Method for hot rolling of magnesium band
FIELD: metallurgy, processes for making hot rolled band of magnesium alloy.
SUBSTANCE: method comprises steps of producing strip blank by continuous casting of melt of magnesium alloy; hot rolling of strip blank directly after casting at several passes for producing hot rolled band with thickness no more than 50 mm. Hot rolling is performed at initial temperature values 250°C - 500°C for providing final thickness of band no more than 4 mm. At first pass of hot rolling reduction degree is equal at least to 15%.
EFFECT: possibility for making magnesium sheets with improved deformation capability at less costs of manufacturing process.
11 cl, 1 dwg, 2 tbl, 1 ex
The invention relates to a method for producing hot-rolled strips of magnesium wrought alloys. Magnesium is the metal with the lowest density, its strength properties similar strength properties of aluminum, and it can replace the latter as material for lightweight constructions. However, a necessary condition for widespread use of magnesium as a material for lightweight constructions is the presence of cheap sheet materials. Currently, magnesium sheets are available on the market only in small quantities and at high prices. This is due to the high costs associated with hot rolling of sheet or strip of wrought magnesium alloys at the modern level of technology. The latter is described in detail in Reference magnesium (Izd-vo "Aluminium-Verlag", , düsseldorf, 2000, 1st edition, str-429). The main difficulty during hot rolling sheets of wrought magnesium alloys is that widely used source material produced by casting in ingots or continuous casting, solidifies with the formation of large grains and pores and contains numerous segregation and large selection. The cast ingots are often subjected to homogenizing annealing subsequent to hot rolling in the temperature range 200-450°C. When such events in most cases is to have to repeatedly heat the rolled material, because otherwise formed marriage due to cracking.
Taken there have been attempts to improve the deformability and properties of hot-rolled magnesium sheet due to the receipt of relevant source materials, and then get to hot rolling tape. This method is known for example from US 5316598. In this known method, conduct rapid solidification of magnesium powder, pressed at a temperature of from 150 to 275°C. By extrusion or forging of such ingot receive the semi-finished product, which is then rolled in a sheet with a thickness of at least 0.5 mm Temperature rolling is thus 200-300°C. thus Obtained hot-rolled magnesium ribbon is characterized by superplastic properties and has at room temperature a high tensile strength and good toughness in the direction of rolling.
However, the disadvantage of this method is that to obtain a semi-finished first prepare magnesium powder, which must be compressed and then cooled quickly. Related costs for personnel and equipment related to the large production costs. In addition, it was found that the deformation of the semifinished product during hot rolling, despite the complexity of its receipt, remains difficult to control.
Along with lists and describes the output of the above prior art of JP 06293944 And a method of obtaining magnesium sheet, which is first made by the casting of the slab from the melt containing 0.5-1.5% of rare-earth metals, of 0.1 to 0.6% zirconium, 2,0-4,0% zinc and the remainder magnesium. Then this slab is subjected to hot rolling in two stages, with the second stage hot rolling temperature rolling is 180-230°C, preferably 180-200°and the total deformation is 40-70%, preferably 40-60%. Received this tape has good deformability. However, hot rolling in two stages makes the rolling process and the necessary temperature time-consuming and hard to control. The closest technical solution, the set of essential characteristics and purpose is a method for hot-rolled magnesium ribbon, known from the publication Altman MB, etc.. Magnesium alloys. Handbook, Vol.2, Moscow, metallurgy, 1978, s-156.
A method of obtaining a hot-rolled magnesium ribbon includes obtaining strip billet continuous casting of molten magnesium alloy hot rolling strip workpiece, which lead directly after casting several passes with getting hot rolled tape. However, this known method has disadvantages of the prior art, since the magnesium refers to metals with a hexagonal crystal lattice, which leads to e is of low plasticity, leading to cracking of the rolled material and, consequently, to marriage. Taking into account the above prior art, the basis of the invention was based on the task of creating a method that allows for a lower cost of production to get magnesium sheets with improved deformability.
This task is solved in that in a method of producing hot-rolled magnesium ribbon, including the production of strip billet continuous casting of molten magnesium alloy hot rolling strip workpiece, which lead directly after casting several passes with obtaining a hot-rolled strip, according to the invention, the receive bandpass billet thickness not exceeding 50 mm, hot rolling is carried out at initial temperatures of at least 250°and not more than 500°to a final thickness not exceeding 4 mm, while on the first pass, during hot rolling, compression is at least 15%.
