Wannan takarda tana ba da shawarar sabonaikimethod using optical surface grinder with self-made special tooling, which has the advantages of high qualification rate, simple operation and controllable aikiaccuracy, and solves the problem of aikitiny ball head parts.



1 Gabatarwa
The ball can be seen as a circular arc rotating around its axis to become a surface. Ball head class parts due to the existence of complex surfaces, so usually use CNC machining to ensure the size, position accuracy and surface quality requirements. With the continuous improvement of machine tool performance and tool material and performance, the ball head class parts with ball head diameter ≥8mm and material hardness ≤64HRC can be processed by traditional methods, including: ① using omnidirectional turning tool or cycloid tool for CNC lathe processing. ② using the rotary milling aikiwith high requirements for tool position adjustment. ③Processing by profile grinding with special grinding wheel dressing device. ④Spreading method grinding aikiwith customized cup-shaped grinding wheels. ⑤ Mass production filing aikiusing a special grinding block (only hemispherical shaft ends with regular shapes can be processed).
However, the analysis of the structural characteristics of the tiny spherical parts suggests that it is difficult to realize the precision forming aikiof the tiny spherical parts by using the traditional aikimethod.

2 Halayen micro ball head sassa
The characteristics of micro ball head parts: ① in the shaft end has a curved ball head structure, divided into small semi-spherical, hemispherical and large semi-spherical structure, as shown in Figure 1, the hardness of about 60HRC. ② ball diameter is small, the general ball diameter ≤ 3.5mm. ③ aikiball transition section by radial force section easy to break. ④The size of the part is small, and the tool structure has a greater impact on the workpiece processing. ⑤ forming grinding wheel dressing is more difficult.



From the characteristics of the tiny ball head class parts, it can be seen that the traditional aikimethod for forming the tiny ball head at the end of the shaft appears to be incompetent.

For a small number of general precision requirements of the tiny ball head class parts, can be used under the soft state carving and milling rough machining, heat treatment after polishing to achieve. But for the high precision requirements of the tiny ball head class parts, still need to find a more suitable aikimethod.

Because of the difficulty of precision hard machining of tiny ball-like parts, it is not easy to achieve batch processing, so according to the formation mechanism of the ball end of the shaft (let the bar material high-speed rotation, in the form of circular arc envelope to form a ball head) and the aikiprinciple of the equipment, proposed a tiny shaft end of the large half ball-like ball parts aikimethod: the production of special tooling, let the rod high-speed rotation, with the optical curve grinder set point into line aikiThe principle is to process the ball head in the form of an envelope for precision forming.

3 Optical curve grinding machine aikimethod
The grinder lankwasa grinder ne yafi hada da gado, wani daidaitawa tebur, a nika dabaran tebur da tsinkaya tsarin. Teburin na iya motsawa a cikin tsayin tsayi, mai juyawa da a tsaye; dabaran niƙa na iya yin babban motsi na juyawa da motsi na linzami akan layin jagorar teburin niƙa; teburin niƙa na iya yin motsi mai tsayi da jujjuyawar ciyarwa da juyawa a kusa da axis X/Y/Z. Za a iya yin niƙa na filayen madauwari da yawa, logarithmic surface ko Archimedean spiral surface.
Optical curve grinder aikiuses an optical projection magnification system to project the workpiece magnification onto the screen against the magnified image of the workpiece on the screen, and operates the grinding wheel to grind the workpiece to grind off the excess material beyond the contour line of the magnified image until the contour of the object image fully coincides with the magnified image. It is possible to compare 25 times or 50 times magnification. The types of diamond grinding wheel structures used in optical curve grinders are flat grinding wheels, sharp grinding wheels, etc., as shown in Figure 2.


Dangane da tsarin gindin niƙa, ana iya amfani da ƙaƙƙarfan niƙa da aka nuna a cikin siffa 2b tare da tsarin sarrafa dijital don niƙa saman tare da diamita na â ‰ ¥ 0.2 mm. Idan an haɗa shi tare da jujjuyawar kayan aikin, za a iya yin madaidaicin madaidaicin madaurin juyawa.

4 Misalin misalai na ƙira
The structure of a ball head rod for a certain type of product is shown in Figure 3. The surface roughness of the spherical surface is Ra=0.4μm, and the spherical surface should not have obvious cutter patterns such as joint marks; the size, position accuracy and hardness of the spherical part are high, the diameter of the transition section between the spherical head and the shaft is only 1.2mm, and the machining quantity is 500. The following difficulties exist in the aikiof this part: ①Higher dimensional accuracy requirements for the ball head and smaller shaft diameter of the part. ②The diameter of the transition section of the ball head is only 1.2mm, the aikistiffness is low, and the force is easy to break. ③ aikiallowance, the aikitechnology, clamping convenience, stability and bar rotation radial runout and other aspects of the higher requirements. ④Higher requirements for the surface roughness quality of the ball head.

