We have carried out a lot of tests on the existing equipment M131W ordinary cylindrical surface grinder, and carried out necessary inspection, scraping and adjustment. Through dressing and finely balancing the grinding wheel, we can properly trim more contour micrometers on the abrasive grains. The blade can completely achieve ultra-high-precision, low-roughness grinding pins, and can effectively grind parts with a precision of h4–h6 and a roughness of Ra0.02–0.04μm. The method is simple, convenient and easy to implement, and the effect is quite good.
1. Superfine grinding mechanism
Ultra-fine grinding is carried out by virtue of the feature that a large number of abrasive grains of the same height can be trimmed on the working surface of the grinding wheel. These contoured micro-blades are capable of cutting thin, minor defects as well as minor shape and dimensional errors and allowances from the work surface. Therefore, the use of these micro-cutting tools is a lot. If the amount of grinding is appropriate, it is possible to leave a large number of extremely fine cutting marks on the machined surface, so a very low surface roughness can be obtained. In addition, in the non-flare polishing stage, there are still obvious functions of friction, sliding, polishing and calendering, so the surface roughness of the processing is further reduced.
2. Maintenance of ordinary surface grinders
In order to grind work-pieces with a roughness of Ra0.02–0.04μm on the flexible surface grinder, the following items should be tested on the old flexible surface grinder. If the accuracy requirements are not met, scraping and grinding should be carried out.
(1) Overhaul bed guide rail
1) Testing and how to scrape the V-shaped guide rail of the bed body: the non-straightness in the vertical plane shall not exceed 0.01mm in the length of 1m; the non-straightness in the horizontal plane shall not exceed 0.01mm in the length of 1m; and The non-perpendicularity of the sliding saddle guide rail shall not exceed 0.02mm in the length of 250mm; the contact point requires 12–14 points (25×25) mm.
2)How much is the plane guide of the scraper bed detected: the inequality of the V-shaped guide rail shall not exceed 0.02mm in the length of 1m; the non-straightness in the vertical plane shall not exceed 0.01mm in the length of 1m; contact The spots require 12–14 points (25×25) mm.
(2) Overhaul the sliding saddle guide rail
1) Check and how to scratch the V-shaped guide rail of the saddle; the non-straightness in the vertical plane shall not exceed 0.01mm on the entire length; the contact spot requires 10–12 points (25 × 25) mm.
2) Check and measure the flat guide rail of the saddle board: the non-parallelism of the V-shaped guide rail shall not exceed 0.02/1000mm in the entire length; the contact spot requires 10–12 points (25 × 25) mm.
(3) Adjust the clearance between the grinding wheel spindle and the bearing bush
Paint on the shaft diameter of the grinding wheel spindle and grind the bearing bush, scrape and grind the surface of the bearing bush with a scraper, the contact spots should reach 12-14 points (25×25) mm, and then install and adjust the grinding wheel spindle and the bearing bush. The gap is adjusted to 0.0025–0.005mm. In this way, the disadvantage of rounded edges in the work-piece during grinding can be overcome.
(4) Balance grinding wheel spindle motor and grinding wheel
Since the vibration of the grinding wheel spindle motor has a great influence on the surface roughness of the work-piece, the grinding wheel spindle motor needs to be balanced, and the grinding wheel should be balanced twice; after the grinding wheel is trimmed with a diamond pen, a rough balance is performed, and then the oil stone or rough turning machine is used. After fine dressing, the grinding wheel is finely balanced.
3. How to finish the grinding wheel twice as fine and fine
In order to make the ground work-piece reach the surface roughness of Ra0.02–0.04μm, the following two methods are used for finishing and dressing the grinding wheel twice
1)Refining with a diamond stylus, and then using the grinding wheel after fine turning, can meet the requirements of surface roughness Ra0.4–0.8μm, but it is very difficult to grind Ra0.02–0.2μm. However, if you use a diamond pen for fine repair, and then use a fine-turned grinding wheel, you can completely meet this requirement.
The grinding wheel of TL60#ZR1–ZR2 can be used for fine repair, with a diameter of about φ100mm. The grinding wheel is first clamped on a mandrel, and then the outer circle is finely turned on a precision lathe to eliminate runout. After that, the grinding wheel is finely repaired on the surface grinder, that is, the office wheel is finely ground with the grinding wheel.
