Ten tips for CNC cars

1. It is skillful to obtain a small amount of deep food. In the turning process, the triangular function is often used to process some workpieces with inner and outer circles above the secondary accuracy. Due to the heat of cutting, the friction between the workpiece and the tool causes the tool wear and the repeated positioning accuracy of the square tool holder, etc., the quality is difficult to guarantee. In order to solve the precise micro-deep depth, in the turning process, we can use the relationship between the opposite side and the oblique side of the triangle as needed to move the longitudinal small knife holder at an angle, so as to accurately reach the horizontal eating depth of the micro-moving turning tool. Purpose, save labor and time, ensure product quality and improve work efficiency. The general C620 lathe tool holder scale value is 0.05mm per grid. If you want to obtain the horizontal eating depth value of 0.005mm, check the sine trigonometric function table: sinα=0.005/0.05=0.1 α=5o44′ so just move the small knife holder When it is 5o44', when moving the longitudinally engraved disc on the small knife holder, it can reach the micro-movement of the cutting tool with a depth value of 0.005mm in the lateral direction. cnc machining part

 

2. The application of reverse turning technology in three long-term production practices proves that in the specific turning process, reverse cutting technology can achieve good results. The following examples are as follows:

(1) When the reverse-cutting thread material is a martensitic stainless steel piece with an internal and external thread workpiece with a pitch of 1.25 and 1.75 mm, since the pitch of the lathe screw is removed by the pitch of the workpiece, the obtained value is An inexhaustible value. If the thread is machined by lifting the handle of the counter nut, the thread is often broken. Generally, the ordinary lathe has no disorderly buckle device, and the self-made set of the disc is quite time-consuming, so in processing such a pitch. When threading, it is often. The method adopted is the low-speed smooth turning method, because the high-speed pick-up is not enough to retract the knife, so the production efficiency is low, the file is easily generated during turning, and the surface roughness is poor, especially in processing martensite stainless steel such as 1Crl3, 2 Crl3, etc. When cutting at low speed, the sickle phenomenon is more prominent. The reverse-cuttering, reverse-cutting, and opposite-direction "three-reverse" cutting methods created in the machining practice can achieve a good overall cutting effect, because the method can turn the thread at high speed, and the moving direction of the tool is The tool is retracted from left to right, so there is no drawback that the tool can not be retracted when cutting the thread at high speed. The specific method is as follows: When the external thread is used, grind a similar internal thread turning tool (Fig. 1);

Grind a reverse internal thread turning tool (Figure 2). plastic part

 

Before machining, adjust the spindle of the reverse friction plate slightly to ensure the reverse rotation speed. For a good thread cutter, close the opening and closing nut, start the forward and low speed to go to the empty sipe, and then put the thread turning tool into the appropriate depth of cut, you can reverse the rotation. At this time, the turning tool is left at high speed. By cutting the knife to the right and cutting the number of knives according to this method, the thread with high surface roughness and high precision can be machined. 

(2) In the traditional knurling process of the reverse knurling, the iron filings and debris are easily entered between the workpiece and the knurling knife, causing the workpiece to be overstressed, causing the lines to be bundled, the pattern is crushed or ghosted, etc. . If the new operation method of the turning and knurling of the lathe spindle is adopted, the disadvantages caused by the smoothing operation can be effectively prevented, and a good comprehensive effect can be obtained.

(3) Reverse turning of inner and outer taper pipe threads When turning various internal and external taper pipe threads with less precision and less batch, it is possible to directly use reverse cutting and reverse loading without the mold device. The new method of operation, while cutting the side of the tool, the tool is moved horizontally from the left to the right. The transverse file is easy to grasp the depth of the file from large diameter to small diameter. The reason is the file. There are pre-stresses. The range of applications of this new type of reverse operating technology in turning technology is increasingly widespread and can be flexibly applied to a variety of specific situations.