According to the invention bandpass billet cast thickness up to 50 mm, which is due to its slight thickness cools rapidly and becomes superior, fine-grained and malabarista structure. Micro - and macrolevel summarized in this state to a minimum. Also primary, necessarily present selection have a thin, evenly distributed form that will complement the flax contributes to the formation of a thin katana patterns. Thus obtained is particularly fine-grained structure contributes to the deformability during subsequent hot rolling and facilitates optimal for the subsequent deformation of alloys. In addition, the formation of fine patterns contributes to the compression of at least 15% on the first pass during hot rolling. Thanks already present in the cast condition and improve in the subsequent rolling process structure up magnesium sheet, technological properties which are much better compared to traditionally produced in the leaves.
Another advantage of applied, according to the invention, the continuous strip casting of billets made of magnesium alloy with further carried out after the casting roll is that previously used to obtain magnesium sheets, the share of scrap decreased significantly. In addition, through the application of appropriate smelting and foundry technology provides significant freedom in the use of raw materials. This minimizes the energy consumption when using casting and rolling technology, according to the invention, and provides more flexibility in terms of the range of manufactured products.
A particularly economical use of the method according to the invention, in the case when the strip workpiece p is dvigaetsa hot rolling immediately after casting. Depending on the properties subjected to processing of the alloy and the equipment used may also be appropriate prior to hot rolling to equalize the temperature in strip harvesting to bring to the temperature at the start of hot rolling.
At this temperature equalization is achieved a uniform temperature distribution in the strip harvesting and additional homogenization of the structure.
Oxidation of the surface of the tape and the formation of unwanted oxides inside the structure can be reliably excluded in the casting alloy in an organized accordingly recrystallization in a protective gas atmosphere.
The formation of the structure can be further promote due to the fact that during the first pass, during hot rolling, compression is at least 20%.
In order to ensure deformability of the tape during hot rolling starting temperature rolling should be at least 250°C.
Good deformability is obtained, according to the invention, the passband of the workpiece allows laminating rolled the tape after the first pass continuously in several passes to the final thickness. Heated between passes of rolling is not required due to the heat generated in the deformation process.
In the absence of line DL is finishing hot rolling tape hot rolled magnesium ribbon can be obtained, according to the invention, by reversing hot rolling in several passes.
If hot rolling is required to compensate for the downtime, during which it is impossible to continue the continuous rolling process, it is advisable to wrap the hot rolled strip at least after the first pass, the hot winder and keeping it at the right temperature rolling. Preferably, when reversing hot rolling hot rolled strip after each passage was tied on a hot winder and was maintained at the appropriate temperature rolling. Temperature rolling, in which the hot rolled strip is maintained on the winder, is preferably at least 300°C.
Based on the properties of deformability and thickness of the tape after finishing the total compression during hot rolling must be at least 60%.
The method according to the invention, it is preferable to apply for magnesium wrought alloy containing up to 10% aluminum, up to 10% lithium, up to 2% zinc and 2% manganese. For the formation of small grains in the structure after solidification can be doped zirconium or cerium in an amount up to 1%.
Below the invention is explained in more details with examples of implementation. In the drawing in schematic form showing the setup 1 beskikbaarheid to obtain slabs of thickness less than 25 mm, view from the top.
Installation 1 direct rolling includes sequentially arranged in the direction F of feed of the melting furnace 2, the mold 3, the first specifying device 4 scissors 5, the second setting device 6, the furnace 7 for homogenization, the first winding device 8, and the third specifies the device 9, the reversing rolling mill 10, the fourth setting unit 11, the fourth winding device 12 and the roller 13.
Winding device 12 and the roller 13 mounted on the platform 14, which is located can be moved transversely to the direction F of feed in such a way that in the first working position of the winding device 12 and in the second operating position, the roller 13 is located at the end of the path 15 move the magnesium ribbon obtained in the installation 1 direct rolling. Similarly furnace 7 for homogenization and winding device 8 is located on the platform 16, resulting in one of these devices in the first operating position is located near route 15 move in the second working position in the path of movement of the obtained magnesium ribbon. At the beginning of production of hot-rolled magnesium ribbon furnace 7 for homogenization and winding device 12 in the form of a winder located on the road 15 movement, and the winding device 8 in the form of the reel 8 and the roller 13 is about the way 15 move.<> Winding device 8 and 12 provided with a not shown heater through which the tape is wound on also not shown winder can be placed at the corresponding temperature deformation until the next pass of rolling.