When dressing the grinding wheel, it is rotated by the headstock, and its rotation speed should be low, the speed of the economic and trade department should be 80–100r/min, and the feed should be small. , it needs to be adjusted properly after many times of reciprocation. The dressing grinding wheel and the dressing grinding wheel rotate in the same direction, that is, the direction of the linear velocity of the contact point of the two is opposite. The coolant should be sufficient to flush out the floating sand and prevent the surface of the work-piece from being roughened by the floating sand during the grinding process.
After the grinding wheel is trimmed twice, more equal-height micro-edges can be trimmed on the abrasive grains of the grinding wheel. After the grinding wheel is trimmed, use a brush to remove the sand grains on the surface of the trimmed grinding wheel. Before grinding, the coolant should be strictly filtered. When grinding, the coolant should be sufficient to prevent the surface of the work-piece from being burned.
2)Fine-tune with a diamond pen, and then fine-tune with a whetstone
First use a sharp single-grain diamond pen for fine trimming, and more micro-edges of equal height can be trimmed on the abrasive grains of the large grinding wheel, and then finely trim with whetstone (or sand bars), that is, on the basis of fine trimming, grinding on the grinding wheel More contoured micro-blades are trimmed on the grain.
When finishing with a diamond pen, the wheel dresser should be installed correctly. However, the feed amount should not be greater than 0.005mm each time, and the minimum value for the longitudinal feed amount is recommended. In the process of dressing the grinding wheel, pay attention to the sound, and it is best to hear a uniform rustling sound. If you hear an abnormal sound of high and low, gradually high and low, or even beeping, you should check whether the workbench is crawling, whether the coolant is sufficient, and whether the diamond pen is sharp. After finishing with a diamond pen, it is finely repaired with a whetstone. Whetstone should be smoothed with a grinding wheel on a surface grinder. When finely repairing, the oilstone must be equal to the circumferential surface of the grinding wheel, make slight contact, and slowly move longitudinally for 2-3 times.
After fine and fine dressing, you can use your fingers to follow the rotation direction of the grinding wheel, gently approach the working surface of the grinding wheel, and move it longitudinally. When you feel the hand, you can use a paint brush with 2/3 of the bristles to gently brush off the scum on the surface of the grinding wheel
4. Grinding amount
When the M131W ordinary surface grinder is used for super-precision grinding, the empirical grinding amount of surface roughness Ra0.02μm is guaranteed to be effectively achieved.
Working line speed m/min4–10
The longitudinal feed rate of the table during grinding (mm/min) 50–100
Grinding depth (mm) 0.0025–0.005
The number of lateral feeds during grinding is 1–2
Reciprocation times of the table during non-spark polishing 4-6
Grinding allowance on radius (mm) 0.003–0.006
Achievable surface roughness (μm) Ra0.02–0.04
5. Grinding precautions and possible problems
(1) When grinding, pay attention to the contact between the grinding wheel and the components
When the work-piece surface is in contact with the grinding wheel, a continuous hissing sound can be heard, the water traces on the work-piece surface can be taken away by the placed grinding wheel, and faint sparks can be seen at the same time. The saponification liquid for grinding is slightly higher, but it requires filtering and cleaning, and then feeding. The amount of each feed is 0.005mm per double stroke, and it is ground to the end until there is no spark. At this time, press and hold the transverse feed hand-wheel in the feeding direction, so that the grinding wheel slightly advances to the work-piece, but does not feed, which is equivalent to polishing the work-piece once, which does not guarantee that the surface roughness of the work-piece can reach Ra0.02μm.
(2) Prevent the work-piece from expanding
When grinding in summer, the machine tool lighting can be close to the work-piece to prevent the heat dissipation of the lamp from the work-piece and cause the work-piece to expand and affect the grinding quality.
(3) Brushing the surface of the workman
This is caused by unclean coolant or floating sand on the surface of the grinding wheel. Strictly filter the coolant or brush off the floating sand.
(4) There are local burns
This is due to insufficient coolant, excessive feed, or dull grinding wheel.
(5) There are local corrugations on the surface of the work-piece
After processing, the surface of the work-piece is mostly good, but there are fine ripples in some parts. This may be caused by loose spindle, motor vibration or other reasons, and corresponding measures should be taken according to the specific situation.
Want to know more about the process of the product? ANTISHI has a mature team of engineers who are very familiar with heat treatment processing and can handle product processing problems including packaging technical problems. In addition, during the installation and design process, our engineer team can be assigned to solve problems on the spot, to the greatest extent possible. Helping producers to carry out convenient and efficient production has always been the goal of our company.