What Is a Hand Reamer?

A reamer is a rotary cutter with one or more teeth for cutting a thin layer of metal on the surface of a processed hole. A reamer has a rotary or helical blade with a straight edge or a spiral edge for reaming or repairing.

Reamer (volume name: mechanical engineering) has one or more teeth to cut the processed hole table

The reamer has one or more teeth, which are used to remove the thin metal layer of the machined surface of the hole. Reamed holes can be precisely sized and shaped.

Reamers for

The reamer structure is mostly composed of a working part and a handle. The working part mainly functions for cutting and calibration, and the diameter of the calibration part has an inverted taper. The shank is used to be clamped by a clamp, and is divided into a straight shank and a tapered shank.

There are many types of reamer according to different purposes, so there are more standards for reamer. Some of the more commonly used standards are GB / T1131 hand reamer, GB / T1132

The reamer diameter tolerance directly affects the dimensional accuracy of the machined hole, the reamer manufacturing cost and the service life. When reaming a hole, the diameter of the reamer is larger than the diameter of the reamer due to the radial runout of the cutter teeth and the amount of reaming and cutting fluid, which is called "reaming". However, because the blunt radius of the blade squeezes the hole wall, the hole Recovery and shrinkage are called reaming "shrinks." Generally, the factors of "expansion" and "contraction" coexist, and the final result should be determined by experiments. Experience has shown that reaming with high-speed steel reamer generally expands, reaming with hard alloy reamer generally shrinks, and shrinkage often occurs when reaming thin-walled holes.

The nominal diameter of the reamer is equal to the nominal diameter of the hole. The up and down deviation of the reamer must consider the amount of expansion and contraction, and leave necessary wear tolerances.

Number of teeth and groove of reamer

The number of teeth of the reamer influences the accuracy of the reamer, surface roughness, chip space and tooth strength. Its value is generally determined by the diameter of the reamer and the material of the workpiece. When the diameter of the reamer is large, more teeth can be taken. When processing tough materials, the teeth should be taken less. When processing brittle materials, the teeth can be taken more. To facilitate the measurement of the reamer diameter, the number of teeth should be even. In the range of commonly used diameter do = 8 ~ 40mm, generally take the number of teeth = 4 ~ 8.

The reamer teeth can be distributed along the circumference with equal or different pitches. For ease of manufacture, reamers are generally distributed at equal pitches.

Geometric angle of the reamer

Main declination

Tough materials such as steel are generally taken = 15 °; brittle materials such as cast iron are generally taken = 3 ° ~ 5 °; rough hinges and reamed blind holes are generally taken = 45 °; hand reamer is generally taken = 0.5 ° ~ 1.5 ° .

Front angle

When reaming, the margin is usually small, the chips are very thin, and the contact length between the chips and the rake face is short, so the influence of the rake angle is not significant. For manufacturing convenience, it is generally taken as 0 °. When processing tough materials, in order to reduce chip deformation, it is preferable to be 5 ° ~ 10 °.

Back angle

The reamer is a precision machining tool. In order to prevent the radial dimension from changing too much after re-grinding, the reamer angle is generally taken as 6 ° ~ 8 °.

Blade inclination

Generally, the reciprocating angle of the blade is 0 °. However, the inclination of the blade can make the cutting process stable and improve the quality of the reaming hole. When reaming tough materials, a cutting angle of 15 ° ~ 20 ° can be ground in the cutting part of the reamer, so that the chips can be discharged forward during reaming without scratching the processed surface. When processing blind holes, a larger recess can be made at the front end of this reamer with a bevel to accommodate chips. ^[2]

Increased aperture, large error

The reamer outer diameter design value is too large or the reamer cutting edge has burrs; the cutting speed is too high; the feed amount is incorrect or the machining allowance is too large; the reamer main deflection angle is too large; the reamer is bent; Chip tumor; the edge of the reamer has a bad swing when sharpening;

The standard name should be called floating boring cutter, and now there is also called floating reamer. Limited by tool size. This kind of boring tool cannot be made very small. Generally, it is a cutter head. After buying it, you must make a floating boring bar. The shank of the boring tool is set according to the loading device of your machine tool. It can be a straight or Morse taper boring. The tool holder should be quenched and quenched by wire cutting to process a through-groove mounting boring head. The dimensional tolerance of the groove is 0 ~ 0.02mm larger than that of the boring head. The boring size of the boring head needs to be adjusted according to the size of the processing hole. ^[2]