UA105644U - METHOD for uniform heating conical unevenness metal mold with currents of industrial frequency - Google Patents

Abstract

The method of heating a conical multi-thickness along the length of the metal form (casting) for casting products is that programmed cyclic heating with industrial frequency currents is used to reduce energy costs and ensure uniform heating of the metal form.

Description

The useful model belongs to the field of mechanical engineering, in particular to the foundry production of products (cylinder sleeves, bushings, bandages, etc.) that are cast in metal molds of various thicknesses and lengths, which are used in centrifugal casting machines.

A widely used method of preparing metal molds for casting various products is known. Taking into account the difference in the shape of cast products, as well as their mass (weight), material (steel, cast iron, alloys), the level of properties that can be achieved, the metal mold for centrifugal casting is heated (to adjust the crystallization conditions) before pouring the metal to different temperatures in special gas furnaces |1). In some cases, during heating, a uniform temperature is not reached along the length of the metal forms when they are removed from the furnace, which is related to their location on the bottom of the furnace, the number of heated equipment, and the location of the gas burners. In addition, the method is not effective due to the large consumption of gas and heat required to heat the entire volume of the furnace. This method of equipment preparation does not allow to provide heating to different temperatures of individual zones of different thicknesses of products to minimize their stress state during installation in a centrifugal casting machine, as well as uniform crystallization conditions to ensure the necessary structure and properties of castings.

There are well-known methods of heating with industrial and high-frequency currents, which are widely used in the heat treatment of products (2-44. They are aimed at surface hardening of products from various materials. At the same time, heating with various types of inductors is used to ensure the saving of energy resources with the formation of the necessary structure of the strengthened layer and level properties of products with the same thickness in height and section.

The closest to the stated one is the well-known method of induction heating of the part for hardening with a curvilinear contour of the working surfaces, which is aimed at increasing the productivity of the process by reducing the heating time of areas that do not perceive the main loads during operation.

To implement this technology, a special device is used, which programs the minimization of the degree of heating of areas of the product that practically do not perceive the load during operation.

This method does not provide for the uniform achievement of temperatures on the treated surface, is difficult to manage and creates increased voltages not only in the metal form, reducing it

From operational stability, but also in the cast product during its crystallization.

The useful model is based on the task of ensuring uniform heating of metal forms of different thicknesses in height for a uniform structure and stress minimization during crystallization of castings, as well as saving energy costs.

To solve the problem, it is recommended to use the induction method of heating metal forms of different thicknesses and heights with currents of industrial frequency before pouring metal into them.

As an example, an evaluation of the method of heating a metal mold of different thicknesses and heights (200-365 mm) for casting a bandage was performed. Along its length, the surface of the inner part of the wall of the metal mold is flat, while the outer surface varies, as a result of which the total thickness of the mold is characterized by different thicknesses. This facilitates its removal together with the casting from the centrifugal machine after the product has crystallized.

An induction heater consisting of an inductor and magnetic wires is proposed as a source. By concentrating and creating a magnetic flux, it is possible to uniformly heat the mold. At the same time, the areas of the product to be treated are determined depending on the purpose of heating. By choosing the shape and dimensions of the inductor and magnetic wires, it is possible to ensure the necessary temperature field in the product in all directions: radial (along the thickness of the mold wall), axial (along the length of the mold).

Since castings for centrifugal casting of tires, cylinder liners are asymmetric products in height, therefore their heating in the circumferential direction must be the same, which can be provided by a round inductor.

On the other hand, in the case when the castings have variable wall thickness along the axis, the heating intensity of individual areas must be different. Therefore, inductors should be made with an uneven arrangement of turns along the length of the metal form.

The area that is located along the walls of increased thickness should also have a greater number of turns than those located in the area with thin walls. This requires heating the metal mold at different intensities along the axis to ensure the same temperature in it. The uniformity of heating of metal forms of different thicknesses in the radial direction of each of the zones is achieved by optimal selection of the power of the induction heater and its duration.

The magnetoconductive system covers the coil and the casting, accelerating the heating of the latter. Such a heating scheme makes it possible to obtain a temperature field of the mold almost uniformly in all directions.

The amount of heat C) needed to heat the mold is estimated as:

O-Set»e(р-Н), (1) where С-0.122 is the specific heat capacity in the temperature range of 0-300 "C for St. 20, kcal/(kge"C); t-940 - the mass of the mold, kg; 12-300 - temperature of heating the mold when pouring cast iron, "C; 11-20 - ambient temperature, "C; 0-0.122:940-(300-20)-32110.4 kcal. (2)

The total amount of heat Osum, taking into account losses ("15 90) for dissipation into the environment will be:

Eight-O21,15-36927 kcal. (3)

The power P required for heating the mold must be at least:

ROsum/0.24t, (4) where 0.24 is the conversion factor, 1 kW is 0.24 kcal/s; t - duration of heating.

