Thread tool is used for processing a variety of internal and external thread tools, widely used in the field of machining, large demand. Thread tool in the tool market occupies an important position, Germany, Japan and other developed countries, thread tool sales accounted for about 25% of total sales, second only to twist drill (about 30%).
In recent years, with the change of cutting conditions and the emphasis on high productivity, higher requirements have been put forward for the material, surface treatment and structural parameters of thread tools. Understanding the current situation and development trend of foreign thread cutting tools is of positive significance for Chinese thread cutting tool manufacturers to adjust product structure, improve product level and actively participate in market competition. MyCIMT This paper makes a preliminary discussion on the current situation and development trend of foreign thread tools in six aspects, such as tool material, surface coating, variety and specification, processing equipment, product quality and marketing technology, hoping to be beneficial to domestic counterparts.

1. Tool material

Most foreign industrial thread tools are made of high-speed steel, and thread tools made of alloy tool steel are usually limited to household use. For example, more than 82% of taps produced by German GUHRING Precision Tools Company are made of high-performance high-speed steel, about 6% are made of hard alloy, and about 8% are made of powder metallurgy high-speed steel. Hand taps, which account for only about 4% of the total output of taps, are also made of ordinary high-speed steel, and alloy tool steel is rarely used. More than 90% of the company's round teeth are made of ordinary high-speed steel, and the rest are made of high-performance high-speed steel. Japan's OSG company, Germany's EMUGE company and other famous thread tool manufacturers about 50% of the thread tool is made of high-speed steel, the remaining 50% are made of powder metallurgy cobalt high-speed steel, hard alloy, high-performance high-speed steel and other high-performance materials. In the thread processing of hard materials and hard materials, MyCIMT, powder metallurgy cobalt high speed steel tool material has been paid more and more attention, and its bending strength, hot hardness and other performance indicators can be increased by 2 to 3 times compared with ordinary cobalt high speed steel. However, due to the high processing cost of powder metallurgy high speed steel, it can not be widely used in the current thread tool selection.

2. Surface coating

After the surface coating of the high-speed steel thread tool, the cutting friction can be reduced, the tool wear can be reduced, and the cutting performance and service life of the tool can be greatly improved (generally, the service life of the tool can be increased by 2 to 3 times). At present, TiN coating and composite coating process has been widely used in foreign thread tool production, such as German GUHRINR, EMUGE and other companies of various coating products have accounted for about 40% of its thread tool production.

Hardness is one of the important parameters of cutting performance of high speed steel thread tool. In the process of thread processing, high cutting heat will be generated and transferred to the tool, which will reduce the hardness of the tool. According to relevant information, when the cutting zone temperature exceeds 550 ℃, the metallographic structure of the tool will change, resulting in a rapid decline in the hardness of the tool; for every 100 ℃ increase in temperature, the hardness drop can reach 300 ~ 400HV; if the tool hardness drops to 59 ~ 60HRC, the basic loss of cutting ability. The surface hardness of the thread tool can be significantly increased after coating: the hardness of the TiN coating can reach more than 2300HV; the hardness of the TiCN coating can reach more than 3000HV. Thread tool surface coating has its own characteristics, and has different scope of application: high-speed steel thread by TiCN coating tool hardness is higher, can achieve and uncoated carbide cutting tool equivalent cutting performance; in addition, in some cutting occasions, TiCN coating high speed steel tap and uncoated carbide cutting tool has the advantage of lower cost. When tapping brass plate or cast aluminum workpiece with TiCN coating tap, the tool life can be increased by more than 10 times; when tapping gray cast iron or hypereutectoid aluminum workpiece with TiAlN coating tap, the tool life can be increased by more than 4 times. Compared with TiN coating, TiAIN coating can make the tool have higher hardness and performance, so TiAIN coating tool is more suitable for high-speed cutting.

