tapered holes, and the processing aperture range is generally 3 to 100 mm. Due to the long cutting edge of the reamer, each cutter tooth participates in the cutting at the same time during reaming, and the production efficiency is high, and it is widely used in the finishing of holes.
The working method of reaming is generally that the workpiece does not move, and the reamer rotates and feeds axially into the hole. When reaming on a lathe, the workpiece rotates and the reamer feeds axially. During the reaming process, the cutting part at the front end of the reamer is cut, and the calibration part at the back plays the role of guiding, anti-vibration, trimming and calibration. The dimensional and geometric accuracy of the reamed hole is directly determined by the reamer. Reaming can be divided into rough reaming and fine reaming. Generally, it is carried out on a lathe, boring machine or drilling machine, which is called machine reaming, and can also be reamed by hand. The cutting depth (one-side machining allowance) of rough reaming is 0.3~0.8mm, the machining accuracy can reach IT10~9, and the surface roughness is Ra10~1.25µm. The cutting depth of fine reaming is 0.06～0.3mm, the machining accuracy can reach IT8～6, and the surface roughness is Ra1.25～0.08µm. The cutting speed of reaming is low. For example, when reaming steel parts with a cylindrical multi-blade reamer of cemented carbide, when the aperture is 40-100mm, the cutting speed is 6-12m/min, and the feed rate is 0.3-2mm /r. Correct selection of cutting fluids such as kerosene, mechanical oil or emulsion can improve reaming quality and tool life, and help reduce vibration.
Reamer
A rotary tool with one or more teeth for removing a thin layer of metal from the surface of a machined hole. The reamed holes are precisely sized and shaped. The reamer is divided into two types according to the method of use; it is divided into three types: cylindrical, conical and stepped according to the shape of the reaming hole; according to the clamping method, it can be divided into two types: the handle type and the set type; Both straight and helical grooves. The picture shows several commonly used reamers.
Cylindrical hole reamer consists of working part, neck and shank. The working part is divided into cutting part, calibration part and reverse taper part; hand reamer can be without reverse taper part. The size of the main declination angle Kr mainly affects the surface roughness, accuracy and axial force of the reaming hole. Usually, Kr=15° for machine reamers, and Kr=31'～1° for hand reamers. The calibration part has a cylindrical shape and functions as the wall of the trimming hole and the aperture for calibrating the aperture. The diameter of the inverted cone part gradually decreases (0.03-0.07mm) toward the shank part to reduce the friction between the working part and the hole wall during reaming. The tooth groove of the reamer is usually a straight groove. When machining holes with discontinuous hole walls in the length direction or holes with longitudinal grooves, the spiral groove reamer works stably and has good chip removal. The working part of the reamer can be made of high-speed steel or cemented carbide. The hand reamer can also be made into a diameter-adjustable type, with two structures: the adjustable reamer relies on adjusting the nuts at both ends to move the wedge-shaped blade along the inclined bottom groove on the cutter body to change the diameter of the reamer; The expansion reamer expands the diameter of the reamer with longitudinal grooves through the movement of the steel ball. Diameter-adjustable reamers are suitable for mechanical repair work.