Since the uniformity of the heating of the mold in the radial direction (along the wall thickness) largely depends on the duration of heating, taking into account the heating rate and thermal conductivity of the material, t-20 min.-1200 s were taken;

RA36927X0.24:1200)-128.222129 kW. (5)

Thus, by changing the heating time, you can control the power, or vice versa, by changing the power, you can control the heating time.

To ensure a uniform temperature in a mold of various thicknesses, it was used

From the scheme of cyclic switching on and off of the indicator. At the same time, the maximum power of the source was used at the level of 80,000 W.

The following parameters were used in the calculations: time step - 0.4 hours; step in the height and thickness of the mold - 20 mm; heating temperature - 400 "C (taking into account that when pouring on the inner part, 1-300 "C will be reached; heating and cooling step during cyclic processing - every 1.2 hours.

The temperature-voltage-time dependence of the source was obtained (Fig. 1).

The temperature is represented by two shades of red: the darker one corresponds to the inner layer; light - external.

The inner layer corresponds to the voltages marked in dark green, the outer one is light green, and the middle section of the metal shape is yellow.

The blue color shows the change in the relative thickness of the source over time (the ratio of the power at the current moment of time to the maximum values).

Comparative studies of the influence of the thickness of the wall of the metal mold on the level of emerging stresses have been carried out. With the wall thickness reduced from 365 mm to 200 mm, the cyclic heating is more stable in terms of the temperature variations achieved and the stress level.

To stabilize the temperature at the same time in different zones along the thickness of the mold, the following parameters are recommended (to and De): to-20000; de-15000 - for a thick zone; up to 15,000; de-15000 - for a thin zone.

In this case, heat flows are almost proportional to the thickness of the metal form.

In the calculations, a special case of the exponential law should be used with the calculation of the parameters at which the given total power is preserved. In this version of the calculation of the heating of the metal form, the stresses in the zones that differ in thickness are minimized and can be ignored (see Fig. 1). At the same time, regardless of the thickness of the mold wall, the temperature and its distribution are stable.

It can be seen from the graphic dependences that there are areas of temperature exposure (close to an exposure of 0.4 hours). For the outer layer of the thick part, it is 500-520 "С, and for the inner layer 330-345 "С. For the thin part of the outer layer, 480-490 "С, and the inner - 390-415 760.

Stabilization of temperatures obeys the law:

O(O--aieg5ip(4gi-a) - for the case when 5ip is not negative; and 0 - if it is negative (corresponds to the shutdown period).

At the same time, the nature of the temperature distribution, the voltage is stabilized for the thin part of the metal form from the second cycle, and the thickened part - from the third.

When adjusting only the power of the source, it is not possible to stabilize the temperature on the surface of the metal form (Fig. 2).

Based on the analysis of the known approaches to assessing the influence of the heating parameters of a metal mold with different cross-sections of its wall in height for casting hollow products with the minimization of the stress level, it was established that this can be most effectively provided by the TPC processing during cyclic heating and disconnection of the inductor. At the same time, the heating and shutdown time step corresponds to 1.2 hours and the number of cycles should be at least three.

Cyclic switching off of the inductors also saves electricity.

Sources of information: 1. Production and application of rolling rolls: Reference book. / T.S. Skoblo, A.I.

Sydashenko, V.M. Vlasovets, O.Yu. Klochko et al. Ed. Prof. T.S. Scrape - Kh.: CD Mo 1, 2013. - 5726. 2. Patent of Ukraine Mo 9578, IPC C2101/10. Method of heat treatment of internal surfaces of cylindrical products / L.A. Zhuchynskyi, M.V. Svysiunov, M.M. Ivakhnenko, S.L. Stoyan. - Application y20041210812; statement 27.12.2004, publ. 15.10.2005

Z. Patent of the Russian Federation Mo 2181649, IPC" C210 11/78, 09/06. Method of restoring hardened cylinder liners / V.N. Khromov, V.P. Lyalyakin, A.A. Shiryaev,

Kostyukov A.Yu. application C22000103148/02; statement 08.02.2000, publ. 04/27/2002 4. Author's certificate of the USSR Mo 1652359 C2101/10. The method of quenching with TVF heating.

