1、 Purpose

In order to ensure that the grinding and polishing process is effectively controlled.

2、 Scope of application

All grinders on duty.

3、 Preparation of general grinding and polishing tools

Angle grinder: a thousand blade or stainless steel bowl brush can be installed on the tool as required; The installation of the blade can be used to polish the welding spatter, the surface collision and scratch, the weld reinforcement and the machining reinforcement; The installation of stainless steel bowl brush can polish the long weld, and its main function is to remove the oxide scale in the welding area. There shall be no crack, weld bead, burn through, arc pit, sand hole and other defects on the polished weld surface. After polishing, the weld shall be free of surface pores, slag inclusion, crater, crack, arc scratch, ignition and other defects.

Straight shank grinder: only special stainless steel bowl brush can be installed on the tool; The tool can only grind the long weld before welding. The main difference from the angle grinder is that the grinder can obtain the same texture as the long weld.

Straight grinder: rotary file and abrasive cloth wheel can be installed on the tool as required; The installation of cone head rotary file can be used for grinding of weld joint, grinding of defects in small space, excessive grinding of deep knock (depth below 1mm), machining and grinding of narrow space, local fine grinding, etc; The installation of abrasive cloth wheel can carry out grinding and polishing in a small space that cannot be completed by the angle grinder, and polishing to the corner area, etc.

Scraper: This tool can remove edges and burrs and make the corner area of the workpiece too smooth.

Air gun: This tool is used to clean the aluminum chips and dust on the workpiece surface after grinding; For safety, it is forbidden to blow directly to the human body. Air duct: This tool is used for the connection between air source and pneumatic tool; For the sake of safety and energy conservation, if there is air leakage in the air duct, the air source shall be closed in time and the maintenance personnel shall be invited to repair. Polishing machine: use cloth wheel to polish stainless steel products into shiny surface or welding parts, and then polish them. Before polishing, the surface of the product needs to be sanded without matte feeling. After polishing, the welding surface shall be free of defects such as pores, slag inclusion, crater, crack, arc scratch, ignition and so on. Wire drawing machine: use the wire drawing wheel to wire the surface of stainless steel products or welding parts. After wire drawing, the wire direction of the product surface is the same, and the thickness is the same. There shall be no obvious stratification, blackening and yellowing.

4、 Operating procedures preparation before operation: clean the machine and workplace; According to the production quantity required in the dispatch list, prepare the workpiece to be polished and placed in a position convenient for operation, and prepare the processed products and place the spare bracket; Check whether there are loose screws and electric leakage, and whether the safety device, shutdown button and accident emergency stop device work normally; Check whether the polished workpiece to be processed has been inspected and approved by the quality inspector. Before polishing, ensure that there are no other sundries on the surface of the workpiece. If cracks and defects are found in the plate, repair welding shall be carried out before polishing; Select the appropriate grinding wheel according to the specific requirements of the parts to be processed; Wear masks and goggles and work clothes; Install and fasten the grinding wheel; Commissioning and adjustment. Ensure that the grinding wheel does not shake; Carry out the first article polishing, check whether it meets the polishing requirements, and start the batch polishing operation after it is confirmed by the quality inspection or the supervisor.

Operation specification: before work, check whether the grinding wheel is damaged, whether the protective device is intact and whether the ventilation and dust removal device is effective; When installing the grinding wheel, it must be checked whether the maximum speed allowed by the grinding wheel is consistent with the speed of the main shaft; The products to be polished shall be placed stably, and small parts shall be fixed to avoid processing defects caused by product displacement during grinding; Use the grinding tools correctly, and check and replace the severely worn grinding wheel or polishing plate in time; Hold the grinding tool tightly during grinding, keep the grinding wheel blade at 15-30 ° to the working surface step by step (a → b), and do not use excessive force to cause surface depression; When polishing the door panel surface, the weight of the polishing tool shall be used. The polishing plate shall be smoothly combined with the machined surface, and the mode of translation or circular motion shall be adopted. It is not allowed to apply force halfway and change the angle at will; In case of pores, slag inclusion, cracks and other phenomena on the product surface during grinding, the electric welder shall be notified in time for repair welding; Self inspection shall be carried out after grinding. There shall be no obvious grinding lines and depressions in the grinding area and no welding spatter around. Products shall be stored in categories, stacked neatly and orderly, and protective measures shall be taken.

