1 Introduction

In the 1970s, China began to apply and manufacture indexable milling cutters. After more than 30 years of hard work, we have developed various types of indexable tools suitable for China's manufacturing industry while absorbing foreign advanced technology. From the installation structure of the blade: mainly the vertical structure and the flat structure, wherein the vertical structure can be indexed milling. Because the blade is tangentially mounted, the direction of the cutting force is large, and the compressive strength is high, so the cutting can be carried out. At the same time, because the blade is clamped by the cutting force, the clamping force increases with the increase of the cutting force, the clamping component is omitted, the chip flute can be increased during design, and the structure is simple and compact. Therefore, it is widely used.

2 Several vertical indexable milling cutters and their applications

1. Ceramic indexable fine-tuning plane fine milling cutter
   1. Structural features
      The ceramic indexable fine-tuning plane finishing cutter is a new type of vertical indexable milling cutter for the special structure of surface finishing. This type of milling cutter is widely used in the finishing of the faceted clamping plate, the machine table and the joint surface of the steam turbine.
      

      figure 1

      As shown in Figure 1, the ceramic fine-tuning plane finisher has a fine-tuning screw that forces the blade to advance or retreat as the fine-tuning screw is screwed in and out. Due to the effect of the 6° back angle, the height position of the blade has a slight change. The end face of the whole milling cutter can be adjusted slightly, so that the end face runout can be reduced by 0.005~0.008mm, and the end face jump after assembly of the milling cutter can reach 0.01mm. Within; the surface accuracy of the processing can reach Ra0.8 or even higher. The milling cutter adopts a ceramic blade. Because of its high hardness, high wear resistance, high heat resistance, excellent chemical stability and low friction coefficient, the ceramic insert material can process high hardness materials and greatly improve the size. Surface accuracy of the processed material. At the same time, the cutting speed of ceramic inserts is 3 to 10 times higher than that of cemented carbide inserts, so it can meet the requirements of high-speed cutting and significantly improve milling efficiency and blade life. In order to adapt to the use of users in China, a 3° guide angle has been added to the conventional blade.
   2. Trial cut example
      The milling test was carried out at the Heavy Machinery Processing Plant of the First Machine Tool Plant in Qiqihar. The test conditions are as follows: Tool: f 200mm ceramic indexable fine-tuning plane fine milling cutter, 6 teeth, milling cutter end beating 0.01mm or less; trial cutting machine: portal milling machine, machine power 15KW; workpiece: 2.5 m vertical column The material is cast iron HT250, the processing length is 9m, and the width is 150mm.
      During the trial cutting, 4 different sets of machine tool spindle speed and feed speed are used for cutting. The cutting process is stable. The amount of knife per tooth can reach 2mm, the feed speed can reach 3000mm/min, and the spindle speed of the machine tool reaches 250~300r/min. The surface roughness of the workpiece reaches Ra0.8 or above, and the machining accuracy fully meets the user's requirements.