If the optical curve grinder is used to realize the precision forming aikiof the ball head bar, special tooling also needs to be made to ensure that when the grinding wheel moves along the contour of the workpiece, the ball head bar rotates around the axis to form the ball head structure. Due to the small size of the ball-head rod, if the grinding wheel moves up and down along the grinding wheel holder, it will reduce the effective contact time between the grinding wheel and the rotating workpiece. Therefore, in order to improve the aikiefficiency, the height position of the grinding wheel is adjusted and fixed during the workpiece processing, and the reciprocating motion of the grinding wheel along the grinding wheel holder is canceled, so that the grinding wheel is always in effective contact with the surface of the workpiece when rotating, and the grinding wheel only moves along the forming contour line when rotating at high speed.
5 Tsarin kayan aiki
Ptauki ƙaramin motar wutar lantarki (saurin 1400r/min) da ƙaramin lathe chuck, gyara chuck akan teburin aiki, yi amfani da murfin bazara (yana iya haɗa kayan aiki daban -daban tsakanin diamita 10mm) don ƙulla kayan aikin. Daidaita tsayin teburin don nisan nesa na tsinkayen aikin ya kasance cikin kewayon motsi na keken. Ta hanyar motar belin bel, saurin jujjuyawar ya kai 2000 r/min, kuma alƙawarin juyawa yana gaba da jagorancin jujjuyawar motar niƙa. Bayan debugging, radial madauwari runout na workpiece ne â ‰ .000.005mm, kuma tsarin da workpiece aka nuna a Figure 4.

6 Tsarin tsari
Considering the number of workpieces, ball head rod and grinding wheel structure, due to the small round angle of the sharp grinding wheel, aikiloss is large, in order to reduce the loss of the sharp grinding wheel and improve the aikiefficiency, choose to use flat grinding wheel aikiwhen removing the large residual, step-by-step aikiprocess is shown in Figure 5. Develop the ball head rod aikiprocess as follows.

(1) Mararrafa sanda na ƙwallon ƙwallo tare da madaidaiciyar niƙa, yana barin gefe na 0.02mm don sassan A da B da 0.1mm don sashin C, tare da saurin fassarar ƙafafun na 3mm/min da saurin jujjuyawar 12000r/ min.

2）Processing the contour of the ball-head rod with the sharp grinding wheel, aikithe A and B sections to control the dimensional accuracy, leaving a margin of 0.01mm in the C section, the grinding wheel translation speed of 1.5mm/min, and the grinding wheel rotation speed of 12000r/min.

(3) Kammala ƙwallon sashin C tare da kaɗa mai niƙa, tare da saurin fassarar ƙafa na 0.5mm/min da saurin jujjuyawar juyawa na 12000 r/min.

7 Binciken tasirin injin
Ana sarrafa sandar ƙwallon ƙwallo a matakai, kuma ingancin farfajiyar silinda da aka ƙera yana da kyau saboda madaidaicin niƙa yana da aikin sake kunnawa ta atomatik; Kafar niƙa mai kaifi tana da alhakin kammalawa, tare da ƙaramin izinin sarrafa kayan masarufi da ƙananan asarar niƙa. Yayin aiwatar da kera sandunan ƙwallon ƙafa guda 500, an sake fasalin ƙaƙƙarfan niƙa. Ana nuna sassan da aka ƙera a cikin siffa 6, kuma ana nuna bayanan gwajin sassan a cikin Table 1. ana iya gani daga sakamakon gwajin cewa wannan hanyar kera sandunan ƙwallon ƙwal ya cika buƙatun ƙira.



8 Kammalawa
Dangane da sifofin tsarin sa, ƙananan sassan ƙwallon ƙwallon ba za a iya sarrafa su ta ɓangarorin ƙwallon ƙwallon ƙwallon ƙafa na gargajiya ba. Ta hanyar amfani da injin ƙwanƙwasa lanƙwasa tare da kayan aikin musamman na gida da ƙira da mataki-mataki aikiprocess, the radial force on the ball head rod is small and the transition section is not easy to break. The grinding method has solved the problem of aikismall-sized ball-end parts with the advantages of high qualification rate, simple operation, controllable aikiaccuracy and good product consistency.