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Process Damping Effect in Milling Process of Titanium Alloy

February 1, 2019 by jincheng  

Key words: milling; flutter; titanium alloy; process damping; plowing effect  

 

Titanium alloy has been widely used in the aerospace manufacturing industry. It has excellent comprehensive properties such as high specific strength, low density, high heat resistance and low temperature resistance. It can be used to manufacture aircraft parts, which not only can extend the life of the aircraft, but also reduce the weight. , reducing fuel consumption, thereby greatly improving its flight performance.
  However, titanium alloy is also a typical difficult-to-machine material, which has poor thermal conductivity, high chemical activity, severe work hardening, short tool life, and due to large unit cutting force and high chattering during processing, flutter is left to the workpiece. The underlying slanting vibration pattern often needs manual honing to remove, affecting the processing efficiency, seriously causing the workpiece to be scrapped, or even destroying the tool. The flutter problem of titanium alloy processing is a major bottleneck restricting the quality and efficiency of aviation manufacturing. 
  The method of controlling flutter can generally be attributed to increasing system damping. The damping of the cutting system can be divided into machine structure damping and damping generated by the tool flank and the workpiece surface interfering with each other, also known as process damping. The modeling and calibration of process damping is a research hotspot in international academic circles in recent years. The famous Canadian scholar Altintas has listed it as an unsolved research difficulty in cutting flutter.
  Tlusty and Sission first discovered process damping in machining, and as the cutting speed decreases, the stability limit of turning can be significantly improved. Sission also concluded that cutting speed, tool relief angle and cutting edge radius are key factors affecting process damping [4]. Later, many scholars studied the process damping, pointing out that the force formed by the interference between the flank face and the surface vibration of the workpiece is the source of process damping. The process damping coefficient in dynamic cutting forces is identified by a series of orthogonal tests controlled by a fast servo system that causes the tool to oscillate at the desired frequency and amplitude, but the test system is complex and requires a lot of work. Budak and Tunc and others overcome the weaknesses of experimental modeling and have done more detailed work on process damping modeling and coefficient calibration. The stability limit prediction analytic method of orthogonal turning and the flutter experiment are combined, and the process depth damping coefficient is directly calibrated by using the limit depth of cut obtained by the two. Based on this, combined with energy analysis, the intrusion coefficient is obtained, then the intrusion area and cutting force are calculated, and the stability analysis model of turning is established. The literature [12] systematically analyzes the influence of cutting parameters and tool geometry parameters on process damping. Ahmadi and Ismail et al. based on the small amplitude assumption, the process damping is equivalent to linear viscous damping, and the semi-discrete method is used to calculate the milling stability limit.
  At present, the international research on process damping mainly focuses on turning. For the process damping of milling, there is still no perfect dynamic analysis model. There are many degrees of freedom, the force analysis requires coordinate transformation, and the time-varying coefficient exists in the cutting force equation. The description of the intrusion area and process resistance is much more difficult than turning. However, there are no scholars in China who have conducted in-depth research on process damping. In the current literature, the cutting stability analysis adopts a more traditional linear model. Without considering the process damping, the model will produce large errors in the low-speed region. For titanium alloy processing, in order to ensure tool life, the cutting speed is generally low. If a conventional linear model is also used, the predicted limit cutting depth is far below the actual limit depth, which will inevitably affect the machining efficiency.
  In view of this problem, this paper establishes a milling dynamics model considering process damping, and uses the implicit fourth-order Runge-Kutta method to calculate the intrusion area and interference resistance of the tool flank and workpiece vibration corrugation during machining of typical titanium alloy materials. Draw a stability limit graph. Finally, the experimental results show that the nonlinear model built in this paper can accurately predict the stability limit of the low-speed zone and provide a reference for the selection of processing parameters of titanium alloy.
  4 Conclusion
  The flutter problem in the milling of titanium alloy materials is a major bottleneck restricting the efficiency of aerospace manufacturing. To ensure tool life, titanium alloy materials are cut at a relatively low speed. At this time, if the stability limit is very low according to the conventional linear model, selecting the depth of cut according to the line model will be very disadvantageous for the processing efficiency. In this paper, a nonlinear milling dynamics model considering process damping is established to calculate the intrusion area formed by the plowing effect and the process resistance. The critical depth of cut is calculated by the time domain simulation method. The experimental results show that the nonlinear calculation model proposed in this paper can accurately predict the stability limit of low-speed region during titanium alloy processing. This provides a necessary reference for the selection of parameters at normal operating speeds for titanium alloys.