Inside the crucible 3, the melt is continuously poured into the protective gas atmosphere in the absence of oxygen to obtain band-pass of the workpiece. Typical alloys contained in the melt, are presented in the following table 1:
|The chemical composition, mass %|
Particularly effective is the use of high-purity magnesium alloys. In such alloys contain, for example, less than 10 km promilla Ni, less than 40 km promilla Fe and less than 150 promilla C.
Coming out of the mould 3 strip the workpiece is cut by scissors 5 and is sent to the master devices 4 and 6 on the way 15 move into the furnace 7 for homogenization. In the latter happens alignment temperature at which it turns evenly distributed over the cross section of the passband of the initial billet temperature rolling in the range from 250 to 500°C.
Strip the workpiece with a predetermined temperature is supplied then driving device 9 in a reversing rolling mill 10, which is her first pass. When this compression is at least 15%. Emerging from the rolling mill hot-rolled strip is wound on the winding device 12 and maintained at a temperature rolling, best for deforming the next passage.
After the first pass, the platform 16 lead in working position in which the winding device 8 is located on route 15 move. Then rolled the tape rolled in several passes to its final thickness, component Myung is e 4 mm, moreover, it alternately wound on the winding device 8 and 12 and incubated at the appropriate temperature rolling. The latter is more than 250°C.
Before the last pass with the rolling platform 14 is in the operating position in which the roller 13 is located at the end of the path 15 move. Coming out of the reversing rolling mill stand 10 after the last pass, we finally rolled hot rolled magnesium ribbon is fed for further processing by the conveyor 13.
Typical properties of magnesium hot-rolled strips at room temperature, obtained as described in the installation 1 direct from rolling are shown in table 1 alloys are listed in table 2. The thickness of the sheet were respectively 1.2 to 1.5 mm
|Mechanical properties at room temperature|
|*) Was determined in the range of 2% to the percentage of Ag.|
It is seen that obtained according to the invention tapes are characterized by fine-grained structure and, thanks to this excellent deformability. In particular, it was found that the properties obtained according to the invention sheets of at least 20% superior to the same properties obtained in the traditional way of leaves.
The list of items
F feed direction
1 installing direct rolling
2 melting furnace
4 specifies the device
6 specifies the device
7 bake for homogenizing
8 winding device
9 specifies the device
10 reversing rolling mill
12 specifies the device
15 the path of movement
1. A method of obtaining a hot-rolled magnesium ribbon, including the production of strip billet continuous casting is C molten magnesium alloy, hot rolling of strip blanks, which lead directly after casting several passes with getting hot rolled tape, wherein receiving the workpiece thickness not exceeding 50 mm, hot rolling is carried out at initial temperatures of at least 250°and not more than 500°to the final thickness of the tape is not more than 4 mm, while on the first pass, during hot rolling, compression is at least 15%.
2. The method according to claim 1, characterized in that the bandpass receive the workpiece in a protective gas atmosphere.
3. The method according to claim 1 or 2, characterized in that prior to hot rolling to equalize the temperature in strip harvesting bring it up to temperature at the start of hot rolling.
4. The method according to any one of claims 1 to 3, characterized in that the compression on the first pass during hot rolling is at least 20%.
5. The method according to any one of claims 1 to 4, characterized in that after the first pass of hot rolling the resulting tape is rolled in several passes to the final thickness.
6. The method according to any one of claims 1 to 4, characterized in that the hot rolling is conducted reversal in several passes.
7. The method according to claim 5 or 6, characterized in that at least after the first pass of hot rolling the tape is wound on a hot winder and maintained at a temperature rolling.
8. The method according to claim 6 or 7 different is the present, the resulting reversible hot rolling the hot rolled strip is wound after each pass of the hot winder.
9. The method according to claim 7 or 8, characterized in that the holding temperature of hot-rolled tape on the winder is more than 300°C.
