Abstract: Based on the analysis of processing conditions and standard reamer structure for the parts and components of the power station equipment manufacturing industry, three edged carbides with straight edged reamers, oblique edged reamers, and spiral edged reamers were used. Reamer design work; dry reaming experiments using three blade reamers; based on a large amount of experimental data, three blade reamers were used in terms of reaming force, surface roughness, and chip shape. For comparison and evaluation, the best reamer for the use effect is a spiral edge reamer.

Fig. 3 Spiral edge reamer solid model

1 Introduction
Due to the rapid growth of China's economy, industrial electricity consumption continues to rise. As a result, the production tasks of the power plant equipment manufacturing industry have increased substantially, making some of the original mechanical processing methods unable to meet the production needs, among which the reaming process is particularly prominent. The reaming process used high-speed steel reamers in the past, which required long processing time, large tool consumption, and low production efficiency. The use of carbide reamers is an effective solution. Previously using a standard reamer, when the hole being machined was deep (L/D>4), chip removal was difficult during processing, clogged chips scratched the machined surface, the surface quality of the hole did not meet the requirements; and due to clogging The squeezing of the chips destroys the reamer blade, resulting in severe damage to the reamer. In order to solve this problem, based on the analysis of processing conditions and standard reamer structure, three kinds of blade-shaped hard alloy reamers were designed and developed.

This paper aims to solve practical production needs, and combines the increasingly widely used dry processing methods in the international advanced processing industry to perform reaming experiments on straight-edged reamers, oblique-edge reamers and spiral-edge reamers. The experimental data comprehensively evaluates the reaming force, surface roughness, and chip shape of three blade reamers, and obtains the comprehensive performance ranking of the straight edge reamer, oblique edge reamer, and spiral edge reamer and realizes The reamer is optimized to optimize the use of the reamer, which solves the actual production requirements.

2 Three Bladed Carbide Reamers Solid Modeling

To better visualize the design of the reamer geometry and its cutting performance, I-DEAS software was used for solid modeling work. In the modeling, first, according to the size of the Morse taper shank, the Morse taper cone is rotated, the tool holder is made by body cutting, and the cylinder is used as the neck of the cutter body, and the cylinder is rotated and stretched to cut the cylinder. The body forms the spiral groove of the reamer and connects the neck of the cutter body with the morse taper shank. Next, the length of the working part of the tool is made into a cylinder, and the blade groove is cut on the cylinder and the knife is provided with the knife. The tool working cylinder portion of the groove is connected with the front body neck and the Morse taper shank to form a body. According to the actual geometry of the blade, the solid model of the blade is designed, and the blade is moved to the position of the blade slot so that the reamer solid model is completed. As shown in FIG. 1, FIG. 2, and FIG. 3, the solid model of the blade-shaped reamer is shown. According to the solid model processing a kind of blade reamer.

Figure 5 Surface roughness comparison curve

3 Reaming force test results and analysis
Dry reaming was used in the experiment, and the reasonable amount of cutting to be taken was finally determined through trial cuts. Straight-edged reamer, inclined-blade reamer and helical-blade reamer type edge reamer were used. The test material was 40Cr steel. The cutting amount was the same amount of feed (f=0.1mm/r) and the amount of back-side knife. In this case, the cutting force value is obtained by changing the spindle speed. The collected data was collated and the reaming forces of the blade reamers were compared, as shown in Fig. 4 (symbol â—† represents the reaming force curve of the straight-edge reamer; symbol â–  represents the reaming force of the reclining reamer Curve; symbol â–² represents the reaming force curve of the spiral edge reamer). In contrast to the reamer, the straight-edged reamer has a greater force than a beveled edge reamer, and the oblique-angle reamer is greater in force than the helical edge reamer. Under the same cutting conditions, the force of the spiral edge reamer is minimal.

3 Surface roughness measurement and analysis

Surface roughness is an important indicator of the microscopic geometric shape error on the part surface. It is mainly due to the friction between the tool and the part surface in the machining process, the plastic deformation when the chip is separated, and the high frequency vibration existing in the process system. Caused by other reasons. The surface roughness of the machined hole is an important index for evaluating a reamer, so the surface roughness of the hole processed in the above experiment is measured. Figure 5 shows a comparison of surface roughness curves.

In the case of a fixed feed (f=0.1 mm/r), the rotational speed was varied and the surface of the machined hole of the spiral edge reamer was found to be the smallest in terms of surface reamer. Straight reamers are the largest.

Figure 6 Comparison of chip shape

4 Comparison of chip shape
Simultaneously with the measurement of the three-way reaming force, chips were collected. As the amount of cutting changes, the shape of the chips changes significantly. First, at a fixed feed (f=0.1mm/r),

The workpiece material is 40Cr steel,

Straight-edged reamer with cutting speed of 550r/min and feed rate of 53mm/min appears as blue turning screw chips, and the color turns blue because of the large amount of cutting heat generated during processing. There was a chemical reaction with oxygen in the air. Among them, the most influential factor was the change in cutting speed. The oblique-edge reamer is used to change the cutting amount to the spindle speed of 760r/min.

This phenomenon occurs only when the feed rate is 64mm/min. Spiral edge reamers in the cutting spindle speed of 760r/min, feed rate of 64mm/min, although the shape of the chip has changed, the color some blue but no serious damage to the above two tools. Fig. 6 shows the comparison of chip shape when the workpiece material is 40Cr steel and the fixed feed amount (f=0.1mm/r).

In the case of low spindle speeds,

The chip shape of the three blade reamers is presented as spiral wound chips. The reamer worked well and no overheating occurred during the machining process. When the spindle speed is selected at 760r/min and the coolant is not used, most of the chips of the straight-edge reamer show blue oxidation and form long continuous chips, which will seriously affect the machining accuracy and surface quality of the workpiece. . In the experiment of machining 40Cr steel with oblique-edge reamers, the chips mostly appeared as short spiral-roll chips, and the color changed obviously. Only the chip shape of the spiral edge reamer kept a short spiral wound chip, indicating that it worked well. Only when the spindle speed was 760 r/min and the feed amount reached 64 mm/min was a short and swarf chip appeared. This also proves that the helical edge reamer has better cutting performance than the oblique edge reamer and straight edge reamer.

5 Conclusion
Through the cutting force test, under the same cutting conditions, that is, the same spindle speed and feed rate, the reaming force of the spiral edge reamer is the smallest, and the reaming force of the straight edge reamer is the largest.

Through the comparative analysis of the surface roughness of the three kinds of edged reamer processing workpieces, the surface roughness value of the spiral edge reamer machining hole is the smallest, the oblique edge reamer is the second, and the straight edge reamer is the largest.

By observing the chip shape of a comparative blade reaming machined workpiece, the chip shape and color of the spiral edge reamer are the best, indicating that the spiral cutting reamer has a good cutting state and the best cutting performance.

In summary, it can be concluded that the spiral cutting reamer has the best overall cutting performance. This reaming experiment provides a basis for practical application of production, and also provides a theoretical basis for further research on dry reaming in the future.

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