Abstract : Deep hole drilling machine retrofitting technology is a very important technology for retrofitting C6163 lathes. This paper mainly focuses on the application of this technology in C6163 lathes and puts forward some insights from the perspective of cutting parameters.
Keywords : C6163 lathe; deep hole drilling machine retrofitting technology; cutting parameters
Hole machining accounts for 30% of total machining volume, highlighting its importance. Deep hole machining, in particular, is beyond the capabilities of ordinary lathes; further depths would hinder processing. Therefore, compared to shallow hole machining, deep hole machining has been modified, making it a crucial technology in this process. However, current professional deep hole machining equipment costs tens of thousands of yuan. This equipment is highly specialized and offers limited processing capabilities, representing a waste of resources for businesses. Consequently, the technology of modifying lathes into deep hole drilling machines is increasingly being adopted. The following analysis focuses on the deep hole drilling modification technology based on the C6163 lathe.
1. Brief Description of Machine Tool Modification
1.1 Prerequisites for Machine Tool Retrofitting
1.1.1 Definition of Machine Tool Modification
Machine tool retrofitting refers to the modification of certain parts of ordinary machine tools, equipping them with suitable devices and control systems, thereby endowing the original machine tool with deep hole machining capabilities. This technology itself exhibits very unique characteristics. After machine tool retrofitting, the equipment becomes more specialized, and disassembly and assembly are very convenient, possessing strong practicality and suitable for mass production of various types of deep hole products. Furthermore, this retrofitting technology has relatively low costs, achieving good economic benefits and further enhancing the utilization value of the machine tool. The retrofitting cycle is relatively short, meeting production requirements without damaging the original lathe's functionality.
1.1.2 Necessity of Machine Tool Retrofitting
Currently, with the rapid development of science and technology, industrial machinery products have been improved in terms of shape, structure, and materials, and product precision is also gradually increasing. This places strict requirements on machine tool equipment, requiring flexibility and versatility to adapt to changing needs of various production objects. At present, deep hole drilling machines are relatively expensive in the market, and the initial investment in production is substantial. This leads to a lack of availability for some small and medium-sized enterprises, resulting in a situation where they have the will but not the means. However, many enterprises now have a large number of ordinary machine tools, which have significant limitations in deep hole machining, unable to process deep holes with large lengths and diameters. This impacts the product cycle of enterprises and consequently affects their development. Therefore, machine tool modification is essential and a crucial link in promoting the development and survival of industrial enterprises.
1.1.3 The Value of Machine Tool Retrofitting
(1) Reduce capital investment. Upgrading machine tools in enterprises can reduce capital costs by 60% compared to purchasing new machine tools. Usually, the upgrading of large machine tools only costs about 30% of the cost of purchasing new machine tools, and the existing foundation can be utilized.
(2) The stability and reliability of performance are improved. Since the basic components of the original machine tool have been used for a long time, it is very likely that stress deformation will not occur and affect the accuracy.
(3) Lathe modification can produce more diversified process products. After the machine tool is modified, the original machine tool can meet the relevant needs of deep hole production, making the enterprise's product processing more diversified. On this basis, the enterprise can also achieve sustainable development and further shorten the product production cycle by saving outsourcing costs.
(4) It provides more possibilities for the income channels of enterprise employees. The diversification of products in enterprises also gradually increases the job opportunities for employees, which in turn increases their economic income.
1.2 Contents of Machine Tool Retrofit
The main aspects of the modification work of machine tools and deep hole drilling machines on production lines in enterprises are as follows.
1.2.1 Ensure existing functions remain unchanged.
After modification, machine tools can be equipped with the function of deep hole machining, but the original basic functions of the lathe will not be damaged and can still be used.
1.2.2 Adding support equipment to ordinary machine tools
After modifying the original machine tool, support equipment such as pads and V-blocks will be added to improve the machine tool's working performance and utilization rate.
2. Deep Hole Drilling Technology for C6163 Lathe
2.1 Deep Hole Machining
In deep hole machining, the cutting condition of the tool cannot be directly observed during actual operation. Therefore, the only way to understand the chip removal and tool wear is by listening to the sound, observing the chips and machine tool load, and checking the cutting fluid pressure. Basic problems in deep hole machining, such as difficulties in heat dissipation and chip removal, poor rigidity during machining, long drill rods, and susceptibility to vibration, all pose challenges to lathe modification. Personnel need to adopt appropriate solutions based on the specific problems to complete the deep hole machining and lathe modification.