5、 Grinding and polishing quality

There shall be no unevenness on the surface of components after grinding, and burr, concave hole and trachoma are not allowed; After polishing, the overall surface shall be smooth, and the surface of stainless steel products or welding parts shall be subject to wire drawing treatment. After wire drawing, the wire direction of the product surface shall be the same, and the thickness shall be the same. There shall be no obvious stratification, blackening and yellowing.

6、 Quality inspection after polishing

Whether the overall dimension after polishing meets the product dimension requirements.

After polishing, the surface of the parts shall be smooth without concave convex holes or poor welding; 6.3 there is no obvious uneven grinding and polishing on the surface of parts, and the overall surface is consistent.

7、 Safety technology

Wear protective masks (or face masks) and glasses when working.

Before work, check whether the grinding wheel is damaged, whether the safety protection device is intact and whether the ventilation and dust removal device is effective.

During installation, pay attention to the compression degree of the nut. It is easy to compress the nut until there is no sliding when the grinding wheel moves. When there are multiple compression screws, tighten them gradually and evenly in diagonal order.

After the grinding wheel is installed, the protective cover must be reinstalled before trial run. The straight grinding wheel shall be idled for 5 minutes. No obvious vibration is allowed when the grinding wheel rotates.

When grinding and polishing, start the dust suction device first, hold the workpiece firmly, do not use excessive force, do not push the element with a lever, and do not stand in the front of the grinding wheel to prevent the grinding wheel from breaking and hurting people.

It is forbidden to grind the end face with a grinding wheel, which is not specially used for polishing.

When the hand-held electric grinder is used for grinding and polishing, it must be provided with a solid protective cover and a protective neutral line, or equipped with a leakage protector, and the following safety operation procedures for electric hand grinding wheel must be observed.

When more than two people are grinding and polishing at the same time, it is not allowed to work in the same direction at the same time to prevent accidents.

The concave and convex parts of the workpiece shall be polished gently without excessive force, and the edges and corners of the workpiece shall not be polished, so as to prevent the grinding wheel from breaking and hurting people.

After work, cut off the power supply and confirm that the grinding wheel stops running before leaving the post.

8、 General grinding and polishing method

Grinding before welding

Grinding range: 15-50mm on both sides of all welds.

Operation method: when grinding long and long welds, use angle grinder or straight shank grinder equipped with stainless steel bowl brush to grind along the weld direction; For the weld requiring laser tracking automatic welding, the straight shank grinder can only be used for grinding; When welding accessories on the surface of workpieces larger than the welding accessories, grind the welding surface with a thousand blade or polish the products requiring deburring treatment before welding forming.

Technical requirements: polish the metal luster, ensure that there is no oxide film in the welding area, the grinding grain is parallel and uniform with the weld direction, and the grinding depth shall not exceed 0.2mm.

Grinding of weld reinforcement

Grinding range: 25-50mm on both sides of the weld.

Operation method: when the angle grinder works, it shall be parallel to the polished surface to remove the weld reinforcement; When there is a depression in the weld, it is strictly prohibited to grind the surface with an oblique shovel at the end of the blade according to the standard of not damaging the base metal.

Technical requirements: the polished surface shall be smooth; No damage to the base metal, with the removal amount of the base metal not exceeding 0.2mm as the standard; The surface texture of the polished part shall be consistent. Irregular grinding is strictly prohibited along the weld direction.

Remove surface scratches

Grinding range: take the rectangular frame and cover the scratched area.

Operation method: use the grinding tool to grind in a certain direction, no more than the rectangular frame.

Technical requirements: the polished surface shall be smooth; No damage to the base metal, with the removal amount of the base metal not exceeding 0.2mm as the standard; The surface texture of the polished part shall be consistent, and the transverse drawing direction of large parts and oven body and the drawing direction of small parts shall be consistent; Irregular grinding is strictly prohibited.

Grinding of machining reinforcement

Grinding range: 40-50mm on both sides of machining reinforcement.

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