 

3. New operation method and tool innovation for drilling small holes In the turning process, when the hole is less than 0.6mm, the diameter of the drill is small, the rigidity is poor, the cutting speed is not up, and the workpiece material is heat-resistant alloy and stainless steel, and the cutting resistance is Large, so when drilling, such as the use of mechanical transmission feed, the drill is very easy to break, the following describes a simple and effective tool and manual feed method. Firstly, the original drill chuck is changed into a straight shank floating type. When the small drill bit is clamped on the floating drill chuck, the drilling can be smoothly performed. Because the rear part of the drill bit is a straight shank sliding fit, it can move freely in the pull sleeve. When the small hole is drilled, the drill chuck can be gently grasped by hand, and the manual micro feed can be realized, and the small hole can be quickly drilled out. Quality and quantity and extend the service life of small drills. The modified multi-purpose drill chuck can also be used for small-diameter internal thread tapping, reaming, etc. (If a larger hole is drilled, a limit pin can be inserted between the pull sleeve and the straight shank).

 

4. Anti-vibration in deep hole machining In deep hole machining, due to the small aperture, the boring tool bar is slender. It is inevitable to generate vibration when the hole diameter is Φ30～50mm and the deep hole is about 1000mm. It is the most effective and effective to prevent the vibration of the arbor. The method is to attach two supports (using a material such as cloth bakelite) to the shank body, and the size is exactly the same as the aperture size. During the cutting process, the arbor is less prone to vibration due to the positioning of the slats, and the deep hole parts of good quality can be processed. machined part

 

5. The anti-break of the small center drill is less than the center hole of Φ1.5mm when the drilling is less than the center hole of Φ1.5mm. The simple and effective anti-break method is to not lock the tailstock when drilling the center hole, let the tailstock The self-weight and the friction generated between the machine bed surface are used to drill the center hole. When the cutting resistance is too large, the tailstock will retreat by itself, thus protecting the center drill.

 

 

6. Anti-vibration of turning thin-walled workpieces During the turning process of thin-walled workpieces, vibrations are often generated due to poor steel properties of the workpieces; especially when turning stainless steel and heat-resistant alloys, the vibration is more prominent, the surface roughness of the workpiece is extremely poor, and the service life of the tool shorten. The simplest methods of shock isolation in several productions are described below.

(1) When turning the outer circle of the stainless steel hollow slender tube workpiece, the hole can be filled with wood chips and plugged. At the same time, both ends of the workpiece are plugged with the bakelite plug, and then the support claw on the tool holder is replaced with The supporting melon of the bakelite material can correct the required arc to perform the turning of the stainless steel hollow slender rod. This simple method can effectively prevent the vibration and deformation of the hollow slender rod during the cutting process.

(2) When turning the inner hole of a heat-resistant (high-nickel-chromium) alloy thin-walled workpiece, the rigidity of the workpiece is poor, the shank is slender, and a serious resonance phenomenon occurs during the cutting process, which is extremely liable to damage the tool and cause waste. If a shock absorbing material such as a rubber strip or a sponge is wound around the outer circumference of the workpiece, the shockproof effect can be effectively achieved.

(3) When turning the outer circle of the heat-resistant alloy thin-walled sleeve workpiece, due to the comprehensive factors such as the high resistance of the heat-resistant alloy, it is easy to generate vibration and deformation during cutting. If the rubber hole or cotton thread is inserted into the workpiece hole, If the debris is used, then the clamping method at both ends can be used to effectively prevent the vibration and the deformation of the workpiece during the cutting process, and the high-quality thin-walled workpiece can be processed.

 

7. The additional anti-vibration tool is easy to generate vibration due to the poor rigidity of the elongated shaft type workpiece during the multi-groove cutting process, resulting in poor surface roughness of the workpiece and damage to the tool. A set of additional anti-vibration tools can effectively solve the vibration problem of the slender parts in the grooving process (see Figure 10). Install the self-made shock-proof tool in a suitable position on the square tool holder before work. Then, install the required slot-shaped turning tool on the square tool holder, adjust the distance and the compression amount of the spring, and then operate. When the turning tool cuts into the workpiece, the additional anti-vibration tool is placed on the surface of the workpiece at the same time, which is good for shockproof. effect.

 

8. Difficult-to-machine materials are honed and finished. When we are in difficult-to-machine materials such as high-temperature alloys and hardened steels, the surface roughness of the workpiece is required to be Ra0.20-0.05μm, and the dimensional accuracy is also high. Final finishing is usually carried out on a grinding machine. Do a self-made simple honing tool and honing wheel, and receive a good economic effect by honing instead of the grinding process on the lathe.