10. The method according to any one of claims 1 to 9, characterized in that the total compression during hot rolling is at least 60%.
11. The method according to any one of claims 1 to 10, characterized in that the magnesium alloy used wrought magnesium alloy containing up to 10% aluminum, up to 10% lithium, up to 2% zinc, up to 2% manganese, up to 1% zirconium, and up to 1% of cerium.
FIELD: rolled stock production, namely apparatuses for mounting -dismounting bearing unit of backup roll of rolling stand.
SUBSTANCE: apparatus includes chock in which bearing assembly for roll journal is arranged. Apparatus that may be temporarily joined with bearing unit and may be axially moved in direction of backup roll and from it includes lever type inner and outer cams. Inner cams are introduced to end part of backup roll journal; outer cams are introduced to bearing unit. Inner and outer cams are mounted with possibility of rotation and locking by means of bayonet type lock in end part of journal and in bearing unit. End part of journal and intermediate ring screwed-on to bearing unit at its outer side are in the form of clover leaf having through grooves for inner and outer cams. Said cams after their rotation to clamp position may engage with respective locking protrusions of journal end part and of intermediate ring. In front of outer cams, pressure ring arranged before bearing assembly of journal is mounted.
EFFECT: lowered costs of changing bearing assemblies, increased useful life period and enlarged using range of apparatus.
5 cl, 3 dwg
FIELD: making of embossing on the commercial packing materials.
SUBSTANCE: the offered technology is dealt with making embossment on the flat materials and is used for packing of tobacco products. Rollers of the devices for making embossment, which are used for machining of the flat materials, including the firs driven roller and the conjugate roller are located in parallel to each other in a holder and may be placed so, that to enter into a definite mutual contact. At least one of the rollers for making embossment is located in a replaceable unit. At that the replaceable unit is supplied with retention tools. The holder contains pockets, the form of which is in essence complimentary for the retention tools so, that the replaceable unit may be entered in a predominantly defined position into the holder by insertion of the retention tools into corresponding pockets. The given technology provides more mild replacement of the rollers.
EFFECT: the invention ensures more mild replacement of the rollers.
20 cl, 16 dwg
FIELD: automation of rolled stock production.
SUBSTANCE: at controlling thickness of tube wall in multi-stand continuous stretch-reducing mill, thickness of tube wall is measured behind mill by means of wall thickness measuring devices. Measured values are processed in computing unit. Revolution numbers of drive engines of rolls are controlled by means of units for controlling revolution number. In order to minimize formation of inner multi-arc profile at passing tube, total elongation value is kept constant due to changing revolution number of drive engines of rolls under control of computing unit.
EFFECT: enhanced quality of products.
5 cl, 4 dwg
FIELD: rolling equipment, namely transporting apparatuses, particularly roller table of rolling mill.
SUBSTANCE: roller table includes driven transporting rollers and lifting mechanism; lifting framework jointly mounted on struts and supporting transporting rollers; additional mechanism for lifting framework. Each mechanism for lifting framework is arranged in strut and it is in the form of sleeve, nut mounted inside said sleeve with possibility of motion and jointly connected through lug with framework; worm reduction gear joined with sleeve. In reduction gear and in sleeve there is opening in which screw is arranged. Said screw has cut splines in one end and in other end it has thread engaged with nut of sleeve. At least in one strut rotary crosspiece is jointly mounted. Lifting mechanism is mounted on said crosspiece.
EFFECT: enhanced operational efficiency of mill due to elimination of jamming movable links.
FIELD: continuous rolling of strip, namely rolling strip having different thickness portions joined through transition wedge-shaped portion.
SUBSTANCE: method is used for rolling metallic strip 1 in rolling mill having at least two rolling stands. Metallic strip 1 has at least two zones 3,4 of different thickness mutually joined through wedge-shaped or approximately wedge-shaped transition portion 2. Rolling rate in rolling stand at rolling wedge-shaped portion 2 is tuned depending upon forward slip of rolling stand and also depending upon temperature of metallic strip 1. Apparatus for rolling includes rolling mill having at least two rolling stands providing tuning of rolling rate at rolling wedge -like or approximately wedge-like transition portion 2 of strip depending upon forward slip of rolling stand and upon temperature of metallic strip 1.