Claims (1)

USEFUL MODEL FORMULA Co.) 1. The method of heating a conical metal mold of varying thickness along the length (casting mold) for casting products, which is distinguished by the fact that in order to reduce the consumption of energy carriers and ensure uniform heating of the metal mold, programmable cyclic heating with currents of industrial frequency is used. 2. The method according to claim 1, which is characterized by the fact that uniform heating and minimization of stresses in a conical metal form of different thicknesses along the length is achieved by periodically turning off the inductor and uniform cyclic heating with a time step corresponding to 1.2 hours. C. The method according to claim 1, which differs in that to stabilize the temperature on the inner surface of the mold, the number of heating-cooling cycles must be at least three. in LIEKENIIY I PO zho s Zo s PESHZHKEINKE OM KK KU OKOM ВХ ho shk Эх s B, MPa и Y ЦО s s s s e o s s COM M COM M E MN s 4. IN KO I -o NAME M M M M I s V I PEYEINNNNY KK OM KO V s is PO OO I s DYNKOKOKNKN nny OM E KK is is o -oSs o PIT KK VH KK Kaya s ss o KE OO V OO M PO I 6 uanyninunnnnsssi VO SO OO s CERTAIN I, mm m zh mch chom I berega tsparekuh m Thick part vo; pk VV VV VEN INN M. and. lk LYNE PO YA E B s LE OK KO OM M YA Ka a KH O.I, 5.5 g Tanya ss 5, Ou B o v 5 SSS: SS: a i B I MOM OK M s s OO M OK M M M M M KK M KINE PENINKINK KK KK, ss u De KK M s ECO Beh -sh u s B 5 o KEN OO I DEC NK MOM M ZO i Bo o OO i PEKY OO KK KOKO KO MOM HO s MKK ZY KOKO PKKNNNKNK KK PI OM OO I OO OO OO OO I s B I SUB B I I 55555 MO po OO I g ok B OO U s is s HYPETSM ENN OO i ss 0: ss s B OO M KN PENNKNNN KY jan. PEK UK UK U OK KK I and" and chu od Hoch ku usu. Which EK Z h uk V h zanki part Fig. 1 с с МНН хошоких TE, ве В я - З з: и В я Ж; ALREADY OO Y ROL M M M M V V Y Y OM I M MO M M M M nya v s M M M U M IOOMMOMO Y OO A M A NM a a a E SchHdnoBOOVEOOOVOOVOOOVOMMOMIOOIOIO OO VV I B I V V o KO KK KK KK nya a M i t M i JAK MK KM M i i I KK KK i M 55555555, 555 MM OV v M V i M A I OO M M M I V I M A V V KV I M M V KK KK KK M A V Y I A MOM M Y M A Y OO OO M OO I o Kn o V V V OK On Y OK Y M PP PTLTY A PP ShM KO KO KK KK KK Konya KO o nya M V V Ya Aa M A NNMI M OO I M I PO M M M M i i i KK I Ia i M I o M M M MO V M V ; g ze ZdeE ha already TEKY du KI me KK Bovstv part M В вх NE o Ee S, IM TITOV - la MOM tA same Ж Ж l Tl, lm t t VVE Vshch MM ! M M M M M M M M M M M a I A M M i nia POV OO OO OO OO OO A A A a a a m OO Or M m I PENYMNNNYMYV NK KK o U 5. IN M o U PEN NN V V M M i I OM M I M YA KK nn BO KE OO Y Vo M OO MM IRO OO M V M M M M M M M V V NO M I ZEKKKKE M M M KO i POM OO I OM A II I C I OIEOMIIIIIIIIIM OO OO OO OO OO II IA OA OA LA I I I I I M MOM M M M M i o o o KK o nn Ya r M m M i KK KK i OO V I M m mm M M Ж PP M Ya o i PEKKIKIKE NIK KK KK KK KK NO, I TT t POVVMMMOVZHVIVMIYOUOOOOVOVOIOOOOOOOOOIVLVOTOYUMVVIOIOOOOVVVOVV OVO I III TT TL PP I M KN M M M V IM MT PP M M I I M I p v i r a M M M M M M V M M V Y A U ozu kv zu yu ka UK, EC, Thin part I Fig. -3Н6НИНИНИНИНИНИНАНЦСШШНУЙНННН 26 т ИВСШЗРфЯ :;ИД:Й: )F ).).).)8((8іЖЯ : (З3.-(-(-Ш2.2Й2 2-2 И3Ш( БЖ ШЩЩТЩКыШЙ) (288: 2 БК.фжЖЖЖЖЖЖЖЖЖЖЖ4и) ---