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Sichuan QianJiu machinery manufacturing co., LTD

January 30, 2019 by jincheng  

Sichuan QianJiu machinery manufacturing co., LTD(Q9MM) is a professional precision machinery parts and components manufacturing enterprises, mainly for the energy, aerospace, military industry and other industries to provide complete and maintenance with all kinds of spare parts. Production base is located in guanghan economic development zone of chengdu road 2 paragraph 10, covers an area of 50 mu, the standard factory building 22000 square meters. With more than 150 employees, including technical management personnel more than 20 people.

Through unremitting efforts, our factory’s comprehensive management level, technology level, equipment level and got great development, has formed annual output of 200000 pieces of the manufacturing capability of all kinds of spare parts. We have imported from Germany SPKA5000 type high energy screw press, 1250 kw intermediate frequency induction furnace, 1000 t hydraulic press,16T forging hammer forging equipment. We offer our customers both at home and abroad from raw materials procurement to finished product service. IN numerical control section,we has precision horizontal machining center, numerical control section in 4-axis linkage machining center, 5-axis linkage machining center, large CNC gantry machining center and so on a large number of international first-class manufacturing equipment. Testing center has three coordinates measuring instrument, projectors, thickness gauge and magnetic powder flaw detector testing equipment. Over the years is always to provide the service Dongfang Turbine Co., Ltd (DTC for short), Haerbing Turbine Co., Ltd., Xi ‘an Shaangu Power Co., Ltd. (SPC for short), Powchina, space technology research institute of sichuan heavy equipment suppliers to provide services, and many times obtains the title of excellent suppliers.

We will take “enterprise technology, quality, customer satisfaction, sustainable development” principle, based on the fine, then the stronger, the product quality as the survival of the enterprise, put the interests of customers first, to strive to provide more precise and more efficient products and delivery for the user.

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We specialize in the production of precision machine parts, mechanical parts,precision machining, OEM machinery parts,cnc machining,cnc milling,cnc turning parts.If you have any mechine parts needs, please contact us:contact

If you want to see more CNC precision products, please click here: Product

If you want to see more news:News

Check out the latest company news on Twitter:twitter

How to ensure the accuracy of parts in milling

January 25, 2019 by jincheng  

Key words: knife compensation; cutting fluid; processing technology; machine tool

With the rapid development of China's machinery industry, the size requirements on the parts are getting higher and higher! There are many factors in the processing that interfere with the accuracy of the parts in the machining, such as the wear of the tool, the heat of cutting during machining, the positioning accuracy of the CNC machine, the processing arrangement of the machining, and so on.

1 Reasonable use of tool compensation to ensure machining accuracy

Knife compensation: It is the tool compensation. The path of the tool-controlled tool travel and the shape cut by the actual tool cutting edge do not coincide. For this reason, the tool coordinate of the tool to the position is calculated and compensated according to the actual machining shape size.

1. Tool compensation is divided into length compensation and radius compensation

(1) Length compensation: compensate for changes in the length direction of the tool

(2) Radius compensation: compensates for the influence of tool radius on the machining of contour size

2. Tool compensation method

(1) Manual compensation: artificially add the tool radius when editing the program

(2) Automatic compensation: it has tool compensation function in CNC machine tools.

3. The role of knife repair

During the machining process, the tool is gradually worn when the tool is cutting on the workpiece, so that the tool is not sharp when the part is machined, and the phenomenon of “make the knife” appears, so that the cutting line of the tool deviates from the original specified cutting path, so that the precision of the part does not meet the specified requirements. . At this time, we have to artificially calculate the size of the tool from the cutting position during the cutting process. Use the same program to use the same tool. By using this value to set the radius value of the tool compensation of different sizes, the cutting allowance can be gradually reduced. The method causes the actual cutting path to coincide with the specified cutting path.