3. Varieties and specifications

In order to meet the needs of different materials, different types and different precision thread processing, foreign thread tool manufacturers continue to improve the tool structure and geometric parameters, and develop a large number of new products. Taking taps as an example, there are taps with blade inclination angle, spiral flute taps, extrusion taps without cutting chips, taps with hole in the center that can spray chips or have internal cooling function, content taps with chip holding function, taps with hexagonal neck, high-precision broaching taps, taps with guide post, and combined taps with drill hinge blades at the front end that can change the discharge direction of chips. There are many kinds and different functions. Among them, there are more than 20 varieties of taps with coolant input holes only, and the * small size is only φ3mm. When this type of tap is used, the cooling lubricant is sprayed directly to the cutting area through the cooling hole. By reducing the temperature of the cutting area, it can effectively prevent the formation of knife tumors, and at the same time facilitate the discharge of chips from the chip groove with the coolant; because the chips are Cooling can reduce the temperature impact on the workpiece and the surface quality of the machined surface. With this kind of tap processing difficult to cut materials, tap service life can be more than doubled. According to the statistics of EMUGE company's product samples in 1998, EMUGE company has nearly 100000 varieties and specifications of thread cutting tools, only M6 tap varieties (different materials, different types) and specifications (different pitch, external dimensions) have more than 200, M6 die varieties and specifications have more than 50. The quantity composition ratio of taps with different structures manufactured abroad is about 30% for straight grooves, 40% for spiral grooves, 20% for screw tips and 10% for extrusion.

Developed countries not only attach importance to the development of new products of thread cutting tools, but also vigorously research and develop new thread processing technologies, such as: ① using double roller method to roll conical, trapezoidal (including multi-head) threads and threads; ② using axial thread rolling head and automatic thread rolling machine to automatically roll M5 ~ M60 on hollow blank with wall thickness of 0.8~3mm; ③ * * rate, high precision, MC planetary tap, which can be processed simultaneously by the machining center three axes, the same pitch of the tap can be processed with different diameters of the thread, the chip is small, easy to exclude, the adjustment of the processing size can be automatically carried out by the NC program.

4. Processing equipment

With the rapid development and wide application of microelectronics technology and computer technology, the manufacturing technology and equipment level of foreign thread cutting tools have undergone tremendous changes and improvements in the past ten years. Such as tap manufacturing has been widely used in the overall grinding process, the use of high-speed grinding, high-pressure cooling, automatic operation and automatic loading and unloading and other advanced technology means to make the tap shape a molding, production efficiency greatly improved. The fast point grinding cylindrical grinder produced by JUNKER Company of Germany uses cubic boron nitride (CBN) grinding wheel, which can complete one-time grinding and forming of tap blade, neck and handle in only 6 seconds (if square head needs to be ground, it only needs to be completed in 0.5 seconds). The company also produces high-speed, **NC and CNC grinding machines that can grind grooves, blade inclination angle and thread, of which 520CNC grinding machine only takes 20 seconds to process the thread of an M10 tap. The RGB25CNC thread grinding machine produced by Swiss REISHAVER can not only directly program and process various taps on the machine tool, but also connect with the computer of the design center to process various taps according to the instructions of the design center, which greatly improves the flexible production capacity of "small batch, multi variety and short cycle". The supply cycle is generally only one week, and special tools * can be delivered within 2-3 days. Japan's OSG company has dozens of German JUNKER company made tap thread grinding machine; Germany's EMUGE company has Swiss REISHAVER company made 14 GBA machine tools and a number of RGB2510 machine tools. On the one hand, foreign thread tool manufacturers attach great importance to the introduction of high processing efficiency, high degree of automation and the lack of high-precision equipment in key processes (generally accounting for 3% to 5% of all equipment); On the other hand, it emphasizes that it is based on itself and relies on technological progress to develop process equipment with its own characteristics. Through the research and development of * * special equipment, computer technology is applied to special equipment, the automation degree of special equipment is improved, the requirements of simple operation, convenient adjustment and stable product quality are met, and the efficiency of imported equipment is brought into full play at the same time, so that the technological level and equipment level of many foreign thread tool manufacturers reach the world * * MyCIMT. For example, Japan's OSG's self-made special equipment accounts for about 60% of all equipment, which can well meet the special needs of developing new products.