Deep Groove With Hook Thin Parts Batch Plating Hard Chrome

Deep groove with hook thin parts,usually with fine structure and high performance requirements.The narrow inner wall of the deep groove and the small hook have conflicting requirements for electroplating process parameters,making it a difficult type of workpiece to electroplate.This ar ticle takes high-speed warp knitting machine slot needles as the research object,mainly conducting research on batch electroplating of hard chromium on thin parts with deep slots and hooks.The slot needle of warp knitting machine,as an important loop fo rming component in warp knitting machinery,greatly affects the production efficiency and quality of knitwear.The volume of warp knitting machine slot needles is small,making it difficult to manufacture high-quality slot needles.When used,the warp knitting machine slot needles cooperate with the comb,needle core,and settling plate to complete the knitting process.During the production process,the needle groove continuously experiences friction due to the movement of the needle core,causing the wall of the needle groove to gradually become thinner and the gap between the needle body and the needle core to increase,which affects the knitting process.At the same time,the inner side of the needle hook will also generate high-frequency friction with the yarn during the production process,resulting in increased roughness of the needle hook and easy scratching of the yarn,resulting in yarn fuzzing and a significant decrease in strength,greatly affecting the quality and efficiency of knitwear productio n.Chromium plating is one of the four common coatings,with high hardness and the lowest dry friction coefficient among all metals.To improve the wear resistance and service life of the groove needle,chromium plating is generally applied to the surface of the groove needle.However,the traditional chromium plating process cannot deposit a coating on the inner wall of the slot needle and is prone to burning the needle hook.In addition,the use of traditional hexavalent chromium plating solutions has gra dually been prohibited.The existing chromium plating process for slot needles is difficult to achieve large-scale electroplating of slot needles.How to solve the above problems has become the focus of this research topic.Donghua University has conducted long-term research on the surface treatment process of slot needles,and has achieved certain results in small-scale electroplating slot needle experiments in the laboratory.This project focuses on how to further improve the electroplating quali ty of slot needles,improve electroplating efficiency,and reduce environmental pollution.The specific research content is as follows:Optimize the existing electroplating process for slot needles and design automated equipment for slot needle electroplat ing.The old process has many steps,takes a long time,and is not conducive to mass production.In order to improve the efficiency of slot needle electroplating to adapt to mass production,it is necessary to optimize the existing old process.The old pro cess stipulated a large amount of time for surface polishing of the groove needle,while the new process omitted the polishing step and directly carried out oil and rust removal,chemical plating,and electroplating after installing the groove needle.Afte r small-scale experiments,it has been proven that eliminating the polishing step results in an acceptable difference in electroplating quality for slot needles,while saving approximately 68.8%of the time and greatly improving electroplating production efficiency.The old process also used reverse electrolysis.Although the process was simplified,the reverse electrolysis process would contaminate the anode,and the surface quality of the cell needle was poor.The new process omitted the step of reverse e lectrolysis,which not only simplified the process but also improved the electroplating efficiency and quality of the cell needle.Finally,an automated electroplating equipment suitable for mass production of warp knitting machine slot needles was designe d and developed based on the new process of slot needle electroplatingConfigure a new plating solution and determine the optimal process parameters for the new plating solution.The old plating solution is all hydrochloric acid trivalent chromium plating solution.During the plating process,chloride ions will be oxidized to release chlorine gas,polluting the environment and posing a huge threat to equipment and human health.The new plating solution is a sulfuric acid type trivalent chromium plating solu tion.After experimental verification,the new plating solution will not release chlorine gas,and the electroplating quality has been improved.The optimal process parameters for the new plating solution have been determined,including a current density of 20A/dm~2,a p H value of 3.3-3.6,an electroplating temperature of 20-30℃,and an electroplating time of 3 minutes.After electron microscopy observation of the new electroplating bath needle,it was found that a large number of chromium elemental particles were produced on the outer wall of the bath needle,and there was also a regular chromium plating layer on the inner wall of the needle slot.After hardness testing,the surface chromium plating layer had a high hardness,which met the usage requirements.Use a new DSA electrode as the anode.Traditional chromium electroplating generally uses graphite flakes as the anode,but the graphite anode cathode cannot suppress the production of hexavalent chromium,which is prone to contaminating the plating solution and has low current efficiency.The hydrogen evolution reaction at the cathode is very intense,and the generated hydrogen gas will be mixed in the coating,causing a decrease in the strength of the coating.The experiment was conducted using DSA elect rodes as anodes,and the characterization results showed that the outer wall surface of the groove needle electroplated with a new type of anode formed a coating with the characteristics of a chromium plating layer,and the structure was more complete and uniform.The inner wall surface could form the same coating structure as the outer wall.Hardness testing shows that the new anode can effectively reduce the generation of hydrogen pores and improve the hardness of the coating.The use of DSA anodes can effectively improve the quality of the coating and enhance the uniform and deep plating capabilities of the plating solution.