2 Determine a reasonable processing technology to ensure processing accuracy

Definition: Refers to the whole process of changing the shape, size, relative position and properties of the blank by machining to make it a qualified part. (Processing is a basis for workers to process).

1. First read the drawings, familiarize yourself with the technical requirements of the products you are processing, the quality inspection standards, the applicable product range and whether the surface has been heat treated. It is necessary to find out which aspects are the most important and most important requirements of the product.

2. Pay attention to the clamping of the parts when processing the parts, and reduce the number of times of clamping as much as possible to ensure the dimensional accuracy of the parts.

3. Follow the principle of the arrangement of the cutting process: first coarse and then fine, first and second, first and second, and the first.

4. For example, the following picture:

5. Determine the processing process according to the requirements of the diagram

1 Processing method: using vertical milling;

2 Processing equipment: vertical machining center of numerical control system;

3 blank material: material 45# steel, specification: 170mm × 130mm × 39mm;

4 machining tools: Φ80 disk milling cutter, Φ12 end mill, Φ10 end mill, Φ8.5 drill bit, Φ9.8 drill bit, M10 tap, SR10 milling cutter;

5 cutting amount: as shown in the following table;

6 Process route: as shown in the following table;

7 Fixture selection: use the flat jaw clamp to clamp the parts;

6. Fill in the process card (omitted)

If it is not divided into rough finishing, it is difficult to ensure that the finished product is directly milled out. For this reason, we usually process the layering so that the cutting amount during finishing is small, and it is not easy to deform the props and the workpiece, and the size becomes easy. Control, so as to ensure its processing accuracy.

3 Reasonable use of cutting fluid to ensure machining accuracy

Cutting fluid

It is an industrial liquid used in metal cutting and grinding process to cool and lubricate tools and workpieces. The cutting fluid is scientifically compounded with a variety of super functional additives.

2. Cutting fluid is divided into two categories according to the chemical composition of the oil.

(1) water-insoluble (oil-based)

(2) Water solubility (water based):

1 emulsion

2 semi-synthetic cutting fluid

3 full synthetic cutting fluid

3. The role of cutting fluid

When roughing, the cutting of the workpiece is large, the rotation speed is low, and the high temperature is easy to cause the workpiece to expand and contract. The workpiece is annealed, quenched, and tempered to change the strength and hardness of the workpiece or the tool. In this case, we use water to dissolve. The cutting fluid cools the cutting part to reduce the thermal deformation of the workpiece to ensure the accuracy of the part.

When the finishing is performed, the cutting amount of the tool is small, the rotation speed is high, and the feeding speed is fast, which easily causes burrs on the workpiece. In this case, we use the water-insoluble cutting fluid to lubricate the cutting portion. Thereby reducing the occurrence of burrs to ensure the processing accuracy.

4 Use high precision machine tools to ensure machining accuracy

1. It is well known that the higher the accuracy of the machine tool, the higher the machining accuracy of the machining. The older generation said this sentence: "The Chinese guarantee the dimensional accuracy by personal feeling and technology, and the accuracy guaranteed by foreigners is Rely on excellent high-precision machine tools." This also tells the advanced of foreign high-precision machine tools from the side! The current machine tool motor is a servo motor, and the measuring point is a ruby ​​sensing point.

There are several high-precision machine tool manufacturers in foreign countries:

Germany: Siemens, Kidman, TRUMPF, Intex, Jue, Imag, Graub

United States: MAG (Cincinnati), Haas

Japan: Mazak, OKUMA, Mori Seiki, Makino, FANUC

Switzerland: Baichao

Korea: DOOSAN

2. The higher the precision of the machine tool, the higher the accuracy of the positioning, measurement, servo system, etc. of the machine itself. In order to achieve the required roughness of the part, the spindle speed of the machine tool is increased and the workpiece is cut. The line speed is increased to allow the roughness to meet the specified requirements of the part.

