The modernization of the piercing press at Železiarne Podbrezová has brought significant improvements to the entire production process of seamless steel tubes. The research and technology team focused on increasing the service life and precision of forming tools, optimizing lubrication and cooling, and introducing new material solutions for mandrel bodies and heads. Key innovations have significantly reduced the eccentricity and internal defects of hollows, resulting in higher quality final tubes. The modernization has also improved workplace safety and overall production efficiency. As a result, the service life of the heads increased nearly 2.5-fold, and tube production rose by 80 tons per month.
00:00The production of seamless steel pipes at Zhelesyarne Podbrezova began in 1978 in the newly built pipe rolling mill facility.
00:20The first and at the same time key forming operation in the technology of rolled pipe production is the piercing of steel billets on the piercing press.
00:28Today we can say that the piercing press is the heart of the entire rolling mill and even of the whole steel works.
00:38The input semi-finished product for the production of seamless pipes is a continuously cast steel billet made from steel scrap in our own steel plant.
00:46The heated steel billet is inserted into the piercing press which transforms it into a hollow preform.
00:52The actual piercing is carried out by a piercing mandrel which through the movement of the press's upper cross beam gradually penetrates the material and creates a cavity inside it.
01:00The material prepared in this way in the form of a thick walled preform enters the rolling line where through a sequence of subsequent forming operations it is rolled into its final shape as a seamless rolled tube.
01:14The key requirement in production on the piercing press is adherence to the technological procedure of piercing.
01:20This requirement also includes the proper lubrication of the forming tools of the piercing press with a special graphite compound.
01:26From the start of tube production in the rolling mill until now the application of this compound has been carried out manually.
01:32The main forming tools of the piercing press are the die and the piercing mandrel.
01:40The mandrel itself consists of a head which performs the forming and a body which supports the head and transmits the force from the press cross head to it.
01:47From the very beginning up to the present the heads have been made from tool steel grade 19678 with appropriate heat treatment to achieve a final hardness of 34 Rockwell.
01:57Given that neither the material nor the manufacturing technology of the heads had been innovated for many years the heads in use exhibited a relatively low lifespan with a significant decline in surface quality as the number of extruded pieces increased.
02:11The degraded surface of the head has a crucial impact on the quality of the inner surface and the eccentricity of the extruded pieces and thus also on the final quality of the rolled tubes.
02:20On the other hand the mandrel bodies have so far been made from used mandrel rods that had reached the end of their service life on the extrusion press.
02:39These rods had undergone thousands of thermal extrusion cycles which negatively affected their resulting mechanical properties.
02:45However, the operating principle of the piercing press clearly requires the use of a piercing mandrel with maximum bending stiffness and thus also the maximum mechanical properties of the body used.
02:55Another important quality parameter of the piercing mandrel as a forming tool is the concentricity of the body and the head which until now has not received sufficient attention.
03:05This factor could also have negatively contributed to the resulting eccentricity of the finished tubes.
03:17In March of this year at the initiative of the General Director of Gelesiarne Podbrezova a research and technology team was formed consisting of employees from the production and technical departments, staff from the quality department as well as representatives from the company's own research and development organization.
03:33The task of the team led by the General Director was to resolve all the aforementioned technological issues, especially the lifespan of the heads and the related quality of the finish tubes.
03:45The result of the management team's work was the decision to carry out technological tests of piercing using heads made from the original material 19678 but heat treated to a higher hardness of up to 44 Rockwell.
03:58A new measure not previously implemented to increase the lifespan of the heads was the decision to refurbish worn heads and reuse them in the piercing cycle.
04:07For the next stage of this part of the research material was purchased for the production of heads from grades 19 720 and 19 740 which are expected to further improve durability.
04:17After evaluating the tests of all three types of materials, the head made from the material with the best test results will be introduced into final production.
04:34Another measure that was implemented was the production of bodies from new mandrel rods which ensured significantly higher rigidity of the piercing mandrel during pressing.
04:42In addition, inspection measurements of the body shape and the surface quality of the head of each piercing mandrel were introduced after removal from the press.
04:49Only bodies and heads that meet strict evaluation criteria are put back into production either directly or in the case of heads after renovation.
04:58A new feature compared to the past is also the new technology for mounting the head onto the mandrel body whereby modifying the existing thread manufacturing process the risk of misalignment between the body and the head on the finished mandrel has been significantly reduced.
05:13In addition to addressing the material aspects of the punching technology the project team was assigned two key innovation tasks.
05:23First, the implementation of automatic lubrication of the punch head using the graphite compound currently in use which would eliminate the strenuous and monotonous task for the press operators.
05:33Second, the optimization of the punch head cooling system with regulated coolant water flow.
05:38The automatic graphite lubricant dosing system was developed and tested in two prototypes, each utilizing a different method of applying the lubricant to the surface of the punched block, one mechanical and one pneumatic.
05:50In the first case we successfully used 3D printing of components during the design and testing phase.
06:04The second type proved to be more effective and has now been operating continuously for a month without any malfunction.
06:09In the first stage the dispenser was operated manually.
06:12In the second stage our technicians developed automatic dispensing based on position and pressure data from the punching press.
06:22Subsequently we proceeded to optimize the cooling of the head.
06:26We launched long term temperature measurements of the head after punching each individual stamping using a non-contact thermal imaging system while simultaneously recording the current flow rate of the cooling water.
06:38The aim of the measurements is to find suitable water flow rates to ensure the optimal temperature of the head without overheating while keeping the cooling water flow as low as possible and this for all lengths of the perforated material.
06:51After three months of work by the project team and technological punching tests with all the mentioned modifications and innovations we can state that we have solved all the aforementioned problems and have significantly advanced the technological level of punching in terms of the service life of forming tools, the level of automation, safety and health protection at work, surface quality and eccentricity of the stamped parts and thus also the final quality of the finished tubes.
07:14In numerical terms as a result of reducing unplanned mandrel changes by 16 we achieved a total net working time saving of 166 minutes which led to an increase in monthly production of rolled tubes by 80 tons.
07:32The occurrence of internal defects dropped from 1.8% to 0.9% and eccentricity decreased from 5.2% to 4.7%.
07:47The main goal increasing the lifespan of the heads was achieved with a significant nearly two and a half times increase in lifespan.
07:54nearly two and a half times increase in lifespan.
08:24fortunes are valuable in a difficult shackles, delle caucyente catwalkères, desig аб e verifference, groundworkируfic caWiseeni karsha-a-epi conじm桶es, frappaxi- samples, versia lacpae-b privates ca preserved midfaxi.
08:27A long time O-8% aured locale for 5 is later, when you can also consider bordering for 5 is later but not thestanden length of can.
08:30the reason you can notice that, the중 co-thermaatic line may even differ from movement, which should be in adventurous 편 mej term if you can actually be there already.
08:32And if you give the support of the
08:39this content consuming, as well as the word has been 섞ed for 9.9% to 5.21% of our understanding can be傳got.
08:41this season comes to 20% of itsbreat divor 평nal been somewhere around.
Be the first to comment