2.2 Machine Tool Modification Process and Methods
Based on the specific characteristics of deep hole machining, when modifying a lathe, the relevant personnel must adhere to the fundamental principle of maintaining a consistent center distance between the workpiece and the lathe. First, the tool post and tailstock of the lathe must be disassembled, and shims must be placed at the tail of the lathe to ensure that the actual height of the shims and the tool post base are always at the same horizontal level. Then, the shim plate is fixed on top, and the height and V-shaped opening size of the V-block are determined according to the actual workpiece diameter and the lathe center distance, ensuring that the workpiece is at the same height as the center of the lathe chuck after the V-block is placed. Finally, the three jaws above the lathe chuck are removed, and a specialized deep hole is selected for fixing. An appropriate pressure pump is chosen to ensure that the cutting fluid can smoothly enter the deep hole and to guarantee the orderly removal of metal chips.
2.3 Deep Hole Machining Related Processes and Technologies
Before actually drilling, a shallow hole with the same diameter as the drill bit should be pre-drilled at the location. This hole will serve as a guide and centering point during the subsequent drilling process. Straightness is particularly important when machining small holes with relatively high profiles. Furthermore, during machine tool installation and debugging, it is necessary to ensure the proper alignment between the workpiece hole's center axis and the drill rod's center axis.
Based on the specific material of the workpiece, select the corresponding cutting parameters to control the degree of chip curling, thereby obtaining C-shaped chips that ensure chip removal. When machining workpieces made of high-strength materials, the cutting speed V needs to be reduced. Feed rate control has a significant impact on chip production; therefore, the smallest possible feed rate should be selected while ensuring chip breaking.
To ensure effective chip removal and cooling, the cutting fluid must be selected and maintained at the appropriate pressure and flow rate. For machining small-diameter deep holes, a high-pressure, low-flow-rate cutting fluid should be chosen; for machining large-diameter deep holes, a low-pressure, high-flow-rate cutting fluid should be selected and used.
Once drilling begins, the personnel should turn on the cutting fluid pump, then start the lathe and begin cutting. When drilling is complete or a malfunction occurs, the cutting process should be stopped immediately, the machine should be stopped, and finally the cutting fluid pump should be turned off.
When machining relatively long holes, but with small diameters, external chip removal is usually used. In actual use, care should be taken not to form the hole in one go. Therefore, the drill gun should be selected according to the basic principle of starting from short to long, and gradually deepening the hole to reduce the wear rate of the drill bit.
2.4 Actual performance of the machine tool after modification
After modification, the machine tool needs to be put into use to test the modification effect. If problems are still found after testing, it needs to be modified again, and corresponding measures should be taken according to the actual problems. Taking deep hole machining as an example, a company modified a C6163 lathe into a deep hole drilling machine. The material of the modified part is 27SiMn, and the workpiece is φ140mm in diameter. Deep hole drilling with a diameter of φ20±0.2mm and a depth of 1050mm is performed on it. In the actual operation, a BTA deep hole drill (f20) produced by a deep hole machining company was selected, the cutting tool is YT798, and the drill rod is made of 45 steel, which is heat treated to achieve a Brinell hardness of HB240~280. In terms of cutting parameters, V=60m/min, S=0.21mm/r are mainly set; 5% emulsion is selected as the cutting fluid, the cutting fluid pressure is 2.5MPa, and the hydraulic pump flow rate is 80L/min.
Before actual machining, shallow holes of φ20mm are pre-drilled at the workpiece's hole locations. For drilling deeper holes, 300, 700, and 1100 drill bits are used. During the actual drilling process, a 300 drill bit is used first, followed by successive applications of 700 and 1100 drill bits until the required drilling size is achieved. The company processed 650 workpieces using this process without encountering any issues such as eccentricity. Therefore, this demonstrates that the modification work was highly feasible.
3. Conclusion
In conclusion, modifying the C6163 lathe into a deep-hole drilling machine can further meet the demands of modern lathe production. Once the deep-hole drilling is completed, it will enable deep-hole machining on a horizontal lathe platform. Therefore, modifying the C6163 lathe into a deep-hole drilling machine not only effectively improves the original lathe's performance but also provides strong support for the processing of the company's products, enabling it to better meet modern technological requirements and ultimately promoting the company's long-term development.