5 Conclusion

In summary, the above method for achieving the accuracy of the parts for better processing of the product is completely capable of solving the parts with high processing precision requirements.

Wonderful sharing:

We specialize in the production of precision machine parts, mechanical parts,precision machining, OEM machinery parts,cnc machining,cnc milling,cnc turning parts.

If you have any mechine parts needs, please contact us:contact

If you want to see more CNC precision products, please click here: Product

If you want to see more news:News

Check out the latest company news on Twitter:twitter:@QianJmechanical

Different characteristics of CNC milling and ordinary milling

January 24, 2019 by jincheng  

1. The parts are highly adaptable and flexible, and can process parts with particularly complicated contour shapes or difficult to control dimensions, such as mold parts and shell parts;

2. It can process parts that cannot be processed or difficult to machine with ordinary machine tools, such as complex curve parts and three-dimensional space surface parts described by mathematical models;

3. Parts that can be processed in multiple processes after being able to process a single clamping position;

4. The processing precision is high, the processing quality is stable and reliable, the pulse equivalent of the numerical control device is generally 0.001mm, and the high-precision numerical control system can reach 0.1μm. In addition, the numerical control processing also avoids the operator's operation error;

5, high degree of production automation, can reduce the labor intensity of the operator. Conducive to the automation of production management;

6. High production efficiency. CNC milling machines generally do not need special process equipment such as special fixtures. When replacing workpieces, it is only necessary to call the machining program, clamping tool and tool data stored in the numerical control device, thus greatly shortening the production. cycle. Secondly, the CNC milling machine has the functions of milling machine, boring machine and drilling machine, which makes the process highly concentrated and greatly improves the production efficiency. In addition, the spindle speed and feed speed of the CNC milling machine are infinitely variable, so it is beneficial to choose the best cutting amount;

Wonderful sharing:

We specialize in the production of precision machine parts, mechanical parts,precision machining, OEM machinery parts,cnc machining,cnc milling,cnc turning parts.

If you have any mechine parts needs, please contact us:contact

If you want to see more CNC precision products, please click here: Product

If you want to see more news:News

Check out the latest company news on Twitter:twitter:@QianJmechanical

machinery and manufacturing company

January 17, 2019 by jincheng  

Sichuan QianJiu machinery manufacturing co., LTD(Q9MM) is a professional precision machinery parts and components manufacturing enterprises, mainly for the energy, aerospace, military industry and other industries to provide complete and maintenance with all kinds of spare parts. Production base is located in guanghan economic development zone of chengdu road 2 paragraph 10, covers an area of 50 mu, the standard factory building 22000 square meters. With more than 150 employees, including technical management personnel more than 20 people.

Through unremitting efforts, our factory’s comprehensive management level, technology level, equipment level and got great development, has formed annual output of 200000 pieces of the manufacturing capability of all kinds of spare parts. We have imported from Germany SPKA5000 type high energy screw press, 1250 kw intermediate frequency induction furnace, 1000 t hydraulic press,16T forging hammer forging equipment. We offer our customers both at home and abroad from raw materials procurement to finished product service. IN numerical control section,we has precision horizontal machining center, numerical control section in 4-axis linkage machining center, 5-axis linkage machining center, large CNC gantry machining center and so on a large number of international first-class manufacturing equipment. Testing center has three coordinates measuring instrument, projectors, thickness gauge and magnetic powder flaw detector testing equipment. Over the years is always to provide the service Dongfang Turbine Co., Ltd (DTC for short), Haerbing Turbine Co., Ltd., Xi ‘an Shaangu Power Co., Ltd. (SPC for short), Powchina, space technology research institute of sichuan heavy equipment suppliers to provide services, and many times obtains the title of excellent suppliers.

We will take “enterprise technology, quality, customer satisfaction, sustainable development” principle, based on the fine, then the stronger, the product quality as the survival of the enterprise, put the interests of customers first, to strive to provide more precise and more efficient products and delivery for the user.

machinery and manufacturing company