 

9. Quick loading and unloading mandrels often encounter various types of bearing sets in the turning process. The outer circle and the inverted guide taper angle of the bearing assembly. Due to the large batch size, the loading and unloading time is more than the cutting time. Long, low production efficiency. The quick-loading mandrel and single-knife multi-blade (hardmetal) turning tools described below can save auxiliary time and ensure product quality in the processing of various bearing sleeve parts. The production method is as follows. Make a simple small taper mandrel. The principle is to use a 0.02mm trace of taper on the back of the mandrel. The bearing set is tightened on the mandrel by friction, and then a single-knife multi-blade turning tool is used. After the round, the 15° cone angle is reversed, and the parking is carried out to remove the parts quickly and well, as shown in Figure 14.

 

10. Turning of hardened steel parts

(1) One of the key examples of hardened steel turning 1 Reconstruction of high speed steel W18Cr4V hardened broach (repair after fracture) 2 homemade non-standard thread plug gauge (hardening hardware) 3 quenching hardware and spraying Turning of 4 pieces of quenching hardware smooth surface plugging 5 Thread rolling taps made of high speed steel tools For the quenching hardware and various difficult material parts encountered in the above production, select the appropriate tool material and cutting amount and tool Geometric angles and methods of operation can achieve good overall economic results. For example, after the square broach is broken, if it is re-launched to manufacture a square broach, not only the manufacturing cycle is long, but also the cost is high. At the root of the original broach, we use the blade of the hard alloy YM052 to sharpen it into a negative. Front angle r. =-6°～-8°, the cutting edge can be turned by careful grinding with oil stone. The cutting speed is V=10～15m/min. After the outer circle, the empty sipe is cut, and finally the thread is divided into coarse and fine. ), after the roughing, the tool must be reamed and ground after the new sharpening and grinding, and then the internal thread of the connecting rod is prepared, and then the joint is trimmed. A square broach with a broken scrap was repaired after turning and it was as old as new.

(2) Selection of tool materials for turning and quenching hardware 1 New grades such as hard alloy YM052, YM053, YT05, etc., the general cutting speed is below 18m/min, and the surface roughness of the workpiece can reach Ra1.6~0.80μm. 2 cubic boron nitride tool FD can process all kinds of hardened steel and sprayed parts, cutting speed up to 100m / min, surface roughness up to Ra0.80 ~ 0.20μm. The composite cubic boron nitride tool DCS-F produced by the State Capital Machinery Plant and the Guizhou No.6 Grinding Wheel Factory also has this performance. The processing effect is worse than that of cemented carbide (but the strength is not as good as that of hard alloy, it is deeper and cheaper than the hard alloy, and it is easy to damage if it is used improperly). 9 ceramic tools, cutting speed of 40 ~ 60m / min, the strength is poor. All of the above tools have their own characteristics in turning and quenching parts, and should be selected according to the specific conditions of turning different materials and different hardness.

(3) Selection of different types of hardened steel parts and tool properties Different materials of hardened steel parts under the same hardness, the requirements for tool performance are completely different, as large as the following three categories; 1 high alloy steel: refers to alloying elements Tool steel and die steel (mainly various high speed steels) with a total mass of more than 10%. 2 alloy steel: refers to tool steel and die steel with alloying element content of 2~9%, such as 9SiCr, CrWMn and high strength alloy structural steel. 3 carbon steel: including various carbon tool steels and carburized steel such as T8, T10, 15 steel or 20 gauge steel carburizing steel. For carbon steel, the microstructure after quenching is tempered martensite and a small amount of carbide, hard hair HV800 ~ 1000, than the hardness of WC and TiC in cemented carbide and A12D3 in ceramic tools It is much lower, and it is less hot-hard than martensite without alloying elements and generally does not exceed 200 °C. As the content of alloying elements in the steel increases, the carbide content of the steel after quenching and tempering increases, and the type of carbide becomes quite complicated. Taking high-speed steel as an example, the content of carbides in the microstructure after quenching and tempering can reach 10-15% (volume ratio) and contains carbides of MC, M2C, M6 and M3, 2C, etc. High hardness (HV2800), which is much higher than the hardness of the hard point phase in general tool materials. In addition, due to the presence of a large number of alloying elements, the hot hardness of martensite containing various alloying elements can be increased to about 600 °C. The hard workability of hardened steels with the same macrohardness is not the same, and the difference is very large. Before turning hardened steel parts, it is analyzed to belong to that category. Master the characteristics, select the appropriate tool materials, cutting amount and tool geometry. The angle can smoothly complete the turning of hardened steel parts.