A precision and efficient milling and grinding head for small thread through hole of SiCp / Al composite material

Abstract

The application provides a precision and high-efficiency milling and grinding head for small thread through hole of SiCp / Al composite material, which comprises a tooth profile surface and a shaft, and is mainly used for the final milling and grinding of internal thread through hole with the size of M4 and below and the precision of 6H and above. The diameter size of each tooth of the tooth profile surface needs to be accurately controlled. Three-dimensional modeling and simulation software is used to simulate the deformation of the milling head under different cutting conditions, and the size of each tooth of the milling head is designed to be in a state of slight increase from inside to outside, so that the accurate milling and grinding of each tooth can be realized during the final processing of the thread, and the precision requirement of the thread is met. While ensuring the precision requirement of the thread, the processing efficiency of SiCp / Al composite material (the volume fraction is more than 40%) is improved.

Description

Technical Field

[0001] This invention relates to a grinding head for precision and efficient milling of small threaded through holes in SiCp / Al composite materials, belonging to the field of machining. Background Technology

[0002] SiCp / Al composite materials possess excellent properties such as high specific strength, high specific stiffness, excellent wear resistance, good thermal conductivity, low coefficient of thermal expansion, and good dimensional stability, and are now widely used in aerospace, automotive, and electronics industries. However, the presence of hard SiC particles (especially those with a volume fraction of over 40%) causes strong high-frequency impacts on cutting tools, leading to rapid tool wear and easy damage. Therefore, machining small threaded holes using ordinary taps and thread milling cutters requires frequent replacements, often resulting in the inability to complete even a single thread. Furthermore, ordinary thread grinding heads on the market are often too small to meet machining requirements, making it difficult to mill small threaded holes with a precision of 6H or higher.

[0003] Therefore, it is necessary to design a dedicated high-precision CNC thread grinding head to ensure the wear resistance of the grinding head while improving the thread accuracy to 6H and above, and at the same time improving the processing efficiency. Summary of the Invention

[0004] The technical problem solved by this invention is: This invention provides a special grinding head for precision and efficient milling of small threaded through holes in SiCp / Al composite materials, which improves the processing quality and efficiency of small threaded through holes and meets the requirements of part precision and efficient processing.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a grinding head for precision and efficient milling of small threaded through holes in SiCp / Al composite materials, comprising a tooth profile and a shaft mounted on a CNC milling machine tool holder, wherein one end of the shaft is provided with a tooth profile; the grinding head is a die steel substrate plated with nickel, and 325 / 400 diamond particles are electroplated on the tooth profile; the grinding head is used for thread processing to ensure that the thread processing accuracy meets the requirements.

[0006] Furthermore, the diameter of the tooth profile of the grinding head increases tooth by tooth from the side where the tooth profile is connected to the shaft to the end side of the tooth profile.

[0007] Furthermore, using 3D modeling and simulation software, the deformation of each tooth diameter during cutting is calculated, and the desired cutting amount for each tooth is superimposed. The increase in the diameter of each tooth of the grinding head is set to twice the cutting amount per tooth during thread hole finishing, while the deformation caused by cutting force is also increased. The number of teeth on the tooth profile is determined by the number of cutting operations required for final machining. The number of teeth is greater than or equal to the number of cutting operations.

[0008] The advantages of this invention compared to the prior art are:

[0009] (1) The present invention provides a simple structure, small size, high precision, high wear resistance and high efficiency of thread milling grinding head, which improves the quality and efficiency of processing.

[0010] (2) The present invention has a wide range of applications and can be applied to thread milling of various difficult-to-machine materials.

[0011] (3) The present invention has a simple structure, is easy to process and form, and is easy to promote and apply. Attached Figure Description

[0012] Figure 1 This is a structural diagram of the grinding head for precision and efficient milling processing according to the present invention.

[0013] Figure 2 A 3D model of the grinding head structure;

[0014] Figure 3 Finite element mesh diagram of the grinding head structure;

[0015] Figure 4 Simulation diagram of M3 grinding head deformation under specific cutting conditions

[0016] Figure 5 This is a detailed dimensional drawing of the M3 grinding head used for precision and efficient milling of the present invention. Detailed Implementation

[0017] The present invention will now be described in conjunction with the accompanying drawings and embodiments.

[0018] To meet the final quality requirements of efficient milling of through holes with precision of M4 or lower and 6H or higher in SiCp / Al composite materials, a precision milling head for thread milling is developed. Figure 2 As shown.

[0019] Figure 1 The structure of the grinding head mainly consists of two parts: tooth profile 1 and shaft 2. The diameter of each tooth on the tooth profile needs to be precisely controlled, while the shaft can have a fixed size.

[0020] Figure 2 The specific dimensions of the grinding head are designed by precisely controlling the diameter of each tooth on the tooth profile, resulting in a gradual increase in size from the inside out. This ensures that each tooth undergoes micro-milling during the final thread machining, improving the durability of the grinding head. Due to the effect of multiple cuts per feed of the grinding head, the machining efficiency is improved while ensuring the thread size requirements are met.