   figure 2

2. Carbide indexable screw rotor milling cutter
   1. Structural features
      Carbide indexable screw rotor milling cutters are special milling cutters for roughing screw compressor rotors. As shown in Fig. 2, the milling cutter is composed of two milling cutters, which are used for rough machining of the female rotor and the male rotor. This kind of milling cutter has high technology content and is difficult to design. There are many types of blades selected by the cutter. When designing the line, it is necessary to ensure that the blades are fully overlapped, and the profile meets the tolerance requirements; in the solid modeling, the blades should be distributed reasonably. It is necessary to ensure that the blade space position does not interfere, and also to ensure smooth cutting of the tool. According to the above design principle, according to the rotor profile coordinates provided by the user, the blade of special shape is selected reasonably: the top part of the female screw screw cutter adopts a convex arc blade, and the top part of the male screw rotor cutter adopts a book, Ultra-long special blade; the bottom part of the female and male milling cutters are concave arc-edged blades; the other parts are straight-edged blades. At the same time, some blades have been angle corrected. When the milling cutter is manufactured, the NC program is programmed by CAM software, and processed on the machining center of five-coordinate linkage, so that the precision of the milling cutter meets the requirements, so as to ensure that the screw rotor profile processed by the milling cutter is uniform and consistent, thereby ensuring the rotor finishing. Accuracy, while also significantly reducing finishing costs. The index of the indexable screw rotor milling cutter currently developed is f 200mm ~ f 360mm, and the thinnest part of the male tooth tip is less than 4mm.
   2. Trial cut example
      The milling test was carried out at Ningbo Xinda Screw Compressor Co., Ltd. Trial conditions:
      Tool: f 230mm female screw rotor milling cutter, effective number of teeth is 4 sets; test cutting machine: domestic semi-automatic screw special machine; workpiece: female screw rotor, material is 45 steel.
      During the trial cutting, the machining is performed twice according to the depth of the workpiece. The machine speed is 130r/min and the feed speed is 35~40mm/min. The cutting of the tool is light, stable and wears less. The processed female screw rotor profile is uniform and the surface roughness is good.
3. Carbide indexable machine bed combined milling cutter
   Carbide indexable machine bed combined cutter is an efficient milling cutter for machining machine bed rails on special machine tools.

   image 3

   1. Structural features
      The combined milling cutter is designed according to the user-provided machine bed mountain rail profile. As shown in Figure 3, the entire profile is reasonably divided, and each segment is designed as a separate milling cutter. The combined milling cutter has a total of 14 pieces, and the bed rail guide is processed by two 45° indexable angle milling cutters (No. 1, No. 2, No. 6 and No. 7 in the figure); the plane part of the bed is made up of multiple three-sided blades. It can be processed by index milling cutter. All the blades of the 14 knives are connected by lap joints, which are precisely lapped into the guide rails of the machine bed. As a combined milling cutter, the thickness of each cutter is required to be very precise, and the thickness tolerance is controlled to ±0.01mm. The width of each cutter is accurately calculated, and the amount of the blade is strictly controlled. At the same time, the outer diameter of the cutter is strictly controlled. To ensure the overall accuracy of the milling cutter after assembly. In order to make the cutting smooth, the teeth and adjacent milling cutters overlap and do not interfere with each other. It is necessary to calculate the blade arrangement of each knife and accurately calculate the relative position between the milling cutters. By properly selecting the blade type and grade to ensure the versatility of the blade and the cutting performance of the combined milling cutter, the combined milling cutter has become an ideal domestic tool for machining the guide rail of the machine bed.
   2. Trial cut example
      The milling test was carried out in the workshop of No. 10 of Shenyang CNC Machine Tool Co., Ltd. Trial conditions:
      Tool: Carbide indexable machine bed combined milling cutter, the minimum diameter is f 242mm, the effective number of teeth per milling cutter is generally 8 sets; test cutting machine: modified gantry milling machine, machine power is only 11Kw; processed Pieces: lathe bed, made of cast iron HT200, large castings (about 15mm), uneven and sand.
      Since the equipment used for trial cutting is a modified old machine tool, its power and rigidity are not very good. Therefore, the amount of cutting taken during the test is increased from small to large, so that the power of the machine tool can be fully utilized. During the trial cutting process, the milling cutter cuts smoothly, the amount of knife per tooth reaches 0.3mm, and the feed speed reaches 80mm/min. In the milling process, the tool is repeatedly fed and retracted, and the tool is not damaged, which shows the excellent impact resistance of the tool. After adjusting the machining position of the tool, the profiled line meets the requirements, the surface roughness greatly exceeds the requirements, reaching Ra3.2 (the technical agreement requires Ra12.5), and the wear of the blade is also light. Through a trial of a class, the number of processed products reached 18 (9 in the past), and the productivity doubled. After the operator became familiar with the performance of the tool, the output of the class reached 25, and the user was very satisfied.

3 Conclusion

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