EFFECT: enhanced quality of rolled products.
2 cl, 5 dwg
FIELD: automation of rolling processes.
SUBSTANCE: method comprises steps of measuring disturbance-stimulated strip thickness in front of rolling stand; controlling measurement result until inlet of stand; compensating it in stand by moving screws of screw-down mechanism at predetermined rate for preset time interval; measuring fluctuation of strip thickness relative to predetermined value when strip leaves stand; acting upon movement rate of screws according to disturbance and to fluctuation of strip thickness after multiplying said values and differentiating received product.
EFFECT: enhanced accuracy and reliability of controlling strip thickness.
FIELD: rolled stock production, namely equipment of shape bending mills, mainly for making tinned corrugated sheets.
SUBSTANCE: drive unit of shape bending mill with first guiding stand and pulling roller devices includes motor, reduction gear, sprockets, forcing and tensioning gear wheels, roller chain embracing sprockets along S-shaped curve and sine curve. Torque of motor is transmitted only to lower shaping rolls of even stands and of last stand of mill and also to both rolls of guiding stand and to horizontal rollers of pulling devices through sprockets mounted on their axles. Chain embraces sprockets of rolls of guiding stand and of rollers of pulling devices along S-shaped curve and it embraces sprockets of drive rolls and sprockets that are not joined with shaping rolls along sine curve. Axles of sprockets that are not joined with shaping rolls may be arranged higher than axles of lower drive rolls by value determined according to relation given in claims of invention.
EFFECT: lowered cost of shape bending mill, reduced power consumption for profiling, enhanced quality of ready shapes.
2 cl, 1 dwg, 1 ex
FIELD: rolling equipment, namely apparatuses for mounting rolls of working stands of rolling mills.
SUBSTANCE: apparatus includes screw-down cylinders connected with chocks of roll; liquid distributor communicated with pressure source and with screw-down cylinders; leverage mechanism joined with chocks of roll and with movable member of liquid distributor. The last is throttling one. Leverage mechanism includes rigid link, lever and doubled slide. First slide is mounted with possibility of horizontal motion relative to foundation of rolling mill; second slide is mounted with possibility of vertical motion relative to first slide. Rigid link is joined with chocks of roll and with second slide through articulation joint. First slide through lever is kinematically joined with movable member of liquid distributor. Rigid link is in the form of triangle. Leverage mechanism and screw-down cylinders are connected with chocks of upper or lower roll. First slide includes in addition controlled check valves of screw-down cylinders and system for controlling them. Invention provides possibility for redistributing pressure between screw-down cylinders in proportion to shift of leverage mechanism that is to automatically prevent skewing of roll.
EFFECT: automatic prevention of roll skewing, enhanced quality of rolled products, improved operational properties of roll.
6 cl, 2 dwg
FIELD: plastic working of metals, possibly manufacture of thin high-strength foil of titanium.
SUBSTANCE: method comprises steps of multi-pass reversing cold rolling and vacuum annealing; repeating cycle; using as initial blank titanium blank with ultra-fine grain structure provided due to intensified plastic deformation by equal-duct angular pressing process; rolling at pitch 15 - 8% for achieving total deformation 70 - 86 % per one cycle; setting number N of cycles necessary for making foil with thickness h according to mathematical expression; realizing vacuum annealing, preferably at temperature 350 -360 C for 0.5 - 1 h. Invention provides possibilities for making titanium foil with thickness up to 10 micrometers.
EFFECT: enhanced strength characteristics of titanium foil of lowered thickness with the same technological platicity7777.
2 cl, 2 tbl
FIELD: rolled stock production, possibly rolling merchant bars and rods of continuously cast carbon (standard and high-quality) steel, low alloy, alloy, roll-bearing and spring steels.
SUBSTANCE: method comprises steps of heating steel continuously cast billet until austenite temperature; further multi-pass hot rolling while providing normalized temperature of rolling termination period; performing multi-pass rolling at temperature 860-1000 C of rolling termination period and at total elongation value γ selected according to kinds of steel. Invention provides complete treatment of axial zone of billet, lowered liquation of chemical elements along cross section and length of bar, regular contour of bar cross section.
EFFECT: enhanced quality, less loss of yield.
4 ex, 1 tbl