[0021] A specialized grinding head with slightly varying diameter is designed, its structure mainly consists of two parts: the tooth profile cutting surface 1 and the shaft 2. The maximum diameter of the grinding head, ΦDn, is the diameter of the threaded hole to be machined minus 0.1–0.2 mm. The cutting amount per tooth of the grinding head is determined according to different requirements, ranging from 0.02–0.1 mm. The tooth profile angle α for metric threads is 60°, and for imperial threads, it is 55°. The tooth pitch t is an integer multiple of the tooth pitch of the machined thread. Due to the precision machining of threads, the chamfers at the tooth crest and root of the grinding head are R0.1. For machining internal threads below M4, the grinding head shank size is Φ6 mm, and the shank size ΦDm at the connection with the grinding head tooth profile is the minor diameter of the internal thread to be machined minus 0.1–0.2 mm. The length L2 should be greater than the thread hole depth plus one pitch.

[0022] Based on the theoretical dimensions above, using 3D modeling and simulation software, the grinding head material is set according to actual conditions. Mesh generation is performed in the simulation software, and the stress module of the finite element analysis software simulates the minute stress deformation of each tooth under specific cutting conditions. These minute deformations are then superimposed into the diameter calculation of each tooth of the grinding head to design a specialized grinding head for precise cutting.

[0023] Example:

[0024] A grinding head for precision and high-efficiency milling of small threaded through holes in SiCp / Al composite materials. Figure 1 It mainly consists of two parts: tooth profile surface 1 and shaft 2.

[0025] Grinding head ( Figure 2 The tooth profile structure is the key to precision milling. Taking the M3 grinding head as an example, the grinding head is made of mold steel plated with nickel, and 325 / 400 diamond particles are electroplated on the tooth profile surface to achieve precision milling of 6H precision threaded holes of SiCp / Al composite materials with a volume fraction of more than 40%.

[0026] Based on the processing difficulty of SiCp / Al composite materials with a volume fraction of over 40%, the initial thread bore is φ2.5mm, and the single-sided allowance for thread milling is 0.25mm. Therefore, the cutting amount per tooth during precision milling is determined to be 0.05mm, the number of tooth profiles is n=7, the tooth pitch is t=0.5, and the tooth profile length L1=3.5mm. The grinding head diameter is determined to increase by 0.1mm per tooth. Due to the possibility of significant errors in the initial hole machining, the initial milling cutting amount is inaccurate. Therefore, the diameters of the first and second teeth are the same, and the same dimension cutting is repeated: D1=D2=1.95mm; successively D3=2.05mm, D4=2.15mm, D5=2.25mm. To ensure the accuracy and reliability of the final dimensions, the diameters of the last two teeth are the same: D6(Dn-1)=D7(Dn)=2.35mm. The diameter Dm of the transition shank connected by the tooth profile is 1.6mm. Since the length of the threaded through hole being machined is 8mm, the length L2 of the transition shank is 9mm. The tool holder installed on the machine tool has a diameter of 6mm and a length of 30mm, and the two are connected at a 90° angle.

[0027] The above are the theoretical design dimensions without superimposed deformation. Based on the simulation analysis results, such as... Figures 3-5 As shown, the deviation of each tooth of the M3 grinding head from the theoretical position is between 0.02 and 0.04 mm on one side. Therefore, the deformation of the grinding head tooth profile is between 0.04 and 0.08 mm. Distributing this deformation evenly across the 5 teeth, the deformation radius of each tooth increases progressively to 0.04, 0.05, 0.06, 0.07, and 0.08 mm respectively. Therefore, the final dimensions of the M3 grinding head are: n = 7 tooth profile surfaces, pitch t = 0.5, tooth profile surface length L1 = 3.5 mm, transition shank Dm = 1.6 mm, and transition shank length L2 = 9 mm. The final diameter of each tooth is D1 = D2 = 1.99 mm; successively D3 = 2.15 mm, D4 = 2.21 mm, D5 = 2.32 mm, D6(Dn-1) = D7(Dn) = 2.43 mm.

[0028] The parts of this invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A grinding head for precision and efficient milling of small threaded through holes in SiCp / Al composite materials, characterized in that, It includes a tooth profile (1) and a shaft (2) mounted on a CNC milling machine tool holder, with the tooth profile (1) provided at one end of the shaft (2); the grinding head is a mold steel base plated with nickel, and 325 / 400 diamond particles are electroplated on the tooth profile (1); the grinding head is used for thread processing to ensure that the thread processing accuracy meets the requirements; The diameter of the tooth profile (1) of the grinding head increases tooth by tooth from the side where the tooth profile is connected to the shaft to the end side of the tooth profile. Using 3D modeling and simulation software, the deformation of each tooth diameter of the tooth profile (1) during cutting is calculated, and the desired cutting amount of each tooth is superimposed. The increase in the diameter of each tooth of the grinding head is set to be twice the cutting amount of each tooth during the finishing of the thread hole, and the deformation caused by the cutting force is increased at the same time. The number of teeth of the tooth profile (1) is determined by the number of cuttings required for the final processing. The number of teeth ≥ the number of cuttings.

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